Dimension Stone

Design Manual
2022

Produced and Published by the

Natural Stone Institute
www.naturalstoneinstitute.org
Disclaimer: This manual contains general guidelines. The Natural Stone Institute and its Member
companies are not responsible for any use or misuse that causes damage of any kind, including loss of
rights, material, and personal injury alleged to be caused directly or indirectly by the information contained
in this manual.

© 2022 Natural Stone Institute

© 2016 Marble Institute of America (Chapter 21, 22, Glossary, Appendix and Index)
© 2011 Marble Institute of America (Chapter 17, Glossary and Index)
© 2010 Marble Institute of America (Chapters 13, 14, 15, and Index)
© 2007 Marble Institute of America (All other Chapters)

All rights reserved. No part of this document may be reproduced or transmitted in any form or by means electronic
or mechanical, including photocopy, recording, or by an information storage and retrieval system, without written
permission from the Natural Stone Institute.
For an online version of the Dimension Stone Design Manual 2022,
please go to www.naturalstoneinstitute.org
and select Resource Library under the Resources tab
Table of Contents

Introduction
Foreword................................................................................ i
Acknowledgements ................................................................... ii
Limitations on Use and Disclaimer ................................................. iii
Organization Web Site ............................................................... iv
Green Building Movement ........................................................... v
Suggested Warranty Provision/Disclaimer ....................................... xii
Suggested Residential Contract ..................................................... xiii
NSI Code of Ethics .................................................................... xiv
NSI Membership ....................................................................... xv
Sample Specification Language ...................................................... xvii

CHAPTER 1 The Geology of Stone .................................................................... 1-1

CHAPTER 2 Standards and Specifications for Stone Products ......................... 2-1

CHAPTER 3 Dimension Stone Selection ........................................................... 3-1

CHAPTER 4 Stone Testing ................................................................................. 4-1

CHAPTER 5 Granite .......................................................................................... 5-1

CHAPTER 6 Limestone ...................................................................................... 6-1

CHAPTER 7 Marble and Onyx .......................................................................... 7-1

CHAPTER 8 Quartz-Based Stone ...................................................................... 8-1

CHAPTER 9 Serpentine ..................................................................................... 9-1

CHAPTER 10 Slate ............................................................................................... 10-1

CHAPTER 11 Soapstone ...................................................................................... 11-1

CHAPTER 12 Travertine...................................................................................... 12-1

CHAPTER 13 Horizontal Surfaces ...................................................................... 13-1

Design Criteria 13-1
Related Materials 13-7
Exterior Installation Methods 13-12
Interior Installation Methods 13-15
Troubleshooting and Cautions 13-17

© 2022 Natural Stone Institute Table of Contents • Page 1

Table of Contents, continued

CHAPTER 14 Vertical Surfaces............................................................................ 14-1

Design Criteria 14-1
Exterior Installation Systems 14-11
Interior Installation Systems 14-14
Troubleshooting and Cautions 14-16

CHAPTER 15 held for future use

CHAPTER 16 Wet Areas ...................................................................................... 16-1

Installation Notes 16-1
Stone Toilet Partitions 16-3
Stone Urinal Partitions 16-4
Stone Slab Shower Partitions 16-5
Stone Slab Residential Showers, Steam
Rooms & Steam Showers 16-7
Stone Tile Residential Showers, Steam
Rooms & Steam Showers 16-10
Accessories and Stone Penetrations 16-12

CHAPTER 17 Counter and Lavatory Tops .......................................................... 17-1

CHAPTER 18 Coping and Stools ......................................................................... 18-1

Exterior Cubic Stone Coping and Walls 18-1
Thin Stone Stools and Cubic Sills 18-3

CHAPTER 19 Stone Furniture ............................................................................. 19-1

CHAPTER 20 Stone-Faced Veneer Precast Concrete .......................................... 20-1

CHAPTER 21 Restoration and Maintenance ...................................................... 21-1

Stone Geology 21-1
Stone Identification 21-5
Stone Behavioral Groups 21-11
Diagnostics 21-17
Equipment 21-27
Repairs 21-39
Repairs Adhesives Chart 21-50
Restorative Processes 21-51
Sealers 21-67
Maintenance 21-75
Commercial/Historic 21-85
Troubleshooting 21-89
Additional Learning Resources 21-121

Page 2 • Table of Contents © 2022 Natural Stone Institute

Table of Contents, continued

CHAPTER 22 Tolerances in the Dimension Stone Industry ............................... 22-1

Chart of Tolerances 22-5
Graphic Interpretation of Tolerances 22-9

CHAPTER 23 Glossary of Common Stone Terms ................................................ 23-1

Appendix ............................................................................................................. 24-1

English - Metric Conversion Tables 24-1
Slab Production Table 24-2
Mohs Scale 24-2
Additional NSI Resources 24-3
ASTM Classification Index 24-4

Index .................................................................................................................... 25-1

© 2022 Natural Stone Institute Table of Contents • Page 3

Directory of Detail Drawings

CHAPTER 7 Marble and Onyx

Veneer Cutting and Patterns ........................................ 7-D-1,-2,-3

CHAPTER 13 Horizontal Surfaces

Exterior Stone Paving................................................. 13-D-1,-2
Interior Stone Flooring ............................................... 13-D-3
Radiant Heat Details .................................................. 13-D-4
Stone Thresholds ...................................................... 13-D-5
Stone Stair Details ..................................................... 13-D-6,-7, -8

CHAPTER 14 Vertical Surfaces

Exterior Stone Veneer
Attachment Details .................................................... 14-D-1,-2,-3,
.................................................................... 14-D-4,-5
Relief Details with Rebated Bearings .............................. 14-D-6
Restraint Anchorage Details ......................................... 14-D-7, -08
Typical Corners, Expansion Joints, Reglets ...................... 14-D-9
Interior Stone Wall Veneer
Wall Facing Details.................................................... 14-D-10, -11
Stone Column Cladding Details .................................... 14-D-12,-13,-14
Crypt with Bracket and Rosette Detail ............................ 14-D-15
Corner Details ......................................................... 14-D-16
Interior Stone Base
Typical Details ......................................................... 14-D-17
Stone Soffits
Exterior Soffit Details ................................................ 14-D-18
Stone Fireplace Facings
Typical Details ......................................................... 14-D-19,-20
Split Face Ashlar and Thin Stone Veneer Attachment Details ....... 14-D-21
Dry-Stack Veneer Attachment Details ................................... 14-D-22
Common Anchors and Accessories ....................................... 14-D-23,-24,-25
CHAPTER 16 Wet Areas
Stone Toilet Partitions
Floor-Supported Partition Details .................................. 16-D-1
Ceiling-Mounted Partition Details ................................. 16-D-2
Floor-Supported Partition Details .................................. 16-D-3
Ceiling-Mounting Details ............................................ 16-D-4
Dowel-Mounted Partition Details .................................. 16-D-5

Page 4 • Table of Contents © 2022 Natural Stone Institute

Directory of Detail Drawings, continued

CHAPTER 16 Wet Areas (continued)

Stone Urinal Partitions
Floor-Supported Partition Details .................................. 16-D-6
Wall Mounted Details ................................................ 16-D-7
Stone Shower Partitions
Typical Plans ........................................................... 16-D-8
Typical Elevations ..................................................... 16-D-9
Typical Details ......................................................... 16-D-10
Typical Details ......................................................... 16-D-11
Typical Details ......................................................... 16-D-12
Typical Details ......................................................... 16-D-13
Typical Details ......................................................... 16-D-14
Stone Shower Ceilings
Typical Details ......................................................... 16-D-15
Stone Shower Accessory Niche
Typical Details ......................................................... 16-D-16
Stone Shower Partitions
Typical Floor Details .................................................. 16-D-17
Typical Door Jambs ................................................... 16-D-18
Typical Wall Penetrations ........................................... 16-D-19
CHAPTER 17 Counter and Lavatory Tops
Typical Kitchen Layout, Joints at Sink ............................. 17-D-1
Typical Kitchen Layout, Joints at Corners in Lieu of Sink ..... 17-D-2
Corner Joinery Examples ............................................ 17-D-3
Typical Joinery at Kitchen Sink ..................................... 17-D-4
Rodding Reinforcement .............................................. 17-D-5
Typical Countertop Support......................................... 17-D-6
Recommended Countertop Overhang ............................ 17-D-7
Undermount Sink Support ........................................... 17-D-8
Support Details for Heavy (Enameled Cast-Iron) Sinks ........ 17-D-9
Support Details for Rimmed or “Drop-in” Sink Types.......... 17-D-10
Vanity Top Details .................................................... 17-D-11
Backsplash Details ..................................................... 17-D-12
Options at Sidesplash ................................................. 17-D-13
Stone Shelf Details..................................................... 17-D-14
Countertop Overhang Details ....................................... 17-D-15
Edge Profile Nomenclature .......................................... 17-D-16
Example Shop Drawing .............................................. 17-D-17
CHAPTER 18 Coping and Stools
Exterior Cubic Stone Coping and Walls
Flashing and Coping Details ......................................... 18-D-1
Thin Stone Stools and Cubic Sills
Window Stool Details ................................................ 18-D-2

© 2022 Natural Stone Institute Table of Contents • Page 5

Directory of Detail Drawings, continued

CHAPTER 19 Stone Furniture

Conference Table Top Details ...................................... 19-D-1,-2
Edge Profile Nomenclature .......................................... 19-D-3
CHAPTER 20 Stone-Faced Veneer Precast Concrete Panels
Typical Detail .......................................................... 20-D-1,-2
CHAPTER 22 Tolerances in the Dimension Stone Industry
Graphic Interpretation of Tolerances .............................. 22-D-1

Page 6 • Table of Contents © 2022 Natural Stone Institute

FOREWORD
How did man discover the beauty hidden in
stone? The curiosity of an unknown genius may
have been sparked by markings on exposed
ledges. Smoothing the surface and cleaning the
stone to get a closer look may have revealed
color, veins, and graining. Rubbing the stone About Natural
with sand may have polished it. To work with
stone is to work with the basic rhythms of the Stone Institute
Earth.
The Natural Stone Institute is a trade association
By the time the pyramids were built, man had representing every aspect of the natural stone
become highly skilled in the use of stone to shape industry. The current membership exceeds
and place it according to his needs. Many of the 2,000 members in over 50 countries. The
stone works of ancient man have survived with association offers a wide array of technical and
little visible sign of change, except for training resources, professional development
earthquakes, wars, natural disasters, and more opportunities, regulatory advocacy, and
recently, the pollution of civilization. networking events. Two prominent
The need for building materials in which beauty publications—the Dimension Stone Design Manual
and permanence are prerequisites is greater and Building Stone Magazine—raise awareness
today than ever before. To meet this increasing within the natural stone industry and in the
need, the dimension stone industry, through its design community for best practices and uses of
international trade association, the Natural Stone natural stone.
Institute, provides products that satisfy
contemporary design concepts while retaining The association serves as the authoritative source
all the outstanding qualities for which the for safety and technical standards and
industry has always been respected. information regarding the use of natural stone. It
operates an industry accreditation program and
two prestigious awards programs, as well as a
Dimension Stone Design Manual continuing education program for architects and
Copyright © 2022, Natural Stone Institute, Inc. designers.
Copyright © 2016, 2011, 2007, 2003, 1999,
1991, 1985, 1983, 1976 (revised), 1971 by the The Natural Stone Institute was formed in 2018
Marble Institute of America, Inc. as a merger of the Marble Institute of America
and the Building Stone Institute. The Building
All rights reserved.
Stone Institute was formed in 1894 as the
International Cut Stone Contractors and
Printed in the United States of America. Quarrymen’s Association; the name was
changed to the Building Stone Institute in 1955.
Established in 1903 as the National Association
Natural Stone Institute, Inc. of Marble Dealers, the Marble Institute of
380 East Lorain Street America officially formed in 1944, when the
Oberlin, Ohio 44074 U.S.A. association merged with the National Association
www.naturalstoneinstitute.org of Marble Producers. In 1962, the National
Email: info@naturalstoneinstitute.org Association of Marble Builders merged with
PH: 440.250.9222; fax 440.774.9222 MIA.

© 2022 Natural Stone Institute i

DIMENSION STONE
DESIGN MANUAL
The purpose of the Dimension Stone Design Manual
is to present reliable performance data and
design information in one volume to facilitate
use of dimension stone in architectural designs.
The dimension stone industry provides quality
products that meet the design and construction
requirements of the buildings of today, as well as
tomorrow.
The Dimension Stone Design Manual presents
current practice in the industry. The information
also represents industry recommendations and
experience published in previous forms as the
former American Standard Specifications for Interior
and Exterior Marble, the Marble Engineering
Handbook, and Dimension Stone Design Manual I, I-
R, II, III, IV, V, VI, VII (these publications are out
of print). Some detail plates from older MIA
publications are reproduced because they still
illustrate current practice.

ACKNOWLEDGEMENTS
The Natural Stone Institute was able to compile
the information in this edition only with the
willing cooperation and assistance of many
Members, Committees of Members, editors,
other individuals and organizations, and NSI
staff. We are grateful for their combined
commitment to NSI and the dimension stone
industry.

ii © 2022 Natural Stone Institute

LIMITATIONS ON USE completed by a competent industry professional
prior to construction. The methods prescribed
AND DISCLAIMER herein do not supersede those in applicable
construction specifications and building codes.
As with any building material and technique: No warranty or guarantee is made by NSI.
1. Many variations, including but not limited
to design, climate, topography, building and
zoning codes, materials, labor cost, and quality,
markedly affect the safety, cost, utility, and
appearance of the applications shown in this
Manual. Accordingly, the variations contained in
the Manual are not being recommended or
endorsed by NSI.
2. Nothing in this Manual should be used
without independent approval by a qualified
architect, professional engineer, contractor, or
other technically qualified person who should
also specify dimension stone and installation
methods and systems, with specific location of
expansion and control joints on drawings, and
use of standards, such as those of the American
National Standards Institute (ANSI) and ASTM
International, to develop specifications.
3. ACCORDINGLY, NATURAL STONE
INSTITUTE DISCLAIMS ANY GUARANTEE
OR WARRANTY, WHETHER EXPRESS OR
IMPLIED, FOR MERCHANT-ABILITY,
FITNESS FOR A PARTICULAR PURPOSE,
OR ANY OTHER PURPOSE, OR FOR
SAFETY FOR ANYTHING DESCRIBED OR
ILLUSTRATED HEREIN, AND ASSUMES NO
RESPONSIBILITY FOR ERRORS AND
OMISSIONS.
4. References to ANSI or ASTM standards are
merely suggested and are not mandatory and are
NOT an NSI express or implied endorsement or
warranty of the adequacy or completeness of
those standards for safety or any other purpose.
This manual represents general practices found
to be successful in natural stone applications.
Regional practices may vary from those
described in this manual. Given the variable
involved in working with natural stone products,
deviation from these practices does not
necessarily result in failure, nor does adherence
to these practices necessarily result in success.
Thorough review of project details should be

© 2022 Natural Stone Institute iii

ORGANIZATION International Masonry Institute (IMI)
www.imiweb.org
WEBSITES
Masonry Institute of America (MIA)
American Concrete Institute (ACI) www.masonryinstitute.org
www.concrete.org
National Association of Architectural
American Geosciences Institute (AGI) Metal Manufacturers (NAAMM)
www.agi-usa.org www.naamm.org

American Institute of Architects (AIA) National Building Granite Quarries

www.aia.org Association, Inc. (NBGQA)
www.nbgqa.com
American National Standards Institute
(ANSI) National Tile Contractors Association
www.ansi.org (NTCA)
www.tile-assn.com
American Society of Civil Engineers
(ASCE) Natural Stone Council
www.asce.org www.genuinestone.com

American Institute of Steel Construction Natural Stone Institute

(AISC) www.naturalstoneinstitute.org
www.aisc.org
NSF International
American Iron and Steel Institute (AISI) www.nsf.org
www.steel.org
Precast/Prestressed Concrete Institute
APA The Engineered Wood Association (PCI)
www.apawood.org www.pci.org

Association of Marble Producers from The International Stone Event

Verona (StonExpo)
www.asmave.it www.tisewest.com

ASTM International Terrazzo Tile and Marble Association of

www.astm.org Canada
www.ttmac.com
Construction Specifications Institute
(CSI) Tile Council of North America (TCNA)
www.csinet.org www.tcnatile.com

European Commission for United States Green Build Council

Standardization (CEN) (USGBC)
www.cenorm.be www.usgbc.org

Indiana Limestone Institute of America,

Inc. (ILI)
www.iliai.com

iv © 2022 Natural Stone Institute

Green Building would change inner-city building construction
dramatically. The invention of air conditioning,
reflective glass, and structural steel popularized
Introduction - History of Green the enclosed glass and steel buildings that
Building dominate the American city today. These
buildings were able to be heated and cooled with
History of Green Building – Historical massive HVAC systems that consumed huge
Buildings amounts of cheap and readily available fossil
fuels.4 The massive consumption of energy
Green building is defined by the Office of the required to inhabit these buildings made their
Federal Environmental Executive as “the viability tenable and entirely dependent upon
practice of: 1) increasing the efficiency with energy availability and cost.
which buildings and their sites use energy,
water, and materials, and 2) reducing building
impacts on human health and the environment, History of Green Building – The Infancy
through better siting, design, construction,
operation, maintenance, and removal Around the time that the “glass box” style high
throughout the complete life cycle.” While the
1 rise had become the icon of the American city
green building movement has gained momentum (circa 1970), a forward-thinking group of
in the last decade, the origin can be traced back architects, environmentalists, and ecologists5
to the late nineteenth century. were inspired by the growing environmental
movement and the higher fuel costs that were
According to David Gissen, curator of prevalent during the 1970s.6 The genesis of
architecture and design for the National Building these two scenarios ultimately resulted in the
Museum in Washington, DC, structures such as modern green building movement.
London’s Crystal Palace and Milan’s Galleria
Vittorio Emanuele II used methods that The first Earth Day, celebrated in April 1970,
decreased the impact of the structure on the gave some credence to this new building
environment. Systems such as roof ventilators concept, but the OPEC oil embargo of 1973
and underground air-cooling chambers were gave the burgeoning environmental movement,
used to regulate indoor air temperature.2 In the and subsequently the green building effort the
early twentieth century, several skyscrapers, kick start it needed. With gas lines stretching for
such as the Flatiron Building and the New York blocks, some Americans began to question the
Times Building in New York, utilized deep-set conventional wisdom of being so reliant upon
windows and the Carson Pirie Scott department fossil fuels for our energy.7
store in Chicago had retractable awnings. Both As a result of the oil embargo, among other
of these techniques were effective in controlling energy concerns, the American Institute of
interior temperature while lessening the Architects (AIA) formed a Committee on Energy
buildings’ impact on the environment.3 that was broken into two camps. “One group
From the 1930s through the 1960s, the forward- looked toward passive, such as reflective roofing
thinking cooling methods mentioned above gave materials and environmentally beneficial siting of
way to some new building technologies that buildings, to achieve energy savings, while the

1 Office of the Federal Environmental Executive, “The 4 Building Design and Construction, “White Paper on
Federal Commitment to Green Building: Experiences Sustainability”, page 4, November 2006
and Expectations,” 18 September 2003. 5 Building Design and Construction, “White Paper on
2 Building Design and Construction, “White Paper on Sustainability”, page 4, November 2006
Sustainability”, page 4, November 2006 6http://www.nyc.gov/html/nycwasteless/html/in_busi
3 Building Design and Construction, “White Paper on ness/green_building.shtml
Sustainability”, page 4, November 2006 7Building Design and Construction, “White Paper on

Sustainability”, page 4, November 2006

© 2022 Natural Stone Institute v
other concentrated more on technological plan to make the White House the “model for
solutions, such as the use of triple-glazed efficiency and waste reduction.”12
windows.”8
The “Greening of the White House” program
As energy concerns subsided, momentum for was designed to improve “energy efficiency and
green building and the environment, in general, environmental performance of the White House
slowed down, but a dedicated core group of complex by identifying opportunities to reduce
architects continued to push their green building waste, lower energy use, and make an
concept forward. A couple of notable buildings appropriate use of renewable resources, all while
constructed during the 1970s that utilized improving the indoor air quality and building
concepts of green design are: The Willis Faber comfort.”13 In March 1996, it was reported that
and Dumas Headquarters in England, which through the first two years of the “Greening”
utilized a grass roof, day-lighted atrium, and project, more than $150,000 per year in energy
mirrored windows, and the Gregory Bateson and water costs, landscaping expenses, and
Building in California, which used energy- expenditures associated with solid waste were
sensitive photovoltaic (solar cells)9, under-floor saved. Since 1996, $300,000 has been saved
rock-store cooling systems, and area climate- annually due to additional projects. In all, 845
control devices.10 metric tons per year of carbon emissions were
eliminated during Clinton’s presidency.14
Through the late 1970s, throughout the 1980s,
and into the early 1990s, much research was Some of the methods utilized to “green” the
commissioned on energy efficient processes. White House were as follows:
This research resulted in more effective solar 1. Building Envelope – decreasing energy lost
panels, pre-fabricated efficient wall systems,
through the roof, windows, walls, etc.
water-reclamation systems, modular
construction units, and direct usage of light 2. Lighting – utilizing energy-saving light bulbs
through windows in order to decrease daytime and maximizing use of natural light.
energy consumption.11 3. Plug Loads – Energy-saving office
equipment was installed. Refrigerators and
History of Green Building – The Greening coolers were replaced with more energy-
of the White House efficient models.
When Bill Clinton was elected President in 4. Waste – a comprehensive recycling program
1992, the green build/sustainability was initiated.
communities began to toss around the idea of 5. Vehicles – leased many vehicles that utilized
“Greening the White House” as a way to put their cleaner-burning fuels.
ideas on the radar screens of everyday American
society. Twenty-three years after the initial 6. Landscaping – reducing unnecessary water
Earth Day, President Bill Clinton announced a and pesticide usage.15

8Building Design and Construction, “White Paper on 13“The Greening of the White House”,
Sustainability”, page 4, November 2006 http://clinton3.nara.gov/Initiatives/Climate/greenings
9“Photovoltaic Fundamentals”, ummary.html
www.fsec.ucf.edu/pvt/pvbasics 14The Greening of the White House”,
10Building Design and Construction, “White Paper on http://clinton3.nara.gov/Initiatives/Climate/greenings
Sustainability”, page 4, November 2006 ummary.html
11 Building Design and Construction, “White Paper on 15The Greening of the White House”,

Sustainability”, page 4, November 2006 http://clinton3.nara.gov/Initiatives/Climate/greenings

12Building Design and Construction, “White Paper on ummary.html
Sustainability”, page 5, November 2006
vi © 2022 Natural Stone Institute
History of Green Building – Where Are Energy and Environmental Design (LEED), the
We Now? program with which points are awarded to
various design applications within a building
With the overwhelming success of the “Greening
ultimately resulting in LEED certification for the
of the White House”, other government
building.
institutions have since been given a green
makeover. The Pentagon, the Presidio, and the
U.S. Department of Energy, among others, have
gone green.16
USGBC (The United States Green
Build Council) & LEED
The concepts of green building and, on a larger
(Leadership in Energy and
scale, sustainability are ideas that we hear all of
the time. These two concepts, however, are Environmental Design)
rarely properly understood. USGBC
“Sustainability is a systemic concept, relating to The USGBC was created to promote the design
the continuity of economic, social, institutional and construction of buildings that are
and environmental aspects of human society, as environmentally responsible, profitable, and
well as the non-human environment. It is healthy places to live and work. They are
intended to be a means of configuring civilization focused on integrating building industry sectors
and human activity so that society, its members and leading a market transformation towards
and its economies are able to meet their needs greener construction. The organization consists
and express their greatest potential in the of various trade associations, architects,
present, while preserving biodiversity and designers, and individuals all interested in the
natural ecosystems, and planning and acting for greening of the construction business.18
the ability to maintain these ideals for a very long
Between 1990 and 1995, the USGBC worked
time. Sustainability affects every level of
feverishly with the American Society of Testing
organization, from the local neighborhood to the
and Materials in order to create a rating system
entire planet”.17 In short, the concept of
for sustainability. ASTM’s rigorous consensus-
sustainability refers to thinking holistically about
based process moved much too slowly for the
how everything you do affects everything around
USGBC, and in 1995, it was determined that
you. It is an attempt to minimize each person’s
they would create their own rating system to
impact on the world.
exist under the USGBC banner. A committee
Today, green building is one of the fastest was formed to study other green building
growing building and design concepts. Every programs currently in existence, and after three
month, new magazines are popping up that years, LEED 1.0 unveiled.19 By 2003, LEED was
report on this growing trend. Architects, refined to its current form that is the talk of the
designers, and homeowners are becoming construction and design communities.
infatuated with the cost-saving possibilities,
energy-saving emphasis, modern look, and the
symbiotic relationship with nature that green LEED
buildings possess. In short, LEED is a system for designing,
The United States Green Build Council constructing, and certifying green buildings.
(USGBC) is the foremost leader and educator Buildings are classified as Certified, Silver, Gold,
within the world of green building today. They or Platinum, depending upon the number of
are the sanctioning body for Leadership in

16Building Design and Construction, “White Paper on 18“An Introduction to the USGBC and LEED Green
Sustainability”, page 5, November 2006 Building Rating System”, www.usgbc.org
17 http://en.wikipedia.org/wiki/Sustainability 19Building Design and Construction, “White Paper on

Sustainability”, page 7, November 2006

© 2022 Natural Stone Institute vii
points they acquire within six building • Support the regional economy by using
components20: materials and products manufactured
1. Sustainable Sites regionally.
2. Water Efficiency • Encourage environmentally responsible
forestry through the use of wood or wood-
3. Energy and Atmosphere
based material that meets Forest
4. Materials and Resources Stewardship Council’s Principles and
5. Indoor Environmental Quality Criteria for wood building components.

6. Innovation and Design Process • Utilize rapidly renewable materials, such as

bamboo flooring, wool carpets, strawboard,
Within each of these categories, there are a cotton ball insulation (made from denim
specific number of credits available via many scrap), genuine linoleum flooring, or poplar
subcategories. LEED ratings are rapidly oriented-strand board (OSB). Using rapid
becoming boasting points for property owners, renewables helps reduce the use and
with property values of LEED-certified buildings depletion of finite raw materials.
skyrocketing.
Construction and Demolition Waste
LEED has been assisted in its success by the early Management
adoption of many government agencies. Today,
however, it is mostly a market-driven engine, • Develop and implement a waste
with the number of LEED registered projects management plan that diverts a substantial
growing each year. amount of construction, demolition, and
land-clearing debris from landfills to
recycling or salvage facilities.
Characteristics of LEED Building • Reuse a percentage of salvage or refurbished
Site Design and Planning materials from construction, demolition, or
land clearing as new building material. For
• Site a building within proximity of more information on the benefits of
commuter rail or bus lines to reduce salvaging materials from existing sites, go to
pollution and any land-development impacts www.deconstruction.com.
associated with increased automobile usage.
Energy and Atmosphere
• Establish building specifications that
maintain the current level of storm-water • Generate building electricity on site from
runoff or decrease the amount of renewable resources like geothermal, solar,
imperviousness already existing on site. or biogas sources.
• Develop a site with a minimum density of • Eliminate the use of chlorofluorocarbons
60,000 square feet per acre. Channeling (CFCs) in new heating, ventilation, air-
development to urban areas with existing conditioning, and refrigeration (HVAC & R)
infrastructure protects green spaces and systems. Eliminating the use of CFCs
preserves natural habitats and resources. reduces ozone depletion.
Material and Product Selection • Contract with a green power provider to
purchase building electricity generated from
• Use building materials and products that renewable resources, such as solar, wind,
contain post-consumer recycled content.

Building Design and Construction, “White Paper on

20

Sustainability”, page 7, November 2006

viii © 2022 Natural Stone Institute
 geothermal, biomass, or low-impact hydro Stone in Green Building
sources.
What is Stone’s Current Perception?
• Optimize energy performance. With the growing influence of green building, it
Water Management is imperative that the natural stone industry does
everything it can to position its product as being
• Install water-efficient or low-flow green friendly. Despite what many of us in the
equipment and appliances in kitchens and industry may think (natural stone is about as
bathrooms to reduce water consumption. green as something can get), that perception is at
• Use water-efficient irrigation, captured rain, odds with the prevailing thought among the
or site-recycled water for onsite architecture and design communities. Many of
landscaping. these misconceptions arise from the inaccurate
idea that mining natural stone is somehow on par
• Utilize innovative wastewater technologies, with strip mining, an environmentally
such as treating wastewater on site or devastating practice.
significantly decreasing the amount of
potable water used for sewage conveyance. One facet of LEED certification in which natural
stone stands out is in product origin. A major
Indoor Environment tenet within the green community is that of
• Design the HVAC system and building supporting local products and business. LEED
envelope to provide for the optimal delivery points are available for products whose origin or
and mixing of fresh air. Effective air manufacturing is within 500 miles of the building
exchange supports the safety, comfort, and site. Regionally manufactured and extracted
well-being of building occupants. materials reduce environmental impact by
lowering emission of greenhouse gases during
• Reduce the number of indoor air transportation while supporting local
contaminants by selecting paints and economies. Fortunately for the stone industry,
coatings, adhesives, carpets, and composite there is a quarry site within 500 miles of nearly
woods that emit low Volatile Organic everywhere in the United States and Canada.
Compounds (VOCs) or none at all.
Future Areas of Emphasis
Examples of low-VOC emitting products
are carpets made of wool, carpets made of There are some areas where natural stone should
recycled plastic bottles, and low-VOC paint. be an obvious choice for green builders, but
where further research is needed to prove the
• Establish segregated areas for chemical-using hypothesis:
operations (such as copy/printing rooms and
housekeeping); these areas should have • The enduring life cycle of natural stone
separate outside exhaust and no air makes it a great green build option. Because
recirculation. stone has proven that over the centuries it
holds up to weathering and time better than
• Maximize day lighting and view any other building material, one would think
opportunities. Day lighting and increased that less energy would be consumed by the
view opportunities can save energy costs and initial fabrication and installation than in
enhance worker productivity. 21 manufacturing and replacing another
product.
• The ease of care and maintenance involved
with maintaining natural stone applications

21http://www.nyc.gov/html/nycwasteless/html/in_bus
iness/green_building.shtml
© 2022 Natural Stone Institute ix
 should be very attractive to those in the The Committee of Sustainability
green community. Harsh chemicals are not In order to properly position natural stone, to
needed to either clean or finish stone.
research elements of building with natural stone
• The recyclability of natural stone is that would qualify for LEED points, and to
unequaled. Nearly 100% of stone from old market the use of natural stone as a green
projects and scrap stone are recyclable. product, the Natural Stone Council has
commissioned a Committee on Sustainability.
These components of natural stone use need to The NSC Committee on Sustainability (NSI is a
be studied and reported on adequately before the member) will take the lead for the industry in
natural stone industry can go to the USGBC and ensuring that stone becomes a viable green
request LEED certification points. building option. A couple of early initiatives for
Quarrying the committee are establishing a set of green best
practices for quarrying and fabrication. The
In the past 15 to 20 years, the business of
committee is also pursuing the commissioning of
quarrying has been vastly cleaned up from an
studies to research Life Cycle Assessment, Life
environmental perspective. Domestic quarries
Cycle Cost, Water Use Reduction, Construction
today are required to comply with a strict code
Waste Management, and Material Reuse for the
of practice and are monitored by OSHA, U.S.
Natural Stone Industry. While the initiatives
Department of the Interior, EPA, the
being undertaken by the Committee on
Department of Resources and Economic
Sustainability are aggressive, they are greatly
Development, and the Mine Safety and Health
needed in order to ensure that stone becomes a
Administration, among others. This message
viable option for green building.
needs to be spread throughout the entire
construction industry: Quarrying is not what it
was 20 years ago, and certainly not what it was
50 or 100 years ago.
Quarry reclamation projects have added to the
ability of quarries to limit their long-term impact
on the environment. Today, many old quarries
are being turned into golf courses, lakes,
recreation areas, and state parks. A list of quarry
reclamation projects appears at the end of this
chapter as examples of how old quarry sites can
be successfully utilized for the public good.
As technology moves forward, the greening of
quarrying will continue and this will, in turn,
continue to further enhance natural stone’s
position within the green community.

x © 2022 Natural Stone Institute

Additional GREEN References Canoe Creek State Park
Quarry Reclamation Site List Hollidaysburg, PA
www.dcnr.state.pa.us/STATEPARKS/PARKS
Quarry Park and Nature Preserve /canoecreek.aspx#history
County of Stearns, MN
https://co.stearns.mn.us/Recreation/CountyP Banning State Park
arks/QuarryParkandNaturePreserve Sandstone, MN
www.dnr.state.mn.us/state_parks/banning/in
Halibut Point State Park dex.html
Gloucester, MA
https://www.mass.gov/locations/halibut- Sleeping Giant State Park
point-state-park Hamden, CT
www.sgpa.org/
The Quarry Golf Club
San Antonio, TX Knightdale Environmental Education
https://quarrygolf.com/home/historic- Park
cementville/ Knightdale, NC
www.hsmm.com/UPLOADS/BD/News/200
Oak Quarry Golf Club 50427_013046/Art_Knightdale_Lnd%20Wtr_
Riverside, CA 10%2004%20(final).pdf
www.oakquarry.com/about
Emerald Lake State Park
Crystal Springs Quarry Golf Club East Dorset, VT
Maryland Heights, MO www.vtstateparks.com/htm/emerhist.cfm
https://www.quarrygc.com/
Elephant Rocks State Park
Old Quarry Nature Center Belleview, MO
Danbury, CT www.mostateparks.com/elephantrock.htm
https://www.danbury-
ct.gov/government/departments/parks/

Quarry Lakes Regional Recreational Area

Fremont, CA
www.ebparks.org/parks/quarry.htm

Quarry Oaks Golf Club

Ashland, NE
www.quarryoaks.com/

Bomoseen State Park

Fair Haven, VT
www.vtstateparks.com/htm/bomoseen.cfm

Natural Bridge State Park

North Adams, MA
www.mass.gov/dcr/parks/western/nbdg.htm

© 2022 Natural Stone Institute xi

Suggested Contract Warranty b) No attempted alteration or repair of the
dimension stone or its installation has been
Provision/ Disclaimer made without Company’s written consent;
The following warranty is provided as a guide c) The dimension stone is inspected by Owner
only to Natural Stone Institute Members who or representative on arrival at the project
desire to or are required to provide warranties in site for visible defects, and complaints
connection with contracts with their customers relating thereto are filed in writing
(“Owner”). However, the Member is cautioned immediately with Company before
installation; and
that such language and the legal obligations d) The dimension stone or installation thereof
arising therefrom must be reviewed and approved is not subjected to misuse, negligence,
by the individual Member’s legal counsel prior accident, or use contrary to Company’s
to usage on a case-by-case basis. NSI is not written instructions.
providing legal advice to Members, nor may a
Member rely on these provisions as being in 3. Company does not warranty dimension
compliance with relevant federal, state or local stone or its installation to any safety,
statutes, ordinances or codes. building, or other code of any state,
municipality or other jurisdiction unless the
Warranty terms of such code are specifically
1. [Name of Company] (“Company”) warrants incorporated into Company’s written
to the Owner on project in which Company contract with Owner. Except for this
installs dimension stone for one year from warranty by Company, Owner assumes all
the date of the completion of installation, risk and liability for the use of such
that the dimension stone shall be free from dimension stone, whether alone or in
defects in material and workmanship IF, combination with other building materials.
BUT ONLY IF: 4. THIS WARRANTY IS EXPRESSLY IN
a) The dimension stone, its specifications, and LIEU OF ALL OTHER WARRANTIES,
installation are set forth in a written EXPRESS OR IMPLIED, INCLUDING
contract signed by Company and Owner; ANY IMPLIED WARRANTY OF
b) The Owner does not hinder Company from MERCHANTABILITY OR FITNESS FOR
installing dimension stone and other A PARTICULAR PURPOSE. COMPANY
materials and performing services in SHALL NOT BE LIABLE UNDER THIS
conformity with the contract; and WARRANTY FOR ANY OTHER LOSS
c) Such dimension stone installation was not OR DAMAGE INCLUDING WITHOUT
exposed to conditions more severe or
LIMITATION, CONSEQUENTIAL
otherwise exceeding those set forth in the
contract specification. DAMAGE, SAFETY PROBLEMS, OR
PERSONAL INJURY RESULTING
2. Company’s obligation under this warranty DIRECTLY OR INDIRECTLY FROM
is limited to replacing or repairing, free of THE PURCHASE, OTHER
charge, F.O.B. point of fabrication, any ACQUISITION, USE, OR LOSS OF THE
defective dimensional stone, IF, BUT DIMENSION STONE, EXCEPT AS
ONLY IF: EXPRESSLY SET FORTH HEREIN.
a) Owner notifies Company by certified mail, 5. No statement by Company’s employee or
return receipt requested, of such breach of agent directly or indirectly admitting
warranty, within ninety (90) days after the liability under this warranty shall be binding
discovery thereof, otherwise such claim is against Company unless: a) made in
waived. (However, without limitation on writing; b) made by a representative of
the foregoing, any alleged defect discovered Company authorized to do so.
more than one year after installation is
excluded from warranty.)

xii © 2022 Natural Stone Institute

Suggested in writing below the stone samples or slabs to
be furnished by the Seller. Seller shall not be
Residential Contract bound by samples furnished by the Purchaser
(Installation of (from third parties) unless indicated below:
Dimension Stone) □ Samples provided by Seller, approved by
Purchaser. ____ (Purchaser’s Initials)
The following residential contract is provided as □ Seller acknowledges review of Purchaser’s
a guide only to Natural Stone Institute Members. samples and acceptance. ____ (Seller’s Initials)
However, the Member is cautioned that such
5. Commencement; Completion. The work
language and the legal obligations arising shall commence on or about __________ and
therefrom must be reviewed and approved by the will be completed on or about __________,
individual Member’s legal counsel prior to usage provided, however, Seller shall not be
on a case-by-case basis. NSI is not providing responsible for delays in commencement or
legal advice to Members, nor may a Member rely completion caused by events beyond the
on these provisions as being in compliance with Seller’s reasonable control.
relevant federal, state or local statutes,
ordinances, or codes (for example, Home Sales 6. Ownership of work. No legal interest in the
Solicitation Act in Ohio). stonework shall pass to Purchaser until full
price has been paid, regardless of the location of
the stonework, and whether it has been
R e s id e ntia l C ontr a ct installed or not installed in the residence.
This RESIDENTIAL CONTRACT to provide and 7. Standards and Guidelines. Installation of
install dimension stone, entered into between the stonework by the Seller shall be in strict
_____________________ (“Purchaser”) residing accordance with the Natural Stone Institute’s
at _____________________ (“Residence”) and Dimension Stone Design Manual, as updated
_____________________ (“Seller”) with from time to time. No deviation from the
principal office at _______________, with standards, guidelines, or other work
effective date of the ___ day of _______, 20__. specifications set forth in said Manual shall be
permitted.
1. Services. Subject to the terms and provisions
herein, Seller agrees to provide to Purchaser 8. Assignment. This agreement is personal to
the following services (check applicable boxes): the parties and may not be assigned without the
□ Fabricating and installing kitchen countertops written consent of the non-assigned party.
□ Supplying and installing stone paving
PURCHASER: ________________________
□ Supplying and installing stone bath work
□ Supplying and installing other stonework: Print Name: ________________________
_________________________________ Date Signed: ________________________
(describe)
2. Contract price. The total contract price, as
installed, is $__________________. PURCHASER: ________________________
Print Name: ________________________
3. Schedule of payments. The contract price
shall be paid as follows: Date Signed: ________________________
A. $______ on signing this contract.
B. $______ on completion of field SELLER: ________________________
measuring.
C. $______ on commencement of Print Name: ________________________
fabrication.
D. $______ on completion of fabrication. Date Signed: ________________________
E. $______ on completion of installation.
4. Sample approval. Fabrication of stone will
not commence until the Purchaser has approved

© 2022 Natural Stone Institute xiii

NSI CODE OF ETHICS We assume these responsibilities freely and
solemnly, mindful that they are continuing
Members of the Natural Stone Institute, upon conditions to and part of our obligation as
acceptance as Members in good standing, agree Members of the Natural Stone Institute.
to abide by the following Code of Ethics:
Members of the Natural Stone Institute believe
and affirm that:
The fabrication and installation of dimension-cut
natural stone should meet NSI and other industry
standards as articulated in the NSI Dimension Stone NOTE: A copy of the NSI Code of Ethics is
Design Manual and other technical publications, presented to each Member upon acceptance into
along with courteous and professional customer membership. The document is suitable for
service. To achieve these goals, we pledge framing and display in the Member’s office or
adherence to the following principles and showroom.
policies:
• Our primary objective is a satisfied and
happy customer, be it a homeowner, a
building owner, or a design professional.
• We will maintain and conduct business in
accordance with fair and honorable
standards of competition.
• Honesty, integrity, quality, and
professionalism guide our firm’s business
philosophy.
• High standards of health, safety, and product
quality will be incorporated into every
installation.
• We shall deal fairly with customers, as well
as with our employees, our subcontractors,
and our suppliers.
• We encourage research to develop new
materials, techniques, tools, and equipment,
as well as improved methods of stone
fabrication and installation.
• We pledge to assist in the education and
product knowledge of our firm’s clients and
customers (builders, kitchen and bath
dealers, architects, designers, and
homeowners) before, during, and after
installation.

• We shall strive to promote a spirit of

cooperation within the industry.

xiv © 2022 Natural Stone Institute

NSI Membership advantages of natural stone to increase demand
within the commercial and consumer markets.
Membership in the Natural Stone Institute
NSI Receivables Management Solutions
provides you with outstanding advocacy,
NSI Members can receive a variety of customized
networking, marketing & publicity, information
outsourcing services to meet their collection needs
& education, and professionalism and stone
from VeriCore. Preferred rates are offered on all
craftsmanship — benefits that continue to make
collection accounts, outsourcing, complimentary
NSI one of the fastest-growing trade associations in
demand letters and many other services to help
the world. Members are also encouraged to take
improve your bottom-line.
advantage of a whole array of value-added services
that can easily pay for your membership costs and The Cutting Edge Newsletter
add money to your bottom line. This monthly newsletter provides valuable
industry and association news, new member
With NSI and its member-friendly, cost-saving
listings, member activity updates, and Technical
services you can save money on collections,
Q&A column.
credit card transactions, office supplies, lead
referrals, shipping, and utility costs. NSI Membership Directory
Print and online versions of the directory give you
NSI Member Benefits Include: quick access to fellow producers/quarriers,
NSI Freight Discount Program fabricators, installers, distributors, and
Save money on your shipping costs by using the contractors with whom you can do business.
services of FedEx®, YRC, and UPS Freight. Discounted StonExpo Registration
NSI Credit Card Processing Program NSI Regular Members receive reduced-rate
NSI members in the U.S. receive tremendous admission to StonExpo, the premier trade show of
savings on Visa, MasterCard, & debit card the natural stone industry, held concurrently with
processing. Online account management, 24 the NSI Annual Meeting.
hour a day customer service, plus exclusive
Office Supplies and Print Services Program
discounts on point-of-sale solutions and
The NSI and OfficeMax introduce the new
additional products and services are all accessible
OfficeMax Partner AdvantageSM program. This
with no monthly minimum fee.
members-only program will allow you to take
Free Technical Guidance advantage of special promotions and other one-of-
NSI serves as the industry’s leading clearinghouse a-kind benefits.
of information about natural stone and can
Internet Exposure
respond to technical and other questions from
NSI operates a web site that can drive new business
Members as well as those in the construction,
your way: www.naturalstoneinstitute.org is
architectural, and design communities.
designed for natural stone professionals, architects
Consultation on specific questions is also available
and members of the design community. Direct
at no charge to Members from NSI’s Technical
links to your web site draw interested parties to
Director.
your business.
NSI Bookstore Discounts
NSI Members save up to 50% on technical And more! For a complete listing of NSI
publications and consumer brochures. member benefits, go to
www.naturalstoneinstitute.org or call the
Industry Promotion Membership Department at 440.250.9222.
NSI actively works to educate design
professionals, homeowners, and others about the

 2022 Natural Stone Institute xv

NOTES:

xvi © 2022 Natural Stone Institute

 NATURAL STONE INSTITUTE
SAMPLE SPECIFICATION LANGUAGE FOR DESIGN PROFESSIONALS
Natural Stone Institute
The Natural Stone Institute was formed in 2018 as a merger of the Marble Institute of America (MIA) and
the Building Stone Institute. The Building Stone Institute was formed in 1894 as the International Cut Stone
Contractors and Quarrymen’s Association; the name was changed to the Building Stone Institute in 1955.
Established in 1903 as the National Association of Marble Dealers, the Marble Institute of America officially
formed in 1944, when the association merged with the National Association of Marble Producers. In 1962,
the National Association of Marble Builders merged with MIA.
The Natural Stone Institute serves as the authoritative source of information on standards of natural stone
workmanship and practice and the suitable application of dimension stone products. Membership in the
association is worldwide and includes natural stone producers, exporters/importers,
distributors/wholesalers, fabricators, finishers, installers, and industry suppliers – all committed to the
highest standards of workmanship and ethics.
Sample specification language is provided for 1) The Dimension Stone Design Manual (DSDM); 2)
Natural Stone Institute Accredited Contractors and Fabricators; and 3) Natural Stone Institute Member
Companies.

1) The Dimension Stone Design Manual (DSDM) is the stone industry's single-source reference for
dimensional stone design and construction facts and details. Contents include sections on granite, marble,
limestone, serpentine, soapstone, travertine, quartz-based stone and slate with product descriptions and
technical data; general installation guidelines; guidelines and typical detailing for horizontal surfaces,
vertical surfaces, wet areas, furniture and countertops; restoration and maintenance of exterior and interior
stone installations; and a glossary of terms relating to dimension stone.
Sample Specification Language to Reference the Natural Stone Institute’s DSDM
For [variety of] dimension stone, comply with recommendations in Natural Stone Institute's
Dimension Stone Design Manual (DSDM) 2022.
2) Natural Stone Institute Accreditation for natural stone fabricators and commercial
contractors recognizes those companies meeting the industry's highest standards for business activities,
product knowledge, fabrication and installation. To earn Natural Stone Institute Accreditation, a company
must complete an intensive, rigorous process that includes documentation of its business and employment
practices, letters of recommendation, a written examination and site visits to the facility and completed
jobs.
Sample Specification Language for Natural Stone Institute
Accredited Natural Stone Fabricators:
Fabricator Qualifications: Preference shall be given to a Natural Stone Institute Accredited Natural
Stone Fabricator. Natural Stone Institute Accredited Natural Stone Fabricators are those companies
meeting the industry's highest standards for business activities, product knowledge, fabrication and
installation. Bidding company must supply their official Natural Stone Institute Accreditation
number as proof of accreditation.

© 2022 Natural Stone Institute Sample Specification Language • xvii

SAMPLE SPECIFICATION LANGUAGE FOR DESIGN PROFESSIONALS (CONTINUED)
Sample Specification Language for Natural Stone Institute
Accredited Commercial Contractors:
Installer Qualifications: Preference shall be given to a Natural Stone Institute Accredited firm
experienced in installing engineered dimension stone cladding systems. Company must be a Natural
Stone Institute Accredited Commercial B Contractor (low rise) or a Natural Stone Institute
Accredited Commercial A Contractor (high rise) of current good standing with the Natural Stone
Institute. Bidding company must supply their official Natural Stone Institute Accreditation number
as proof of accreditation.
Installer’s responsibilities include sourcing of qualified fabricator of dimension stone cladding and
providing professional engineering services per project requirements. Engineering Responsibility
includes comprehensive design of stone attachment systems by an experienced, licensed
professional in accordance with practices outlined by the Natural Stone Institute Dimension Stone
Design Manual and compliant with applicable codes. Comprehensive shop drawings with attachment
details shall accompany engineering analysis.
3) Natural Stone Institute members include marble, granite, limestone, sandstone and other
natural stone producers and quarries, fabricators, installers, distributors and contractors around the world.
Natural Stone Institute Members, upon acceptance as members in good standing, agree to abide by a Code
of Ethics.
Sample Specification Language for Fabricator/Installer Qualifications (Residential
or Commercial Projects)
Fabricator/Installer Qualifications: A Natural Stone Institute (Natural Stone Institute) member firm
experienced in fabrication/installation of dimension stone as indicated for this project and whose
work has a record of successful in-service performance.

For more information:

Natural Stone Institute
380 E. Lorain Street
Oberlin, OH 44074
USA
PH: 440-250-9222
FAX: 440-774-9222
www.naturalstoneinstitute.org

Sample Specification Language • xviii © 2022 Natural Stone Institute

The geology of 2.0 STONE CATEGORIES
Stone 2.1 Three general rock or stone categories
are recognized according to their mode of
1.0 INTRODUCTION origin. This is a genetic classification, and it not
only states how and under what general
1.1 Earth is geologically classified as a “stony conditions a stone was formed, but also implies
planet,” as it is entirely stone (rock) of various a general compositional range. The basic stone
mineral compositions and forms, excluding its groups are:
water and atmosphere.
2.1.1 Igneous rock is formed by
1.2 Earth scientists prefer the term “rock,”1 solidification (cooling) or, in some cases, by
while the commercial stone industry, prefers solid-state transformation3 of molten or semi-
the term “stone”.2 Both words are correct in molten material in the Earth’s upper mantle or
their respective frame of reference, and for crust into crystalline rock generally consisting
practical purposes, interchangeable. Every of silicates (compounds with SiO4) and some
type of rock or stone is composed of one or dark-colored accessory minerals such as iron
more minerals. For those who work with oxides or other iron- and magnesium-bearing
dimension stone, it is important to know these silicate minerals. Example: granite.
minerals—there are about 25 common
minerals—that make up the bulk of all 2.1.2 Sedimentary rock can be:
dimension stone commonly used. These 25
minerals are easy to learn to recognize, and this 2.1.2.1 Detrital sedimentary stone,
basic knowledge in turn helps to identify the which is the naturally cemented accumulation
many varieties of natural stone. of solid granular materials or particles derived
from both mechanical and chemical weathering
1.3 Identifying the minerals in a particular of any existing rock. Examples include
type of stone is important because the limestone, shale, sandstone, and
properties and behavior of stone are the sum conglomerate.
total of the properties and behavior of the
minerals found in the stone. Knowing 2.1.2.2 Chemical sedimentary stones,
something about the mode of formation or the precipitates of chemicals like salt that are
“genesis” of a stone further aids predicting the the dissolved weathering products of any
behavior of a stone. Thus, performance existing rocks. Chemical weathering yields
questions can be knowledgeably approached, some soluble salts, and examples of the
such as how a particular stone might behave in resulting stones include onyx (CaCO3),
a given application. Stone industry limestone (CaCO3), dolomite (CaMg(CO3) 2),
professionals need this information to reduce alabaster (CaSO4), some types of travertine
waste and avoid costly mistakes. (CaCO3 + SiO2) and common table salt
(NaCl). Onyx is actually precipitated in
caverns and travertine is a precipitate deposited

1 The Glossary of Geology, 4th edition, 1997, Robert L. 3 A solid-state transformation is an atomic or molecular-
Bates and Julia A. Jackson, eds., American Geological level process by which a compound changes from one
Institute (AGI), defines rock as “a mixture of one or crystalline solid to another new crystalline solid–
more minerals.” without going through an intervening liquid and/or
2 The Glossary of Geology (ibid) defines stone as: “A gaseous state. This process occurs under conditions of
general term for rock that is used in construction, very high pressure, temperature, and chemistry
either crushed for use as aggregate or cut into shaped through time at depths in the crust of several to tens of
blocks as dimension stone.” kilometers.

© 2022 Natural Stone Institute The Geology of Stone • Page 1-1

around freshwater springs in shallow marine rigid outermost rock layer, which varies from
(salty) water. Alabaster is usually a slightly about 3 to 25 miles (5-40 km) thick.
metamorphosed anhydrite or calcium sulfate.
3.2 The underlying mantle is about 1,800
2.1.2.3 Many other chemical precipitates are miles (2,900 km) thick and can be is envisioned
of no use as dimension stone due to solubility as two parts: a weak upper mantle of about
and softness, but may be much more valuable 400 miles (640 km) of rock, mostly uniform in
as chemical feedstock, table salt, or fertilizer. composition and capable of flow, i.e., not quite
molten. Below it, the lower mantle is a
2.1.3 Metamorphic4 rock is formed denser, “mushy” or partially molten material
from any pre-existing rock type in the Earth’s somewhat different in composition from the
crust under variable conditions of high upper mantle.
pressures, high temperature, chemistry, and
time. The process produces mechanically 3.3 Deep in its center, Earth has a solid,
deformed stone and chemically alters the iron-rich inner core about 760 miles (1,200
mineral assemblages of the parent stone. The km) thick, and a molten metallic outer core
new mineral suite may be a different or the about 1,420 miles (2,200 km) thick.5 As the
same chemical composition as the parent, but inner core is under tremendous pressure, it is
as newly formed crystals. Examples of hard to conceive what its “molten” physical
metamorphic stones include marble, slate, state is really like.
schist, and gneiss.
3.4 Ocean basins cover approximately 70%
2.1.3.1 Earth scientists have assigned of Earth’s surface and are underlaid by
hundreds of names for rocks in each of the oceanic-type crust, while a thicker continental-
genetic groups, and for minerals or stones type crust, being lighter in weight, floats on
resulting from different processes of formation older, denser, oceanic crust. Continents
and slightly different chemical makeup. The comprise the remaining 30% of Earth’s
many technical names are confusing; the few surface.
names given in this chapter will suffice for most
commercial purposes. When legal questions 3.5 The chart on the following page
arise, it may be appropriate to consult a contrasts characteristics of the two major kinds
professional earth scientist about stone types of rock in the lithosphere (see next page):
and nomenclature of a particular stone.

3.0 STONE FORMATION

3.1 Igneous Stone (Oceanic and

Continental Stone). The Earth’s crust is
composed of two general types of stone:
oceanic and continental. Each has distinct
characteristics, mineral and chemical
compositions, colors, specific gravities, and
behaviors. Most, but not all, commercial stone
is quarried from continental rock. Earth’s
lithosphere, or rocky crust, is the cool and

4 Metamorphic is a word derived from Greek that 5 Since deep Earth materials cannot be physically
literally means to change in form. examined, the above information is known through
geophysical studies of earthquakes and vibrations from
atomic bomb tests.

Page 1-2 • The Geology of Stone © 2022 Natural Stone Institute

 Oceanic Stone Continental Si, K, Na, etc., to low Fe, Mg, Ca and high Si,
Stone K and Na.
Dark in color Light in color
Comp: High Iron High silica (SiO2, 3.8 Andesite, named after the Andes
(Fe), Magnesium ≈70%), Potassium Mountains of South America, is a lava stone
(Mg), Calcium (Ca) (K), Sodium (Na) with an intermediate composition at about the
and Aluminum (Al) middle of the element spectrum. It is gray and
Low: SiO2 Low: Fe, Mg, Ca has a medium specific gravity. Andesite flows
(<50%), K, Na & well or poorly depending on its silica content,
Al and may contain all of the following elements
Heavy: Specific Not heavy: Specific in its variable composition: Si, Fe, Mg, Na, Ca,
gravity ≈2.9 Gravity ≈2.6+ K and Al. It is known simply as an
Melting “intermediate” or “Andean-type” stone.
temperatures: High Low: ≈800°+ C.
(1000-1500° C.) 3.9 Plate Tectonics. According to the
Viscosity of Lava: theory of plate tectonics, the lithosphere of the
Very runny – flows Very stiff – Earth is divided into large crustal plates that
like water like honey in winter have continuously separated or collided with
Kind of eruption: each other over millions of years, always
Quiet like Hawaii Explosive like Mt. moving and forming new and destroying old
St. Helens crustal material in the process. Almost all of
Scientific name of the ocean floor is basaltic or volcanic rock
lava type: Basaltic Granitic created by plate movement called “sea-floor
Scientific code spreading,” initiated from mid-oceanic ridges.
word: Mafic6 Felsic7 These linear ridges or rifts are the spreading
centers between undersea crustal plates that
3.6 In each case, it is the elemental content allow molten rock to emerge from the mantle
of the major minerals that make the sharply through volcanic action. Conversely, when
different characteristics shown in the chart. plates collide, the far edge of one oceanic floor
The generalizations of composition in the chart plate is thrust under the edge of the adjacent
hold for most cases. Although the differences plate in a process called subduction. Subducted
in specific gravity or density of the two material is reincorporated into the Earth’s
classifications of stone appear to vary little, that upper mantle.
apparently small difference is enough for
oceanic rock to float on denser layers 3.9.1 The life-span of oceanic floor is typically
underneath. Like blocks of wood in ponds, the no more than 180 million years from formation
world’s continents are floating on heavier, at spreading centers to disappearance of
darker crust below. subduction. This is a relatively short time
compared with some continental stone that is
3.7 Nature, however, is by no means quite 3.9 billion years old. Thus, the sea floor is
so accommodating as to always exactly fit this similar to a conveyor belt moving from zero to
twofold classification. The compositional 180 million years old, then disappearing.
differences of these stone classifications However, because of its comparatively young
represent the end members of a continuous age, oceanic stone lacks the abundant variety of
element spectrum of high Fe, Mg, Ca and low

6Mafic is a word made up from the first letters of its 7Felsic is derived from feldspar and silica, from the high
characterizing components. In this case, ma- from quartz content.
magnesium plus –fic from ferric, which means “of iron
content.”

© 2022 Natural Stone Institute The Geology of Stone • Page 1-3

types, colors, and textures found in the much Hawaii were born in this manner. Subsea
older continental stone. volcanic activity is continually creating new
oceanic floor and volcanic islands.
3.9.2 The lower crust and upper mantle of
Earth are composed of rocks remarkably 3.10.2 However, not all igneous stone is
similar in composition, closely related to volcanic. All genuine granites8 are solidified
basaltic lava: dark-colored, heavy, with silicate slowly from a melt miles deep in the crust, well
minerals having high amounts of Fe, Mg, and encapsulated and thus well insulated by
Ca-rich silicates and lesser amounts of silica in surrounding solid rock. This is significant to the
the form of quartz (SiO2). The natural process quality of granite dimension stone because
of crustal formation through nearly 4.5 billion slow cooling yields the larger crystals that give
years has chemically differentiated these dark, many commercial granites their distinctive
heavy stones into the lighter-colored and textural character and beauty.
lighter specific gravity stones of the continents.
3.11 Clastic Sedimentary Stone. The
3.9.3 Other stone formation processes that formation of clastic sedimentary stone is
are a part of or affect plate tectonics include relatively uncomplicated compared to the
continental movement and collision, mountain complex chemistry and natural processes
formation, earthquakes, chemical weathering associated with either igneous or metamorphic
of stone, the freeze/thaw cycle, landslides, and stone.
climatic events, such as violent storms,
torrential rain, and floods. 3.12 Clasts are fragments or grains of any
existing stone, produced by one or more
3.9.4 These and other natural processes processes, such as freezing and thawing,
continuously operate to form new stone and to earthquakes, and other events of weathering,
chemically differentiate existing stone both mechanical and chemical. Clasts are also
materials through time, yielding a spectrum of called “detritus;” thus, clastic sedimentary
colors and unique designs in an abundance that stone is sometimes referred to as detrital
satisfies an increasingly demanding market. sedimentary stone.

3.10 Igneous Stone. Igneous stone is 3.13 Sizes of clasts range from boulders to
cooled and solidified from material melted by cobbles, pebbles, sand grains, silt, and clay-
heat from decay of radioactive minerals in the sized particles. They are moved by gravity,
Earth’s crust (lithosphere), and by frictional wind, and water, and are further abraded or
heat caused by crustal movements. The release rounded and dissolved in the process, and
of these powerful forms of thermal energy can sorted and carried vast distances. The rivers of
produce explosive volcanism like the type seen the world are the prime movers of sediment
in mountain ranges such as the Cascades in the while sorting them by size, weight, and shape,
northwestern United States. Mount St. Helens grinding or abrading the particles to very fine
in Washington is an example of this geologic sand, silt, and finally, clay-sized grains carried
process. in suspension to the oceans and deposited on
continental margins. As deposits thicken,
3.10.1 Other volcanic areas known as “hot compaction occurs and the natural process of
spots” are formed from molten rock emerging chemical cementation takes place through time
on the ocean’s floor through stationary spots or to produce clastic sedimentary stone.
plumes or vents in the underlying upper mantle
and crust. The basaltic volcanic islands of

8 Some types of stone defined by ASTM International as

“granite” are not true, geological granites.

Page 1-4 • The Geology of Stone © 2022 Natural Stone Institute

3.13.1 Chemical alteration is a continual 3.14.6 Particle Name: Clay
process acting on stone, from the moment of Size Range: <1/256 mm
solidification, exposure and weathering, to its Rock Name: Mudstone and Shale
transportation, deposition, compaction, Stone Abbreviation: Sh.
burial, and cementation throughout the time
that piece of stone exists. Chemical change 3.15 Sandstones and Conglom-
during burial continues. Change continues erates. Sedimentary stones most important to
after quarrying, fabrication, and installation on the dimension stone industry are sandstones
a structure, and faster if water is present. But and some of the smaller-grained
if stone is kept dry, chemical action slows up to conglomerates. Siltstone, shale, and the very
a minimal level. large-grained conglomerates are of less
commercial importance except for landscaping
3.14 Clast Sizes. Clasts are graded and occasional artistic constructions. Siltstone,
according to size, and the resulting stone after where well-cemented and readily available,
compaction and cementation is classified as was utilized as a fieldstone for buildings or
follows: other structural work in earlier centuries.

3.14.1 Particle Name9: Boulders 3.16 Sand Grain Composition. Sand

Size Range: >256 mm grains are graded very fine, fine, medium,
Rock Name: Boulder Conglomerate coarse, and very coarse. They may be further
Stone Abbreviation: Cgl. characterized as well-rounded, almost
spherical, to very angular. Angular grains tend
3.14.2 Particle Name: Cobbles to interlock well, and when cemented, are
Size Range: 64 to 256 mm desirable in sandstone, just as angular sand is
Rock Name: Cobble Conglomerate desirable for the same reason in masonry.
Stone Abbreviation: Cgl. Sandstones buried over tens to thousands of
feet become compacted, and the flow, often
3.14.3 Particle Name: Pebble miniscule, of chemical-charged aqueous fluids
Size Range: 2 to 64 mm proceed to cement the grains with one or more
Rock Name: Pebble Conglomerate of cementing minerals. Chemical activity does
Stone Abbreviation: Cgl. not cease, but continues to cement or de-
cement the stone, or change the stone by
3.14.4 Particle Name: Sand introduction and sometimes substitution of one
Size Range: 1/16 to 2 mm mineral for another of both grains and cement.
Rock Name: Sandstone10
Stone Abbreviation: Sst. 3.17 Cementing Minerals. The
common cementing minerals of clastic
3.14.5 Particle Name: Silt sedimentary stone in order of hardness and
Size Range: 1/256 to 1/16 mm desirability are the following:
Rock Name: Siltstone
Stone Abbreviation: Sltst. 3.17.1 Silica: Either hydrous or
crystalline, both types are hard and relatively
insoluble.

9 Particle names are simply names for a defined grain sandstone is generally regarded as “quartz” sandstone.
size. They do not suggest the mineralogical content Quartz is among the longest-lasting minerals in the
unless a mineral name precedes the particle name as a environment, resisting chemical degradation and
modifier. abrasion.
10Although sand-sized grains can be from any rock
fragment and one or more of several minerals,

© 2022 Natural Stone Institute The Geology of Stone • Page 1-5

3.17.2 Carbonate: Even though calcite is fossiliferous limestone, which is not strictly a
soluble in dilute acids like rain, it is a good chemical sedimentary stone (see the Travertine
cement, and much clastic sedimentary stone is chapter).
cemented with calcite and/or a mixture of
calcite and silica cements. Other carbonates 3.18.1 Salt, anhydrite, and gypsum form in
may be less soluble, but these are rare as other marine settings such as the Red Sea,
cements. which has very wide tidal flats in a hot climate
that promotes evaporation and precipitation.
3.17.3 Iron Oxides: These are fairly Even the Mediterranean Sea was a closed basin
common as clastic cements, but tend to be millions of years ago in which thick evaporates
softer and bleed ugly stain. Although some formed similar to those now found in the Dead
excellent sandstones are red to red-brown Sea.
from some iron cement and stained quartz
grains, the better brownstones may have silica 3.19 Metamorphic Stone. Many of the
cements, making them truly excellent, highly most colorful, highly figured, and beautiful
colored stones. dimension stones are the result of
metamorphic processes. The popularity of
3.17.4 Clay Minerals: These are generally these spectacular stones has encouraged the
considered a rather poor cementing medium. exploration for the new types of stone that
Even though clay cemented stone may appear frequently appear in the market. Metamorphic
well-cemented, the clay cement is soft, weak, processes are capable of producing stone in a
easily crushed, and readily removed by water. color palette and textural complexity that
rivals that of igneous and sedimentary
3.17.5 Other mineral cements may be processes.
found from time to time, but are rare.
3.19.1 Metamorphic stone makes up a large
3.17.6 All of the cementing minerals part of all continents, is exposed on all
mentioned in this section, plus some other rare continents, and is found deep beneath the
mineral cements, can combine in various relatively flat areas of continents thickly
mixtures that will bond stone satisfactorily. covered by sedimentary rocks, such as the U.S.
Midwest. It makes up the core areas of
3.18 Chemical Sedimentary Stone. continents. For example, the ancient, complex
This class of sedimentary stone precipitates metamorphics of the Canadian Shield in
from chemically dense bodies of water such as northern Canada comprise the core of the
the Great Salt Lake, the Dead Sea, and other North American continent. The root areas of
closed marine basins lacking outlets. Salt-laden many mountain chains such as the Himalayas,
water flows in and evaporation constantly Rockies, and Urals are the same type of
increases the salt content until precipitation strongly metamorphosed rock that underlies
takes place. Common building stones that are the central Midwest from Ohio to Illinois.
chemical precipitates include travertines
(CaCO3), onyx (CaCO3), alabaster (CaSO4), 3.19.2 Metamorphic stones are among the
and cherts such as flint, jasper, and agate. Chert most interesting of Earth’s products, for they
is a sedimentary deposit of hydrous silica are the only direct evidence of major
(SiO2∙nH2O). The popular dimension stones catastrophic events in the history of the Earth’s
travertine and onyx are chemical crust. Some of this stone is up to 3.8 billion
precipitates of mostly limestone or calcium years old, and has changed in its long existence
carbonate (CaCO3) deposited around ground from igneous to sedimentary to metamorphic.
springs, in caves, or springs in bodies of saline
water, although some travertine is actually

Page 1-6 • The Geology of Stone © 2022 Natural Stone Institute

3.19.3 Any deeply buried, existing stone– 4.4 Two great energy sources drive the rock
igneous, sedimentary or metamorphic–may be cycle: the sun, and the heat from the Earth’s
subjected to forces that cause profound interior generated from the decay of
mechanical, textural, and ultimately, chemical radioactive materials. The sun heats the Earth’s
changes in the mineral content. gaseous atmosphere, driving the weather
Metamorphosed stone may or may not patterns that cause weathering and erosion of
resemble its parent stone. Metamorphism is any exposed or nearly exposed rock —the
caused by regional-scale crustal movements beginning of the sedimentary cycle. Biological
and mountain-building forces, or by local activity on the Earth’s surface, and to some
crustal disturbance, at temperatures about depth beneath it, also interacts with the
200ºC to near-melting, ≈700-800ºC, and chemical processes affecting stone.
pressures from around 450,000 pounds per
square inch (psi) to several million psi in the 4.5 The rock cycle has been going on
presence of chemically charged aqueous fluids continuously for much of the Earth’s 4.5 billion
through time. years. Some zircon grains (zirconium silicate,
ZrSiO4) from an Australian sandstone have
3.19.4 Metamorphic rock produced from been through the rock cycle five times,
widely variable conditions yields three distinct covering more than 3.9 billion years.
grades of metamorphism, from low-grade Continuous cycling through the multiple
through medium- to high-grade metamorphic processes, mechanical and chemical, serves to
rock, each characterized by specific stone chemically and mineralogically differentiate
colors, textures, and mineral content. Stone of stone; thus, the rock cycle allows continental
all metamorphic grades can be found as stone to develop into the wide range of colors
beautiful dimension stone of many types, and varieties of beautiful dimension stone that
including slate, quartzite, marble, and have been used by mankind throughout
serpentine. history.

4.0 THE ROCK CYCLE

4.1 Basic processes and relationships

inherent in the geological concept known as
“the rock cycle” help to understand the variety
and complexity of stone.

4.2 As shown in the rock cycle

illustration on the following page, the curved
arrows at each stone type indicate that a new
igneous, metamorphic, or sedimentary stone
can be developed from an existing stone by a
repetition of melting and metamorphism, or by
the weathering, transportation, deposition,
compaction, and cementation processes.

4.3 The straight arrows from one stone type

to another show that any of the three basic
types of stone can be produced from an existing
stone of one of the other types.

© 2022 Natural Stone Institute The Geology of Stone • Page 1-7

 THE ROCK CYCLE

SEDIMENTARY Solar
Rocks Heating
SEDIMENTARY
Rocks
BIOLOGIC LIFE ZONE

IGNEOUS METAMORPHIC
Hi Pressure
(Melting)
Heat
Heat from
from
decay
Decay of of
Radioactive Isotopes
Radioactive Isotopes © ccr.03

The geological concept of the rock cycle illustrates that new igneous, metamorphic, or sedimentary
stone can form from existing stone of another type through the repetition of natural processes.

NOTES:
Each Material chapter has a section that further
details geological information about that
specific stone.

Page 1-8 • The Geology of Stone © 2022 Natural Stone Institute

STANDARDS AND 2.0 WHY ASTM STANDARDS
SPECIFICATIONS FOR AND OTHER LIKE STANDARDS
STONE PRODUCTS ARE IMPORTANT

1.0 ORGANIZATIONS 2.1 In today’s building environment, the

emphasis is on safe, permanent, low
1.1 ASTM International maintenance products, of which stone leads the
100 Barr Harbor Drive list in the minds of architects, designers, and
West Conshohocken, PA 19428-2959 U.S.A. consumers worldwide.
Telephone: 610.832.9585
Fax: 610.832.9555 2.2 Without a consistent, realistic set of
www.astm.org standards and testing procedures for stone
European Office: products, the stone industry as a whole would
Telephone: 146.243.7933 be in disarray. The standards that have been
Fax: 146.243.3678 developed and set in place for these products
are important tools to help protect end users,
1.2 American National Standards individual companies, and the industry from
Institute (ANSI) negative effects related to product failures.
25 West 43rd Street, 4th Floor Materials standards help to prevent the use of
New York, NY 10036 U.S.A. stone products for unsuitable applications. For
Telephone: 212.642.4900 instance, without the minimum standards for
Fax: 212.398.0023 Abrasion Resistance of Stone Subjected to Foot
www.ansi.org Traffic (ASTM C241), it would be more likely
that very soft, easily damaged materials would
1.3 NSF International be installed in commercial applications. This
P.O. Box 130140 may cause the owner to incur additional cost
789 N. Dixboro Road for repair and maintenance, and negatively
Ann Arbor, MI 48113-0140 U.S.A. affect the reputation of the stone industry as a
Telephone: 734.769.8010 whole.
Fax: 734.769.0109
www.nsf.org 2.3 These standards also serve as
European Office: benchmarks for quality limits of products. If a
Kleine Kloosterstraat 6 stone with a below-minimum flexural strength
1932 Zaventem is used for a lintel, then it may be more likely
Belgium to fail, thus causing damage and possible injury.
Telephone: 32.2.771.36.54 Interior or exterior flooring or paving with an
Fax: 32.2.763.00.13 inadequate slip resistance level will more likely
cause slipping accidents in public or private
1.4 European Commission for projects.
Standardization (CEN)
36 rue de Stassart 3.0 HOW AND WHEN THESE
B-1050 Brussels STANDARDS APPLY
Belgium
Telephone: 32.2.550.08.11 3.1 As stone industry professionals, it is our
Fax: 32.2.550.08.19 task to apply the correct standards to materials
www.cenorm.be at appropriate times in order to keep the stone
industry strong and to remain a reliable source
of quality products.

© 2022 Natural Stone Institute Standards and Specifications for Stone Products • Page 2-1
3.2 Most architectural specifications require testing is not available, require that it be done
that stone meet certain specified ASTM or or avoid the product’s use.
other testing standards before it will be
accepted for use. Some products on the market 4.0 ASTM INTERNATIONAL
today have not been tested for quality standards
that are required for certain projects. The 4.1 The American Society for Testing and
required testing should be reviewed and, if test Materials International (ASTM), founded in
results are not available for the stone product, 1898, is a not-for-profit organization that
then testing should be performed by the quarry provides a global forum for the development
or representative company as required. Some and publication of voluntary consensus
quarries and their representatives do not standards for materials, products, systems, and
embrace this idea because their products can be services. Over 30,000 individuals from 100
marketed to homeowners and residential nations are the members of ASTM
projects without the need to perform testing. International, who are producers, users,
It is up to our industry to know how to identify consumers, and general interest parties such as
these products and make sure to request the government representatives and academicians.
required material data needed.
4.2 Committees are established that focus
3.3 Testing of stone can be performed by on and have jurisdiction over standards for
other companies in the event that required test different designations, such as Dimension
data are not available. Independent labs can Stone (Committee C18) or Cement
perform the appropriate tests and provide the (Committee C01). These committees are
information in a well organized, professional made up of several subcommittees which are
report. tasked to develop and discuss individual
segments within the committee’s jurisdiction.
3.4 It is important to know when a certain For example, one subcommittee may deal with
test is not required for a product. For example, the development of standards dealing with Test
a test for Slip Resistance would not be Methods of Dimension Stone, and another with
necessary for stone used in a vertical Anchorage Components and Systems for
application, which will never receive foot Natural Stone. These committees meet on a
traffic. Some examples are not as easily regular basis to discuss and present information
established. For instance, what are the needs for each new or existing standard.
for testing a stone to be used for interior
flooring in a commercial application where the 4.3 The entire membership of ASTM
stone is installed over a raised floor deck International votes on whether a standard is
subject to deflection, and will be subject to suitably developed and researched before it is
traffic from pedestrians and cleaning carts forwarded for final approval. Negative votes
weighing 1,000 pounds? It may be required cast during the balloting process are fully
that the stone of choice meets standards related resolved before forwarding.
to Slip Resistance, Abrasion Resistance,
Absorption, Compressive Strength, and 4.4 Companies, agencies, and individuals
Bending Strength. These are all physical use ASTM standards. Buyers and sellers of
requirements of the stone product during materials, products, and services include these
everyday use. standards in contracts; engineers, scientists,
architects, and designers use them in their
3.5 Be aware of the requirements of work; government agencies reference them in
performance that will be placed on the stone at codes and regulations; and many others refer to
the time of installation, and in the future. If a them for performance information.
stone has proven not to perform for a particular
use, then avoid marketing it for that use. If

Page 2-2 • Standards and Specifications for Stone Products © 2022 Natural Stone Institute
4.5 ASTM International is recognized (IEC). In many instances, U.S. standards are
globally and continues to review and develop taken forward to ISO and IEC through ANSI or
new standards needed in a wide range of the USNC, where they are adopted in whole or
materials. in part as international standards.

5.0 ANSI 6.0 NSF INTERNATIONAL

5.1 The American National Standards 6.1 NSF International, formerly the
Institute (ANSI), founded in 1918 by five National Sanitation Foundation, is a not-for-
engineering societies and three government profit, non-governmental organization that
agencies, is a private, not-for-profit provides standards, certification, education,
organization that administers and coordinates and risk management services in the fields of
U.S. voluntary standards and conformity public health safety and the environment. NSF
assessment activities. The Institute represents was founded in 1944 in response to a need for
the interests of its nearly 1,000 company, a single set of food equipment sanitation
organization, government agency, standards that manufacturers and operators
institutional, and international members could accept and regulators could adopt into
through its office in New York City and its code. NSF has 21 standards for all types of
headquarters in Washington, D.C. products and materials used in food service.
The standards contain requirements for
5.2 ANSI currently provides a forum for materials, design, construction, and
over 270 ANSI-accredited standards performance of food service equipment to
developers representing approximately 200 ensure that it is safe and can be kept sanitary.
distinct organizations in the private and public Today, NSF Food Equipment Standards are
sectors. These groups work cooperatively to globally recognized, and certification to the
develop voluntary national consensus standards standards is required by regulators, specified
and American National Standards (ANS). by end users, and marketed by manufacturers.

5.3 The ANSI standardization process 6.2 NSF Material Requirements –

provides and promotes standards that Standard 51. An important component of the
withstand scrutiny, yet protect the rights and NSF Food Equipment Standards is the material
interests of all participants. This process helps requirements. While each standard can have
quicken the market acceptance of products, its own unique material requirements, all food
while advising how to improve the safety of equipment standards reference NSF/ANSI
those products to protect consumers. Standard 51-2002, Food Equipment Materials.
The material require-ments help to ensure that
5.4 U.S. standards are promoted only nontoxic and cleanable materials are used.
internationally by ANSI. The organization also Material suppliers have utilized NSF
advocates U.S. policy and technical positions in Certification to Standard 51 as an effective
international and regional standards method for marketing their products to food
organizations, as well as supporting the equipment manufacturers. Manufacturers who
acceptance of international standards as U.S. purchase NSF-certified materials have one less
standards where they meet the needs of the item of concern when getting their own
user community. equipment certified.

5.5 The Institute is active internationally 6.3 Applying Standard 51 to Natural

with the International Organization for Stone. When reviewing granite, marble, and
Standardization (ISO), and, via the U.S. other natural stones to the requirements of
National Committee (USNC), the Standard 51, there are essentially two issues
International Electrotechnical Commission
© 2022 Natural Stone Institute Standards and Specifications for Stone Products • Page 2-3
that can determine its acceptance: smoothness 7.0 ASTM SPECIFICATIONS
and toxicity. AND STANDARDS
6.4 Smoothness. The standard defines 7.1 Material Specifications
“smooth” as free of surface imperfections that
are detectable by visual or tactile inspection. 7.1.1 ASTM C503, Standard Specification for
This includes pits, cracks, and crevices. This Marble Dimension Stone
concern for smooth surfaces applies not only to
the natural surface, but also the treatments 7.1.2 ASTM C568, Standard Specification for
used to make a surface smooth. Application of Limestone Dimension Stone
a coating is sometimes considered a way of
addressing smoothness; however, coatings 7.1.3 ASTM C615, Standard Specification for
have a tendency to chip or flake over time, thus Granite Dimension Stone
creating their own difficult-to-clean surface.
As a result, there is a prohibition on the use of 7.1.4 ASTM C616, Standard Specification for
coatings for surfaces subjected to cutting and Quartz-Based Dimension Stone
chopping actions, such as countertops and
cutting boards. It is important to note that this 7.1.5 ASTM C629, Standard Specification for
prohibition would not necessarily apply to all Slate Dimension Stone
surface treatments the natural stone industry
might use. Sealers that are buffed off to the 7.1.6 ASTM C1526, Standard Specification
point where they only remain to fill surface for Serpentine Dimension Stone
imperfections are not considered a “coating”
for the purposes of NSF standards, and could 7.1.7 ASTM C1527, Standard Specification
potentially be used on countertops and cutting for Travertine Dimension Stone
boards.
7.2 Test Standards
6.5 Toxicity. Standard 51 requires that
materials meet FDA regulations for their 7.2.1 ASTM C97, Standard Test Method for
intended end use, as specified in the Code of Absorption and Bulk Specific Gravity of
Federal Regulations, Title 21 (21 CFR). Dimension Stone
Applying Standard 51 toxicity requirements to
the stone is fairly easy. Because natural stone 7.2.2 ASTM C99, Standard Test Method for
does not fall under the scope of 21 CFR, we Modulus of Rupture of Dimension Stone
simply conduct extraction testing to verify that
the material does not contain any regulated 7.2.3 ASTM C120, Standard Test Method of
heavy metals. When sealers are used, NSF Flexure Testing of Slate (Modulus of Rupture,
must have verification from the sealant Modulus of Elasticity)
manufacturer that it meets 21 CFR. An
alternative is that the sealant manufacturer can 7.2.4 ASTM C121, Standard Test Method for
obtain an NSF certification. Water Absorption of Slate
Copies of each standard can be obtained online 7.2.5 ASTM C170, Standard Test Method for
or by fax from the source. Compressive Strength of Dimension Stone

7.2.6 ASTM C217, Standard Test Method for

Weather Resistance of Slate

Page 2-4 • Standards and Specifications for Stone Products © 2022 Natural Stone Institute
7.2.7 ASTM C241, Standard Test Method 7.3.7 ASTM C144, Standard Specification
for Abrasion Resistance of Stone Subjected to for Aggregate for Masonry Mortar
Foot Traffic
7.3.8 ASTM C150, Standard Specification
7.2.8 ASTM C880, Standard Test Method for Portland Cement
for Flexural Strength of Dimension Stone
7.3.9 ASTM C207, Standard Specification
7.2.9 ASTM C1201, Standard Test for Hydrated Lime for Masonry Purposes
Method for Structural Performance of Exterior
Dimension Stone Cladding Systems by 7.3.10 ASTM C270, Standard Specification
Uniform Static Air Pressure Difference for Mortar for Unit Masonry

7.2.10 ASTM C1352, Standard Test 7.3.11 ASTM C482, Standard Test Method
Method for Flexural Modulus of Elasticity of for Bond Strength of Ceramic Tile to Portland
Dimension Stone Cement Paste

7.2.11 ASTM C1353, Standard Test 7.3.12 ASTM C630/C630M, Standard

Method for Abrasion Resistance of Dimension Specification for Water-Resistant Gypsum
Stone Subjected to Foot Traffic Using a Rotary Backer Board (Withdrawn 2005). Replaced by
Platform Abraser C1396/C1396M.

7.2.12 ASTM C1354, Standard Test 7.3.13 ASTM C920, Standard Specification
Method for Strength of Individual Stone for Elastomeric Joint Sealants
Anchorages in Dimension Stone
7.3.14 ASTM C1242, Standard Guide for
7.3 Other Application Standards Selection, Design, and Installation of Exterior
Dimension Stone Anchors and Anchoring
7.3.1 ASTM Manual Series: MNL 21. Systems
Modern Stone Cladding: Design and
Installation of Exterior Dimension Stone 7.3.15 ASTM C1515, Standard Guide for
Systems. 1995. Cleaning of Exterior Dimension Stone,
Vertical and Horizontal Surfaces, New or
7.3.2 ASTM A666, Standard Specification Existing
for Annealed or Cold-Worked Austenitic
Stainless Steel Sheet, Strip, Plate, and Flat Bar 7.3.16 ASTM C1528, Standard Guide for
Selection of Dimension Stone for Exterior Use
7.3.3 ASTM B221, Standard Specification
for Aluminum and Aluminum-Alloy Extruded 7.3.17 ASTM C1721, Standard Guide for
Bars, Rods, Wire, Profiles, and Tubes Petrographic Examination of Dimension Stone

7.3.4 ASTM C36/C36M, Standard 7.3.18 ASTM C1722, Standard Guide for
Specification for Gypsum Wallboard Repair and Restoration of Dimension Stone
(Withdrawn 2005). Replaced by
C1396/C1396M. 7.3.19 ASTM E72, Standard Test Methods
of Conducting Strength Test of Panels for
7.3.5 ASTM C91, Standard Specification Building Construction
for Masonry Cement
7.3.20 ASTM E119, Standard Test Methods
7.3.6 ASTM C119, Standard Terminology for Fire Test for Building Construction
Relating to Dimension Stone

© 2022 Natural Stone Institute Standards and Specifications for Stone Products • Page 2-5
7.3.21 ASTM E575, Standard Practice for
Reporting Data from Structural Tests of
Building Constructions, Elements,
Connections, and Assemblies

7.4 ANSI Specifications and Standards

7.4.1 ANSI A10.20, Safety Requirements

for Ceramic Tile, Terrazzo and Marble Work

7.4.2 ANSI A108, Standards for

Installation of Ceramic Tile

7.4.3 ANSI A118, Specifications for

Mortars and Grouts

7.4.4 ANSI A326.3, Method for

Measuring Dynamic Coefficient of Friction of
Hard Surface Flooring Materials.

7.5 NSF/ANSI Specifications and

Standards

7.5.1 NSF/ANSI Standard 51, Food

Equipment Materials

7.6 CEN Specifications and

Standards

7.6.1 CEN specifications and standards are

in the process of being compiled. This
information will be available at a later date.
All standards and specifications are revised or
updated periodically. The current status of any
standard or specification can be confirmed by
contacting the proper authority.

Page 2-6 • Standards and Specifications for Stone Products © 2022 Natural Stone Institute
Dimension STONE there are several significant influencing factors.
Among them are aesthetics, color, strength,
SELECTION durability, design, texture, finish, size,
thickness, availability, stone testing, stone
1.0 INTRODUCTION sampling, and cost. The effects any of these
factors may have on another can influence the
1.1 Stone Selection Options. Architects final choice. But aesthetic considerations
and builders throughout the ages have chosen nearly always drive the selection process.
stone for its permanence and beauty. Where
selection was once limited mainly to what was 2.0 AESTHETICS &
locally available, today’s stone marketplace is APPEARANCE
virtually worldwide. With the broad and
growing array of options, the stone selection 2.1 Factors beyond Appearance. A
process has become more complex under the palette of colors and a variety of textures
weight of multiple considerations. provide ready options in the aesthetic choices
among dimension stones. Yet, as the following
1.2 Stone Is A Product Of Nature. pages suggest, it is advisable to examine and
Dimension stone has its own unique qualities apply other factors that may recommend
that not only distinguish it from man-made alternatives to a selection based purely upon
materials, but also should be considered in aesthetic appeal, particularly on exterior
selecting it for a particular project. Stone is not applications. A stone that is most desirable in
manufactured; it is a product of nature. Blocks appearance, for example, may lack needed
are removed from the quarry, slabs are cut strength or durability for a particular
from these blocks, and the slabs are further application.
fabricated into the final stone to be installed.
Each block is different; each slab is different. 2.2 Exterior Cautions. The cautions
Skillful blending or matching of the dimension regarding exterior applications are of far less
stone blocks, veneer panels, tops, etc., results concern when considering interior
in a beautiful blending of nature’s variety and installations. Aesthetics can be allowed much
man’s design. In contrast to the uniformity of freer rein for stone that is not subjected to the
materials produced by machine or assembly elements.
line, dimension stone’s naturally varied
appearance has wonderful character. 2.3 Variegated or veined materials,
“Uniformity of material,” when applied to especially marbles, that offer interesting colors
natural stone, is a term of relative value that and patterns and that are by their nature
needs to be understood when making a “faulted” and not generally suitable for exterior
selection. use are often highly valued for their decorative
qualities in interior installations.
1.3 Exterior vs. Interior Installations.
The factors to be weighed in selection may not 2.4 Translucence occurs in some white or
be equally applicable to exterior and interior very lightly colored marbles and onyxes having
installations. The following discussion is a crystal structure that will transmit light to
therefore divided, as appropriate, between varying degrees depending upon stone
exterior and interior uses if the factors do not thickness and finish. Translucence can be an
readily apply to both. aesthetically intriguing decorative attribute.
1.4 Selection Influencers. While any 2.5 Sample Variations. Assuming that all
number of stipulations may direct selection of critical factors support the desired choice in a
a particular stone for a specific application, given application, expectations as to final

© 2022 Natural Stone Institute Dimension Stone Selection • Page 3-1

appearance must be realistic. Unless a choice is 2.9.3.1 Flamed or Thermal: Plane surface
made and marked on an actual slab, variation with flame finish applied at high temperature
from a submitted sample is a fact and should by mechanically controlled means to ensure
not come as a surprise. uniformity; changes the color of the stone.

2.6 Fleuri Cut Stones. Many dimension 2.9.3.2 Water-jet Flamed Finish: Gives a
stones today are being cross cut or fleuri cut. more uniform, textured finish and allows more
This is true in travertines and some granites, of the natural color to show.
for example. Many times, the reason this is
done is to avoid a directional vein and achieve 2.9.3.3 Sandblasted: Coarse plane surface
a more “cloudlike” effect. In any case, the produced by blasting an abrasive, allowing a
Specifier and the Stone Supplier should know if fine-textured finish; may lighten the color.
this is done and investigate the test data, as it
may change from normal, conventional means. 2.9.3.4 Bush-hammered: Coarsely
See illustration at the close of chapter 7. textured surface produced by hammering, and
may vary according to the metallic head used,
2.7 Filling Might Be Required. Another from fine point to very coarse, and may leave
issue is where cross cut (fleuri cut) stones are high, lighter-colored markings.
used. As in the case of travertine, a limestone,
it may require filling with cement or epoxy, 2.9.3.5 Natural Cleft: A cleavage face
which may or may not hold up under heavy formed when the stone is split into any
traffic conditions, and the fills may come out. thickness.

2.8 Choosing a Finish. Choosing the 2.9.3.6 Picked, Hand-hewn Rock Face:
manner in which stone will be finished is an Using a chisel or other metallic object that
integral part of the selection process. Finish gives deeper indentations and cleavage to the
can be anything from saw cut to high polish. A stone.
high polish will bring out the color of the stone
to its fullest, because it will optimally reflect 2.9.3.7 Sawn: Usually refers to slabs
the light. Conversely, a textured finish will coming from a gang saw, with blades that are
always appear lighter. A combination of applied to the block of stone using water and
finishes can add interest to a chosen stone. New fine grit.
finishes are appearing on the market yearly, so
check and investigate all finishes available with 2.9.3.8 Gauged: Done by a machine,
your Stone Supplier. usually with circular abrasives to grind the
material to a specific thickness.
2.9 Finishes commonly available are:
2.9.3.9 Planed: Usually refers to slate,
2.9.1 Polished: Mirror gloss, with sharp where a metallic scraper peels a layer of stone,
reflections. making the stone flat and smoother.

2.9.2 Honed: Dull sheen, without re- 2.9.3.10 Acid Washed: Usually applied to a
flections, achieved by abrasive heads. The sawn finish to lower the degree of sawn marks
degree of honing depends on the stone, but showing, yet maintain a natural textured finish.
may vary from light to heavy.
2.9.3.11 Tumbled: Method of putting tiles
2.9.3 Fine Rubbed: Smooth and free in a mixing container with sand and rotating
from scratches; no sheen. them, allowing the edges and corners of the
tiles to chip.

Page 3-2 • Dimension Stone Selection © 2022 Natural Stone Institute

NOTE: Many new finishes are being applied to boxes during the installation to achieve a more
stone as the market demand increases and new even, visually pleasing result in the finished
uses for stone are being conceived. In some surface.
productions, combinations of finishes on the
same stone are being made. Check with the 3.5 Matched-vein Patterns. In contrast
Supplier to verify the finish and how it was to modular tiles, panels cut from the slab
made in order to specify properly. usually will give the best results aesthetically.
There are different ways that veined dimension
3.0 DESIGNING WITH stones or other stones can be matched to form
DIMENSION STONE a pattern, and stones must be of types that lend
themselves to specific pattern arrangement.
3.1 Design Considerations are nearly Patterned and matched panels require that the
equal among the factors of aesthetics, strength material be selected and thus, often increases
and durability. This is particularly true of the cost of the stone. See diagrams at the close
interior applications. The imagination of of chapter 7 for a detailed description of vein
Designers is boundless, and it is the Fabricator patterns.
or Supplier who must counsel the design
professionals as to what is feasible and what is 3.6 Mixing Types of Materials. Designs
not. Stone is not a plastic material. It is rigid calling for a mixture of stones with different
and breakable when handled in fabrication. physical properties, while aesthetically
interesting, can give rise to problems of wear
3.2 Yield. Before making final selection of and of maintenance, mainly on floor areas. Re-
a stone, particularly on a larger project, take polishing will pose problems, should that need
wastage into account to make certain there will arise. The Specifier should be aware that
be enough material to complete the project. mixing types of stones means there will be
An often-forgotten fact is that the material different abrasion resistance levels as well as
from a quarry today may be different from different densities of stones that must be
what was available six months ago. Further, considered in the long-term maintenance of the
there may be more than one quarry of the stone and its wearability.
material. The criteria of the Producer to select
stone also vary from quarry to quarry. 4.0 EXTERIOR APPLICATIONS

3.3 Modular Stone Tiles. For ease and 4.1 Strength. A most important concern
economy, modular stone tiles offer a good when selecting stone is strength. This is
alternative to stone panels for walls and level particularly true in cases of exterior stone
floors. Thin stone tiles, varying in thickness cladding for buildings over two stories high.
from 1 cm to 1.5 cm, are available in modular Strength in those situations should be the
sizes of 12" x 12" (300 mm x 300 mm), 16" x determining factor in the final selection of the
16" (400 mm x 400 mm), 18" x 18" (450 mm stone.
x 450 mm), and other sizes, up to a maximum 4.2 Exterior Stone Stresses. Exterior
of 24" x 24" (600 mm x 600 mm). The proper stones must be able to withstand the stresses
tile thickness for the installation will depend that will be imposed upon them, such as the
upon the stone type selected and the modular following:
size of the tile specified.
4.2.1 Gravity load, which must be borne by
3.4 Mixing Tiles. The final look of mixed the anchorage system.
tiles may fall short of appearance expectations,
especially if the stone is variegated and veined. 4.2.2 Windload, which exerts both positive
The Installer should mix tiles from different and negative pressure on the panels and is

© 2022 Natural Stone Institute Dimension Stone Selection • Page 3-3

typically higher at building corners and other porosity is important, as well as the density of
areas of discontinuity. the stone. The finish applied to the stone will
be a factor in the slip resistance specified for the
4.2.3 Water vapor, which must be released area.
to prevent condensation and efflorescence
problems. 4.5 Durability. For durability, exterior
stone should be free from structural defects
4.2.4 Freeze/thaw cycles, which can cause and varying characteristics of vein structure,
stone to crack and joints to fail. scaling planes, hairline cracks, earthly parts,
and cavities. Panel dimensions should be
4.2.5 Structural contraction, which controlled in size for optimal results.
occurs during the curing stage of the concrete.
4.6 Granites have been historically favored
4.2.6 Creep, or permanent structural for exterior use. Their composition makes
distortion, which takes place progressively them both resistant and stable, and surfaces
over the years until the structure has settled. will hold a high polish longer. As a rule,
weaker stones require greater and more costly
4.2.7 Elastic distortion, which is caused by reinforcement.
movement produced by load charges on the
structure. 4.7 In dry and temperate climates,
softer stones like limestones can also be used
4.2.8 Thermal expansion and successfully in thicknesses appropriate to the
contraction, which affects stone and other job. However, exteriors of gray or black
structural elements limestones with a bituminous or carbon
composition should be avoided because the
4.2.9 Absorption or porosity of the stone action of atmospheric agents will rapidly cause
is a factor, as it will affect the durability and life the surface to deteriorate. Other stones
of the stone, as well as its appearance. considered inappropriate are the ophicalcites
and the breccia in general, as well as all stone
Note: The durability of the installation method containing pyrites, which may produce rust
for walls is determined by the substrate it is spots when exposed to air and moisture.
being applied to and the anchoring method
being used. Consult an engineer to evaluate all 5.0 INTERIOR APPLICATIONS
installation issues.
5.1 Selection Criteria. The fact that
4.3 Test Data. Where structural capability interior stone is sheltered from the action of
is critical, test data for compressive strength, the elements makes all types of stone, from the
flexural strength, modulus of elasticity, and hardest granite to the softest limestone,
sheer strength should be studied. Where suitable for application. Criteria for the
weather is a factor, absorption, porosity, and selection of interior stone for both commercial
permeability studies should be made. and residential projects tend to be similar.
Freeze/thaw compressive strength testing Selection considerations focus on whether the
should also be carried out. For walls, the type application will be on vertical or horizontal
of anchoring, and performing an anchorage planes.
pull-out test, are important.
5.2 Interior Vertical Surfaces. Nearly
4.4 High-traffic Floor Areas. For high- any stone may be chosen for interior cladding
traffic floor areas, abrasive hardness testing of commercial buildings. Practical
should be a requisite. The absorption or considerations for highly used areas, however,

Page 3-4 • Dimension Stone Selection © 2022 Natural Stone Institute

lead to stones that are dense, resistant, and 5.7 In light-volume traffic and
easily maintained. These prove to be the best residential areas, where problems of etching,
choice when aiming for a long-term scratching, and staining are minimal, it is quite
investment. acceptable to make a selection based mainly on
aesthetics and choose a highly polished floor if
5.3 Water Resistance. The action of desired. In all cases, proper maintenance must
water in areas such as fountains and showers is be done.
a factor to be reckoned with. Stones must be
able to withstand frequent or continuous water 5.8 Countertops. Stones for kitchen and
projections, and in the case of showers, the lavatory tops should be chosen with regard to
presence of hot steam. Again, the best results functionality. Foods and their handling will
are obtained with a dense, resistant stone, such affect long-term appearance as acids and grease
as a granite, or a compact stone with a low come in contact with the surface. Not all stones
absorption coefficient. The action of water on are resistant to staining; therefore, selection
polished marble or limestone might cause should be carefully considered. In all cases and
surface dulling, spalling, warpage, or regardless of the type of stone, spills should be
deterioration of stone over time. wiped up immediately and cutting knives not
used directly on the surfaces. There are also
5.4 Interior Horizontal Surfaces. nontoxic sealers (necessary in food preparation
Traffic is obviously a major consideration in areas) that can improve the performance of a
selecting floor stone, whether for heavy, stone to a great degree.
medium, or light duty. In heavy-traffic
situations, floors need to withstand vehicles or 5.9 Lavatory Tops. As a rule, lavatory
carts, stiletto heels, mud and sand, salting tops in residential bathrooms can be chosen
compounds, spilled high-acidity liquids, and according to taste, since the surface receives
other pollutants and indignities. little abuse other than pollutants that might be
contained in cosmetics.
5.5 Heavy-volume traffic and abuse
require stone of maximum resistance–granite, 5.10 MIA Statement of Position on
quartzite, or highly compact marble, Sealing Natural Stone Countertops.
depending on the degree of punishment it must Most granite countertops do not need to be
take. Testing for hardness as measured by sealed. Before 1995 there were very few
ASTM C241 or C1353 and discussed quality penetrating sealers on the market and
elsewhere in this manual can help in the there were very few cases of staining. Both
selection process. prior to and after the availability of penetrating
sealers, no cases of food poisoning, radon, or
5.6 For medium-volume traffic, stones food preparation issues associated with treated
can be somewhat softer. Many dimension or untreated granites have been reported. If a
stones will perform well, if properly homeowner cleans their countertops after each
maintained. There are good methods and meal, they will rarely, if ever, have staining or
maintenance products available to preserve the cleanability issues with granite. All this being
stone’s appearance. Generally, it is said, many granite countertops receive
recommended that a dimension stone floor additional benefit from being sealed. That
receive a honed rather than a highly polished benefit is the further reduction of moisture
finish in commercial applications. Etching, migration into an already moisture resistant
scratching, and traffic paths will be far less surface.
obvious on a honed surface, thus making for
easier maintenance. Should natural stone counters be sealed? In
many cases it makes sense to seal marble and

© 2022 Natural Stone Institute Dimension Stone Selection • Page 3-5

granite countertops with a quality sealer. The historical data is sufficient on small jobs, but on
product should have a life expectancy of ten to larger jobs historical test data should only be
fifteen years and be of an oliophobic (resistant taken as indicative, and new tests should be run
to water and oil based stains) nature. Once on the specific stone from the specific quarry to
properly sealed, the stone will be more be used.
resistant against everyday dirt and spills.
7.0 SAMPLING
In today’s natural stone industry, many species
of granite receive a resin treatment at the 7.1 Stone Samples and Mockups.
factory where the blocks of granite are cut into Preparation and supply of dimension stone
slabs and then polished. The treatment is used samples and mockups are often expensive and
to fill microfissures, indentations and other time-consuming, but an essential part of stone
minor characteristics that are found in many projects. Samples and mockups help ensure
natural stones. The reason for the resin that materials meet contract requirements.
treatment is to address what most consumers
consider as imperfections, but in reality are 7.2 Promotional samples are for color
“birth marks.” The consuming public gravitates consideration only, but must be representative
to perfection, defined as no “birth marks,” and of the color and finish being proposed for use.
so the marble and granite industry tries to They should be supplied in small sizes, such as
fulfill the desire. Both resined as well as 3" x 4" (75 mm x 100 mm), 4" x 6" (100 mm
unresined slabs will outlast most of our x 150 mm), or 6" x 6" (150 mm x 150 mm).
lifetimes. Granite should, and in most cases
will, be the last countertop surface a person 7.3 Project samples should be 1' x 1' (300
will buy, providing a strong return on mm x 300 mm) in size or larger. Care must be
investment. The bottom line: Sealing resin taken to select samples that accurately reflect
treated countertops may increase the resistance the shades, markings, and anticipated ranges of
of the already resistant nature of stone color, texture, finish, veining, filling, and
(adopted 11/8/06). other characteristics of the variety of stones
specified.
6.0 TESTING FOR PHYSICAL
PROPERTIES 7.4 Large Projects. For very large
projects, multiple samples are needed in order
6.1 ASTM Tests. Stone is tested under a to show the range of variations. These are
rigorous set of standards developed by the normally assembled by selecting from the
ASTM International, the world’s largest blocks that best meet the requirements at that
voluntary standards development organization. point in time. Sometimes visits to the quarries
become a necessary step in the selection
6.2 Purpose of Tests. The tests apply process. Selecting slabs to be cut for the
standard methods to uniformly evaluate stone project is necessary to see the overall variation
characteristics and performance. ASTM of the stone and finish to be used. In all cases,
standards are the recommended guidelines for availability of the material should be secured.
installation in the stone industry. See Chapter
2 for more information about this organization 7.5 Number of Samples. The number of
and a list of ASTM specifications and standards. sample submissions required on a specific
project depends primarily on the amount and
6.3 Original Test Data. The Specifier has particular use of the stone required. However,
the right to request from the Supplier original there should never be fewer than two sets of
test data on the stone to be used and verify the samples submitted. Control samples should be
age of the test and its validity. In some cases kept by the Architect, Contractor, and

Page 3-6 • Dimension Stone Selection © 2022 Natural Stone Institute

Producer for verification of the selection meaningless if all the other information is not
approved. supplied.

7.6 For stone that will be matched, 7.9 Viewing Samples. When natural
prepare at least two sets of four matched stone samples are viewed for approval, the
samples each, showing proposed veining, viewer should be no closer than 6 ft. (2 m)
flows, movements, texture, and range in each from the sample surface and viewing from an
set. angle normal to the surface. Natural light is
preferred, striking the samples at an angle
7.7 Support Documentation. Depend- normal to the surface.
ing on the stone selected and quantity required,
a mock-up containing a full range of colors may 8.0 COST
be needed to further define the texture and
characteristics of the stone. The Specifier or 8.1 Pricing Stone for the Job. A key
Buyer should request all samples and factor in determining which stone to use will
submission of stone be accompanied by the be the price. Today, thanks to the development
following in writing: of new technologies, stone is plentiful and
competitively priced. There are many
7.7.1 Actual name of stone and name of stone alternatives in stone selection, with a range of
as applied by the Quarrier, as well as alternate prices to fit any budget. The Specifier should
names of stones in the marketplace, if any are ask for a budget price when initially
known. considering a stone for the stone only. In the
final consideration and determination, the
7.7.2 Country or state of origin. Specifier should know the real cost of the stone
based on the design and its installation costs to
7.7.3 Quarrier, if known. see if the stone fits into the budget of the job.

7.7.4 ASTM test data or European equivalent 8.2 Size of stone is also important. Not all
for first evaluation purposes. stones are available either in the size being
designed or to get the best yield from the
7.7.5 Age of sample, if known. blocks or boulders. Price will be determined
many times by the size and waste factor of the
7.7.6 References of where this stone has been blocks in relation to the finished project.
used near where the job may be located.
8.3 Stone Thickness. In the past,
7.7.7 Photos of slabs showing more range of buildings were erected using blocks or thick
the material and other finishes available. Define slabs. Now, cladding systems make it possible
whether there is more than one quarry and bed to use panels only ¾" or 1¼" thick, and with a
level of quarry where this stone is located. notable reduction in the cost of stone. The
thickness of the stone will be determined by
7.8 This information will assure the engineering and the anchoring system for the
Specifier of writing a specification that will specific stone.
control that the material being specified will
indeed be the stone to be used on the job. 8.4 Modular thin stone tile, a product
of modern technology cut to a thickness of only
Note: As an example, specifying White 1 cm, is suitable for many applications and is
Carrara (a generic name with over 30 quarries, competitive in price. These panels and tiles
and each quarry having possibly 4 selections) is compare very favorably with other natural and
manufactured products available for

© 2022 Natural Stone Institute Dimension Stone Selection • Page 3-7

construction, and have the added advantage of Specifier should be aware of the maintenance
conferring character and durability to the required to maintain the color and finish of the
structure. stone for years to come. Ask the Stone Supplier
and Salesperson for maintenance suggestions or
8.5 Multiple Factors Affect Price. requirements. Investigate with authoritative
Many factors determine the price of a maintenance companies what they recommend
particular stone. Availability, ease of for a specific stone and the cost factors involved
extraction, market demand, quality, and in maintaining the stone. The more
transportation are a few of the variables that knowledgeable the Specifier and End Buyer are
will affect the price. This is an advantage when about stone maintenance, the longer and
cost is important, for there is always the happier all parties will be in giving the Owner
possibility to select alternatives offering a quality finished job that will last for years to
essentially the same desired characteristics. come.
Availability is important to check to determine
whether the stone is still quarried, is available 9.2 Sealers. If sealers are to be used, have
in the quantity required, and in the time frame the stone tested to ensure in writing the
of installation of the project. Sometimes the sealer’s performance for the stone and
more limited the availability, the higher the application of the stone intended. New surface
cost. If the stone is only available from one and penetrating sealers are becoming available
company, the Producer can demand a very high on the market every year.
price and the Specifier should be made aware
of this. 9.3 Maintenance and Cost. The
maintenance issues for a specific stone and the
8.6 Other factors affecting the cost on cost attributed to it can vary from one type to
large projects may include: another, and may impact the decision to use
that stone in a particular application.
8.6.1 Quantity allowed for storage or attic
material. NSI Bookstore Resources:
Reprints of this chapter, along with the Stone
8.6.2 Extra material needed in the event of Testing chapter, can be purchased in a separate
damages, improperly fabricated material, or publication from the NSI Bookstore. The “Stone
other reasons replacement material might be Selection & Stone Testing” technical module
needed. includes the contents of both chapters and
additional illustrations and pictures.
8.6.3 Determination of who will pay taxes Two NSI-produced, consumer-focused brochures
may be an issue and should be clarified. are available on the use and care of natural stone:
“Beautify Your Home with Natural Stone (A Guide
8.6.4 Availability of a storage facility at the to Choosing Natural Stone and a Qualified Stone
jobsite that is of adequate size to properly and Contractor),” and “Care & Cleaning of Natural
Stone Surfaces.” Stone professionals can purchase
securely store material until job is complete.
both brochures from the NSI Bookstore.
8.6.5 Consult with your local MIA Member to
review these and other costs that factor into the
overall project budget.

9.0 MAINTENANCE
9.1 General. Maintenance of the stone
after it is installed is commonly forgotten. The

Page 3-8 • Dimension Stone Selection © 2022 Natural Stone Institute

Stone Testing to 2" x 3" (50 mm x 75 mm)], and slicing the
stone thin with an ultraprecision, thin-blade
diamond saw. The stone slice on a slide is then
1.0 INTRODUCTION precision-ground to a precise thickness of
about 20 to 30 microns. At that thickness most
1.1 General. Testing evaluates the minerals, regardless of color, are translucent
suitability of a specific stone for a particular and can be studied under a microscope. In this
application. The strength of the stone is tested way minerals can be identified, the crystal or
to determine its resistance to crushing and fragment boundaries can be evaluated, and
bending. The density, or specific gravity, is incipient microfractures can be seen, as can any
tested to design a support system capable of chemical degradation that may weaken stone,
carrying the weight of the stone. The amount permit water entry, or allow unanticipated
of water the stone will absorb (absorption rate) breakup.
will help determine the resistance of the stone
to staining and freezing. The stone’s wear 1.3.2 Exact identification of the minerals by
resistance and slip resistance are crucial in
thin section is a subjective, experience-based
flooring applications. skill and is largely being replaced by exact
methods of chemical analysis. Having both the
1.2 ASTM tests, many of which are thin section and chemical analysis is the
conducted within engineering parameters, do preferred procedure, as the physical features
not include petrographic and other geologic can be seen documented on known mineral
tests useful to evaluating stone behavior crystals or grains.
through time in adverse environmental
settings. If and when a failure occurs, questions 1.4 X-ray diffraction (XRD) analysis is
about what went wrong and why are asked; one of the tried-and-true analytical techniques
however, test data reviewed frequently may used for decades in petrology and remains the
not reveal information useful to answer these preferred technique in certain situations.
questions. Stone behavior is directly related to However, more modern analytical techniques
the behavior of the mineral or minerals that have evolved that are far more precise, analyze
make up the stone. Knowing something about far more compounds and elements, and are
physical and chemical characteristics of the rapidly replacing XRD for most routine
common minerals found in stone can be very purposes.
useful in understanding its behavior.
1.5 Lithogeochemistry, the chemical
1.3 Petrography is the science of analysis of stone, relies on many new
description and classification of rocks. A procedures too numerous to attempt
petrographic analysis can be arranged through explanation here. The following are just a few
most construction material laboratories. A notable lithogeochemical analysis procedures:
comprehensive petrographic analysis will often
suffice to answer many behavioral questions. 1.5.1 Instrumental Neutron Activation
Other, more sophisticated analyses performed
Analysis (INAA)
in well-equipped chemical laboratories to
determine exact chemical and trace element 1.5.2 Atomic Absorption Spectroscopy (AA)
content can also be useful.
1.5.3 Inductively Coupled Plasma Emission
1.3.1 Perhaps the most common and time- Spectroscopy (ICP-OES)
tested petrologic studies use thin sections of
stone. These are prepared by polishing small 1.5.4 X-ray Fluorescence Spectroscopy (XFS)
samples very flat, gluing them to glass
microscope slides [1" x 3" (25 mm x 75 mm)

© 2022 Natural Stone Institute Stone Testing • Page 4-1

1.5.5 Inductively Coupled Plasma Emission formally reaffirmed without change in 2018.
Mass Spectrometry (ICP-MS) The latest edition should be used. Copies of
ASTM standards can be obtained from ASTM
1.5.6 A few grams of a stone can be International, 100 Barr Harbor Drive, West
qualitatively and quantitatively analyzed Conshohocken, Pennsylvania 19428-2959
accurately for bulk stone chemical content plus U.S.A. Telephone 610.832.9585. Copies can
more than 53 trace elements–some to also be ordered through ASTM’s web site and
fractional parts per billion. downloaded electronically. The Internet
address is www.astm.org.
1.5.7 Although the ASTM Committee on
Stone, C-18, has yet to include petrologic tests 2.3 ASTM Standard Specifications. In
in their repertoire, lithogeochemistry is addition to the standard test methods, ASTM
already quality-standardized by the has developed a series of standard specifications
International Organization for Standardization prescribing the minimum performance of each
(ISO). ISO/IEC Guide 25 is an accreditation kind of stone when tested in accordance with
that many laboratories have because of the the standard test methods. The ASTM
importance of these studies in the global Standards and Specifications are listed in
mineral-extraction industries. Chapter 2.

2.0 ASTM STANDARD TEST 2.3.1 These specifications are the standard
METHODS AND methods for determining the characteristics of
building stone needed for proper design for a
SPECIFICATIONS
particular application. They should be
performed with care and the results used with
2.1 ASTM International, formerly
an understanding of their intent and
known as the American Society for Testing and
limitations. An independent testing laboratory
Materials, has developed several standard test
properly equipped and capable of performing
methods to evaluate stone characteristics so
the tests should perform all tests. Stone
that stones can be compared on a uniform basis.
Producers or Distributors, Associations, and
The Marble Institute of America recommends
other Promotional Organizations may publish
ASTM methods and standards for dimension
typical test values. While these values can serve
stone as guidelines for specification and
as a guide, current tests should be conducted
installation. ASTM International is the world’s
on the actual stone to be used for a particular
largest voluntary standards development
project.
organization. Note that stone testing according
to European methods and conditions may use
2.4 Review for Suitability. ASTM test
different procedures that give different results
results for various stones are guidelines and
than do ASTM methods for the same stone.
information on the stone characteristics. In
This is particularly true of tests for abrasion
many cases, an Engineer should be employed
(wear). The ASTM Standard Test Methods are
to review the results of the test data and
listed in Chapter 2.
compare with actual installation methods to
determine if the stone is suitable for the
2.2 Current Standards. ASTM standards
application in the specified thickness suggested,
are revised from time to time. A revised
and if not, what changes should be employed to
version is indicated with a hyphen followed by
make the stone work as intended for the job in
a two-digit number after the basic designation
question. Evaluation and/or testing of
of the standard, e.g., ASTM C119-20, showing
compatibility of grouts, sealers, setting
that it was revised in 2020. An additional
methods, and anchoring must be performed
number in parentheses, e.g., ASTM C1527-
along with the stone.
11(2018), indicates that the 2011 edition was

Page 4-2 • Stone Testing © 2022 Natural Stone Institute

3.0 OVERVIEW OF STANDARD sedimentary stone such as slate, than in a stone
TEST METHODS with a less definite rift, such as some igneous
stones. The variation also depends on how
3.1 Stone Uniformity. Stone is a product strongly the layers are cemented or adhered to
of nature, and as such, it varies. The properties each other. To determine the variation,
of stone from one part of a quarry may not be strength tests are conducted with the load
truly representative of the same stone from a parallel and perpendicular to the rift. For
different part of the quarry. Some Architects general information only one direction is
specify strength-testing specimens from each tested, but the Specifying Authority may
quarry block to verify sufficient uniformity for specify testing in both directions to ensure that
the application. At the very least, current test the stone strength is adequate for the
results should be used because they are more application. When specimens are submitted for
apt to reflect the stone currently being such testing, it is important that the rift be
quarried. clearly marked. The strength tests can be
conducted by four conditions, wet or dry, and
3.2 Wet/Dry Testing. For most tests, the with the load parallel or perpendicular to the
stone specimens are tested dry. However, rift.
since the strength may vary when the stone is
wet, the strength tests (i.e. compressive 3.4 Horizontal Applications. ASTM
strength, flexural strength, modulus of C99, Standard Test Method for Modulus of
rupture) are sometimes performed using wet Rupture of Dimension Stone, ASTM C170,
stone specimens. For the dry condition, the Standard Test Method for Compressive
stone specimens are dried in an oven at 60°C Strength of Dimension Stone, and ASTM
±2°C (140°F ±4°F) for at least 48 hours or C880, Standard Test Method for Flexural
until the weight does not change with Strength of Dimension Stone test results are
additional drying. For the wet condition, the not suitable to use for horizontal (floor)
stone specimens are soaked in water at 22°C applications where the thickness of the stone
±2°C (72°F ±4°F) for 48 hours, wiped, and tile being used is less than 1¼" (30 mm).
immediately tested. For general “catalog type”
information, the stone is usually tested in a dry 3.5 Limitations of Thin Stone Pavers.
condition. The Specifying Authority may It is the position of the Natural Stone Institute
specify additional wet testing for a particular that stones less than 1¼" (30 mm), when used
project to ensure that the stone will have for paving, do not possess any structural
adequate strength for the application. qualities other than abrasion resistance. The
flexural, compressive, and breaking strengths
3.3 Testing Parallel/Perpendicular these thin stones have will not materially
with the Rift. The strength of stone also improve the engineering quality of the
varies with the relation of the load or force to designed surface. These thin stones are
the direction of the “rift” of the stone. The rift furnished for their aesthetic appearance and to
is the plane of easiest splitting of the stone. supply abrasion resistance only.
Consider that a block of stone is like a deck of
cards with rift direction corresponding to the 4.0 ABSORPTION AND BULK
plane of the cards. The cards are like the layers SPECIFIC GRAVITY TESTING OF
of the stone. The stone will be weaker if the DIMENSION STONE
applied loads tend to make the cards (layers)
slide against each other than if the load is 4.1 Water absorption is a measure of the
applied to squeeze the cards against each other. porosity of a stone and can be an indicator of its
The variation in strength is likely to be greater susceptibility to damage during freezing. A
in a stone with a more pronounced rift, like a stone that has greater water absorption will

© 2022 Natural Stone Institute Stone Testing • Page 4-3

also tend to absorb liquid stains more readily. 4.4 Stone Density. The density of the
In general, the lowest water absorption is stone indicates the unit weight of the stone,
desired. The absorption is expressed as the which is necessary for the Architect or
percent weight change due to absorbed water. Engineer who is designing the structure to
The maximum allowable water absorption for support the stone. The standard specifications
each type of stone is prescribed in the standard prescribe minimum densities. The minimum
specifications for that specific stone. The densities are used to classify stones. For
required values range from 0.20% for marble example, there are three classes of limestone,
to 12% for low-density limestone. According with each class having a different density as well
to ASTM C97, at least 5 specimens, as as different strength requirements. Generally,
described for the density determination, are a higher-density stone is probably harder, less
dried and weighed. It is important that the porous, and stronger, but this is not always the
surface not be fractured by the cutting process case. Note that there is no density for slate
because these fractures will increase water specified in ASTM C629, although it could be
absorption. The specimens are then soaked in determined, if desired, using the procedure of
water for 48 hours, wiped dry, and weighed ASTM C97.
again. The difference in weights is divided by
the dry weight and multiplied by 100 to give 4.5 Specific Gravity is the ratio of the
the percentage of water absorption. Variations density of the stone to the density of water. If
in the wiping of the wet specimen before a stone has a specific gravity of 2.6, it is 2.6
weighing will cause variations in the result. The times as heavy as water. Density is expressed as
standard test method describes removing the pounds per cubic foot (lb/ft3) or kilograms per
specimens from the water and surface drying cubic meter (kg/m3). The density in lb/ft3 can
with a damp cloth, but this is still somewhat be determined by multiplying the specific
subjective. A dryer wet specimen will result in gravity by 62.4 (the weight of 1 cubic foot of
a lower absorption number. water) or by multiplying by 1000 for the
density in kg/m3. One lb/ft3 equals 16.02
4.2 Specimen Thickness. This standard kg/m3. The specific gravity is the same in both
requires that the specimens have minimum measurement systems.
dimensions of 2 inches (50 mm). However,
sometimes the stone is not available in that 4.6 Stone Dry and Wet Weights. The
thickness, especially flooring material, which dry weight of the stone specimen is divided by
may be only 3/4" (20 mm) or 3/8" (10 mm). the volume. The specimen should be a cube,
Depending on the porosity of the stone, testing cylinder, or other regular solid with the
these thinner specimens may result in an dimensions between 2 and 3 inches (50 and 75
“apparent” water absorption higher than if the mm). The surface should be reasonably
standard-sized specimens were used. During smooth, e.g., saw, core drill or better, but no
the soaking, water may not be absorbed to the chisels or tools which tend to fracture the
center of the standard specimen, but water stone. At least 5 specimens should be tested
might be absorbed to the center of the thinner and the results averaged. The dry weight of
specimens. each specimen is determined after drying 48
hours. The stone is then soaked in water for 48
4.3 Slate. The water absorption test for hours, wiped almost dry, and weighed. It is
slate, ASTM C121, uses different-size then suspended in water by fine wire and the
specimens. They should be 4" (100 mm) suspended weight is measured. The difference
square and the “as cleft” thickness, which is between the two weight measurements in
typically ¼" to 3/8" (6.5 to 9.5 mm). grams is the volume in cubic centimeters (one
Otherwise, the procedure is the same. cubic centimeter of water has a mass of 1
gram). The dry weight in grams divided by the

Page 4-4 • Stone Testing © 2022 Natural Stone Institute

volume in cubic centimeters is the specific U.S. system, we tend to think of mass and
gravity. The specific gravity is multiplied by weight interchangeably. Therefore, when a
62.4 to obtain the density in lb/ft3. Subtracting weight or force is intended, the term used is
a tare weight of the suspended wire in water pound force (lbf).
provides a correction for the mass of the fine
wire. The following conversions can be used:
1 lbf/in2(psi) = 6,895 pascals (Pa)
4.6.1 This method of measuring the volume is 1 lbf/in2 (psi) = 4.882 kilograms/square
based on the principle that a body suspended in meter (kg/m2)
water has an apparent weight loss equal to the 1 kg/m2 = 9.807 Pa
volume of water displaced. In the metric The terms kilopascal (kPa) and megapascal
system, the 1 cubic centimeter of water has a (MPa) are used for 1,000 Pa and 1,000,000 Pa,
weight of 1 gram. In other words, there is a respectively.
buoyant force on the object equal to the weight
of the water displaced. 5.3 Compressive Strength of
Dimension Stone. Compressive strength is a
5.0 STRENGTH TESTING OF measure of the resistance to crushing loads. If
DIMENSION STONE one were to build a stone wall, for example,
the stone at the bottom would have to
5.1 Compressive Loads and Strength. withstand the compressive load of the weight
The loads on a material such as stone are of the stones above. A stone floor must be able
expressed as the applied force divided by the to bear the crushing loads of people, furniture,
area which must bear the material. For and other objects on the floor. The
example, the compressive (crushing) load on a compressive strength is the maximum load per
floor caused by a flat-bottomed round planter unit area that the stone can bear without
is the weight of the planter (including the soil crushing. A higher compressive strength
and plants) divided by the area of the bottom of indicates that the stone can withstand a higher
the planter. The compressive strength of the crushing load. The required values range from
floor is the maximum compressive load the 1,800 psi (12.45 MPa) for marble to 19,000 psi
floor material can bear without crushing or (131 MPa) for granite. To determine the
deforming more than is allowed. In practice, compressive strength, at least 5 specimens are
the allowable loads in actual use are less than tested in ASTM C170. They should be cubes at
the maximum loads that a material can least 2" to 3" (50 to 75 mm) on each side. Each
withstand during testing, to provide a safety face must be perfectly flat and they must be
factor. In all structural design, the maximum parallel or perpendicular with each other.
material strengths are reduced by a safety Faces must be smooth with no tool marks and
factor to establish the allowable design there should be no nicks at the corners. The
strengths. The safety factor allows for faces must be honed or polished with no saw
variations in the material strength, possible marks or other tool marks remaining. Any
overloads in use, and similar considerations. flaws in the specimens can result in a lower
compressive strength. In some instances, the
5.2 Strength Units of Measure. The testing laboratory may have to refinish the
strengths are expressed as pounds/square inch specimens to produce surfaces sufficiently flat
(psi) or pascals (Pa). A pascal is a force of 1 for testing.
newton per square meter. Occasionally, the
strength is expressed as kilograms/square 5.3.1 The compressive strength can be
meter (kg/m2), which is technically incorrect determined in the dry or wet condition and
because the kilogram is a unit of mass while the with the load parallel or perpendicular to the
newton is a unit of force (or weight). In the rift. For the dry and wet conditions, the

© 2022 Natural Stone Institute Stone Testing • Page 4-5

specimens are dried or soaked for 48 hours as can result in an apparent low modulus of
described in the density test. For the rupture strength. The flexural (bending)
compressive strength testing, the specimen is strength may be tested in a dry or wet
placed on the flat plate of the testing machine condition and with the load parallel or
and increasing loads are applied to the top of perpendicular to the rift. The specimens must
the specimen through another flat plate. The be dried or soaked for 48 hours. For the
test apparatus allows the top plate to swivel on modulus of rupture test, the stone specimen is
a ball joint to adjust for any slight slope on the laid flat on two crosswise parallel steel edges 7"
top of the specimen. The rift of the specimens (175 mm) apart. The 7" (175 mm) span allows
should be vertical for the load to be parallel to the 8" (200 mm) long specimen to overhang
the rift, or horizontal for the load to be the supports by ½” (12.5 mm) at each end. The
perpendicular to the rift. supports of the fixture are gimbaled to
accommodate any warp of the test specimen
5.4 Bending Strength. The tests for and prevent the introduction of torsional
modulus of rupture, ASTM C99 and ASTM stresses applied to the stone. The test load, or
C120 (Slate), and for flexural strength, ASTM force, is applied to the center of the top of the
C880, determine the strength of the stone in specimen through another crosswise edge. The
bending. A stone or door lintel must resist the load is increased until the specimen breaks.
bending loads from the weight of the stone. A The flexural strength is then calculated from a
veneer must bear bending loads, between formula based on the geometry of the test
anchor points, from exterior wind loads or condition.
persons leaning against interior veneers. Floor
stone must bridge possible gaps in the grout or 5.5.1 If the specimens are to be tested with the
thin-set support. For all three tests, the stone load perpendicular to the rift, then the rift
specimens are supported near the ends and a plane must be parallel to the 4" x 8" (100 x 200
downward load applied to the top. The mm) faces. Returning to the card deck analogy,
modulus of rupture tests, ASTM C99 and the “deck” of the specimen must be placed flat
ASTM C120, prescribe applying the load to a on the supports. If the specimens are to be
single point at mid-span. The flexural strength tested with the load parallel to the rift, the
test, ASTM C880, prescribes applying the load plane of the rift must be parallel to the 2¼" x
simultaneously to two points, each one quarter 4" (60 x 100 mm) ends of the specimen. In the
of the span from the end support. The flexural analogy, several decks would have to be
strength is expressed as lb/in2 or Pa. A higher stacked up to a height corresponding to the 8"
flexural strength or modulus of rupture (200 mm) specimen length, and the card stack
indicates a higher bending strength. The or specimen would be placed so the cards are
required minimum values range from 400 psi on edge with each card parallel to the
(2.8 MPa) for low-density limestone to 10.3 supporting edges. This is illustrated in ASTM
MPa for granite. C99.

5.5 Modulus of Rupture of Dimension 5.5.2 In general, the flexural strength with the
Stone. ASTM C99 requires a minimum of 5 load parallel to the rift will be less than that
specimens that are 4"x 8"x 2¼" (100 x 200 x with the load perpendicular to the rift. The
60 mm) thick. All of the faces, except the ends, variation would be greater for a stone with a
must be flat and be parallel or perpendicular more pronounced rift than for a stone with a
with each other. The faces must be smooth rift less distinct.
with no tool marks and there should be no
nicks at the corners. The faces should be honed 5.6 Flexure Testing of Slate. The
or polished with no saw marks or other tool modulus of rupture testing for slate, specified
marks remaining. Any flaws in the specimens in ASTM C120, is somewhat different than

Page 4-6 • Stone Testing © 2022 Natural Stone Institute

C99. The specimens are 12" x 1½" x 1" (300 corners. Faces should be honed or polished
x 38 x 25 mm) thick. Rubbing or sanding the with no saw marks or other tool marks
cleft faces achieves the specified 1" (25 mm) remaining. Any flaws in the specimens can
thickness. Six specimens are required: 3 with result in a lower flexural strength. Since the
length parallel to the rift, and 3 with length length of the specimens serves only to provide
perpendicular to the rift. For the test, the span sufficient overhang, exact length is not critical
between the supporting knife edges is 10" (250 to the results.
mm).
5.7.1 The second difference that distinguishes
While these test methods are useful, they have the ASTM C880 flexural strength test from the
certain limitations. Since the specimen for modulus of rupture tests is that the flexural
ASTM C99 is always 2¼" (60 mm) thick or 1" strength test is conducted with quarter-point
(25 mm) for ASTM C120, the test does not loading. That is, the test load on the top of the
indicate any reduction in the strength for specimen is not applied to a single location at
thinner stone when used as a veneer or for midspan, but rather, the total test load is split,
flooring. They are valid for thicker sections. with half of the load applied at each of two
Because of the midspan loading, any weakness points one quarter of the span from the
that is not in the center third (approximately) supports, In this way, the entire center half of
of the specimen will usually not affect the the specimen is subjected to the same
strength value determined by the test. These maximum bending forces. Thus any local
limitations are overcome by the flexural weakness, as from a vein, is more likely to be
strength test of ASTM C880. reflected in the resulting flexural (bending)
strength.
5.7 Flexure Testing of Dimension
Stone. The flexural strength test of ASTM 5.7.2 The flexural strength test can be
C880 is similar to the modulus of rupture tests, performed in the dry or wet condition and with
with two significant differences. First, the the load parallel or perpendicular to the rift.
stone is tested at the thickness at which it will The stone specimens are dried, or are soaked
be used. The test span is proportional to that in water, for 48 hours. The rift directions are
thickness by a ratio of 10:1. Thus any reduction the same as described for the modulus of
in the bending strength due to the stone rupture test. At least 5 specimens are tested for
structure, e.g., grain size, grain cementing, each condition, and the results averaged.
etc., will be reflected in the test results. The
test span is 10 times the thickness, but the 5.7.3 As in the modulus of rupture test, the
actual length of the specimens should be about load is increased until the specimen breaks.
12 times the thickness to allow for some Then the flexural strength is calculated using a
overhang. The width is 1½ times the thickness, formula based on the geometry of the test
but, if the thickness is less than 2.67" (70 mm), conditions.
the width is 4" (100 mm). If specimens for an
exterior building veneer are 4" x 1¼" x 15" 5.8 Flooring Applications. There are
(100 x 30 x 380 mm), the test span should be two additional considerations for stone used
12.5. For a 3/8" (10 mm) floor tile, the for flooring: the wear or abrasion resistance, as
specimens would be 4" x 3/8" x 4½" (100 x measured by ASTM C241, and slip resistance
38 x 120 mm) and the test span would be 3.75" as measured by its coefficient of friction,
(95 mm). As for modulus of rupture formerly evaluated according to ASTM C1028.
specimens, all faces, except the ends, must be This test method was withdrawn in 2014 and
flat and be parallel or perpendicular with each no replacement method was offered. See
other. The faces must be smooth with no tool section 5.11, below, for an explanation.
marks, and there should be no nicks at the

© 2022 Natural Stone Institute Stone Testing • Page 4-7

5.9 Abrasion Resistance of Stone (225 revolutions at 45 rpm), dusted off, and
Subjected to Foot Traffic. Wear resistance weighed. Knowing the dry weight of the
is an essential characteristic that will determine specimens, they are soaked in water for at least
whether a stone is suitable for use as a floor. 1 hour, and a bulk density is determined in the
The abrasion test of ASTM C241 results in an same way as the density procedure of ASTM
index number proportional to the volume of C97. However, the abrasion specimen is
material abraded or worn off the stone during thinner than that required by ASTM C97 and
the test. The abrasion index numbers are scaled the specimen is not soaked for 48 hours.
to generally range between 0 and 100. The Consequently, the density may not be exactly
ASTM specifications for stone list a minimum the same as determined by ASTM C97.
abrasion index for each type of stone. Marble
and limestone, for example, should have an 5.10 The abrasion resistance index,
index of at least 10 (12 in heavy traffic areas); which is proportional to the volume abraded,
quartzitic sandstone and slate should have an is calculated for each specimen using the
index of 8; and granite, 25. average weight (before and after abrading), the
weight loss, and the apparent density. An
5.9.1 During the test, the weight loss of stone abrasion resistance index will usually be in a
specimens is measured before and after being numeric value less than 100, but not always.
abraded, and then the density of the specimen
is determined. The abrasion index is calculated 5.10.1 There are two concerns regarding
using the average weight, the abrasion weight this test method. First, it is not always possible
loss, and the density. to obtain specimens that are 1" (25 mm) thick.
Although the ASTM method does not indicate
5.9.2 The test requires 3 specimens, 2"(50 it, specimens of other thicknesses can be
mm) square and 1" (25 mm) thick. One 2" (50 determined by adjusting the 2,000-gram load
mm) square face should have the finish to be on the specimen so that the load on the bottom
evaluated, e.g., polished, honed, etc. The of the specimen, the abrading face, is the same
others may have saw marks, but should not be as it would be if the specimen were actually 1"
cut in a manner that fractures the stone because (25 mm) thick. For a specimen ¾" (20 mm)
the fractures would affect the density thick, the 2,000 grams would be increased by
determination. the mass of the missing ¼" (6.5 mm) thickness
of the specimen.
5.9.3 The stones are abraded using a machine
developed by Kessler. The machine includes a 5.10.2 The second concern is the abrasive.
horizontal, round, cast iron “lap” about 9" (225 ASTM C97 specifies a particular abrasive that
mm) in diameter, which rotates at a speed of is no longer being produced. The ASTM
45 revolutions per minute (rpm). The committee is currently conducting round-
specimens are mounted in a holder that rotates robin tests among different laboratories to
in the same direction as the lap, but at a determine a possible correction factor or a
different speed. While the lap and the different test method which will produce
specimen rotate, an abrasive flows onto the lap abrasion index numbers that are the same as
to abrade the bottom of the specimens. Each from the methods of ASTM C241, so that new
specimen supports a load of 2,000 grams, test results can be compared with earlier
which includes the weight of the specimen results. In the meantime, test laboratories have
holder, but not the specimen itself. had to develop a correction factor by
comparing the results for stones having
5.9.4 For the test, the stones are dried for different abrasion resistances, e.g., soft and
48 hours and weighed. The specimens are then medium marble and granite, using the old and
abraded in the Kessler machine for 5 minutes currently available abrasives.

Page 4-8 • Stone Testing © 2022 Natural Stone Institute

5.11 Coefficient of Friction Testing. specifically addresses in situ testing in addition
Slippery floors are a safety hazard, thus some to laboratory testing.
measure of slip resistance is needed to evaluate
stone and its finish as a floor material. 5.12 Other Stone Selection
Traditionally in the stone industry, slip Considerations.
resistance was evaluated by measuring the
static coefficient of friction (the force required 5.12.1 Other considerations for selecting
to initiate slipping divided by the normal force) exterior stones are the freeze/thaw capabilities
per the ASTM C1028 method. This test of the stone in extreme climates. Also, the
method was withdrawn in 2014, for two effect of ultraviolet light on the fading or
reasons: changing of color of certain dimension stones.
1. The load application is not automated, and Tests are available for these considerations.
therefore substantial operator influence is
experienced in the load application rate, 5.12.2 Sealants, seals, and gaskets for
directional bias, and uniformity. exterior applications are also considerations in
2. Since the test apparatus takes some time to the overall design of the building, and
set up, wet condition tests can produce a terminologies relating to these are available
suction, referred to by many as “sticktion”, from ASTM under C717, and specific tests are
preventing it from providing reliable data for also available.
testing in wet conditions. It can in fact produce
data suggesting that frictional properties are 5.12.3 Considerations for testing and
improved by the wetting of the substrate and evaluating stone must include petrographic and
no replacement method was offered. mineralogical data. The use of stone can be a
factor directly related to whether it is an
To address these concerns, the ANSI igneous rock like granite, a sedimentary rock
accredited standards committee A108, of like limestone, or a metamorphic rock like
which the Tile Council of North America marble. The petrographic information may
(TCNA) is the secretariat, developed an indicate a stone’s elastic condition to change,
entirely new procedure which measures not or absorption degrees, or determine its
static, but dynamic friction to assess walkway strength and durability, as does the mineral
safety. The new procedure first published in content of the stone. The mineralogical
the ANSI A137.1-2012 document was entitled information is important to see if the stone
the “DCOF AcuTestSM” method. It uses a contains any minerals that may cause rust (as
commercially available instrument, the BOT- with stones containing ferrous minerals),
3000 (Binary Output Tribometer), but with exfoliation like some carbon stones, or
very specific protocols regarding the redressing minerals that may decompose and change due
of the test foot between tests to ensure to weather conditions. The silicates in granite
reliability and repeatability. Building on a large weather better than the carbonates of marble
collection of data previously obtained by or limestones. The performance of a stone is
German researchers, substantial additional data related to its composition, and this is why some
was collected to develop the new more reliable stones are more brittle than others, and why
and repeatable method of COF measurement. some stones, like common limestone, become
In 2017, the test procedure, which was harder when exposed to air through a process
originally part of ANSI 137.1, was published as called “curing.”
a standalone document entitled ANSI A326.3
Standard Test Method for Measuring Dynamic 5.12.4 In designing stone exterior facades,
Coefficient of Friction of Hard Surface Flooring consider the environmental conditions: rain,
Materials. Its primary improvement versus the snow, hail, freezing and high temperature
previous version is that the procedure now variations, and others. The stone must be

© 2022 Natural Stone Institute Stone Testing • Page 4-9

resistant to weathering and decay. Carbon Special Note: A worldwide directory of
monoxide, sulfates, and other atmospheric ASTM-approved testing laboratories is
pollutants form an acid, and with rainwater, available from ASTM International,
can corrode certain stones over the course of www.astm.org.
time.
NSI Bookstore Resources:
6.0 OTHER ASSOCIATIONS FOR Reprints of this chapter, along with the Dimension
Stone Selection chapter, can be purchased in a
ADDITIONAL INFORMATION separate publication from the NSI Bookstore. The
“Stone Selection & Stone Testing” technical module
American Geosciences Institute (AGI) includes the contents of both chapters and
www.americangeosciences.org additional illustrations and pictures.
American Society of Civil Engineers
(ASCE)
www.asce.org
American Concrete Institute (ACI)
www.concrete.org
American Institute of Steel
Construction (AISC)
www.aisc.org
American Iron and Steel Institute (AISI)
www.steel.org
American Society of Landscape
Architects (ASLA)
www.asla.org
Construction Specifications Institute
(CSI)
www.csiresources.org
International Masonry Institute (IMI)
www.imiweb.org
Masonry Institute of America (MIA)
www.masonryinstitute.org
National Association of Architectural
Metal Manufacturers (NAAMM)
www.naamm.org
National Tile Contractors Association
(NTCA)
www.tile-assn.com
Precast/Prestressed Concrete Institute
(PCI)
www.pci.org
Tile Council of North America (TCNA)
www.tcnatile.com

Page 4-10 • Stone Testing © 2022 Natural Stone Institute

GRANITE 1.2.2.9 C270, Standard Specification for
Mortar for Unit Masonry
1.0 GENERAL 1.2.2.10 C295, Standard Guide for
Petrographic Examination of Aggregates for
1.1 Related Documents Concrete
1.1.1 Drawings and general provisions, 1.2.2.11 C880, Standard Test Method for
including General and Supplementary Flexural Strength of Dimension Stone
Conditions of the Contract and Division I
Specification sections, apply to this section. 1.2.2.12 C1201, Standard Test Method for
Structural Performance of Exterior Dimension
1.2 Applicable Publications Stone Cladding Systems by Uniform Static Air
Pressure Difference
1.2.1 The following publications listed here
and referred to thereafter by alphanumeric 1.2.2.13 C1242, Standard Guide for
code designation only, form a part of this Selection, Design, and Installation of Exterior
specification to the extent indicated by the Dimension Stone Anchors and Anchoring
references thereto: Systems

1.2.2 ASTM International (ASTM): 1.2.2.14 C1352, Standard Test Method for
Flexural Modulus of Elasticity of Dimension
1.2.2.1 C615, Standard Specification for Stone
Granite Dimension Stone
1.2.2.15 C1353, Standard Test Method for
1.2.2.2 A666, Standard Specification for Abrasion Resistance of Dimension Stone
Annealed or Cold-Worked Austenitic Stainless Subjected to Foot Traffic Using a Rotary
Steel Sheet, Strip, Plate, and Flat Bar Platform Abraser

1.2.2.3 B221, Standard Specification for 1.2.2.16 C1354, Standard Test Method for
Aluminum and Aluminum-Alloy Extruded Strength of Individual Stone Anchorages in
Bars, Rods, Wire, Profiles, and Tubes Dimension Stone

1.2.2.4 C97, Standard Test Methods for 1.2.2.17 C1515, Standard Guide for
Absorption and Bulk Specific Gravity of Cleaning of Exterior Dimension Stone,
Dimension Stone Vertical and Horizontal Surfaces, New or
Existing
1.2.2.5 C99, Standard Test Method for
Modulus of Rupture of Dimension Stone 1.2.2.18 C1528, Standard Guide for
Selection of Dimension Stone for Exterior Use
1.2.2.6 C119, Standard Terminology
Relating to Dimension Stone 1.2.2.19 C1721, Standard Guide for
Petrographic Examination of Dimension Stone
1.2.2.7 C170, Standard Test Method for
Compressive Strength of Dimension Stone 1.2.2.20 C1722, Standard Guide for Repair
and Restoration of Dimension Stone
1.2.2.8 C241, Standard Test Method for
Abrasion Resistance of Stone Subjected to Foot
Traffic

© 2022 Natural Stone Institute Granite • Page 5-1

1.2.3 Natural Stone Institute (NSI): 1.6 Samples
1.2.3.1 Membership, Products and Services 1.6.1 The Granite Contractor shall submit
Directory through the General Contractor, for approval
by the Specifying Authority, at least two sets of
1.2.3.2 Dimension Stone Design Manual samples of the various kinds of granite
specified. The sample size shall be 1'-0" x 1'-
1.2.3.3 Additional publications may be 0" (300 mm x 300 mm) minimum and shall
available from the NSI Bookstore. Go online at represent approximately the finish, texture,
www.naturalstoneinstitute.org and anticipated range of colors to be supplied.
One set of approved samples shall be retained
1.2.4 National Building Granite by the Specifying Authority, and one set shall
Quarries Association (NBGQA) be returned to the Granite Supplier for record
and guidance. It is noted herein that granite is
1.2.4.1 Specifications for Architectural a natural material and will have intrinsic
Granite variations in color, markings, and other
characteristics. Depending on granite selected
1.3 Scope of Included Work and quantity required, a range mockup may be
used to further define the characteristics of the
1.3.1 The work to be completed under this material. Cost of mockup, if required, shall
contract includes all labor and materials not be included in this section.
required for the furnishing and installation of
all granite work shown or called for on the 1.6.2 Prior to fabrication, an inspection and
contract drawings, specifications, and approval by the Specifying Authority and/or
addenda. General Contractor and/or End User of the
finished slabs is recommended to understand
1.4 Definition of Terms the finish and full range of the material.

1.4.1 The definitions of trade terms used in 1.7 Shop Drawings

this specification shall be those published by
NSI, NBGQA, or ASTM International. 1.7.1 The Granite Contractor shall submit
through the General Contractor, for approval
1.5 Source of Supply by the Specifying Authority, sufficient sets of
shop drawings, showing general layout,
1.5.1 All granite shall be obtained from jointing, anchoring, stone thickness, and other
quarries having adequate capacity and facilities pertinent information. These drawings shall
to meet the specified requirements, and from a show all bedding, bonding, jointing, and
firm equipped to process the material promptly anchoring details along with the net piece
on order and in strict accord with dimensions of each granite unit. One copy of
specifications. The Specifying Authority the approved shop drawings shall be retained
(architect, designer, engineer, contracting by the Specifying Authority, one copy shall be
officer, end user, etc.) reserves the right to retained by the General Contractor, and one
approve the Material Supplier prior to the copy returned to the Granite Contractor for
award of this contract. Stone and workmanship fabrication. NO FABRICATION OF
quality shall be in accordance with Industry GRANITE SHALL BE STARTED UNTIL
Standards and Practices as set forth by the NSI. SUCH DRAWINGS HAVE BEEN FULLY
APPROVED AND MARKED AS SUCH. The
Granite Contractor shall not be responsible for
determining, making, or verifying (1) design,

Page 5-2 • Granite © 2022 Natural Stone Institute

structural, wind, seismic, or other design 2.1.2.2 Provide information as in (1) for each
loads; (2) engineering estimates; (3) plans or different granite/finish combination in the
specifications; or (4) the types, sizes, or project.
locations of anchors, unless specifically added
to the scope of work. 2.1.3 Finishes: Finishes listed in the
schedule shall conform with definitions by NSI,
1.8 Defective Work NBGQA, or ASTM International.

1.8.1 Any piece of granite showing flaws or 2.2 Setting Mortar

imperfections upon receipt at the storage yard
or building site shall be referred to the 2.2.1 Mortar for setting shall be Type N, as
Specifying Authority for determination as to defined in ASTM C270, Standard Specification
responsibility and decision as to whether it shall for Mortar for Unit Masonry. All mixing,
be rejected, patched, or redressed for use. handling, and placing procedures shall be in
accordance with ASTM C270.
1.9 Repairing Damaged Stone
2.3 Pointing Mortar
1.9.1 Chips at the edges or corners may be
patched, provided the structural integrity of 2.3.1 Mortar for pointing shall be Type N,
the stone is not affected and the patch matches as defined in ASTM C270 (Standard
the color and finish of the natural stone so that Specification for Mortar for Unit Masonry).
it does not detract from the stone’s All mixing, handling, and placing procedures
appearance. shall be in accordance with ASTM C270.

2.0 MATERIALS 2.4 Sealants and Backup

Material (If Applicable)
2.1 Granite
2.4.1 Where specified, (state type or name of
2.1.1 General: All granite shall be of sealant) shall be used for the sealing of joints.
standard architectural grade, free of cracks, The backup material used with the sealant shall
seams, starts, or other traits which may impair be (identify material).
its structural integrity or function. Inherent
color variations characteristic of the quarry 2.5 Anchors, Cramps, and
from which it is obtained will be acceptable. Dowels
Texture and finish shall be within the range of
samples approved by the Specifying Authority. 2.5.1 All anchorage components shall be of
300 Series stainless steel (refer to ASTM A666)
2.1.1.2 ASTM C615 [C97] [C99] [C170] or aluminum (refer to ASTM B221) with
[C241/C1353] [C880] See the chart of strength and durability properties meeting or
applicable ASTM standards and tests in the exceeding those of 6063-T6. Anchor types and
Appendix. assemblies shall comply with ASTM C1242.
Reliance on adhesives alone for material
2.1.2 Schedule: Granite shall be provided attachment will not be permitted.
as follows:

2.1.2.1 For (state location on building) (state

name and color) granite with a (type) finish,
supplied by (name company or list several approved
suppliers).

© 2022 Natural Stone Institute Granite • Page 5-3

3.0 FABRICATION 3.5 Cutting for Anchoring,
Supporting, and Lifting Devices
3.1 Beds and Joints
3.5.1 Holes and sinkages shall be cut in
3.1.1 Bed and joint width shall be stones for all anchors, cramps, dowels, and
determined by analysis of anticipated building other tieback and support devices per industry
movements and designed to accommodate standard practice or approved shop drawings.
such movements without inducing undue However, additional anchor holes may be
stresses in the stone panels or joint filler drilled at job site by Granite Contractor to
materials. Expansion joints shall be designed facilitate alignment.
and located to accommodate larger
movements. 3.5.2 No holes or sinkages will be provided
for Granite Contractor's handling devices
3.2 Backs of Pieces unless arrangement for this service is made by
the Granite Contractor with the Granite
3.2.1 Backs of pieces shall be sawn or Fabricator.
roughly dressed to approximately true planes.
Back surfaces shall be free of any matter that [NOTE: It is not recommended that lewis pins
may create staining. be used for stones less than 3½" (90 mm)
thick.]
3.3 Moldings, Washes, and
Drips 3.6 Cutting and Drilling for
Other Trades
3.3.1 Moldings, washes, and drips shall be
constant in profile throughout their entire 3.6.1 Any miscellaneous cutting and drilling
length, in strict conformity with details shown of stone necessary to accommodate other
on approved shop drawings. The finish quality trades will be done by the Granite Fabricator
on these surfaces shall match the finish quality only when necessary information is furnished
of the flat surfaces on the building. in time to be shown on the shop drawings and
details, and when work can be executed before
3.4 Back-checking and Fitting fabrication. Cutting and fitting, due to job site
conditions, will be the responsibility of the
to Structure or Frame
Granite Contractor.
3.4.1 Stone coming in contact with
3.6.2 Incidental cutting such as for window
structural work shall be back-checked as
frame clips, etc., which is normally not
indicated on the approved shop drawings.
considered to be the responsibility of the Stone
Stones resting on structural work shall have
Supplier, will be provided only by arrangement
beds shaped to fit the supports as required.
by the General Contractor and Granite
Contractor with the Granite Fabricator.
3.4.2 Maintain a minimum of 1" (25 mm)
between stone backs and adjacent structure.
(Note: many bolted connections will require 3.7 Carving and Models
more space than this; 2"(50 mm) space may be
more desirable. Large-scale details should 3.7.1 All carving shall be done by skilled
illustrate and control these conditions.) Stone Carvers in a correct and artistic manner,
in strict accordance with the spirit and intent of
the approved shop drawing, or from models
furnished or approved by the Specifying
Authority.

Page 5-4 • Granite © 2022 Natural Stone Institute

4.0 SHIPPING AND HANDLING 5.1.3 Granite shall be free of any ice or frost
at time of installation. Salt shall not be used for
4.1 Packing and Loading the purpose of melting ice, frost, or snow on
the granite pieces. Adequate protection
4.1.1 Finished granite shall be carefully measures shall be taken to ensure that exposed
packed and loaded for shipment using all surfaces of the stone shall be kept free of
reasonable and customary precautions against mortar at all times.
damage in transit. No material which may
cause staining or discoloration shall be used for 5.2 Mortar Setting of Granite
blocking or packing. (See “6.2 Protection of
Finished Work” in this chapter.) 5.2.1 Clean base materials to remove dirt or
other foreign matter.
4.2 Site Storage
5.2.2 Saturate concrete substrate several
4.2.1 Upon receipt at the building site, stone hours prior to setting granite. Prepare and
shall remain in the factory-prepared bundles place mortar in accordance with ASTM C270.
until beginning of the installation. Bundles Thoroughly wet stones prior to setting in
shall be staged in an area which is least mortar bed. Apply neat cement parge of
susceptible to damage from ongoing approximate 1/16" (1.5 mm) thickness to
construction activity. Once unbundled, the granite units prior to placing on mortar bed.
granite shall be stacked on timber or platforms Tamp stones into place using a rubber or plastic
at least 2" (50 mm) above the ground, and the mallet to obtain full contact with the setting
utmost care shall be taken to prevent staining bed and proper stone unit alignment.
or impact damage of the granite. If storage is to
be prolonged, polyethylene or other suitable, 5.3 Mortar Joints
nonstaining film shall be placed between any
wood and finished surfaces of the granite. 5.3.1 Mortar joints shall be raked out to a
depth of ½" to ¾" (12 to 20 mm). Apply
4.2.2 Any holes or slots in the granite which pointing mortar in layers not exceeding 3/8"
are capable of collecting water shall be (10 mm) and allow each layer to get hard to the
temporarily covered or plugged to prevent touch before the next layer is applied. Tool
freezing of collected water. Such covers or finished joints with a concave tool having a
plugs are to be removed immediately prior to diameter approximately 1/8" (3 mm) greater
installation of the piece. than the joint width.

5.0 INSTALLATION 5.3.2 Care shall be taken to keep expansion

joints free of mortar, which would
compromise their function.
5.1 General Installation

5.1.1 Installation shall be accomplished with 5.4 Anchorage

competent, experienced Stone Setters, in
accordance with the approved shop drawings. 5.4.1 All granite shall be anchored in
accordance with the approved shop drawings.
5.1.2 All granite pieces shall be identified
with a unique piece number corresponding 5.4.2 To the furthest extent possible, all
with the number on the shop drawings. anchor preparations in granite units shall be
Interchanging of numbered pieces is not shop-applied.
permitted.

© 2022 Natural Stone Institute Granite • Page 5-5

5.4.3 All anchorage devices and anchor 6.0 CLEANING AND
hole/slot fillers shall be in accordance with PROTECTION
ASTM C1242. Care must be taken to ensure
that any holes capable of retaining water are
6.1 Cleaning
filled after use to prevent water collection and
freezing.
6.1.1 Granite shall be cleaned after
installation and all pointing or caulking is
5.5 Sealant Joints complete. All dirt, excess mortar, weld
splatter, stains, and other defacements shall be
5.5.1 Where so specified, joints requiring removed.
sealant shall be first filled with a closed-cell
ethafoam rope backer rod. The backer rod 6.1.2 All cleaning methods shall be in
shall be installed to a depth that provides accordance with ASTM C1515.
optimum sealant profile after tooling.
6.2 Protection of Finished
5.5.2 If recommended by the Sealant
Work
Manufacturer, primers shall be applied to the
substrate surfaces according to the
6.2.1 Granite installation in progress shall be
manufacturer’s directions prior to application
protected with film or fabric tarps secured over
of the joint sealant.
the work.
5.6 Expansion Joints 6.2.2 After the granite is installed, it shall be
the responsibility of the General Contractor to
5.6.1 It is not the intent of this specification properly and adequately protect it from
to make control or expansion-joint damage until all trades are finished. This
recommendations for a specific project. The responsibility includes the stone cleaning costs
Specifying Authority must specify control or prior to the required final inspection. Where
expansion joints and show locations and details lumber is required for protection, care should
on drawings. be taken to protect the granite from staining by
the lumber, using plastic film or other suitable
5.7 Caulking materials. Any fasteners used in construction
of temporary protection fixtures shall be
5.7.1 Where so specified, joints shall be corrosion resistant.
pointed with the sealant(s) specified in Section
2.4 after first installing the specified backup 6.2.3 Finishes commonly available are
material and applying a primer if required, all defined as follows:
in strict accordance with the printed
instructions of the Sealant Manufacturer. 6.2.3.1 Polished: Mirror gloss, with sharp
reflections.
5.7.2 All sealants shall be tooled to ensure
maximum adhesion to the contact surfaces. 6.2.3.2 Honed: Dull sheen, without
reflections.
5.8 Weep Tubes
6.2.3.3 Fine Rubbed: Smooth and free from
5.8.1 Plastic or other weep tubes shall be scratches; no sheen.
placed in joints where moisture may
accumulate within the wall, such as at base of 6.2.3.4 Rubbed: Plain surface with
cavity, continuous angles, flashing, etc., or as occasional slight “trails” or scratches.
shown on architectural drawings.

Page 5-6 • Granite © 2022 Natural Stone Institute

6.2.3.5 Shot Ground: Plain surface with 6.2.3.13 Split Faced: Stone on which the
pronounced circular markings or “trails” having face has been broken to an approximate plane.
no regular pattern.
6.2.3.14 Rock (pitch) Faced: Similar to
6.2.3.6 Thermal (Flamed): Finish produced split faced, except that the face of the stone is
by application of high-temperature flame to the pitched to a given line and plane producing a
surface. Large surfaces may have shadow lines bold appearance rather than the comparatively
caused by overlapping of the torch. This finish straight face obtained in split face.
will vary in texture and depth between
different types of granite, as the finish is largely 6.2.3.15 Jet Washed: After certain
dependent upon the granite structure of the treatment finishes on stone, such as flaming, a
stone. high pressure jet wash can be used to assist in
cleaning the stone and bringing back more
6.2.3.7 Sandblasted, Coarse Stippled: color to the stone. Some producers have the
Coarse plain surface produced by blasting with machinery to use high pressure water with
an abrasive; coarseness varies with type of additives which gives a jet washed finish that
preparatory finish and grain structure of the looks like a flamed finish, yet maintains the
granite. color in the stone.

6.2.3.8 Sandblasted, Fine Stippled: Plain 6.2.4 Minimum Thickness: The

surface, slightly pebbled, with occasional slight suggested minimum thickness for all exterior
“trails” or scratches. veneer is as follows:

6.2.3.9 Bush-hammered, 8-cut: Fine bush- 6.2.4.1 Percussion produced finishes, such as
hammered finish, interrupted by parallel bush-hammered (sometimes referred to as a
markings not over 3/32" (2.5 mm) apart. A pointed finish), require a 1¼" (30 mm)
corrugated finish, smoother near arris lines and thick slab minimum to apply.
on small surfaces.
6.2.4.2 Other finishes can usually be applied to
6.2.3.10 Bush-hammered, 6-cut: any thickness slab, with the exception of some
Medium bush-hammered finish, similar to but granites not being able to withstand thermal
coarser than 8-cut, with markings not more finishing processes in thicknesses less than
than 1/8" (3 mm) apart. 1¼".

6.2.3.11 Bush-hammered, 4-cut: Coarse 6.2.4.3 Determination of proper stone

bush-hammered finish with same thickness must be evaluated using the following
characteristics as 6-cut, but with markings not criteria:
more than 7/32" (5.5 mm) apart. • Piece Size.
• Final Face Finish.
6.2.3.12 Sawn: Relatively plain surface
• Anchoring Detail.
with texture ranging from wire sawn (a close
approximation of a rubbed finish), to shot • Structural Design Load Requirements.
sawn, with scorings 3/32" (2.5 mm) in depth. • Flexural Strength of the Granite.
Gang saws produce parallel scorings; rotary or
circular saws make circular scorings. Shot- 6.2.5 Minimum safety factors of 3 to 1
sawn surfaces should be cleaned to remove all minimum on granite flexural stresses and 4 to
rust stains. 1 minimum on anchorage components in
granite are recommended.

© 2022 Natural Stone Institute Granite • Page 5-7

6.2.6 Ashlar or veneer used as a facing 1.2 The commercial stone industry,
requires a setting space of at least 1" (25 mm), depending on the supplier or organization,
as measured from the nominal thickness of the loosely accepts various granite-like stones
piece. under the label of “granite.” These include,
among others, banded or massive, nonbanded
6.2.7 Bed and Joint Width. The gneiss, and a few quartz-based stones. Such
minimum recommended bed and joint width is stones are marketed as “granitelike” or
¼" (6 mm) for exteriors and 1/8" (3 mm) for “granitoid,” though they are not true granite.1
interiors. Gneisses, high level metamorphic stone, are
included in the granite category by commercial
6.2.8 Sawn backs. Because of physical interests.
characteristics, most granites cannot be split to
a thickness less than 1/3 of the lesser face 1.3 The quartz-based stones are definitely
dimension. Consequently, sawn backs (see 3.4 not granite, but rather the silica-cemented
in this chapter) should be specified for most sedimentary stone quartzite or its
veneers, and are frequently specified also for metamorphic equivalent, orthoquartzite.
thicker ashlar, because of design Quartzite, and especially orthoquartzite, have
considerations. a distinct cleft or cleavage at a mica-rich
parting. Knowing the difference between true
6.2.9 Staining. Granite should be granite and granitelike stone helps the stone
protected from wet (green) wood, oils, mud, industry professional to understand the
construction waste, and asphalt compounds. physical properties, performance, and
Contact Fabricator or Granite Contractor for ultimately, the comparative quality of these
proper remedies to staining problems that natural materials.
occur.
1.4 Granite, as defined by the AGI, usually
has three to four basic mineral components:

PRODUCT 1.4.1 Quartz (SiO2 ±25-35%), appears as

DESCRIPTION – irregular, watery-looking, or translucent
grains.
Granite
1.4.2 Orthoclase Feldspar (KAlSi3O8
1.0 GEOLOGICAL ≈20-80%). In most, but not all, commercial,
CLASSIFICATION geologic granites, the light-colored minerals,
white- to flesh-colored are orthoclase feldspar.
1.1 The American Geological Institute
(AGI) defines granite as an intrusive igneous 1.4.3 Plagioclase Feldspar (NaAlSi3O8 to
rock (cooled slowly in the deep upper part of CaAl2Si3O8 ≈20-80%) features darker gray to
the Earth’s crust) composed of 25% to 35% bluish grains, with some grains exhibiting fine,
quartz and over 50% potassium- and sodium- grooved lines and/or an iridescent sheen.
rich feldspars, with a common accessory Sometimes the mineral is a light, creamy color,
mineral of less than 20%, usually muscovite nearly indistinguishable from orthoclase,
(clear mica), biotite (dark, iron-bearing mica), except for the occasional presence of the fine
or hornblende (amphibole). lines.

1 The following terms are derivations of the word granolite. The use of these terms commercially is not
granite, which are now obsolete because their recommended.
definitions have become obscured and imprecise:
granide, granilite, granitelle, granitello, granitine, and

Page 5-8 • Granite © 2022 Natural Stone Institute

1.4.4 Dark accessory minerals (→20%) 1.6 Gneiss, a true metamorphic stone
biotite and hornblende are complex silicates that exhibits strong mineral segregation in the
with all the elements in quartz, orthoclase form of contorted bands indicating
feldspar, and plagioclase feldspar, plus iron and metamorphic origin, is universally included in
magnesium, which gives these minerals their the granite group by the stone industry.
dark color. Magnetite (Fe3O2) is often a trace Banded gneiss is a classical rock end member
mineral (±2-4%) in granite, and easily of the metamorphic process of high pressure,
recognized by its strongly magnetic property. time, temperature, and the presence of fluids
It, too, is black and opaque. Magnetite has a that begins with the sedimentary rock shale and
hardness rating of H=6, polishes well, has a proceeds through slate, to phyllite, then schist
metallic appearance, and is opaque (i.e., it does and finally, banded gneiss—from low to high
not transmit light even when very thin). levels of metamorphic rank.

1.4.5 All of these granitic minerals have a 2.0 COLOR AND VEINING
Mohs Scale2 hardness rating of H=7 or H=6
with the exception of biotite, which has a 2.1 The color of a granite is governed
variable hardness of 2.5 to 4.5, depending on largely by that of the feldspar, usually the most
the angle of the polished surface in relation to abundant mineral. However, it may be
the edges of the “books” of sheets that biotite modified to some extent by the quartz,
mica crystals exhibit. Thus, biotite does not hornblende, or mica, if considerable amounts
polish well and appears as small, rough spots on are present. Almost white, light gray, dark
a polished surface. This is not a flaw in either gray, green, pink, and red granites are
the stone or polishing, but simply the way common. Uniform color distribution is usually
biotite is—softer than all other minerals in a desirable feature. Lighter-colored granites
granite. Biotite hardness makes little difference are the average composition of continental
in most applications, as the overwhelmingly crust, while darker granites are more likely
dominant feldspar and quartz minerals are associated with or influenced by nearby oceanic
much harder. Biotite “plucks” slightly in composition stone.
polishing, but generally not when in use.
2.2 Dark, granular igneous rocks,
1.5 Granitization. Earth scientists came classified petrographically as anorthosite,
to realize that much granite is associated with basalt, diabase, diorite, and gabbro, are also
metamorphic stone of extremely high levels. used as dimension stone, and are classed
These are often massive, nonbanded commercially as “black granite.”
granites with no noticeable mineral
segregation into bands. Many examples come
from, but are not limited to, some Far Eastern
locations and Sri Lanka. These often have a
strong presence of red garnet3, a mineral
indicative of metamorphism. Geologic granite,
in terms of mineral content, can be formed by
granitization, a true metamorphic process
by which a solid rock is converted to granite by
entry and/or exit of material or change of
chemical components without going through a
liquid or molten state.

2See Appendix for information about the Mohs Scale of 3Garnet is most often noticeable when red, but also
mineral hardness. occurs in light green and light yellow.

© 2022 Natural Stone Institute Granite • Page 5-9

3.0 TEXTURE Member/Supplier should assist in final
approval.
3.1 The term “texture,” as applied to
granite, means size, degree of uniformity, and 7.0 PRODUCT SAMPLING
arrangement of constituent minerals.
7.1 Granites are formed by nature; thus
3.2 The texture of granite is determined there are variations in the tonal qualities of the
by the size and arrangement of mineral grains. stones. However, it is these natural differences
Uniform grain size usually is demanded in that make granites unique, valuable, and highly
commercial granites. Grain size varies greatly desirable. Because of these variations, selection
in different types of granite. of a granite should never be made on the basis
of one sample only. It is recommended that
3.3 Uniform distribution of the minerals is selection be based on viewing sufficient
as important as uniform grain size. Light and samples to show the complete range of colors
dark minerals should be distributed evenly of the desired stone. NSI Members can provide
throughout the rock mass, for this gives these range samples.
uniform color and texture. Many commercial
deposits display remarkable homogeneity; the 8.0 PROPER USAGE TIPS
rock may not vary in color or texture for many
feet, either vertically or horizontally. 8.1 Recommendation for commercial
floors:
4.0 FINISHES
8.1.1 Minimum ¾" (20 mm) thickness.
4.1 Granite surfaces may be finished in a
number of ways. See the listing of typical 8.1.2 A honed finish.
finishes on page 5-7 of this chapter.
8.1.3 A minimum hardness value of 25 as
5.0 THICKNESS measured by ASTM C241/C1353.

5.1 Standard nominal thicknesses for 8.2 Avoid the use of gypsum or molding
granite are generally 3/8", ¾", 1¼", 1½", 2", plaster setting spots for the installation of
3", 4", 6", and 8" (10 mm, 20 mm, 30 mm, stone.
40 mm, 50 mm, 75 mm, 100 mm, 150 mm,
and 200 mm). 9.0 VENEER CUTTING
6.0 SIZES 9.1 Quarry blocks are reduced to slabs by
a gang saw or wire saw. The gang saw consists
6.1 Granite is a product of nature with of a series of steel blades set parallel in a frame
hundreds of varieties available, each possessing that moves forward and backward. They are
unique characteristics. Little can be done to fed a cutting abrasive in a stream of water.
alter the condition in which nature presents
these varieties to us. Therefore, size may
become a limiting factor to consider in the
selection of a particular granite.

6.2 A jointing scheme that permits the use

of smaller sizes of granite will greatly facilitate
selection and delivery. The NSI

Page 5-10 • Granite © 2022 Natural Stone Institute

TECHNICAL DATA – 1.6 Physical Properties of Granite
(This historical data and information are
Granite provided only as a guideline. Recommended
minimums or maximums are established and
1.0 PROPERTIES OF GRANITE provided by ASTM International.)*
DIMENSION STONE
Property Range of Values
1.1 In centuries past, relatively little Compressive Strength (C170)
importance was attached to the ultimate lbs/in² .............................. 4,700-60,000
physical capabilities of most building materials. Recommended (min): 19,000
Rule of thumb was a common structural design
criterion. As a result, the widely used materials Flexural Strength (C880)
of the day, for the most part natural rather than lbs/in² ...................................700-5,500
manmade materials, were seldom stressed to Recommended (min): 1,200
their ultimate limits.
Modulus of Elasticity (C1352)** (in millions)
1.2 In present-day construction, this is far lbs/in²…………………………..2.0-10.0
from being true. Performance requirements
are daily becoming more demanding. In Density (C97), lb/ft3 .................. 150-200
striving for taller structures, greater spans, Recommended (min): 160
firmer foundations, thinner walls and floors,
stronger frames, and generally more efficient Coefficient of Thermal Expansion,
buildings with more usable space, today’s in/in/ºF ........................4.7 x 10-6 average
Architects and Engineers must get the most out
of the materials with which they work. Modulus of Rupture (C99)
lbs/in² ................................ 1,000-3,000
1.3 Granite is a product of nature and not Recommended (min): 1,500
always subject to the rules of consistent
behavior that may apply to manufactured Absorption % (by weight) ........... 0.02-0.40
building materials. Recommended (max): 0.40
1.4 Physical property values of stone may, Abrasion Resistance Ha ..................... 20-90
however, be measured using the standard test Recommended (min): 25
methods approved by the Dimension Stone
Committee C18 of ASTM International. The
NSI and Member companies are represented * Test methods described in current ASTM
on the ASTM committee and are active in its standards.
technical work of establishing proper test ** Also known as Young’s Modulus.
methods and specifications consistent with the
latest technology. 2.0 STRENGTH (ASTM C99,
C170, C880)
1.5 Final design should always be based on
specific values for the stone variety ultimately 2.1 Values for modulus of rupture,
to be installed. These values may be obtained compressive strength, and flexural strength are
from the Stone Supplier. All materials are not ascertained by testing specimens of granite
suitable for all uses. In order to avoid mistaken under laboratory conditions until they fail.
selections, tests for material values should be
made prior to final material selection. The C170 procedure is used for determining
the compressive strength of a granite

© 2022 Natural Stone Institute Granite • Page 5-11

specimen. A cube or cylinder of 2" to 3" in all considered a fire-resistant material. Because of
dimensions is crushed under a hydraulic ram its thermal conductivity, heat transfer is fairly
and the compressive strength is calculated as rapid. Most stone is not considered a highly
the total load divided by the area of the rated thermal insulator.
specimen. Compressive strength of granite is
seldom a factor in design, as the compressive 3.2 Underwriters’ fire-resistance ratings
strength is many times the anticipated evaluate whether or not a material will burn,
compressive stresses. This value is most often as well as how long it will keep surrounding
used for comparison of stone types or as a combustible materials from reaching
general strength benchmark for the material. temperatures that will cause them to ignite.
Methods of estimating fire-resistance periods
2.2 The C99 and C880 procedures are of masonry walls and partitions utilizing
both used for determining bending strength. component laminae are given in “Fire
The C99 procedure is much older, and the test Resistance Classifications of Building
protocol is seldom modified, so data obtained Construction,” BMS92, National Bureau of
from this test has some value for comparison to Standards.
historical data or between different stone
types. As a measure of resistance to bending 4.0 ABRASION RESISTANCE
loads, it is not considered to be a representative (ASTM C241/C1353)
modeling of panel behaviors in building
applications. The ratio of beam length to beam 4.1 Abrasion resistance is a property of
depth is very small, resulting in what is stone that should be tested per ASTM
referred to as “thick beam behavior.” The C241/C1353 to provide an indication of the
results of this test are usually artificially high stone’s wearing qualities when exposed to foot
due to the thick beam behavior and high shear traffic.
stresses in the loaded specimen
4.2 The hardness and uniform wearing
2.3 The C880 procedure is much qualities of most granites make them extremely
preferred when testing granite for resistance to desirable and economically practical for floors
bending stresses. The procedure calls for a and stairs. Varieties with an abrasive hardness
span-to-depth ratio of 10:1, which eliminates (Ha/Iw) of 25 or more, as measured by ASTM
the influence of thick beam behavior. C241/C1353 tests, are recommended for use
Furthermore, the test allows specimen as flooring subject to normal foot traffic.
modification to allow the use of actual building
cladding thickness and actual finish, which
provides a better representation of the stone 5.0 FACTORS AFFECTING
behavior in the cladding application. This PROPERTIES
procedure also uses a four-point bending
fixture, which provides a constant stress region 5.1 The ultimate test of a building material
over approximately 50% of the specimen. This is its ability to have and maintain the necessary
provides a greater chance that the weakest structural strength, as well as beauty of
point of the specimen will fall within this appearance and low cost of maintenance, over
region and produce more reliable data for the useful life of the structure. Experience has
design use. proven that stone meets this test as few other
building materials can. Studies have shown that
3.0 FIRE RESISTANCE the durability of most stones is little affected by
cycles of weather. This is because most have a
3.1 Stone is not combustible according to low rate of moisture absorption.
underwriters’ ratings, and therefore is

Page 5-12 • Granite © 2022 Natural Stone Institute

6.0 SAFETY FACTORS determine specific requirements for each area.
The National Bureau of Standards has published
6.1 Good engineering practice requires two documents on the topic: “Earthquake
that allowable design stress must provide a Resistant Masonry Construction,” NBS Science
margin of safety in any structural element. As a Series 106; and “Abnormal Loading on
necessary precaution against such conditions as Buildings and Progressive Collapse: An
wind, ice, snow, impact, temperature changes, Annotated Bibliography,” NBS Science Series
and imperfect workmanship, these allowable 67. The U.S. Army Corps of Engineers has also
stresses must be smaller than those that published TM 5-809-10, “Seismic Design for
produce failure. Buildings.”

6.2 Within the accepted limits of safe 8.0 EFFLORESCENCE AND

design practice, the closer the allowable load is STAINING
to the ultimate failure load in a structure, the
more efficient is the use of the material and the 8.1 Efflorescence is a salt deposit, usually
less the cost of the construction. white in color, which appears on exterior
surfaces of masonry walls. The efflorescence-
6.3 Contemporary building design does producing salts found in masonry are usually
not usually employ granite as part of the sulfates of sodium, potassium, magnesium,
structural frame, but rather as an independent calcium, and iron. Salts that are chlorides of
unit, a curtain wall, or veneer. Therefore, the sodium, calcium, and potassium will
primary concern in such cases is with wind or sometimes appear, but they are so highly
seismic loads. Safety factors of 3.0 for the soluble in water that they will be washed off by
granite and 4.0 for anchorage assemblies are rain.
recommended. Where the stone is to be
subjected to concentrated loading, such as stair 8.2 The water-soluble salts causing
treads or lintels supported only at the ends, a efflorescence come from other materials in the
factor of 4.0 or greater should be used. wall. The salts exist in small amounts and are
leached to the surface by water percolating
6.4 These safety factors may be adjusted through the wall. The most feasible means of
using sound engineering principles and prevention is to stop the entrance of large
judgment. amounts of water. Absorption from the face
will not cause efflorescence unless there are
6.5 As buildings become taller and open joints.
individual stone slab veneer becomes larger in
area, the lateral forces due to wind loads must 8.3 Some of the salt crystals may form in
be considered. Wind tunnel tests are often the stone’s pores near the surface. Crystal
used on major structures to determine wind growth (recrystallization) in the pores can
dynamics and force magnitude. cause stress on the walls of the pores and cause
the stone to flake off. If the conditions bringing
7.0 SEISMIC about this action persist, scaling may continue
CONSIDERATIONS and flake off, one layer after another. For this
to happen, large amounts of water must enter
7.1 Seismic considerations generally the wall and contain large amounts of salts.
require that low buildings be stiff, and that tall
buildings be relatively flexible. Design of 8.4 Research indicates that staining and
connections must account for seismically discoloration occurring on new buildings are
induced horizontal loading. Local building caused by the action of water percolating
codes vary and must always be checked to through concrete, from which soluble alkali

© 2022 Natural Stone Institute Granite • Page 5-13

salts are leached. The salts are then carried by content of the stone, the more pits it will have.
the water through the stone, where partially All polished igneous/metamorphic rock will
oxidized organic matter is picked up. This is have varying degrees of pits, depending on the
then transported to the surface of the stone, amount of biotites, muscovite, and phlogopite.
where it is deposited as a stain as the water
evaporates. 9.2 Pitting does not make the granite less
durable or of inferior quality. Pits exist in all
8.5 This staining phenomenon is similar to granites and should be expected when dealing
efflorescence, except that it involves organic with a natural, polished stone containing
material. It does not harm the stone, other than several types of minerals with different
leaving an objectionable appearance during or hardnesses.
soon after erection. However, if left alone, the
stain is removed naturally by the action of the 10.0 BACTERIA
elements, usually in the course of a few
months. 10.1 Bacteria requires several things in
order to thrive and grow: oxygen, water,
8.6 Granite is one of the most durable of sunlight, nutrients, and a substrate to form on.
all building materials because the quartz and The minerals in granite are toxic to bacteria. As
feldspar in it are highly resistant to normal a result, there is no habitable environment for
weathering. Feldspars will, however, dis- the bacteria to live and grow on a granite
integrate slowly if exposed to an acid-bearing surface.
atmosphere, as in regions where hydrocarbons
are prevalent. All granites disintegrate very
slowly under repeated contraction and 11.0 RADON AND GRANITE
expansion due to diurnal and seasonal
temperature changes, but under ordinary 11.1 Radon is a naturally occurring gas
atmospheric conditions, granite will endure for generated by the decay of trace amounts of
years without significant change in color or uranium found in the Earth’s crust. It is an
durability. unstable gas that quickly breaks down and
dissipates in the air.
9.0 PITTING IN GRANITE
11.2 Radon is measured in units called
picocuries per liter (pCi/l). A picocurie is one
9.1 Granites are made up of several
trillionth (10-12) of a curie, which is the amount
different minerals, each having a different
of radioactivity emitted by a gram of radium.
hardness. They can contain feldspars, biotites,
The U.S. Environmental Protection Agency
amphiboles, ferrous titanium oxides, and other
has established 4 pCi/l as the standard for
mineral combinations. For comparison, on the
indoor air; 20 pCi/l represents the maximum
Mohs Scale, diamonds are the hardest
amount of exposure to radium that is now
substance, with a hardness of 10. By
allowed by U.S. regulations.
comparison, feldspars have a hardness of 6.5 to
7, which is still quite hard and durable.
11.3 Measurements of Radon from
Biotites, the black minerals throughout the
Granite Countertops. “Over 500
slab, are by contrast very soft (2.5 to 4.5) and
measurements of radon emissions from granite
flake easily. All true granites have biotite in
have been published in the peer reviewed
their composition. Because biotites are soft and
flaky, the first few layers are removed during
the polishing process, causing pits. Some
granites have more biotites throughout their
composition than others. The higher the biotite

Page 5-14 • Granite © 2022 Natural Stone Institute

scientific literature.4” This study and other
radon and radiation information and test results
may be found at
https://www.naturalstoneinstitute.org/rad
on/. None of the research found a single stone
that would be a health risk to homeowners.

12.0 CAUTION ABOUT

ENHANCED GRANITE

12.1 Several methodologies are being used

to enhance varieties of granite. Caution, in
some cases avoidance, should be exercised for
the following methodologies:

12.1.1 Tinting. The adding of color dyes in

sealer-type products to make the color of the
stone conform to a more pleasing one. This is
a short term “fix,” as the color will bleed out
from the stone when it is exposed to the sun,
or is otherwise used.

12.1.2 Epoxy (polyester) Filling. Several

varieties of over-burdened stones that do not
meet the ASTM criteria for Granite Dimension
Stone are being filled with epoxy or polyester
resins (similar to the typical filling techniques
employed in travertine) and marketed for a
variety of uses. This type of stone is generally
not suitable for wet or exterior applications.

12.1.3 Resin filling. This process is being

performed to reduce the effects of “pits” in
granite. Once treated, these stones are
required to be marketed as “filled.” Verify with
the Producer and the End User that the type of
fill being used is both safe and acceptable for
the application intended.

4Natural Stone Countertops and Radon, 2008.

Environmental Health & Engineering, publisher.

© 2022 Natural Stone Institute Granite • Page 5-15

NOTES:

Page 5-16 • Granite © 2022 Natural Stone Institute

LIMESTONE 1.2.3.3 Additional publications may be
available from the NSI Bookstore. Go online at
www.naturalstoneinstitute.org.
1.0 GENERAL
1.2.4 Indiana Limestone Institute of
1.1 Related Documents America (ILI)
1.1.1 Drawings and general provisions, 1.2.4.1 Indiana Limestone Handbook
including General and Supplementary
Conditions of the Contract and Division I 1.3 Scope of Included Work
Specification sections, apply to this section.
1.3.1 The work to be completed under this
1.2 Applicable Publications contract includes all labor and materials
required for the furnishing and installation of
1.2.1 The following publications listed here all limestone work shown or called for on the
and referred to thereafter by alphanumeric contract drawings, specifications, and
code designation only, form a part of this addenda.
specification to the extent indicated by the
references thereto: 1.4 Definition of Terms
1.2.2 ASTM International (ASTM): 1.4.1 The definitions of trade terms used in
this specification shall be those published by the
1.2.2.1 C568, Standard Specification for NSI, ILI, or ASTM International.
Limestone Dimension Stone

1.2.2.2 C97, Standard Test Methods for

1.5 Source of Supply
Absorption and Bulk Specific Gravity of
Dimension Stone 1.5.1 All limestone shall be obtained from
quarries having adequate capacity and facilities
1.2.2.3 C99, Standard Test Method for to meet the specified requirements, and from a
Modulus of Rupture of Dimension Stone firm equipped to process the material promptly
on order and in strict accord with
1.2.2.4 C170, Standard Test Method for specifications. The Specifying Authority
Compressive Strength of Dimension Stone (architect, designer, engineer, contracting
officer, end user etc.) reserves the right to
1.2.2.5 C241/C1353, Standard Test approve the Material Supplier prior to the
Method for Abrasion Resistance of Stone award of this contract. Stone and workmanship
Subjected to Foot Traffic quality shall be in accordance with Industry
Standards and Practices as set forth by the NSI.
1.2.2.6 C880, Standard Test Method for
Flexural Strength of Dimension Stone 1.6 Samples

1.2.3 Natural Stone Institute (NSI): 1.6.1 The Limestone Contractor shall submit
through the General Contractor, for approval
1.2.3.1 Membership, Products, and Services by the Specifying Authority, at least two sets of
Directory samples of the various kinds of limestone
specified. The sample size shall be 1'-0" x 1'-0"
1.2.3.2 Dimension Stone Design Manual (300 mm x 300 mm) and shall represent
approximately the finish, texture, and
anticipated range of color to be supplied. One

© 2022 Natural Stone Institute Limestone • Page 6-1

set of approved samples shall be retained by the or shown on the approved shop drawings that
Specifying Authority, and one set shall be changes be made. Each stone indicated on the
returned to the Limestone Supplier for his/her setting drawings shall bear the corresponding
record and guidance. It is noted herein that number marked on an unexposed surface.
limestone is a natural material and will have Provision for the anchoring, doweling, and
intrinsic variations in color, markings, and cramping of work, in keeping with standard
other characteristics. Depending on limestone practices, and for the support of stone by shelf
selected and quantity required, a range angles and loose steel, etc., when required,
mockup may be used to further define the shall be clearly indicated on the shop drawings.
characteristics of the material. Cost of NO FABRICATION OF LIMESTONE SHALL
mockup, if required, shall not be included in BE STARTED UNTIL SUCH DRAWINGS
this section. HAVE BEEN FULLY APPROVED AND
MARKED AS SUCH. The Limestone
1.6.2 Prior to fabrication, an inspection and Contractor shall not be responsible for
approval by the Specifying Authority (and/or determining, making, or verifying (1) design,
General Contractor and/or End User) of a structural, wind, seismic, or other design
representative number of the finished slabs loads; (2) engineering estimates; (3) plans or
may be desirable to understand the finish and specifications; or (4) the types, sizes, or
full range of the material. locations of anchors, unless specifically added
to the scope of work.
1.7 Shop Drawings
1.8 Defective Work
1.7.1 The Limestone Contractor shall submit
through the General Contractor, for approval 1.8.1 Any piece of limestone showing flaws or
by the Specifying Authority, sufficient sets of imperfections upon receipt at the storage yard
shop drawings, showing general layout, or building site shall be referred to the
jointing, anchoring, stone thickness, and other Specifying Authority for determination as to
pertinent information. These drawings shall responsibility and decision as to whether it shall
show all bedding, bonding, jointing, and be rejected, patched, or redressed for use.
anchoring details along with the net piece
dimensions of each limestone unit. One copy 1.9 Repairing Damaged Stone
of the approved shop drawings shall be retained
by the Specifying Authority, one copy shall be 1.9.1 Repair of stone is an accepted practice
retained by the General Contractor, and one and will be permitted. Some chipping is
copy returned to the Limestone Contractor for expected; repair of small chips is not required
fabrication. All jointing as shown by the if it does not detract from the overall
Specifying Authority on the contract drawings appearance of the work, or impair the
shall be followed, unless modifications are effectiveness of the mortar or sealant. The
agreed upon in writing, or indicated upon the criteria for acceptance of chips and repairs will
approved shop drawings. If the contract be per standards and practices of the industry
drawings do not show the intent of the jointing, unless other criteria are mutually agreed upon
it will be the fabricator's responsibility to in writing by the Limestone Contractor and the
establish the jointing in accordance with Specifying Authority.
industry standards and practices.

1.7.2 The cutting and setting drawings shall be

based upon and follow the drawings and full
size details prepared by the Specifying
Authority except where it is agreed in writing

Page 6-2 • Limestone © 2022 Natural Stone Institute

2.0 MATERIALS between the stone and the backup or
underlayment, the use of nonstaining cement
2.1 Limestone may not prevent all discoloration.
Discoloration will disappear as the stone dries.
2.1.1 General: All limestone shall be of
standard architectural grade, free of cracks, 2.2.2 The addition of hydrated lime or like
seams, or other traits which may impair its amounts of ground limestone may increase
structural integrity or function. Inherent color initial shrinkage, but the improved working
variations characteristic of the quarry from qualities and the water retention will enable
which it is obtained will be acceptable. Texture the mixture to adjust to the initial shrinkage
and finish shall be approved by the Specifying and will give good bonding strength in both
Authority as shown in the samples. horizontal and vertical joints. Hydrated lime
should conform to ASTM C207 Type S.
2.1.2 ASTM C568 [C97] [C99] [C170]
[C241/C1353] [C880] See the chart of 2.2.3 Sand should comply with ASTM C144.
applicable ASTM standards and tests in the
Appendix. 2.2.4 Mixing water must be potable quality.

2.1.3 Schedule: Limestone shall be 2.2.5 Mortar mixes vary in proportions from
provided as follows: a hard mixture (1:1:4) to a flexible mixture
(1:1:9). Hard mixes can be expected to set up
stress conditions between the stone and mortar
2.1.3.1 For (state location on building) (state
in joints since the thermal coefficient of mortar
name, grade (if applicable), and (color)
expansion is greater than that of stone. In
limestone with a (type) finish, supplied by (name
paving installations, stress is often sufficient to
company or list several approved suppliers).
break the bond between the stone and the
substrate. Flexible mortars are not suitable for
2.1.3.2 Provide information as in (1) for
exterior work.
each different limestone/finish combination in
the project.
2.2.6 The Indiana Limestone Institute
recommends a 1:1:6 or Type N mortar be used
2.1.4 Finishes: Finishes listed in the with Indiana limestone.
schedule shall conform with definitions by the
NSI, ILI, or ASTM International.
2.3 Pointing Mortar
2.2 Setting Mortar 2.3.1 Pointing mortar shall be composed of
one part (white or other) portland cement, one
2.2.1 Cement used with limestone shall be part hydrated lime, and six parts white sand
white portland cement, ASTM C150, or white passing a #16 sieve.
masonry cement, ASTM C91. Non-staining
cement (at the present time there are few
masonry cement mortars produced labeled
2.4 Sealants and Backup
nonstaining) shall contain not more than Material (if Applicable)
0.03% of water-soluble alkali when
determined in accordance with procedure 2.4.1 Where specified, (state type or name of
#15, calculation #16 of ASTM C91 or Federal sealant) shall be used for the pointing of joints.
Specification SS-C181C. However, if a large The backup material used with the sealant shall
amount of normal cement has been used in the be (identify material).
backup (underlayment) material, and if an
effective water barrier has not been provided

© 2022 Natural Stone Institute Limestone • Page 6-3

2.5 Anchors, Cramps, and joints shall have a uniform thickness of 3/8"
Dowels (10 mm) unless otherwise shown or noted on
drawings.
2.5.1 The Limestone Contractor shall furnish
and set all anchors shown on approved shop 3.1.2 Reglets for flashing, etc., shall be cut in
drawings unless otherwise specified. All the stone where so indicated on the drawings.
anchors shall be fabricated from Type 304 or All flashing, whether installed by the Stone
316 stainless steel or other suitable nonferrous Contractor or others, must be installed with
metal. Multipart anchors may contain metal nonstaining, oil-free caulk.
other than stainless steel provided such metal is
not embedded in sinkages in the limestone. 3.2 Backs of Pieces

2.6 Stain Prevention 3.2.1 Backs of pieces shall be sawn or roughly

dressed to approximately true planes. Back
2.6.1 Where necessary, such as when surfaces shall be free of any matter that may
limestone is used at/below grade or at create staining.
horizontal water stops, specify one or both of
the following systems: 3.3 Moldings, Washes, and Drips
2.6.1.1 Dampproof unexposed stone 3.3.1 Moldings, washes, and drips shall be
surfaces. Joint surfaces should be dampproofed constant in profile throughout their entire
only to within 1" of finished surface when using length, in strict conformity with details shown
bituminous solutions. on approved shop drawings. The finish quality
on these surfaces shall match the finish quality
2.6.1.2 Dampproof all concrete surfaces on of the flat surfaces on the building.
which limestone will rest. Dampproof adjacent
concrete structure, haunches, etc. 3.4 Back-checking and Fitting to
Structure or Frame
2.7 Adjacent To Water
3.4.1 Stone coming in contact with structural
2.7.1 Limestone used in areas adjacent to work shall be back-checked as indicated on the
water that is chemically purified should be approved shop drawings. Stones resting on
tested to ensure that there is no reaction structural work shall have beds shaped to fit the
between the stone and the purification supports as required.
chemicals.
3.4.2 Maintain a minimum of 1" (25 mm)
(See Horizontal Surfaces chapter for more between stone backs and adjacent structure.
information.) (Note: many bolted connections will require
more space than this; 2" (50 mm) space may be
3.0 FABRICATION more desirable. Large-scale details should
illustrate and control these conditions.)
3.1 Beds and Joints
3.5 Cutting for Anchoring,
3.1.1 All stone shall be cut accurately to shape Supporting, and Lifting Devices
and dimensions and full to the square, with
jointing as shown on approved drawings. All 3.5.1 Holes and sinkages shall be cut in stones
exposed faces shall be dressed true. Beds and for all anchors, cramps, dowels, and other
joints shall be at right angles to the face, and tieback and support devices per industry

Page 6-4 • Limestone © 2022 Natural Stone Institute

standard practice or approved shop drawings. customary and reasonable precautions against
However, additional anchor holes may be damage in transit. All limestone under this
drilled at job site by Limestone Contractor to contract shall be loaded and shipped in the
facilitate alignment. sequence and quantities mutually agreed upon
by the General Contractor, Limestone
3.5.2 No holes or sinkages will be provided Contractor, and the Limestone Fabricator.
for Limestone Contractor’s handling devices
unless arrangement for this service is made by 4.2 Unloading and Storage at Job
the Limestone Contractor with the Limestone Site
Fabricator.
NOTE: It is not recommended that lewis pins 4.2.1 Receipt, storage, and protection of
be used for stones less than 3½" (90 mm) limestone work prior to and during installation
thick. shall be the responsibility of the Limestone
Contractor.
3.6 Cutting and Drilling for
4.2.2 All limestone shall be received and
Other Trades
unloaded at the site with necessary care in
handling to avoid damaging or soiling.
3.6.1 Any miscellaneous cutting and drilling
of stone necessary to accommodate other
4.2.3 Stones shall be stored above the ground
trades will be done by the Limestone
on nonstaining skids (cypress, white pine,
Fabricator only when necessary information is
poplar, or yellow pine without an excessive
furnished in time to be shown on the shop
amount of resin). Chemically treated wood
drawings and details, and when work can be
should not be used. DO NOT USE
executed before fabrication. Cutting and
CHESTNUT, WALNUT, OAK, FIR, AND
fitting, due to job site conditions, will be the
OTHER WOODS CONTAINING TANNIN.
responsibility of the Limestone Contractor.
Completely dry limestone shall be covered
with nonstaining waterproof paper, clean
3.6.2 Incidental cutting such as for window
canvas, or polyethylene.
frame clips, etc., which is normally not
considered to be the responsibility of the Stone
Supplier, will be provided only by arrangement 5.0 INSTALLATION
by the General Contractor and Limestone
Contractor with the Limestone Fabricator. 5.1 General Installation

3.7 Carving and Models 5.1.1 Installation shall be accomplished with

competent, experienced Stone Setters, in
3.7.1 All carving shall be done by skilled Stone accordance with the approved shop drawings.
Carvers in a correct and artistic manner, in
strict accordance with the spirit and intent of 5.1.2 All limestone pieces shall be identified
the approved shop drawing, or from models with a unique piece number corresponding
furnished or approved by the Specifying with the number on the shop drawings.
Authority. Interchanging of numbered pieces is not
permitted.
4.0 SHIPPING AND HANDLING
5.1.3 Limestone shall be free of any ice or
frost at time of installation. Salt shall not be
4.1 Packing and Loading used for the purpose of melting ice, frost, or
snow on the limestone pieces.
4.1.1 The cut limestone shall be carefully
packed for transportation with exercise of all
© 2022 Natural Stone Institute Limestone • Page 6-5
5.1.4 Adequate protection measures shall be in courses below has hardened sufficiently to
taken to ensure that exposed surfaces of the avoid squeezing.
stone shall be kept free of mortar at all times. 5.2.6 While joints can be tooled when initial
set has occurred, pointing cut stone after
5.2 Mortar Setting setting, rather than full bed setting and
finishing in one operation reduces a condition
5.2.1 All limestone shall be set accurately in which tends to produce spalling and leakage. It
strict accordance with the contract, approved is generally best to set the stone and rake out
shop drawings, and specifications. White the mortar to a depth of ½" to 1½" (12 to 38
portland cement with a low-alkali content is mm) for pointing with mortar or sealant at a
recommended. later date. If pointed with sealant, the raked
depth and sealant applications shall conform to
5.2.2 Cut limestone is customarily shipped as manufacturer’s instructions.
it comes from its final operation in the
supplier’s plant. Its surfaces and joints may be 5.2.7 Projecting stones shall be securely
covered with dust or saw slush, especially those propped or anchored until the wall above is set.
pieces which have not been exposed to rain in
stacking areas. Cleaning prior to installation or 5.2.8 Only the ends of lugged sills and steps
erection of cut limestone is typically not shall be embedded in mortar. Balance of joint
required where the existence of dust or saw shall be left open until finally pointed.
slush does not impede the erection process or
the application of joint sealants or pointing. 5.2.9 All cornice, copings, projecting belt
The exception to this rule is interior courses, other projecting courses, steps, and
stonework. Thoroughly clean interior stones platforms (in general, all stone areas either
prior to installation and protect the work once partially or totally horizontal) should be set
in place from construction traffic. Among the with unfilled vertical joints. After setting,
methods used is washing with a fiber brush and insert properly sized backup material or backer
soap powder, followed by a thorough rinsing rod to proper depth, and gun in sealant.
with clear water. Further information on
cleaning can be found in section 6.1 of this In cold weather, the International Masonry
document. Industry All Weather Council re-
commendations for setting from 40ºF to 20ºF
5.2.3 All stone joint surfaces not thoroughly (4ºC to -6ºC) shall be followed, except that no
wet shall be drenched with clear water just additives shall be used in the setting mortar,
prior to setting. and below 20ºF (-6ºC), all work shall be done
in heated enclosures.
5.2.4 Except as otherwise specially noted,
every stone shall be set in full beds of mortar 5.2.10 Individually set thin tile [nominal
with all vertical joints slushed full. Completely 3/8" (10 mm) thick] on vertical surfaces
fill all anchor, dowel, and similar holes. All bed exceeding 8' (2.5 m) is not recommended.
and vertical joints shall be 3/8" (10 mm) unless
otherwise noted. 5.3 Anchorage

5.2.5 Plastic setting pads shall be placed under 5.3.1 All limestone shall be anchored in
heavy stones, column drums, etc., in the same accordance with the approved shop drawings.
thickness as the joint, and in sufficient quantity
to avoid squeezing mortar out. Heavy stones or 5.3.2 To the furthest extent possible, all
projecting courses shall not be set until mortar anchor preparations in limestone units shall be
shop-applied.

Page 6-6 • Limestone © 2022 Natural Stone Institute

5.3.3 All anchorage devices and anchor 5.6.1 Where so specified, joints shall be
hole/slot fillers shall be in accordance with pointed with the sealant(s) specified in Section
ASTM C1242. Care must be taken to ensure 2.4, after first installing the specified backup
that any holes capable of retaining water are material and applying a primer if required, all
filled after use to prevent water collection and in strict accordance with the printed
freezing. instructions of the Sealant Manufacturer.

5.4 Sealant Joints 5.6.2 All sealants shall be tooled to ensure

maximum adhesion to the contact surfaces.
5.4.1 Where so specified, joints requiring
sealant shall be first filled with a closed-cell 5.7 Weep Tubes
ethafoam rope backer rod. The backer rod
shall be installed to a depth that provides 5.7.1 Plastic or other weep tubes shall be
optimum sealant profile after tooling. placed in joints where moisture may
accumulate within the wall, such as at base of
5.4.2 If recommended by the Sealant cavity, continuous angles, flashing, etc., or as
Manufacturer, primers shall be applied to the shown on architectural drawings.
substrate surfaces according to the
manufacturer’s directions prior to application 6.0 CLEANING AND
of the joint sealant.
PROTECTION
5.5 Expansion Joints 6.1 Cleaning
5.5.1 Joints shall be adequate to allow for
6.1.1 Among the methods most frequently
thermal and structural differential movement.
used to clean cut limestone are washing with a
fiber brush and soap powder, followed by a
5.5.2 Filler material for these joints shall be
thorough rinsing with clear water. Pressure
nonstaining.
washing is another option, and often the
required pressure can be delivered from
5.5.3 It is not the intent of this specification to
ordinary hose taps. Greater water pressure can
make control or expansion-joint
be used in some situations if delivered by a
recommendations for a specific project. The
wide-angle nozzle from a distance no closer
Specifying Authority must specify expansion
than one foot to the stone surfaces. Most often
and control joints and show location and details
a lower pressure and greater distance will be
on the drawings.
equally effective. Suppliers or trade
associations representing the specified
5.5.4 NSI recommends a maximum area of
limestone should be contacted for pressure
400 square feet (37 m2) between
recommendations for their particular product.
expansion/control joints for horizontal
surfaces. In areas where there are large
6.1.2 Special consideration and protection
sections of natural light, this area should be
shall be provided when brickwork is cleaned
reduced dependent on the quantity of natural
above the limestone. Strong acid compounds
light entering the area. In glass ceiling atriums,
used for cleaning brick will burn and discolor
it has been shown that 120 square feet (11 m2)
the limestone.
is the maximum area that an expansion/control
joint should encamp.
6.1.3 In general, sand-blasting, wire brushes
or acids should never be used on limestone.
5.6 Caulking When circumstances arise that cause one or
more of these methods to be considered,

© 2022 Natural Stone Institute Limestone • Page 6-7

suppliers or trade associations representing the stone. Almost all limestone is composed of
specified limestone should be contacted for grains or fragments of biologic origin, ranging
recommendations. from fossils or organically derived grains that
weigh a mere fraction of an ounce, to dinosaur
6.2 Protection of Finished Work bones that may weigh tons (though the latter is
an extremely rare example). Most limestone
6.2.1 During construction, tops of walls shall is marine in origin, composed of micro-sized
be carefully covered at night and especially fossils of marine invertebrate organisms rather
during any precipitation or other inclement like the shells found on most beaches.
weather. Limestone composed of inorganic, precipitated
calcium carbonate is rare, and even more rare
6.2.2 At all times, walls shall be adequately is limestone of igneous origin called
protected from droppings. carbonatites,2 found in diamond-bearing rock. In
former times it was thought that pure, fine-
6.2.3 Whenever necessary, substantial grained limestone was a precipitate from
wooden covering shall be placed to protect the marine waters super enriched with calcium
stonework. Nonstaining building paper or carbonate, but that is not the case; almost all
membrane shall be used under the wood. fine-grained limestone is of biological origin.
Maintain all covering until removed to permit
the final cleaning of the stonework. 1.2 Limestone is a carbonate stone, that is,
it has the -CO3 radical combined with the
6.2.4 The Limestone Contractor will outline calcium atom. Other carbonate minerals seen
the needs for protection in writing to the in dimension stone are the carbonates siderite
General Contractor. The General Contractor (FeCO3), magnesite (MgCO3), and dolomite
shall be responsible for protection of the Ca,Mg(CO3) 2. Dolomite is both a mineral and
finished work until all trades are finished. This a stone, and is used extensively as a commercial
responsibility includes the stone cleaning costs limestone. The origin of dolomite is post
prior to the final inspection. depositional; it is chemically transformed from
a pure calcium limestone after deposition and
burial, and sometimes, after total cementation.
Thus the dolomitization process of a limestone
PRODUCT is termed a “diagenetic” chemical process in
DESCRIPTION – which magnesium ions are inserted into the
Limestone calcium carbonate molecules to make
dolomite, both the mineral and rock.
1.0 GEOLOGICAL 1.3 All the carbonate minerals mentioned
CLASSIFICATION share certain chemical and physical properties:
they are all approximately the same hardness
1.1 Limestone is a sedimentary stone with (H=3) on the Mohs Scale3; all have three good
at least 50% by weight calcite or calcium cleavages (i.e., they easily break into
carbonate (CaCO3) content1. However, parallelograms, indicating they have the same
commercial limestone usually has a much atomic geometry); and they all react in some
higher percentage of calcium carbonate than manner to cold, dilute hydrochloric acid and
50%. Limestone is a “clastic” sedimentary other dilute acids.

1 The Glossary of Geology, 2nd ed., 1980, Bates and 2 Carbonatites often occur in kimberlite pipes, a rare and
Jackson eds., Amer. Geol. Inst. special kind of geologic formation in which diamonds
are found.
3 See Appendix for the Mohs Scale of mineral hardness.

Page 6-8 • Limestone © 2022 Natural Stone Institute

1.4 Since limestone by definition must be at not be well enough cemented to hold together,
least 50% calcium carbonate, the other 50% the clays may wash out, or if sandy, the sands
can be one of various clasts or minerals of other may wash or weather out too easily, or the
kinds of stone. These include clay, silt, quartz stone will not take an acceptable finish.
or other sands, pebbles, and especially fossils–
usually calcite or aragonite (a mineral with the 1.8 Clay is the source of coloring in many
same chemistry as calcite (CaCO3), but with an limestones, because it contains the iron oxides
unstable atomic geometry unlike calcite, which that yield yellow through red stain; thus, a very
has a stable atomic geometry. small component of clay may be acceptable in
commercial limestone. A simple chemical
1.5 It is proper to add a descriptive prefix in analysis of a limestone will indicate precisely
identifying types of stone; for example, muddy the percent of calcite composition, while a
or shaly limestone, or silty, sandy, or pebbly petrographic examination would establish the
conglomeratic limestone. characteristics of the calcite/clay mixture.
Large inclusions or bands of clay seriously
1.6 Dolomite, the stone, is a calcium- weaken the stone.
magnesium carbonate classed in the dimension
stone industry as “limestone,” and is important 1.9 Recrystallization of any limestone is
commercially not only due to the large amount usually initiated with burial, and the deeper the
quarried and sold, but because of two special burial, the more pervasive is the
physical properties of dolomite: recrystallization. Grain size has much to do
with the process of recrystallization in some
1.6.1 Dolomite is somewhat less soluble than types of limestone; it appears to proceed
calcite, enough so that dolomite generally rapidly in some very fine-grained limestones,
exhibits somewhat greater weathering perhaps accelerated by trace amounts of
resistance in exterior applications. The biological material and the larger amount of
standard procedure to test for calcite is to put surface area of multiple small grains. Marbles
a drop of dilute hydrochloric acid (HCl), ≈10% by geological definition are metamorphic
or less, on the mineral. A vigorous “fizzing” limestones. It is often nearly impossible to
reaction occurs immediately, a positive differentiate a strongly recrystallized limestone
indication of calcite. By contrast, a drop of from a marble because the two behave exactly
dilute HCl on dolomite mineral or stone the same; thus in commercial practice, the
produces no reaction unless the dolomite is differentiation is often incorrectly stated, but
pulverized first; then a fizzing reaction is the error may be of little or no importance. If
observed, but it will be less vigorous than with the exact name and origin is needed, a
calcite. metamorphic marble can be identified by
indications of strain in calcite crystals observed
1.6.2 Dolomite hardness H=3.5 is slightly in a petrographic thin-section.
harder than calcite. Calcite hardness is H=3 by
comparison, a human fingernail is H=2.5, and 1.10 Many fossiliferous limestones are of
the mineral fluorite (CaF2) is H=4. Thus exceptional biological interest as they form in a
dolomite hardness at 3.5 will scratch the softer variety of mostly marine environments much
calcite. Although this doesn’t seem like much studied for baseline standards against which
of a difference, it is enough of an increase to modern environments are compared. These
provide longer service life in high abrasion would include constructional biological reefs,
applications, for instance, for entrance steps. barrier reefs like Australia’s Great Barrier
Reef, lagoons and carbonate tidal flats similar
1.7 In general, limestone diluted with too to the back side of Andros Island in the
much clay, sand, or other noncarbonate grains Bahamas, or Florida Bay. Fossiliferous
is not acceptable as dimension stone—it may limestone has fascinated mankind since ancient

© 2022 Natural Stone Institute Limestone • Page 6-9

times, and continues to be a stone in high 4.1.1 Honed: A satin smooth surface with
demand. Fossils over three billion years old are little or no gloss.
studied from carbonate rocks. Fossiliferous
limestone preserves the only record of life 4.1.2 Smooth: Smooth finish, with minimum
available for the period of Earth history prior of surface interruption.
to the advent of mankind, and retains the
charisma associated with unknown creatures 4.1.3 Plucked: A rough texture.
from times long past. 4.1.4 Abrasive: A flat, nonreflective surface.

2.0 COLOR AND VEINING 4.1.5 Sawn: A comparatively rough surface;

can be chat, shot, sand, or diamond sawn.
2.1 The color, veinings, clouds, mottlings,
and shadings in limestone are caused by 4.1.6 Polished: Mirror gloss, with sharp
substances included in minor amounts during reflections.
formation. These include iron-bearing
minerals, clay, and organic material thought to 4.1.7 Bush-hammered: Textured surface
be residual from the soft parts of tiny marine that varies from subtle to rough.
animals. Most of these dark materials are found
between calcite crystals or the shell materials, 4.1.8 Thermal (Flamed): Finish produced
and some shells and calcite crystals are darker by application of high-temperature flame to the
than others. Colors of biologic inclusions are surface. Large surfaces may have shadow lines
strongly affected by the environment of caused by overlapping of the torch. This finish
deposition, e.g., whether bottom conditions will vary in texture and depth between
are aerobic or anaerobic. Iron oxides make the different types of limestone, as the finish is
pinks, yellows, browns, and reds. Most grays, largely dependent upon the limestone
blue-grays, and blacks are of bituminous structure of the stone. The thermal method is
origin. not commonly used on limestone.

3.0 TEXTURE 4.1.9 Antiqued: A finish that replicates

rusticated or distressed textures.
3.1 The term “texture,” as applied to
limestone, means size, degree of uniformity, 4.1.10 Tumbled: A weathered, aging
and arrangement of constituent minerals. finish created when the stone is tumbled with
sand, pebbles, or steel bearings.
3.2 Limestone contains a number of
distinguishable natural characteristics, 4.1.10.1 Other finishes such as machine
including calcite streaks or spots, fossils or shell tooled are available and it should be noted that
formations, pit holes, reedy formations, open not all finishes may be applicable to all
texture streaks, honeycomb formations, iron limestones.
spots, travertine-like formations, and grain-
formation changes. One or a combination of 4.1.11 Some stone finishes can affect
these characteristics will affect the texture. strength and durability. Examples are bush-
hammered and thermal finishes, which reduce
a stone’s thickness, making it more vulnerable
4.0 FINISHES
to weakening from exposure to freeze and
thaw cycles.
4.1 Limestone surfaces may be finished in a
number of ways. Typical finishes are:
4.1.12 The type of finish desired may affect
the final cost. For further information on cost

Page 6-10 • Limestone © 2022 Natural Stone Institute

differences between various finishes contact viewing sufficient samples to show the general
NSI member companies. range of colors of the desired stone. NSI
Members can provide these range samples.
5.0 THICKNESS
8.0 PROPER USAGE TIPS
5.1 Standard nominal thicknesses for
limestone are generally 3/8", ¾", 1¼", 1½", 8.1 Recommendation for commercial
2", 2¼", 2½", 3", 3½", and 4" (10 mm, 20 floors:
mm, 30 mm, 38 mm, 50 mm, 60 mm, 75 mm,
90 mm, 100 mm). The recommended 8.1.1 Minimum ¾" (20 mm) thickness.
thicknesses vary depending on the type of
limestone used. 8.1.2 A honed finish.

5.2 Cutting can be made to exact metric 8.1.3 A minimum hardness value of 10 as
measurements through conversion of U.S. measured by ASTM C241/C1353.
Conventional System values to SI International
System units. See conversion table in the 8.2 Avoid the use of gypsum or molding
Appendix. plaster setting spots for the installation of
limestone.
Note that as limestone is cut thinner, its tensile
strength is diminished. 9.0 VENEER CUTTING
6.0 SIZES 9.1 Quarry blocks are reduced to slabs by a
gang saw, belt saw, or wire saw. The gang saw
6.1 Limestone is a product of nature with consists of a series of steel blades set parallel in
many varieties available, each possessing a frame that moves forward and backward.
unique characteristics. Little can be done to They are fed a cutting abrasive in a stream of
alter the condition in which nature presents water. See illustration at end of chapter 7.
these varieties to us. Therefore, size may
become a limiting factor to consider in the 10.0 DAMPPROOFING
selection of a particular limestone.
10.1 Some limestones have moisture
6.2 NSI Members should be consulted for absorption rates which will cause bleeding of
specific size information for a particular stone setting or joint materials. If unsure, test the
and its desired use. A jointing scheme which limestone for tolerance of the setting material.
permits the use of smaller sizes of limestone Wetting the joint surfaces prior to applying the
may greatly facilitate selection and delivery. mortar and avoiding the use of too much water
The NSI Member/Supplier should assist in the in the mix may reduce the probability of such
final scheme approval. bleeding If necessary, edges and back faces
must be dampproofed with materials that will
7.0 PRODUCT SAMPLING bond with the setting/jointing material, but
not cause bleeding.
7.1 Limestone is formed by nature; thus
there are variations in the tonal qualities of the
stones. However, it is these natural variations
that make limestone unique, valuable, and
highly desirable. Because of these variations,
selection of a limestone should never be made
on the basis of one sample only. It is
recommended that selection be based on
© 2022 Natural Stone Institute Limestone • Page 6-11
TECHNICAL DATA – 1.6 Physical Properties of Limestone.
(This historical data and information are
Limestone provided only as a guideline. Recommended
minimums or maximums are established and
1.0 PROPERTIES OF provided by ASTM International.)4
LIMESTONE DIMENSION STONE
Property Range of Values
1.1 In centuries past, relatively little
importance was attached to the ultimate Compressive Strength (C170)
physical capabilities of most building materials. lbs/in² ............................. 1,600-32,000
Rule of thumb was a common structural design Recommended (min):
criterion. As a result, the widely used materials 1,800 (low density),
of the day, for the most part natural rather than 4,000 (medium density),
manmade materials, were seldom stressed to 8,000 (high density)
their ultimate limits.
Property Range of Values
1.2 In present-day construction, this is far Flexural Strength (C880)
from being true. Performance requirements
lbs/in² ................................. 400-2,700
are daily become more demanding. In striving
for taller structures, greater spans, firmer Modulus of Elasticity5 (in millions)
foundations, thinner walls and floors, stronger lbs/in² ..................................... 0.6-1.4
frames, and generally more efficient buildings
with more usable space, today’s Architects and Density, lb/ft3 (C97) ................. 110-185
Engineers must get the most out of the Recommended (min):
materials with which they work. 110 (low density),
135 (medium density),
1.3 Limestone is a product of nature and not 160 (high density)
always subject to the rules of consistent
behavior that may apply to manufactured Coefficient of Thermal Expansion,
building materials. in/in/ºF ......................... 4.4 x 10-6 average
1.4. Physical property values of limestone Modulus of Rupture (C99) lbs/in²...400-1000
may, however, be measured using the standard Recommended (min):
test methods approved by the Dimension Stone 400 (low density),
Committee C18 of ASTM International. The 500 (medium density),
NSI and Member companies are represented 1,000 (high density)
on the ASTM committee and are active in its
technical work of establishing proper test Absorption % (by weight) (C97) ... 0.6-29.0
methods and specifications consistent with the Recommended (max):
latest technology. 12.0 (low density),
7.5 (medium density),
1.5 Final design should always be based on 3.0 (high density)
specific values for the stone variety ultimately
to be installed. These values may be obtained Abrasion Resistance (Ha/Iw) (C241/C1353)
from the Stone Supplier. All materials are not ...3.0-33.0
suitable for all uses. In order to avoid mistaken Recommended (min): 10
selections, tests for material values should be
made prior to final material selection.

4 Test methods described in current ASTM 5 Also known as Young’s Modulus.

standards.

Page 6-12 • Limestone © 2022 Natural Stone Institute

2.0 STRENGTH (ASTM C99, 4.0 ABRASION RESISTANCE
C170, C880) (ASTM C241/C1353)

2.1 Values for modulus of rupture, 4.1 Abrasion resistance is a property of

compressive strength, and flexural strength are stone that should be tested per ASTM
ascertained by testing specimens of limestone C241/C1353 to provide an indication of the
under laboratory conditions until they fail. stone’s wearing qualities when exposed to foot
traffic.
2.2 Size and finish of test samples required
by the standard ASTM test methods may not 4.2 The hardness and uniform wearing
reflect the actual performance of stone when qualities of most limestones make them
used in lesser thicknesses or with other finishes extremely desirable and economically practical
that affect strength. For this reason, the for floors and stairs. Varieties with an abrasive
Modulus of Rupture (C99) test is hardness (Ha) of 10 or more, as measured by
recommended when the stone to be used will ASTM C241/C1353 tests, are recommended
be two or more inches thick. The Flexural for use as flooring exposed to normal foot
Strength (C880) test is recommended when traffic. A minimum abrasive hardness of 12 is
the stone thickness will be less than two inches. recommended for commercial floors, stair
treads, and platforms subject to heavy foot
2.3 The strength of a limestone is a measure traffic. If floors are constructed with two or
of its ability to resist stresses. There are several more stone varieties, the Ha values of the
varieties in the limestone group, including stones must not differ by more than 5, or the
calcarenite, coquina, dolomite, micro- floor surface will not wear evenly and
crystalline, oolitic, travertine, and re- uniformly.
crystallized. Their strength depends on several
factors, such as the rift and cleavage of the 5.0 FACTORS AFFECTING
calcite crystals, the degree of cementation, the
PROPERTIES
interlocking of the calcite crystals, and the
nature of any cementing materials present.
5.1 The ultimate test of a building material
is its ability to have and maintain the necessary
3.0 FIRE RESISTANCE structural strength, as well as beauty of
appearance and low cost of maintenance over
3.1 Stone is not combustible according to the useful life of the structure. Experience has
underwriters’ ratings, and therefore is proven that limestone meets this test as few
considered a fire-resistant material. Because of other building materials can. Studies have
its thermal conductivity, heat transfer is fairly shown that the durability of most limestones is
rapid. Most stone is not considered a highly little affected by cycles of weather. This is
rated thermal insulator. because most have a low rate of moisture
absorption.
3.2 Underwriters’ fire-resistance ratings
evaluate whether or not a material will burn, 5.2 Limestone exterior paving is not
as well as how long it will keep surrounding recommended for environments where de-
combustible materials from reaching icing chemicals may be used to melt ice and
temperatures which will cause them to ignite. snow because these chemicals will damage
Methods of estimating fire resistance periods of most limestone.
masonry walls and partitions utilizing
component laminae are given in “Fire 5.3 Exteriors of gray or black limestones
Resistance Classifications of Building with a bituminous or carbon composition
Construction,” BMS92, National Bureau of should be avoided as the action of atmosphere
Standards.
© 2022 Natural Stone Institute Limestone • Page 6-13
agents will rapidly cause the surface to codes vary and must always be checked to
deteriorate. determine specific requirements for each area.
The National Bureau of Standards has published
6.0 SAFETY FACTORS two documents on the topic: “Earthquake
Resistant Masonry Construction,” NBS Science
6.1 Good engineering practice requires that Series 106; and “Abnormal Loading on
allowable design stress must provide a margin Buildings and Progressive Collapse: An
of safety in any structural element. As a Annotated Bibliography,” NBS Science Series
necessary precaution against such conditions as 67. The U.S. Army Corps of Engineers has also
wind, ice, snow, impact, temperature changes, published TM 5-809-10, “Seismic Design for
and imperfect workmanship, these allowable Buildings.”
stresses must be smaller than those which
produce failure. 8.0 EFFLORESCENCE AND
STAINING
6.2 For a particular construction, the closer
the allowable load is to the ultimate failure 8.1 Efflorescence is a salt deposit, usually
load, the more efficient is the use of the white in color that occasionally appears on
material and the less the cost of the exterior surfaces of masonry walls. The
construction. efflorescence-producing salts found in masonry
are usually sulfates of sodium, potassium,
6.3 Contemporary building design does not magnesium, calcium, and iron. Salts which are
usually employ stone as part of the structural chlorides of sodium, calcium, and potassium
frame, but rather as an independent unit, a will sometimes appear, but they are so highly
curtain wall, or veneer. Therefore, the soluble in water that they will be washed off by
primary concern in such cases is with wind or rain.
seismic loads, and a safety factor of 8.0 is
recommended. Where the stone is to be 8.2 The water-soluble salts causing
subjected to concentrated loading, such as stair efflorescence come from other materials in the
treads or lintels supported only at the ends, a wall. The salts exist in small amounts and are
factor of 10.0 should be used. These safety leached to the surface by water percolating
factors may be adjusted using sound through the walls. The most feasible means of
engineering principles and judgment. prevention is to stop the entrance of large
amounts of water. Absorption from the face
6.4 As buildings become taller and will not cause efflorescence unless there are
individual stone-slab veneer becomes larger in open joints.
area, the lateral forces due to wind loads must
be considered. Wind tunnel tests are often 8.3 Limestone is seldom injured by
used on major structures to determine wind efflorescence. However, some of the salt
dynamics and force magnitude. Reinforcement crystals may form in the pores near the surface.
is sometimes necessary for large dimension slab Crystal growth (recrystallization) in the pores
veneer in critical areas. can cause stress on the walls of the pores and
cause the stone to flake off. If the conditions
7.0 SEISMIC CONSIDERATIONS bringing about this action persist, scaling may
continue and flake off one layer after another.
7.1 Seismic considerations generally require For this to happen, large amounts of water
that low buildings be stiff, and that tall must enter the wall and must contain large
buildings be relatively flexible. Design of amounts of salts.
connections must account for seismically
induced horizontal loading. Local building

Page 6-14 • Limestone © 2022 Natural Stone Institute

8.4 Staining or discoloration occurring on 9.0 THERMAL EXPANSION
new buildings can be a brown stain found on
buff limestone, or a dark gray stain on gray 9.1 The thermal expansion of limestone is
limestone. Research indicates that the stains an important consideration where limestone is
are caused by the action of water percolating used with dissimilar materials to form large
through cement from which soluble alkali salts units that are rigidly fixed.
are leached. The salts are then carried through
the stone, where partially oxidized organic 9.2 The coefficient of thermal expansion
matter is picked up. This is then transported to varies from one variety to another; actual
the surface of the stone, where it is deposited thermal characteristics of a specific limestone
as a stain as evaporation of the water takes should be obtained from the Quarrier or
place. Fabricator before making a final selection.

8.5 This staining phenomenon is similar to

efflorescence except that it involves organic
material. It does not harm the stone other than
leaving an objectionable appearance during or
soon after erection. However, if left alone, the
stain is removed naturally by the action of the
elements, usually in the course of a few
months.

8.6 A considerable amount of water passing

through the stone is necessary to bring out
conspicuous discolorations. Proper pre-
cautions taken during construction of the walls
will usually prevent such troubles. A simple
and helpful expedient is to provide frequent
weep holes in the base course and above shelf
angles. These should be placed in the vertical
joints so they can be sloped upward from the
front to back.

8.7 Stains sometimes appear on the base

course when limestone is in contact with soil,
due to the carrying of soluble salts and some
colored soil constituents up through and to the
surface of the stone by capillary action. Almost
all soils contain soluble salts. Therefore, this
staining phenomenon should disappear when
the source of moisture is eliminated.

8.8 Avoid contact between soil and stone.

Dampproofing treatments of either a
bituminous or cementitious nature may be
used as a barrier to the ground water or
construction moisture causing these stains.

© 2022 Natural Stone Institute Limestone • Page 6-15

NOTES:

Page 6-16 • Limestone © 2022 Natural Stone Institute

MARBLE and onyx 1.2.3.1 Membership, Products, and Services
Directory
1.0 GENERAL 1.2.3.2 Dimension Stone Design Manual
1.1 Related Documents 1.2.3.3 Additional publications may be
available from the NSI Bookstore. Go online at
1.1.1 Drawings and general provisions, www.naturalstoneinstitute.org.
including General and Supplementary
Conditions of the Contract and Division I 1.3 Scope of Included Work
Specification sections, apply to this section.
1.3.1 The work to be completed under this
1.2 Applicable Publications contract includes all labor and materials
required for the furnishing and installation of
1.2.1 The following publications listed here all marble work shown or called for on the
and referred to thereafter by alphanumeric contract drawings, specifications, and
code designation only, form a part of this addenda.
specification to the extent indicated by the
references thereto: 1.4 Definition of Terms
1.2.2 ASTM International (ASTM): 1.4.1 The definitions of trade terms used in
this specification shall be those published by the
1.2.2.1 C503, Standard Specification for NSI or ASTM International.
Marble Dimension Stone

1.2.2.2 C97, Standard Test Methods for

1.5 Source of Supply
Absorption and Bulk Specific Gravity of
Dimension Stone 1.5.1 All marble shall be obtained from
quarries having adequate capacity and facilities
1.2.2.3 C99, Standard Test Method for to meet the specified requirements, and by a
Modulus of Rupture of Dimension Stone firm equipped to process the material promptly
on order and in strict accord with
1.2.2.4 C170, Standard Test Method for specifications. The Specifying Authority
Compressive Strength of Dimension Stone (architect, designer, engineer, contracting
officer, end user, etc.) reserves the right to
1.2.2.5 C241 Standard Test Method for approve the Material Supplier prior to the
Abrasion Resistance of Stone Subjected to Foot award of this contract. Stone and workmanship
Traffic quality shall be in accordance with Industry
Standards and Practices as set forth by the NSI.
1.2.2.6 C880, Standard Test Method for
Flexural Strength of Dimension Stone 1.6 Samples

1.2.2.7 C1353, Standard Test Method for 1.6.1 The Marble Contractor shall submit
Abrasion Resistance of Dimension Stone through the General Contractor, for approval
Subjected to Foot Traffic Using a Rotary by the Specifying Authority, at least two sets of
Platform Abraser samples of the various kinds of marble
specified. The sample size shall be 1'-0" x 1'-0"
1.2.3 Natural Stone Institute (NSI): (300 mm x 300 mm) and shall represent
approximately the finish, texture, and
anticipated range of color to be supplied.

© 2022 Natural Stone Institute Marble and Onyx • Page 7-1

Where necessary to show variations in color dimensions necessary for fabrication. If
and markings, larger samples or range sets of measurements are not established and
samples should be submitted. If marble is to be guaranteed in advance, the Marble Contractor
matched, a minimum of two sets each shall obtain and verify measurements at the
containing four matched samples showing building. The General Contractor shall be
proposed veining and range of color in each set responsible for all reasonable assistance to the
must be supplied. Samples designating finished Marble Contractor, including the services of an
face shall be clearly labeled on the back with Engineer, if required, for the establishment of
the name of the marble, the group classification levels, bench marks, and the like. The Marble
for soundness, and the use for which the Contractor shall not be responsible for
marble is intended. One set of samples shall be determining, making, or verifying (1) design,
retained by the Specifying Authority, and one structural, wind, seismic, or other design
set shall be returned to the Marble Supplier for loads; (2) engineering estimates; (3) plans or
his/her record and guidance. It is noted herein specifications; or (4) the types, sizes, or
that marble is a natural material and will have locations of anchors, unless specifically added
intrinsic variations in color, markings, and to the scope of work.
other characteristics. Depending on the marble
selected and quantity required, a range 1.8 Defective Work
mockup may be used to further define the
characteristics of the material. Cost of 1.8.1 Any piece of marble or onyx showing
mockup, if required, shall not be included in flaws or imperfections upon receipt at the
this section. storage yard or building site shall be referred to
the Specifying Authority for determination as
1.6.2 Prior to fabrication, an inspection and to responsibility and decision as to whether it
approval by the Specifying Authority and/or shall be rejected, patched, or redressed for use.
General Contractor and/or End User of the
finished slabs is recommended to understand 1.9 Repairing Damaged Stone
the finish and full range of the material.
1.9.1 Small chips at the edges or corners of
1.7 Shop Drawings marble may be patched provided the structural
integrity of the stone is not affected and the
1.7.1 The Marble Contractor shall submit patch matches the color and finish of the
through the General Contractor, for approval marble so that the patch does not detract from
by the Specifying Authority, sufficient sets of the stone’s appearance.
shop drawings showing general layout,
jointing, anchoring, stone thickness, and such
other pertinent information. These drawings
2.0 MATERIALS
shall show all bedding, bonding, jointing, and
anchoring details along with the net piece
dimensions of each marble unit. One copy of 2.1 Marble
approved drawings shall be retained by the
Specifying Authority, one copy shall be 2.1.1 General: All marble shall be of kind or
retained by the General Contractor, and one kinds shown on the Architect's drawing or as
copy returned to the Marble Contractor for specified herein, conforming to or within the
fabrication. NO FABRICATION OF MARBLE range of approved samples and in accordance
SHALL BE STARTED UNTIL SUCH with the characteristics and working qualities
DRAWINGS HAVE BEEN FULLY set forth under their respective Soundness
APPROVED AND MARKED AS SUCH. The Group Classifications, A, B, C, or D, as defined
General Contractor shall furnish all field by the Marble Institute of America. Care shall
be taken in selection to produce as harmonious

Page 7-2 • Marble and Onyx © 2022 Natural Stone Institute

effects as possible. Patching and waxing, where conform to the requirements of the Standard
permitted under the Marble Institute of Specifications for Masonry Cement, ASTM
America Group Classifications, shall be C91.
carefully done to conform to the marble’s
general character and finish. Texture and finish 2.2.2 Sand. All sand shall be clean, free from
shall be within the range of sample(s) approved organic and other deleterious matter likely to
by the Specifying Authority. stain the finished work, and shall be screened
as required for the desired results.
2.1.1.1 ASTM C503 [C97] [C99] [C170]
[C241/C1353] [C880] See the chart of 2.2.3 Portland cement shrinkage-
applicable ASTM standards and tests in the reducing accelerator used with portland
Appendix. cement to give it the quick-setting
characteristics of plaster of paris, shall be a
2.1.2 Schedule: Marble shall be provided nonstaining admixture that will not corrode
as follows: anchors or dowels.

2.1.2.1 For (state location on building) (state 2.2.4 Nonstaining adhesive shall be of a
name and color) marble with a (type) finish, type that will not stain the marble, that is not
supplied by (name company or list several approved affected by temperature changes or moisture,
suppliers). and that adheres with strong suction to all clean
surfaces.
2.1.2.2 Provide information as in (1) for
each different marble/finish combination in 2.3 Pointing Mortar
the project.
2.3.1 Mortar for pointing shall be Type N, as
2.1.3 Finishes: Finishes listed in the defined in ASTM C270 (Standard Specification
schedule shall conform with definitions by NSI for Mortar for Unit Masonry). All mixing,
or ASTM International. handling, and placing procedures shall be in
accordance with ASTM C270.
2.1.3.1 Polish Finish: A mirror-like, glossy
surface which brings out the full color and 2.4 Sealants and Backup
character of the marble. This finish is not
Material (if Applicable)
recommended for exterior or commercial
floor use.
2.4.1 Where specified (state type or name of
sealant) shall be used for the pointing of joints.
2.1.3.2 Honed Finish: A velvety smooth
The backup material used with the sealant shall
surface with little or no gloss.
be (identify material).
2.1.3.3 Abrasive Finish: A flat, nonglossy
2.4.2 Sealants, used for pointing to exclude
surface usually recommended for exterior use.
moisture and provide a joint that will remain
plastic for many years, shall be nonstaining.
2.2 Setting Mortar (And
Adhesives) 2.5 Anchors, Cramps, and
Dowels
2.2.1 Portland cement shall conform to the
requirements of the Standard Specifications for
2.5.1 Anchors, cramps, and dowels shall be
Portland Cement, ASTM C150. White
made of corrosion-resistant metals. Special
portland cement is recommended for white or
cramps, dowels, and the like shall be used
light colored marble. Nonstaining cement shall
where shown on shop drawings, but

© 2022 Natural Stone Institute Marble and Onyx • Page 7-3

elsewhere, #8 copper or stainless steel wire 3.4.1 Stone coming in contact with structural
anchors shall be used. It shall be the work shall be back-checked as indicated on the
responsibility of the Marble Contractor to approved shop drawings. Stones resting on
anchor all marble securely. For standing structural work shall have beds shaped to fit the
marble, the following practices usually prevail: supports as required.

2.5.1.1 A minimum of four anchors should 3.4.2 Maintain a minimum of 1" (25 mm)
be provided for pieces up to 12 square feet (1 between stone backs and adjacent structure.
m2), with two additional anchors for each (Note: many bolted connections will require
additional 8 square feet (0.75 m2) of surface more space than this; 2" (50 mm) space may be
area. Shims used to maintain joints shall be more desirable. Large-scale details should
plastic. illustrate and control these conditions.)

2.5.1.2 Use of copper wire for anchors to be 3.5 Cutting for Anchoring,
installed over 12' (3.5 m) off the ground is not Supporting, and Lifting Devices
recommended.
3.5.1 Holes and sinkages shall be cut in stones
3.0 FABRICATION for all anchors, cramps, dowels, and other
tieback and support devices per industry
3.1 Beds and Joints standard practice or approved shop drawings.
However, additional anchor holes shall be
3.1.1 Bed and joint width shall be determined drilled at job site by Marble Contractor to
by analysis of anticipated building movements facilitate alignment.
and designed to accommodate such
movements without inducing undue stresses in 3.5.2 No holes or sinkages will be provided
the stone panels or joint filler materials. for Marble Contractor’s handling devices
Expansion joints shall be designed and located unless arrangement for this service is made by
to accommodate larger movements. the Marble Contractor with the Marble
Fabricator.
3.2 Backs of Pieces
NOTE: It is not recommended that lewis pins
3.2.1 Backs of pieces shall be sawn or roughly be used for stones less than 3½" (90 mm)
dressed to approximately true planes. Back thick.
surfaces shall be free of any matter that may
create staining. 3.6 Cutting and Drilling for
Other Trades
3.3 Moldings, Washes, and Drips
3.6.1 Any miscellaneous cutting and drilling
3.3.1 Moldings, washes, and drips shall be of stone necessary to accommodate other
constant in profile throughout their entire trades will be done by the Marble Fabricator
length, in strict conformity with details shown only when necessary information is furnished
on approved shop drawings. The finish quality in time to be shown on the shop drawings and
on these surfaces shall match the finish quality details, and when work can be executed before
of the flat surfaces on the building. fabrication. Cutting and fitting, due to job site
conditions, will be the responsibility of the
3.4 Back-Checking and Fitting Marble Contractor.
to Structure or Frame
3.6.2 Incidental cutting such as for window
frame clips, etc., which is normally not

Page 7-4 • Marble and Onyx © 2022 Natural Stone Institute

considered to be the responsibility of the Stone 5.1.2 All marble and onyx pieces shall be
Supplier, will be provided only by arrangement identified with a unique piece number
by the General Contractor and Marble corresponding with the number on the shop
Contractor with the Marble Fabricator. drawings. Interchanging of numbered pieces is
not permitted.
3.7 Carving and Models
5.1.3 Marble and onyx shall be free of any
3.7.1 All carving shall be done by skilled Stone ice or frost at time of installation. Salt shall not
Carvers in a correct and artistic manner, in be used for the purpose of melting ice, frost, or
strict accordance with the spirit and intent of snow on the stone pieces.
the approved shop drawing, or from models Adequate protection measures shall be taken to
furnished or approved by the Specifying ensure that exposed surfaces of the stone shall
Authority. be kept free of mortar at all times.

5.2 Mortar Setting of Marble

4.0 SHIPPING AND HANDLING and Onyx

4.1 Packing and Loading 5.2.1 Floor Marble

4.1.1 Finished marble shall be carefully 5.2.1.1 Floor Preparation. It is the
packed and loaded for shipment using all General Contractor’s responsibility to clean all
reasonable and customary precautions against subfloor surfaces to remove dirt, dust, debris,
damage in transit. No material which may and loose particles immediately prior to setting
cause staining or discoloration shall be used for marble floor and to ensure that the area to
blocking or packing. receive the stone flooring meets the deflection
standards of the industry.
4.2 Site Storage
5.2.1.2 Curing Compounds. Curing
4.2.1 It shall be the responsibility of the compounds of any kind shall not be used on the
Marble Contractor to receive, store, and slab on which floor marble is to be directly set.
protect the marble from damage by others after If a curing compound is present, it is the
it is delivered to the job site and prior to its General Contractor’s responsibility to remove
erection in the building. All marble shall be it by scarifying the slab.
received and unloaded at the site with care in
handling to avoid damage or soiling. If marble 5.2.1.3 Before being set, all marble shall be
is stored outside, it shall be covered with clean and free of foreign matter of any kind.
nonstaining waterproof paper, clean canvas, or
polyethylene. 5.2.1.4 Mortar Bed. The mortar bed to
receive the marble tile shall consist of 1 part
portland cement to not more than 4 to 5 parts
5.0 INSTALLATION of clean, sharp sand mixed quite dry for
tamping. White portland cement is
5.1 General Installation recommended for light-colored marbles.

5.1.1 Installation shall be accomplished with 5.2.1.5 Marble Tamped. The marble shall
competent, experienced Stone Setters, in be tamped with a suitable mallet until firmly
accordance with the approved shop drawings. bedded to the proper level of the floor.

© 2022 Natural Stone Institute Marble and Onyx • Page 7-5

5.2.1.6 Marble Removed. The marble place. Stone tile shall not be applied to skinned-
shall then be removed and the back parged with over mortar. Alternatively, back butter the
wet cement or the bed sprinkled with water stone tiles to ensure 100% contact. In either
and cement. In the latter procedure, the back method, ensure 100% contact on 3/8" (9.5
of the marble shall be wet. The method of fully mm) tile; not less than 80% contact on ¾" (20
buttering edges of the marble as it is laid is mm) or thicker material, noting that all corners
equally approved. and edges of stone tiles must always be fully
supported, and contact shall always be 100% in
5.2.1.7 Joints. Joints between the marble exterior and/or water-susceptible conditions.
pieces shall show an even width when laid and
finished. 5.2.2 Interior Veneer Marble

5.2.1.8 Traffic after Installation. The 5.2.2.1 The marble shall be set by spotting
floor shall be roped off for 24 hours after with cement mortar and the use of concealed
installation and then grouted with water and anchors secured in the wall backing.
white portland cement grout or nonstaining
dry set portland cement grout. 5.2.3 Marble Wall Tile

5.2.1.9 Timeline for Additional 5.2.3.1 Individually set thin tile [nominal
Cleaning. Cleaning or additional surfacing, if 3/8" (9.5 mm) thick] on vertical surfaces
required, shall not be undertaken until the new exceeding 15'-0" (4.5 m) is not recommended.
floor is at least seven days old. Where thin marble tile is installed, nonstaining
adhesives or thin-set mortars may be used as
5.2.1.10 Thin-set Method. The thin set setting beds.
method of installing marble tile employing the
use of dry-set portland cement mortars is 5.2.4 Toilet and Shower
recommended for thin marble tiles [nominal Compartments
3/8" (9.5 mm) thick] where optimum setting
space is not available. Subfloor shall be clean, 5.2.4.1 Stiles and partitions shall be
smooth-finished, and level. assembled with concealed dowel fastenings or
corrosion-resistant angles, three in height of
5.2.1.10.1 Stone dust must be washed off the stall.
back face of stone pavers prior to installation.
Apply mortar with flat side of trowel over an 5.2.4.2 For ceiling-hung units, metal
area that can be covered with tile while mortar supporting members in ceiling are to be
remains plastic. Within ten minutes, and using furnished and installed by the General
a notched trowel sized to facilitate the proper Contractor.
coverage, comb mortar to obtain an even-
setting bed without scraping the backing 5.3 Mortar Joints
material. Key the mortar into the substrate
with the flat side of the trowel. Comb with the 5.3.1 Mortar joints shall be raked out to a
notched side of the trowel in one direction. depth of ½" to ¾" (12.5 to 20 mm). Apply
Firmly press stone tiles into the mortar and pointing mortar in layers not exceeding 3/8"
move them perpendicularly across the ridges, (9.5 mm) and allow each layer to get hard to
forward and back approximately 1/8" to ¼" (3 the touch before the next layer is applied. Tool
to 6.5 mm) to flatten the ridges and fill the finished joints with a concave tool having a
valleys. Ensure a maximum mortar thickness of diameter approximately 1/8" (3 mm) greater
3/32" (2.5 mm) between stone tile and than the joint width.
backing after stone tile has been tamped into

Page 7-6 • Marble and Onyx © 2022 Natural Stone Institute

5.3.2 Care shall be taken to keep expansion material and applying a primer if required, all
joints free of mortar, which would in strict accordance with the printed
compromise their function. instructions of the Sealant Manufacturer.

5.4 Anchorage 5.7.2 All sealants shall be tooled to ensure

maximum adhesion to the contact surfaces.
5.4.1 All marble shall be anchored or doweled
in accordance with the approved shop 5.8 Weep Tubes
drawings.
5.8.1 Plastic or other weep tubes shall be
5.4.2 To the furthest extent possible, all placed in joints where moisture may
anchor preparations in the marble units shall be accumulate within the wall, such as at base of
shop-applied. cavity, continuous angles, flashing, etc., or as
shown on architectural drawings.
5.4.3 All anchorage devices and anchor
hole/slot fillers shall be in accordance with
ASTM C1242. Care must be taken to ensure 6.0 CLEANING AND
that any holes capable of retaining water are
PROTECTION
filled after use to prevent water collection and
freezing.
6.1 Cleaning
5.5 Sealant Joints
6.1.1 Marble shall be shop cleaned at the time
of final fabrication. It shall also be cleaned after
5.5.1 Where so specified, joints requiring
installation and all pointing or caulking is
sealant shall be first filled with a closed-cell
completed. All dirt, excess mortar, weld
ethafoam rope backer rod. The backer rod
splatter, stains, and other defacements shall be
shall be installed to a depth that provides
removed.
optimum sealant profile after tooling.
6.1.2 All cleaning methods shall be in
5.5.2 If recommended by the Sealant
accordance with ASTM C1515.
Manufacturer, primers shall be applied to the
substrate surfaces according to the
6.1.3 Stiff bristle fiber brushes may be used,
manufacturer’s directions prior to application
but the use of wire brushes or of acid type
of the joint sealant.
cleaning agents and other solutions which may
cause discoloration is expressly prohibited.
5.6 Expansion Joints Fabricator should be contacted before cleaners
other than neutral detergents are used.
5.6.1 It is not the intent of this specification to
make control or expansion-joint
6.2 Protection of Finished Work
recommendations for a specific project. The
Specifying Authority must specify control or
6.2.1 After the marble work is installed, it
expansion joints and show locations and details
shall be the responsibility of the General
on drawings.
Contractor to see that it is properly and
adequately protected from damage or stains
5.7 Caulking until all trades are finished. This responsibility
includes the stone cleaning costs prior to the
5.7.1 Where so specified, joints shall be required final inspection. The Marble
pointed with the sealant(s) specified in Section Contractor will outline the needs for
2.4, after first installing the specified backup

© 2022 Natural Stone Institute Marble and Onyx • Page 7-7

protection, in writing, to the General 1.1.1 A commercial definition equally
Contractor. For the protection of projecting important and long used in the industry is that
members, corners, window stools, and marble is any crystallized carbonate rock and
saddles, wood guards using lumber that will certain types of limestone that take a polish and
not stain or deface with marble shall be can be used as architectural or ornamental
supplied, installed, and maintained by the stone2. The dimension stone industry
General Contractor. All nails used shall be traditionally includes other types of stone, such
galvanized or nonrusting. Damage to finished as onyx, in the same classification as marble.
marble by other trades shall be repaired or
replaced at the expense of the General 1.1.2 Almost all metamorphic marbles are
Contractor. Marble flooring shall be developed by high pressures in the process of
adequately protected by the General metamorphism, while recrystallization of
Contractor against traffic and other damage limestone can occur under normal overburden
with nonstaining materials without cost to the pressures in thick sedimentary sequences.
Marble Contractor. Obviously, due to the high pressures of
metamorphism, it is expected that
6.2.2 All marble work in progress shall be metamorphic marble is tighter, denser, and
protected at all times during construction by more fracture-free than other kinds of marble,
use of a strong, impervious film or fabric and generally that is true. Metamorphic marble
securely held in place. and recrystallized limestone will not be
differentiated in the remainder of this discourse
unless otherwise noted.

PRODUCT 1.1.3 In commercial usage, descriptives may

DESCRIPTION – be added that refer to a marble’s color, e.g.,
white or blue marble. More useful to the trade
Marble and Onyx because of the necessity to judge the properties
and behavior of the stone, is the scientific
1.0 GEOLOGICAL convention of referring to the mineralogical
CLASSIFICATION content of the stone, such as dolomitic marble
or sandy marble, indicating marbles with some
1.1 Marble is geologically defined as a dolomite or sand content. Assuming the
metamorphic rock predominately consisting of marble user knows something about the
fine- to coarse-grained, recrystallized calcite properties of the minerals, an idea of the
(CaCO3), and/or dolomite, (CaMg(CO3)2), stone’s behavior can be anticipated.
which has a texture of relatively uniform
crystals ranging from very large (inches) to 1.1.4 Colors. In dolomitic marble, the
very fine, small, uniform sized crystals1. Two dolomite often weathers to a tan or buff color
aspects of the definition are important to the from the oxidation of a slight amount of iron
stone industry professionals and scientists released from the marble. The chemical series
alike: It is metamorphic and, it is recrystallized; of dolomite, with the end members of
that is, many marbles are formed by processes CaMg(CO3)2 to CaFe(CO3)2 is continuous
of recrystallization and/or metamorphism and from 100% Ca to 100% Fe, so many dolomitic
have recrystallized textures that obscure most marbles, while nearly white when cut, will
previous texture and depositional features. probably weather slightly buff to tan due to the

1 Adapted from: Bates, R. L. and J. A. Jackson, eds.,

1980, Glossary of Geology, 2nd Edition, American
Geological Institute, 1980.
2 Ibid.

Page 7-8 • Marble and Onyx © 2022 Natural Stone Institute

release of iron, which then oxidizes to iron 1.1.7 Geological origin. Limestone that
oxides that yield the characteristic colors from begins as an accumulation of shelly debris,
off-white to tan, buff, yellow to red, and dark mostly fragmental but also including whole
brown to the stone as a whole. In dolomitic shells, is mostly the aragonite form of CaCO3.
marble these colors are often uniformly Original sediment usually has a matrix of
distributed. Bands, streaks, or swirls of distinct organically derived, clay-sized carbonate grains
color may have other explanations relating to of aragonite. If buried, compacted, and
the stone’s original deposition and subsequent cemented, it takes about 50 to 60 million years
geological formation. under standard conditions of temperature and
pressure for aragonite to convert to calcite. In
1.1.5 Calcite, the dominant mineral of addition to fossils, other features, artifacts of
marble, occurs in many colors. Among the deposition, may also be preserved. Examples
many common trace-amount impurities that include voids, often the internal void space of
color marbles are organic matter (generally shells of clams and snails. Commonly, these are
gray to black), chlorite3 (generally light green filled in with carbonate dust that has
to yellowish-green), epidote4 (the same green crystallized solid. Voids of any origin
as above), and minor amounts of land-derived commonly contain calcite crystals totally filling
clays, silts, and sands. These clastic silicate in the void space.
sediments may already be stained with iron to
yield any color from very light buff to dark 1.1.8 Cross-bedding and ripple marks on the
brown, and almost any red color; or the silicate sea floor are visibly preserved, as are raindrop
grains themselves may contain trace amounts imprints and mud cracks from shrinkage during
of iron available by chemical release to stain exposure and drying that form if the surface is
and color. Other known coloring agents are exposed to air, for example at low tide, and
too numerous to mention here. Iron is by far then buried, preserving the features. There are
the most common. many more examples, some of which are called
“faults,” but are entirely natural. Most of these
1.1.6 Impurities are often confused with other features formed at the time of deposition
features that can be found in marble, most of disappear and are lost in the recrystallization
which are primary depositional features5 or process of limestone or in pressure-related
artifacts of chemical changes prior to, during, metamorphism. Some of these primary
or subsequent to metamorphism and/or re- features can be detrimental, as they could
crystallization. Such features are intrinsic to the weaken stone.
character of many exotic marbles, making
some rare types quite valuable. Conversely, 1.1.9 Another kind of feature, known as a
the same features could be detractions, stylolite, is formed as a result of geochemical
weakening the stone or making it unattractive, processes either after burial or cementation
thus rendering it unsuitable as a decorative and long geologic aging. A stylolite is a spiked
dimension stone. surface within and usually parallel or
subparallel to a bedding planes. Stylolites are
evidence of dissolution along fractures or

3 Chlorite is a very complex hydrous silicate of aluminum. Being very hard, heavy, and insoluble, it
magnesium, iron, and aluminum has a platy habit. It is weathers out of metamorphic terrain and can be
soft, flexible (micalike, but not elastic), and usually an deposited in near-shore marine deposits of carbonate
alteration product in igneous or low-grade debris, lending its green color to marble.
metamorphic stone, or is transported into sedimentary 5 Primary depositional features are developed at the time

sequences. of deposition of sedimentary particles.

4 Epidote is often found with chlorite and has about the

same color range. It is a complex, low-grade,

metamorphic hydrous silicate of iron, calcium, and

© 2022 Natural Stone Institute Marble and Onyx • Page 7-9

partings, possibly initiated by a thin film of dark contact with granite or volcanic igneous rock,
organic matter. Such dissolution can remove then the accessory minerals may include a suite
several feet of section in a carbonate sequence. of complex carbonates and silicates. If the
These lines become increasingly irregular in a marble is in contact with, or influenced by
vertical plane as dissolution proceeds at varying other complex metamorphic stone, then it may
rates from place to place along the surface. have complex carbonate/metamorphic
Stylolites can occur in any carbonate rock from minerals other than the few already
limestone to metamorphic marble, and are mentioned. It is geologic factors like these that
purely a phenomenon of chemical dissolution. can produce the highly colorful and complex
Stylolites are identifiable as a thin, spiky, or marbles seen in both antique and modern
crenellated black line. works. Such stones may occur in limited
deposits. The more common and universally
1.1.10 Other minerals found in marbles used marbles from antiquity to the present are
include the various common carbonate mostly calcite, many close to ±99% calcium
minerals previously mentioned. One, carbonate, found in large deposits with
magnesite (MgCO3), is characteristic of the adequate reserves for extended quarrying.
metamorphic marbles and not usually found in
recrystallized, limestone-type marbles. A 1.1.13 The great variety of colorful, often
generally undesirable mineral, pyrite (FeS2) or exotic marbles from Italy is formed in
iron sulfide may also occur in marble and are juxtaposition to intrusive and extrusive igneous
alteration minerals formed after deposition and rocks and/or a variety of metamorphics. Italy
during the metamorphism and recrystallization has an exceedingly complex geology, with
phase from small amounts of entrained sulfates active igneous activity and nearly every known
or fluids containing dissolved, sulfur-bearing level of metamorphism, as well as a variety of
salts that enter the stone during its burial sedimentary deposits. Italy also has
history. experienced remarkable dry periods clearly
indicated by the kinds of sedimentary rocks
1.1.11 Pyrite will occur as discrete cubic surrounding the Mediterranean (e.g., mottled
crystals, finely disseminated, or as masses in red marbles), dating from when the area was
marble. It is hard (H=6+ on the Mohs scale6 ) an empty, desert-like basin before the Straits of
and sometimes has an attractive, brassy Gibraltar opened to flood the present
appearance–it will bleed ugly stains from Mediterranean Sea.
oxidation during repeated water incursion.
Pyrite is often found disseminated throughout 1.1.14 Physical and Chemical
shelly limestone, a natural occurrence with Properties of Calcite. To understand the
biological materials deposited in anoxic stone, one must first understand the minerals.
conditions (without oxygen). Pyrite exposed Many of the desirable qualities and many of the
on the face of cut and polished stone easily problems commonly encountered with marble
reacts with moisture to form the undesirable are direct consequences of the properties of
and difficult to remove staining. Its brassy calcite, the dominant mineral, or in some
metallic luster is not necessarily unattractive, cases, the less abundant accessory minerals. A
but not for use in wet environments. review of the physical and chemical properties
of calcite follows:
1.1.12 The accessory mineral variation
found in marble is diverse and dependent on 1.1.14.1 Crystals. Calcite crystals are found
the geologic origin and burial history of the in several different and predictable crystal
limestone or marble. If the marble was in shapes exactly controlled by atomic geometry

6 See Appendix for the Mohs Scale of mineral hardness.

Page 7-10 • Marble and Onyx © 2022 Natural Stone Institute

of the CaCO3 molecule. Crystals may grow in colorless clear or transparent. It can be almost
isolated free spaces or voids called “vugs7” or in any other color of the spectrum. Calcite is also
open fractures or in masses like an entire easily dyed with proprietary dyes and
sequence of stone. More geometrically techniques. Many are organic compounds that
complex crystals, if they occur, are generally have limited longevity in sunlight and thus fade
unrecognizable from randomly oriented cuts in time. Or these manmade dyes wash out
on polished marble surfaces. Both fractures and from chemical spills and ordinary cleaning
vugs eventually fill completely with crystals, compounds. Dyed stone of any kind should be
often obscuring their former existence. The considered with extreme caution for these
most common calcite crystal shapes are reasons.
parallelograms or truncated, faceted, or
tapering prisms8. Fractures are generally 1.1.14.4 Composition. Calcite is a
identifiable even if filled, while a totally infilled carbonate of calcium or CaCO3. While calcite
vug is easily overlooked. Fractures may be a is the most abundant component, carbonates of
potential line of breakage, but a small, closed iron, manganese, magnesium, zinc, and
vug, being virtually unrecognized on a polished strontium are sometimes present. Many other
surface, is of little significance to the carbonates and hydrous carbonate minerals of
commercial quality of a stone. various metals such as lead, barium, and copper
are rarely seen in commercial marble.
1.1.14.2 Cleavage. Calcite has a definite
geometric molecular structure; i.e., the atoms 1.1.14.5 Acid Reaction. Calcite
of calcium, oxygen, and carbon are always effervesces—reacts and bubbles vigorously in
arranged in a fixed geometry such that three dilute hydrochloric acid. This is a positive
planes of weakness occur not at 90°, along diagnostic chemical property of calcite. Calcite
which calcite crystals will generally break.9 can dissolve without visible bubbling in the
The result is a parallelogram-shape fragment presence of other kinds of dilute acids or even
with very flat sides. This is termed cleavage. It acidic liquids, such as red wine and salad
reflects atomic planes of weakness that vinegars. In acidic atmospheres with sulfur,
predetermine how and where a mineral will marble is not only etched, but will react with
break apart. Other minerals may have one, to very dilute sulfuric acid in moist air to form a
as many as six, cleavages. Any two exactly powdery calcium sulfate, the mineral gypsum.
parallel sides constitute one cleavage. Thus, a
six-sided parallelogram of calcite exhibits three 1.1.14.6 Optical Character. Optically clear
cleavages, with one for each pair of parallel cleavage fragments–parallelograms–of calcite
sides. A cleavage face is very flat. It may be have the curious optical property of double
stepped but the stepped surfaces are exactly refraction. Objects or print seen through the
parallel and reflect light as a single surface. cleavage fragment will appear as a double
image. The varietal name for optically clear
1.1.14.3 Color. Calcite can be any color from calcite is Iceland Spar10.
black to white (the most common), and

7 Vugs are mostly small to microscopic, but some have 9 In addition to cleavage, any mineral can be fractured
been found large enough to walk into. A vug in other than along known planes of weakness in atomic
limestone, dolomite, or marble may contain crystals of geometry. Such noncleavage breaks are always very
calcite in addition to some of the other mentioned irregular and rough. Fracture and cleavage may be
accessory minerals. microscopic in scale.
8 Calcite is rarely found in the unusual crystalline form 10 Named after Iceland, where it is found in abundance.

of fibrous masses. Because the individual fiber-like Some specialized 19th century microscopes utilized the
bundles of crystals are so small, it is easily carved and optical characteristics of Iceland Spar and incorporated
has been mistakenly called alabaster, though it is not a pair of precisely cleaved parallelogram-shaped calcite
the true gypsum-based material. crystals. Such instruments are now obsolete.

© 2022 Natural Stone Institute Marble and Onyx • Page 7-11

1.1.14.7 Anisotropy. Calcite is one of many recognizes the collective phenomena as thermal
minerals that exhibit different values of hysteresis. Hysteresis is defined as “a lag in the
physical and chemical properties on different return of an elastically deformed body to its
crystal sides or optical directions in its original shape after the load has been removed.
crystalline shape. These variable properties, One of the effects of anisotropy and repeated
changes in numerical values in different thermal cycles is to defer and/or arrest the
crystallographic directions, are known as elastic rebound that would normally occur
anisotropic properties. The differences, with hysteresis.
although very slight numerically, add up from
thousands to hundreds of thousands of 1.1.15.1 Events that can occur in calcite
crystalline mineral grains, to significant totals crystals in marble because of anisotropy and
that profoundly affect stone performance when thermal hysteresis include:
dealing with polished slabs of fine-grained
crystalline calcite. These slight, but important 1.1.15.1.1 Measurable extension on a
differences and behavioral characteristics must surface due to repeated, cyclic heating from the
be dealt with in the engineering design of sun or some other heat source.
marble installations. The anisotropic
properties of calcite that most seriously affect 1.1.15.1.2 Differential linear increases
marble performance are: across the front of thin panels vs. the back sides
can yield bowing, pillowing, or dishing of the
1.1.14.7.1 Solubility. Slight differences of sheet if too thin.
solubility on one or more of the three calcite
cleavages in the crystalline parallelogram- 1.1.15.1.3 Changes of intracrystalline
shaped crystals. The differential number may pressures, either increased or decreased, from
be very small, but the cumulative effect can be distorted shape, induces growth of calcite
a serious problem in an installation. crystals or dissolution of calcite (on different
crystal surfaces). Both chemical effects tend to
1.1.14.7.2 Ease of Cleavage. The ease of reduce strength and induce failure.
cleaving may be minutely different for each of
the three cleavages of a cleavage fragment, thus 1.1.15.1.4 Strained or distorted crystals
allowing preferential slippage to occur. accumulate from repeated heating cycles and
Although slight, in total it allows visible and become permanent.
permanent dislocations to accumulate,
ultimately leading to failure in some thinner 1.1.15.1.5 Microfractures develop from
sheets of marble. expansion or distortion of crystals and slippage
on cleavage.
1.1.14.7.3 Thermal Expansion and
Contraction. Varies with the various faces 1.1.15.1.6 Microfractures allow entrance of
and optical direction in crystals. For example, moisture and/or acid rain, which enlarges
calcite thermal expansion occurs in one fractures by solution, and in some cases,
crystallographic direction, while thermal loosely re-cements some areas and may at the
contraction occurs in crystallographic same time initiate formation of gypsum and
directions normal to the direction of granulation inside the stone and on the surface.
expansion. Both effects weaken stone, particularly on the
backside of bowed or pillowed sheets when
1.1.15 Thermal Hysteresis. Thin sheets moisture is present.
of certain marbles can sometimes fail under the
combined effects of the aforementioned
anisotropic properties. Engineering practice

Page 7-12 • Marble and Onyx © 2022 Natural Stone Institute

1.1.15.1.7 Reduction in strength of marble drop. Thus onyx is also a chemical sedimentary
sheets from the above microfractures and stone, and may envelop terrestrial fossil
growth of softer, in-filling minerals. remains. Prehistoric human remains have been
found encased in cavern onyx. Although this
1.1.15.1.8 Permanent distortion of shape: process of drop-by-drop addition of material
bowing, pillowing, and dishing, ultimately does take time, large deposits of onyx begin to
causing fractures and catastrophic failure. mature (filling caverns or fractures) in a
relatively short period of geologic time.
1.1.15.1.9 Reduced aesthetic appearance. 1.2.1 Although onyx is occasionally called
travertine, commercial practice generally
1.1.15.2 Such events do not occur in all distinguishes the two stones because of obvious
marbles. Anisotropic/hysteretic effects are differences that relate to their respective
most pronounced in the finer-grained, highly attractiveness. Onyx tends to be more
compacted, truly metamorphic marbles. crystalline, strongly banded and colored in
Anisotropic- and thermal-hysteretic problems browns to yellows and clear. It can be
generally are not seen with marbles of large translucent, and light-colored varieties sliced
grain or crystal size, nor are they seen where thin are used for attractive backlit display
the slabs are thick enough to counteract the panels or even light-admitting windows. By
forces and negate thermal differential between contrast, travertine displays large void spaces
front and back sides of the stone when effective and abundant, visible porosity, and is in all
moisture control is practiced for back sides. cases an opaque stone. Onyx, like most
limestone, will recrystallize in time (not a
1.1.15.3 Problems with marble arising from metamorphic process), often enhancing
anisotropy and thermal hysteresis can be translucency. It is the material that cameos are
avoided by intelligent stone selection, careful made from, and cameo makers use the stone’s
design, and engineering practices that colored bands to achieve artistic effects. Italy
recognize known chemical and physical produces much onyx, and the cameos carved in
properties and the effects of the variable Tuscany from highly-colored, banded onyx are
properties in calcite. world-renowned.

1.1.15.4 An excellent and complete

discussion of thermal hysteresis including 2.0 COLOR AND VEINING
actual test data and thickness recommendations
has been written by Bernard Erlin11 and 2.1 The color, veinings, clouds, mottlings,
published by ASTM International. and shadings in marble are caused by substances
included in minor amounts during formation.
1.2 Onyx originates in the dripstone Iron oxides make the pinks, yellows, browns,
deposits of limestone caverns, where it forms and reds. Most grays, blue grays, and blacks are
stalactites, stalagmites, and other formations of bituminous origin. Greens are caused by
that can fill an entire cavern or void space. It is micas, chlorites, and silicates.
deposited by gentle, dripping water movement
followed by evaporation between drops that
deposits calcium carbonate from the water
onto the formation, incrementally enlarging
formations by thousandths of an inch or less per

11Erlin, Bernard, “Contribution to a Better Construction, Evaluation, and Repair, ASTM STP 1394,
Understanding of the Mechanism Causing Dishing ASTM International, 2000.
Failures of the Carrara Marble When Used for Outside
on Building Facades.” Dimension Stone Cladding:

© 2022 Natural Stone Institute Marble and Onyx • Page 7-13

3.0 TEXTURE 6.0 SIZES

3.1 The term “texture,” as applied to 6.1 Marble is a product of nature with
marble, means size, degree of uniformity, and hundreds of varieties available, each possessing
arrangement of constituent minerals. Grains of distinct characteristics. Little can be done to
calcite, the chief constituent of most marbles, alter the condition in which nature presents
are crystalline and have definite cleavage that these varieties to us. Therefore, size may
show bright, reflecting faces on a broken become a limiting factor to consider in the
surface. In most marbles, however, the grains selection of marble. Check with the Stone
are elongated in one direction by the folding Supplier as to the sizes that are available for the
and placation of the beds. specific marble.

4.0 FINISHES 6.2 Selection and delivery can be greatly

facilitated by a jointing scheme that permits the
4.1 Marble’s surface may be finished in a use of smaller sizes. A final jointing scheme
number of ways. In general, smooth finishes should be agreed upon after the marble has
tend to emphasize color and veining, whereas been selected and the Marble Contractor has
rough finishes tend to subdue the veining or been consulted.
markings.
7.0 PRODUCT SAMPLING
4.2 Typical finishes for marble are:
7.1 Marble is formed by nature; thus, there
4.2.1 Polished: A glossy surface that brings are variations in the tonal qualities of the
out the full color and character of the marble. stones. However, it is these natural variations
It is not generally recommended for exterior that make marbles unique, valuable, and highly
use or commercial floors. desirable. Because of these variations, selection
of marble should never be made on the basis of
4.2.2 Honed: A satin-smooth surface with one sample only. It is recommended that
little or no gloss, recommended for selection be based on viewing sufficient
commercial floors. samples to show the complete range of colors
of the desired stone.
4.2.3 Abrasive: A flat, nonreflective surface,
usually recommended for exterior use. 8.0 PROPER USAGE TIPS
4.2.4 Other finishes, such as axed, bush 8.1 Recommendation for commercial
hammered, rock faced, rough sawn, or floors:
tooled, are also available.
8.1.1 Minimum ¾" (20 mm) thickness.
5.0 THICKNESS
8.1.2 A honed finish.
5.1 Standard nominal thicknesses for marble
veneer are ¾", 7/8", 1¼", 1½", and 2" (20 8.1.3 A minimum hardness value of 10 as
mm, 22 mm, 30 mm, 38 mm, and 50 mm). measured by ASTM C241/C1353.
When a marble thinner than ¾" is specified,
the ratio between thickness and overall size and 8.2 Avoid the use of gypsum or molding
the use of reinforcing backup materials must be plaster setting spots for the installation of
considered. Marble thicker than 2" (20 mm) is stone.
usually regarded as cubic stock.

Page 7-14 • Marble and Onyx © 2022 Natural Stone Institute

8.3 Avoid using Soundness Classification C comparatively fragile marbles classified under
and D marbles in wet areas, saunas, and steam Groups C and D, which may require additional
rooms. fabrication before or during installation.

8.4 Certain green colored marbles may 10.3 The basis of this classification is the
warp when installed with water based characteristics encountered in fabricating and
adhesives. Ask the Supplier for instructions. has no reference whatsoever to the
comparative merits or value of each type of
9.0 VENEER CUTTING marble. The classification indicates what
method of fabrication is considered necessary
9.1 Quarry blocks are reduced to slabs by and acceptable in each instance as based on
a gang saw. The gang saw consists of a series of standard trade practice and applies only to
steel blades set parallel in a frame that moves marble.
forward and backward. The most productive
and precision gang saws have diamond-tipped 10.4 Classification of marble is done by NSI
blades with individual hydraulic blade Member producers. A written warranty should
tensioners. be obtained from them prior to installation.

9.2 Marble blocks can be sawn either 10.5 The four groups of Marble
parallel or perpendicular to the bedding plane. Soundness Classification are:
The perpendicular cut is referred to as an
across-the-bed or vein cut. The parallel cut is 10.5.1 Group A marbles
with-the-bed or fleuri cut. Some marbles Sound marbles with uniform and favorable
produce a pleasing surface when sawed in working qualities containing no geological
either direction, and are available as either vein flaws or voids. They include completely
or fleuri. Other marbles produce a pleasing metamorphosed limestone or dolostone, in
surface only when sawed in one direction, and which impurities such as clays and silt have
are generally available only in that variety. reacted chemically with the calcite or dolomite
to form other minerals. These stones have
uniform working qualities, can be used on the
10.0 SOUNDNESS exterior or interior, and do not require any
filling or patching.
CLASSIFICATION
10.5.2 Group B marbles
10.1 As a result of knowledge gained from
Marbles similar in character to Group A,
extensive practical experience in the dimension
except that all the impurities have not changed
stone industry, marbles have been classified
into other minerals. Occasional small holes and
into four groups known as the Marble
voids are to be expected, and are
Soundness Classification.
characteristics of this group of marbles. The
holes or voids are filled by the Marble
10.2 The groupings–A, B, C, and D–should
Craftsman with epoxy, shellac, or polyester
be taken into account when specifying marble,
resin. (The terms “waxing,”12 “sticking,”13 and
for all marbles are not suitable for all building
“filling” are common industry terms.) Filling is
applications. This is particularly true of the

12Waxing refers to the practice of filling minor surface 13 Sticking describes the butt edge repair of a broken
imperfections such as voids or sand holes with melted piece, now generally done with dowels, cements, or
shellac, cabinetmaker’s wax or certain polyester epoxies. The pieces are “stuck” together; thus “sticking.”
compounds. It does not refer to the application of paste
wax to make surfaces shinier.

© 2022 Natural Stone Institute Marble and Onyx • Page 7-15

not intended to be noticeable to a great degree, 1.1 In centuries past, relatively little
perfectly color matched, or “glass” smooth. importance was attached to the ultimate
May be used on the exterior or interior. physical capabilities of most building materials.
Rule of thumb was a common structural design
10.5.3 Group C marbles criterion. As a result, the widely used materials
Marbles with some variations in working of the day, for the most part natural rather than
qualities. Geological flaws, voids, veins, and manmade, were seldom stressed to their
lines of separation are common. Many of the ultimate limits.
impurities have not changed into other
minerals, and metamorphosis is not complete. 1.2 In present-day construction,
This is the largest and most colorful group of however, this is far from being true.
marbles, and also contains significant holes, Performance requirements are daily becoming
voids, lines of separation, and structural flaws. more demanding. In striving for taller
It is standard practice to repair these variations structures, greater spans, firmer foundations,
by use of reinforcing, liners, sticking together, thinner walls and floors, stronger frames, and
filling with resin or cement, fabricating corners generally more efficient buildings with more
or missing stone with terrazzo and resin, and usable space, today’s Architects and Engineers
doing all other work necessary to hold the must get the most out of the materials with
stone together to yield a finished product that which they work.
is usable for architectural purposes. On
completion, most repairs are visible and 1.3 Marble is a product of nature and not
apparent, with a difference in light reflection. always subject to the rules of consistent
With few exceptions, these marbles are not behavior that may apply to manufactured
suitable for exterior installation. building materials. It may not be proper for
certain applications.
10.5.4 Group D marbles
Marbles similar to the preceding group, but 1.4 Physical property values of marble
containing a larger proportion of natural faults, may, however, be measured using the standard
maximum variations in working qualities, and test methods approved by the Dimension Stone
requiring more of the same methods of Committee C18 of ASTM International. The
finishing. Few stones carry this designation at values found when stone is tested for
this time; it is reserved for very laborious absorption, density, compressive strength,
Group C stones. abrasion resistance, and flexural strength
should be useful for the Designer and Engineer
10.6 The Marble Soundness Classifications when preliminary construction calculations are
indicate what method and amount of repair and being made. However, these tests should be
fabrication are necessary prior to or during made before the project specifications are
installation, as based on standard trade written, not after. Member companies of the
practices. Marble Institute of America are represented on
this committee and are active in its technical
work of establishing proper test methods and
specifications consistent with the latest
TECHNICAL DATA - technology.
Marble
1.5 The data shown in the following
1.0 PROPERTIES OF MARBLE table is the result of testing sixteen domestic
DIMENSION STONE marble varieties at the Illinois Institute of
Technology Research Institute, as well as
historical data and information established and

Page 7-16 • Marble and Onyx © 2022 Natural Stone Institute

provided by ASTM International. Final design 2.0 STRENGTH (ASTM C170,
should always be based on specific values for ASTM C880)
the marble variety ultimately to be installed.
These values may be obtained from the Marble 2.1 The strength of a marble is the measure
Supplier. of its ability to resist stresses. This strength
depends on several factors: the rift and cleavage
1.6 Physical Properties of Marble* of the crystals, the degree of cohesion, the
interlocking of the crystals, and the nature of
Property Range of Values any cementing materials present.
Compressive Strength (C170)
lbs/in² .............................. 6,000-35,000 3.0 FIRE RESISTANCE
Recommended (min): 7,500
3.1 Marbles are not combustible, according
Flexural Strength (C880) to underwriters’ ratings, and so are considered
lbs/in² .................................. 600-4,900 a fire-resistant material. Because of its thermal
Recommended (min): 1,000 conductivity, however, the heat transfer
through marble is fairly rapid. Marble is not
Modulus of Elasticity** (in millions) considered a highly rated thermal insulator.
lbs/in² ..................................... 1.5-5.0
3.2 Underwriters’ fire resistance ratings
Density, lb/ft3 (C97) ................. 140-185 evaluate whether or not a material will burn,
Recommended (min): as well as how long it will keep surrounding
162 (calcite), combustible materials from reaching
175 (dolomite) temperatures which will cause them to ignite.
Pilot plant tests at The Ohio State University
Thermal Conductivity “k” Pyrotechnics Laboratory indicate that a 10-
Btu/in/hr/ft2/ºF ................... 10.45-15.65 minute rating could be expected from 7/8"
(22 mm) thick marble.
Water Vapor Permeability
Perm-inch............................ 0.324-4.460 3.3 The use of an insulating material with
marble substantially improves the fire rating, as
Coefficient of Thermal shown below.
Expansion in/in/ºF…. 3.7 x 10-6 – 5.0 x 10-6
7/8" (22 mm) marble with 1" (25 mm) core
Modulus of Rupture (C99) of:
lbs/in² …. ........................... 1,000-4,000 Paper Honeycomb…………….…..½ hour
Recommended (min): 1,000 Cement-Bonded Wood Excelsior…...1 hour
Autoclaved Cellular Concrete…….1½ hour
Absorption, by weight % (C97) .....0.060-1.0
Recommended (max): 0.20 3.4 Methods of estimating fire resistance
periods of masonry walls and partitions
Abrasion Resistance Ha/Iw (C241/C1353) 5.0-
utilizing component laminae are given in “Fire
50.0
Resistance Classifications of Building
Recommended (min): 10
Construction,” BMS92, National Bureau of
Standards.
* Test methods described in current ASTM
standards.
** Also known as Young’s Modulus.

© 2022 Natural Stone Institute Marble and Onyx • Page 7-17

4.0 ABRASION RESISTANCE of safety in any structural element. As a
(ASTM C241/C1353) necessary precaution against such conditions as
wind, ice, snow, impact, temperature changes,
4.1 Abrasion resistance is a property of and imperfect workmanship, these allowable
stone that should be tested per ASTM stresses must be smaller than those which
C241/C1353 to provide an indication of the produce failure.
stone’s wearing qualities when exposed to foot
traffic. 6.2 Within the accepted limits of safe design
practice, the closer the allowable load is to the
4.2 The hardness and uniform wearing ultimate failure load, the more efficient is the
qualities of most marble varieties make them use of the material, and the less the cost of the
extremely desirable and economically practical construction.
for floors and stairs. Varieties with an ASTM 6.3 Contemporary design of buildings,
C241/C1353 abrasive hardness rating (Ha) of exclusive of the monumental type, does not
10 or more are recommended for use as usually employ marble as part of the structural
flooring. A minimum abrasive hardness of 12.0 frame, but rather as an independent unit, a
is recommended for commercial floors, stair curtain wall, or veneer. Therefore, the
treads, and platforms subject to heavy foot primary concern in such cases is with wind
traffic. Surfaces of floors constructed with two load, and a safety factor of 5.0 is
or more varieties, with Ha differences more recommended. Where the marble is to be
than 5, will not wear evenly and uniformly. subjected to concentrated loading, such as stair
treads or lintels supported only at the ends, a
factor of 10.0 should be used.
5.0 FACTORS AFFECTING
As buildings become taller and individual stone
PROPERTIES slab veneer becomes larger in area, the lateral
forces due to wind loads must be considered.
5.1 The ultimate test of a building material Wind tunnel tests are often used on major
is its ability to have and maintain the necessary structures to determine wind dynamics and
structural strength, as well as beauty of force magnitude. Reinforcement is sometimes
appearance and low cost of maintenance over necessary for large-dimension slab veneer in
the useful life of the structure. Experience has critical areas.
proven that marble meets this test as few other
building materials can.

5.2 Illinois Institute of Technology Research 7.0 SEISMIC CONSIDERATIONS

Institute’s studies have shown that the
durability of marble is little affected by cycles 7.1 Seismic considerations generally require
of weather. This is because of marble’s low rate that low buildings be stiff, and that tall
of moisture absorption. The rates of absorption buildings be relatively flexible. Design of
of all the marbles studied were less than 1 connections must account for seismically
percent by weight. Other masonry materials induced horizontal loading. Local building
range upward from 4% to 12%. codes vary and must always be checked to
determine specific requirements for each area.

7.2 Additional Readings:

6.0 SAFETY FACTORS The National Bureau of Standards has published
two documents on the topic: “Earthquake
6.1 Good engineering practice requires that Resistant Masonry Construction,” NBS Science
allowable design stress must provide a margin Series 106; and “Abnormal Loading on

Page 7-18 • Marble and Onyx © 2022 Natural Stone Institute

Buildings and Progressive Collapse: An transported to the surface of the stone, where
Annotated Bibliography,” NBS Science Series it is deposited as a stain as evaporation of the
67. water takes place.
8.5 This staining phenomenon is similar to
The U.S. Army Corps of Engineers also
efflorescence except that it involves organic
published TM 5-809-10, “Seismic Design for
material. It does not harm the marble other
Buildings.”
than leaving an objectionable appearance
during or soon after erection. However, if left
alone, the stain is removed naturally by the
8.0 EFFLORESCENCE AND action of the elements, usually in the course of
STAINING a few months.

8.1 Efflorescence is a salt deposit, usually 8.6 A considerable amount of water passing
white in color that appears on exterior surfaces through the stone is necessary to bring out
of masonry walls. The efflorescence producing conspicuous discolorations. Proper
salts found in masonry are usually sulfates of precautions taken during construction of the
sodium, potassium, magnesium, calcium, and walls will usually prevent such troubles. A
iron. Salts which are chlorides of sodium, simple and helpful expedient is to provide
calcium, and potassium will sometimes appear, frequent weep holes in the base course and
but they are so highly soluble in water that they above shelf angles. These should be placed in
will be washed off by rain. the vertical joints so they can be sloped upward
from the front to back.
8.2 The water-soluble salts causing
efflorescence come from other materials in the 8.7 Stains sometimes appear on the base
wall. The salts exist in small amounts and are course when marble is in contact with soil, or
leached to the surface by water percolating on interior and exterior horizontal surfaces,
through the walls. The most feasible means of due to the carrying of soluble salts and some
prevention is to stop the entrance of large colored soil constituents up through and to the
amounts of water. Absorption from the face surface of the stone by capillary action. Almost
will not cause efflorescence unless there are all soils and most of the veining in marble
open joints. contain soluble salts. Therefore, this staining
phenomenon is similar to the discoloration
8.3 Marble is not injured by efflorescence. described previously, and will disappear when
However, some of the salt crystals may form in the source of moisture is eliminated. However,
the pores near the surface. Crystal growth materials from the veining may remain on the
(recrystallization) in the pores can put stress on stone’s surface. In walls, provide venting so
the walls of the pores and cause the stone to that moisture can escape through the venting
flake off. If the conditions bringing about this rather than through the stone. On horizontal
action persist, scaling may continue and flake surfaces, the use of a vapor barrier between the
off one layer after another. For this to happen, setting bed and the concrete slab, or between
large amounts of water must enter the wall and the setting bed and the ground, is
must contain large amounts of salts. recommended.

8.4 Research indicates that staining or

discoloration occurring on new buildings is
caused by the action of water percolating 9.0 HYSTERESIS
through concrete from which soluble alkali
salts are leached. The salts are then carried 9.1 Hysteresis is a phenomenon that affects
through the marble, where partially oxidized certain “true” marbles. Unlike most stones,
organic matter is picked up. This is then which return to their original volumes after

© 2022 Natural Stone Institute Marble and Onyx • Page 7-19

exposure to higher or lower temperature, possess this translucent quality, nor is the
these marbles show small increases in volume degree of translucence the same in all varieties
after each rise in temperature above the that transmit some light.
starting point. This can result in differential
expansion within the stone, which is more 11.2 Translucence is dependent, to a
likely to be accommodated or restrained in greater or lesser extent, on the following
thick veneers than in thin ones. factors:

9.2 If it is not restrained, bowing of the 11.2.1 Crystal Structure: Marbles of

marble panels ensues and produces certain crystal structure are especially
compressive forces in the backs of panels. This adaptable to transmitting light.
causes creep, which in turn leads to permanent
deformation. “Dishing” also stretches the 11.2.2 Color: The white and lighter-
marble’s face, which makes stones more colored marbles are generally more
porous and increases their vulnerability to translucent.
corrosion from acids in the atmosphere and 11.2.3 Thickness: The light transmission
deterioration from freezing and thawing diminishes as panel thickness increases.
effects. If marbles with this tendency are
selected, it is important to determine the 11.2.4 Surface Finish: Translucency is
minimum thickness needed to overcome more apparent in smooth finishes than in rough
effects of hysteresis by testing under conditions finishes.
which simulate in place temperature gradients
of the wall.

10.0 THERMAL EXPANSION

10.1 The thermal expansion of marble is an

important consideration where marble is used
with dissimilar materials to form large units
which are rigidly fixed.
Laboratory tests for the coefficient of thermal
expansion of marble indicate that after several
cycles of heating and cooling, a residual
expansion of about 0.20% of the original
increase can be expected. This should be taken
into account when computing clearances. The
coefficient of thermal expansion varies from
one variety to another, so the actual thermal
characteristics of a specific marble should be
obtained from the quarries or fabricator before
making a final selection.

11.0 TRANSLUCENCE
11.1 The translucency of marble is one of
its most intriguing attributes. Not all marbles

Page 7-20 • Marble and Onyx © 2022 Natural Stone Institute

 VENEER CUTTING
Quarry blocks are commonly reduced to slabs by a gang saw. The gang saw consists of a series of
steel blades set parallel in a reciprocating frame.
Stone blocks can be sawed either parallel or perpendicular to the bedding plane. The perpendicular
cut is referred to as am across-the-bed or veiny cut. The parallel cut is with-the-bed, or fleuri cut.
Some stones produce a pleasing surface when sawed in either direction, and are available as either
vein or fleuri. Other stones produce a pleasing and/or structurally sound surface only when sawed
in one direction, and are therefore only available in that direction.

REV DATE
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0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

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© 2022 Natural Stone Institute 7-D-1

 VENEER PATTERNS
Only certain stones lend themselves to specific veining pattern
arrangements, such as side slip or end slip. This is because not
all stones exhibit the near constant natural marking trend
throughout the block that is required to accomplish these
effects. Formal patterns require careful selection which often
increases the costs of producing the stone veneer. Usually, a
stone sawed in a veiny direction can be matched, while a stone
sawed in a fleuri direction must be blended. Any desired
pattern other than "blended" must be indicated on the
contract bid documents to inform the stone contractor of the
additional labor required.

REV DATE
VENEER VEIN PATTERNS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

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www.naturalstoneinstitute.org SCALE:
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7-D-2 © 2022 Natural Stone Institute
 VENEER PATTERNS
Although the illustrations below depict a perfect match or mirror image of veining, such perfection is not
realistic in actual stone veining. A portion of the block is lost due to the width of the saw kerf when the
slabs are cut, and the veining position is likley to shift slightly across this offset. Brecciated marbles, for
example, are extremely difficult to accurately cut into matched patterns. Ideally, jointery of the wall
should plan for 4 panels of equal size.

REV DATE
RIFT & SAWING DIRECTIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

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NOTES:

Dimension Stone Design Manual Ó 2022 Natural Stone Institute

QUARTZ-BASED STONE Subjected to Foot Traffic Using a Rotary
Platform Abraser
1.0 GENERAL 1.2.3 Natural Stone Institute (NSI):
For purposes of this manual, Quartz-based 1.2.3.1 Membership, Products, and Services
stone refers to sandstone, quartzitic sandstone, Directory
and quartzite.
1.2.3.2 Dimension Stone Design Manual
1.1 Related Documents
1.2.3.3 Additional publications may be
1.1.1 Drawings and general provisions, available from the NSI Bookstore. Go online at
including General and Supplementary www.naturalstoneinstitute.org.
Conditions of the Contract and Division I
Specification sections, apply to this section. 1.3 Scope of Included Work
1.2 Applicable Publications 1.3.1 The work to be completed under this
contract includes all labor and materials
1.2.1 The following publications listed here required for the furnishing and installation of
and referred to thereafter by alphanumeric all Quartz-based stonework shown or called
code designation only, form a part of this for on the contract drawings, specifications,
specification to the extent indicated by the and addenda.
references thereto:
1.4 Definition of Terms
1.2.2 ASTM International (ASTM):
1.4.1 The definition of trade terms used in this
1.2.2.1 C616, Standard Specification for specification shall be those published by the NSI
Quartz-based Dimension Stone
or ASTM International.
1.2.2.2 C97, Standard Test Methods for
Absorption and Bulk Specific Gravity of
1.5 Source of Supply
Dimension Stone
1.5.1 All Quartz-based stone shall be obtained
1.2.2.3 C99, Standard Test Method for from quarries having adequate capacity and
Modulus of Rupture of Dimension Stone facilities to meet the specified requirements
and by a firm equipped to process the material
1.2.2.4 C170, Standard Test Method for promptly on order and in strict accord with
Compressive Strength of Dimension Stone specifications. The Specifying Authority
(architect, designer, engineer, contracting
1.2.2.5 C241, Standard Test Method for officer, end user, etc.) reserves the right to
Abrasion Resistance of Stone Subjected to Foot approve the Material Supplier prior to the
Traffic award of this contract. Stone and workmanship
quality shall be in accordance with Industry
1.2.2.6 C880, Standard Test Method for Standards and Practices as set forth by the NSI.
Flexural Strength of Dimension Stone
1.6 Samples
1.2.2.7 C1353, Standard Test Method for
Abrasion Resistance of Dimension Stone 1.6.1 The Quartz-based Stone Supplier shall
submit through the General Contractor, for
approval by the Specifying Authority, at least

© 2022 Natural Stone Institute Quartz-Based Stone • Page 8-1

two sets of samples of the various kinds of DRAWINGS HAVE BEEN FULLY
Quartz-based stone specified. The sample size APPROVED AND MARKED AS SUCH. The
shall be 1'-0" x 1'-0" (300 mm x 300 mm) and Quartz-based Stone Supplier shall not be
shall represent approximately the finish, responsible for determining, making, or
texture, and anticipated range of color to be verifying (1) design, structural, wind, seismic,
supplied. One set of samples shall be retained or other design loads; (2) engineering
by the Specifying Authority, and one set shall estimates; (3) plans or specifications; or (4) the
be returned to the Quartz-based Supplier for types, sizes, or locations of anchors, unless
project record and guidance. It is noted herein specifically added to the scope of work.
that Quartz-based stone is a natural material
and will have variations in color, markings, and 1.8 Defective Work
other characteristics. Stone is a product of
nature. It is not possible to guarantee that all 1.8.1 Any piece of Quartz-based stone
the colors and markings of a large stone deposit showing flaws or imperfections upon receipt at
will be present in every piece and that every the storage yard or building site shall be
characteristic will be uniformly present in referred to the Specifying Authority for
other pieces. Depending on Quartz-based determination as to responsibility and decision
stone selected and quantity required, a range as to whether it shall be rejected, patched, or
mockup may be required to further define the redressed for use.
characteristics of the material. When required,
the cost of the mockup shall be included in this 1.9 Repairing Damaged Stone
section.
1.9.1 Chips at the edges or corners may be
1.6.2 Prior to fabrication, an inspection and patched provided the structural integrity of the
approval by the Specifying Authority (and/or stone is not affected and provided the patch
General Contractor and/or End User) of a matches the color and finish of the natural
representative number of the finished slabs stone so that it does not detract from the
may be desirable to understand the finish and stone’s appearance.
full range of the material

1.7 Shop Drawings 2.0 MATERIALS

1.7.1 The Quartz-based Stone Supplier shall
2.1 Quartz-based Stone
submit through the General Contractor, for
approval by the Specifying Authority, sufficient
2.1.1 General: All Quartz-based stone shall
sets of shop drawings showing general layout,
be of architectural standard grade, free of
jointing, anchoring, stock thickness, and such
cracks, seams, starts, or other traits which may
other pertinent information. These drawings
impair its structural integrity or function.
shall show all bedding, bonding, jointing, and
Inherent color variations characteristic of the
anchoring details along with the net piece
quarry from which it is obtained will be
dimensions for each Quartz-based unit. Setting
acceptable. Texture and finish shall be as
numbers are to be shown, if applicable. One
shown in the sample(s) approved by the
copy of the approved shop drawings shall be
Specifying Authority.
retained by the Specifying Authority, one copy
shall be retained by the General Contractor,
2.1.2 ASTM C616 [C97] [C99] [C170]
and one copy returned to the Quartz-based
[C241/C1353] [C880] See the chart of
Stone supplier for fabrication. NO
applicable ASTM standards and tests in the
FABRICATION OF QUARTZ-BASED
Appendix.
STONE SHALL BE STARTED UNTIL SUCH

Page 8-2 • Quartz-Based Stone © 2022 Natural Stone Institute

2.1.3 Schedule: Quartz-based stone shall comply with ASTM C920. Submit samples for
be provided as follows: stain testing in accordance with ASTM D2203.

2.1.3.1 For (state location on building) (state 2.5 Anchors, Cramps, and
name and color) Quartz-based stone with a (type) Dowels
finish, supplied by (name company or list several
approved suppliers). 2.5.1 All wire anchors, cramps, dowels, and
other anchoring devices shall be nonferrous
2.1.3.2 Provide information as in (1) for metal of the types and sizes shown on approved
each different Quartz-based stone/finish shop drawings.
combination in the project.

2.1.4 Finishes: Available in cleft, chat

3.0 FABRICATION
sawn, and diamond sawn, sand sawn, honed,
polished, rubbed, machine tooled, smooth
planed, split face, and rock face. 3.1 Beds and Joints

2.1.5 Finishes listed in the schedule shall 3.1.1 Bed and head joint size shall be
conform with definitions by the NSI or ASTM determined by analysis of anticipated building
International. movements and designed to accommodate
such movements without inducing undue
stresses in the stone panels or joint filler
2.2 Setting Mortar
materials. Expansion joints shall be designed
and located to accommodate larger
2.2.1 Mortar for setting and pointing shall
movements.
be one part portland cement and one part
plastic lime hydrate to three to five parts of
3.1.2 Some slight lippage and variation is
clean, nonstaining sand. It shall be mixed in
natural and unavoidable where a rough finish
small batches, using clean, nonalkaline water
face comes together at the sawed joints.
with a pH of 7 until it is thoroughly
homogeneous, stiff, and plastic. After mixing,
3.1.3 Joints ¼", 3/8", or ½" (6.5 mm, 9.5
the mortar shall set for not less than one hour
mm, or 12.5 mm) are recommended between
or more than two hours before being used.
standard-size panels. All joints are to be water-
and moisture-tight and caulked with a proper
2.3 Pointing Mortar sealant.
2.3.1 Mortar for pointing shall be Type N,
3.2 Backs of Pieces
as defined in ASTM C270 (Standard
Specification for Mortar for Unit Masonry).
3.2.1 Backs of pieces shall be sawn or roughly
All mixing, handling, and pacing procedures
dressed to approximately true planes. Back
shall be in accordance with ASTM C270.
surfaces shall be free of any matter that may
create staining.
2.4 Sealants and Backup
Material (If Applicable) 3.3 Moldings, Washes, and Drips
2.4.1 Where specified, (state type or name of 3.3.1 Moldings, washes, and drips shall be
sealant) shall be used for the pointing of joints. constant in profile throughout their entire
The backup material used with the sealant shall length, in strict conformity with details shown
be (identify material). Joint sealants are to on approved shop drawings. The finish quality

© 2022 Natural Stone Institute Quartz-Based Stone • Page 8-3

on these surfaces shall match the finish quality drawings and details, and when work can be
of the flat surfaces on the building. executed before fabrication. Cutting and
fitting, due to job site conditions, will be the
3.4 Back-checking and Fitting to responsibility of the Quartz-based Stone
Contractor.
Structure or Frame
3.6.2 Incidental cutting such as for window
3.4.1 Stone coming in contact with structural
frame clips, etc., which is normally not
work shall be back-checked as indicated on the
considered to be the responsibility of the Stone
approved shop drawings. Stones resting on
Supplier, will be provided only by arrangement
structural work shall have beds shaped to fit the
by the General Contractor and Quartz-based
supports as required.
Stone Contractor with the Quartz-based Stone
Fabricator.
3.4.2 Maintain a minimum of 1" (25 mm)
between stone backs and adjacent structure.
(Note: many bolted connections will require
more space than this; 2" (50 mm) space may be 4.0 SHIPPING AND HANDLING
more desirable. Large-scale details should
illustrate and control these conditions.) 4.1 Packing and Loading

3.5 Cutting for Anchoring, 4.1.1 Finished Quartz-based stone shall be

carefully packed and loaded for shipment using
Supporting, and Lifting Devices
all reasonable and customary precautions
against damage in transit. No material which
3.5.1 Holes and sinkages shall be cut in stones
may cause staining or discoloration shall be
for all anchors, cramps, dowels, and other
used for blocking or packing.
tieback and support devices per industry
standard practice or approved shop drawings.
However, additional anchor holes shall be 4.2 Site Storage
drilled at job site by Quartz-based Stone
Contractor to facilitate alignment. 4.2.1 Upon receipt at the building site, stone
shall remain in the factory-prepared bundles
3.5.2 No holes or sinkages will be provided until beginning of the installation. Bundles
for Quartz-based Stone Contractor's handling shall be staged in an area which is least
devices unless arrangement for this service is susceptible to damage from ongoing
made by the Quartz-based Stone Contractor construction activity. Once unbundled, the
with the Quartz-based Stone Fabricator. granite shall be stacked on timber or platforms
at least 2" (50 mm) above the ground, and the
NOTE: It is not recommended that lewis pins utmost care shall be taken to prevent staining
be used for stones less than 3½" (90 mm) or impact damage of the stone. If storage is to
thick. be prolonged, polyethylene or other suitable,
nonstaining film shall be placed between any
wood and finished surfaces of the stone.
3.6 Cutting and Drilling for
Polyethylene or other suitable, nonstaining
Other Trades film may also be required as protective
covering.
3.6.1 Any miscellaneous cutting and drilling
of stone necessary to accommodate other
trades will be done by the Quartz-based Stone
Fabricator only when necessary information is
furnished in time to be shown on the shop

Page 8-4 • Quartz-Based Stone © 2022 Natural Stone Institute

5.0 INSTALLATION Average contact area shall be not less than
80%, except on exterior or shower
5.1 General Installation installations, where contact shall be at least
95% when no less than three tiles are removed
5.1.1 Installation shall be accomplished with for inspection.
competent, experienced Stone Setters, in
accordance with the approved shop drawings. 5.2.4 Veneer shall be set by spotting with
gypsum molding plaster for interior use, or
5.1.2 All Quartz-based stone pieces shall be cement mortar and the use of concealed
identified with a unique piece number anchors secured in the wall backing.
corresponding with the number on the shop
drawings. Interchanging of numbered pieces is 5.2.5 Where thin wall tile [nominal 5/8" (16
not permitted. mm) thick] is used, nonstaining adhesives or
dry-set mortars may be employed. Individually
5.1.3 Quartz-based stone shall be free of any set thin tile [nominal 3/8" (9.5 mm) thick] on
ice or frost at time of installation. Salt shall not vertical surfaces exceeding 8' (2.5 m) is not
be used for the purpose of melting ice, frost, or recommended.
snow on the stone pieces.
5.2.6 Panels set in metal frames shall have
5.1.4 Adequate protection measures shall be rabbeted edges and a sealant for all joints to
taken to ensure that exposed surfaces of the prevent moisture seepage. Hairpin spring
stone shall be kept free of mortar at all times. anchors in the back of the panels make Quartz-
based stone easily adaptable as facings for
precast units and systems.
5.2 Mortar Setting

5.2.1 Unless otherwise shown on approved 5.3 Mortar Joints

shop drawings, each piece shall be carefully laid
in a full bed of mortar and tapped to a full and 5.3.1 Mortar joints shall be raked out to a
solid bearing. Exposed surfaces shall be kept depth of ½" to ¾" (12.5 mm to 20 mm).
free of mortar at all times. Apply pointing mortar in layers not exceeding
3/8" (9.5 mm) and allow each layer to get hard
5.2.2 If the thin-set method is used [for 5/8" to the touch before the next layer is applied.
(16 mm) thick stone] a dry-set portland cement Tool finished joints with a concave tool having
mortar is applied with a 3/8" or ½" (9.5 or a diameter approximately 1/8" (3 mm) greater
12.5 mm) notched trowel with back buttering than the joint width.
of the clean, moist tile surface.
5.3.2 Care shall be taken to keep expansion
5.2.3 Apply mortar with flat side of trowel joints free of mortar, which would
over an area that can be covered with tile while compromise their function.
mortar remains plastic. Within ten minutes
and using a notched trowel of type 5.4 Anchorage
recommended by Mortar Manufacturer, comb
mortar to obtain even-setting bed without 5.4.1 The stone shall be anchored or doweled
scraping backing material. Cover surface in accordance with the approved shop
uniformly, with no bare spots, with sufficient drawings.
mortar to ensure a minimum mortar thickness
of 3/32" (2.5 mm) between tile and backing 5.4.2 To the furthest extent possible, all
after tile has been tamped into place. Tile shall anchor preparations in the Quartz-based stone
not be applied to skinned-over mortar. units shall be shop-applied.

© 2022 Natural Stone Institute Quartz-Based Stone • Page 8-5

5.4.3 All anchorage devices and anchor 6.0 CLEANING AND
hole/slot fillers shall be in accordance with PROTECTION
ASTM C1242. Care must be taken to ensure
that any holes capable of retaining water are
6.1 Cleaning
filled after use to prevent water collection and
freezing.
6.1.1 Upon completion of various portions of
work, all mortar stains, grease marks, and dirt
5.5 Sealant Joints should be removed by washing with a good
grade of nonabrasive detergent with a pH of 7.
5.5.1 Where so specified, joints requiring Flush and clean with clear water. Floors can be
sealant shall be first filled with a closed-cell swept, damp-mopped, or hosed off with clean
ethafoam rope backer rod. The backer rod water.
shall be installed to a depth that provides
optimum sealant profile after tooling.
6.2 Protection of Finished Work
5.5.2 If recommended by the Sealant
6.2.1 Quartz-based stone installation in
Manufacturer, primers shall be applied to the
progress shall be protected with film, fabric
substrate surfaces according to the
tarps, and wood for exposed edge protection
manufacturer’s directions prior to application
secured over the work.
of the joint sealant.
6.2.2 After the Quartz-based stone has been
5.6 Expansion Joints installed, it shall be the responsibility of the
General Contractor to see that it is properly
5.6.1 It is not the intent of this specification to and adequately protected from damage and
make control or expansion-joint stains until all trades are finished. This
recommendations for a specific project. The responsibility includes the stone cleaning costs
Specifying Authority must specify control or prior to the final inspection. The Quartz-based
expansion joints and show locations and details Stone Contractor will outline the needs for
on drawings. protection, in writing, to the General
Contractor.
5.7 Caulking
5.7.1 Where so specified, joints shall be
pointed with the sealant(s) specified in Section PRODUCT
2.4 after first installing the specified backup DESCRIPTION –
material and applying a primer if required, all Quartz-based Stone
in strict accordance with the printed
instructions of the sealant manufacturer. 1.0 GEOLOGICAL
5.7.2 All sealants shall be tooled to ensure CLASSIFICATION
maximum adhesion to the contact surfaces.
1.1 Most types of Quartz-based stones are
clastic sedimentary stone, composed of
5.8 Weep Tubes
particles or grains usually cemented with
varying amounts of either hydrous silica or
5.8.1 Plastic or other weep tubes shall be
crystalline quartz. A notable exception is the
placed in joints where moisture may
chert group, including chert, agate, and flint,
accumulate within the wall, such as at base of
which are siliceous chemical sedimentary
cavity, continuous angles, flashing, etc., or as
stones.
shown on architectural drawings.

Page 8-6 • Quartz-Based Stone © 2022 Natural Stone Institute

1.2 The following are the main groups mountains, hills, and highlands, and across the
of Quartz-based stone: plains to lakes, seas, and into the oceans,
depositing the debris on beaches and beyond to
1.2.1 Quartz, Crystalline Quartz form into new sedimentary stone. During this
natural process, soluble salts are released from
1.2.2 Sandstone the debris, and some of these salts ultimately
run off into below-sea level lakes and into
1.2.3 Quartzite oceans as dissolved salts, giving the oceanic
water its briny content.
1.2.4 Metaquartzite
1.6 Crystalline quartz has a fixed chemical
1.2.5 Quartz Pebble Conglomerates composition: SiO2. Some other quartz types
occur as hydrous silica (SiO2•NaH2O), the
1.2.6 Metaconglomerates mineral of chert, agate, flint, and fire opal.
These stones are about H=6 to 6.5 on the
1.2.7 Chert, Agate, Flint Mohs Scale,2 not quite as hard as crystalline
quartz.
1.3 The key to understanding all Quartz-
based stone is the understanding of crystalline 1.7 Physical properties of crystalline
quartz as a mineral. The basic physical quartz:
properties of quartz – with the possible
exception of absorption and porosity – are the 1.7.1 Hardness. Quartz has a Mohs Scale
same as those of any Quartz-based stone. hardness rating of 7. It can scratch minerals
with a hardness of less than 7, such as calcite
1.4 Quartz (SiO2) is composed of the two and feldspar, but cannot scratch other quartz or
most abundant elements in the Earth’s crust: minerals with a hardness greater than 7, such as
silicon and oxygen, which respectively make corundum and diamond.
up 28% and 47% by weight of our planet’s
lithosphere. Of all the common minerals, 1.7.2 Shape. Quartz crystals are always six-
quartz lasts the longest in the environment. sided, elongate prisms with a pyramid-shaped
Most of the beaches in the world, with a few termination usually on one end of the prism
exceptions, are quartz sand.1 Almost all other only. The prisms may be imperfect, but the
minerals are abraded away, broken up angles between sides are always equal, even
mechanically through weathering and though the prismatic sides are very unequal in
transportation, or, if soluble, dissolved. width.
Quartz is itself slightly soluble, giving rise to
the chert deposits found in many sedimentary 1.7.3 Lack of Cleavage. Quartz does not
sequences. have “cleavage,” the weakness in molecular
geometry along which a mineral consistently
1.5 Weathering of igneous, sedimentary, break.
and metamorphic rocks releases grains of
quartz sand. Water, gravity, and wind 1.7.4 Fracturing. When quartz fractures, it
transport this rock debris (detritus) down can break with dish-shaped, irregular surfaces.

1 A few beaches are entirely carbonate sand created by small, red, single-cell marine organisms. In Hawaii,
waves breaking up seashells into coarse, sand-sized there are beaches of only black or green volcanic sand
grains. Some of these beaches have no land-derived with no quartz sand content.
silicate minerals or rock fragments. The beaches of 2 See Appendix for the Mohs Scale of mineral hardness.

Bermuda are a well-known example. There, the sands

are pink from coloration derived from the remains of

© 2022 Natural Stone Institute Quartz-Based Stone • Page 8-7

The dished surfaces often have small concentric 1.9 Quartzite, the silica-cemented,
ridges giving it a “conchoidal” surface effect, unmetamorphosed variety, tends to occur in
after seashells with similar shapes and sedimentary units or beds, and the thicker
concentric ridges. Fractured quartz faces are quartzite ledges are generally more useful than
rough, uneven, and never flat.3 the thinner occurrences. With thicker units of
quartzite, the distinction between
1.7.5 Coloring. Quartz occurs naturally in a metamorphosed and unmetamorphosed types
range of colors. Some colored quartz crystals makes little difference to those in the stone
are prized as semiprecious gems, e.g., citrine industry. Quartzite breaks across grains, not
(yellow), amethyst (lavender to purple), and around grains. Thus it is very hard (H=7),
jasper (yellow, brown, red), to name a few. durable, and for practical purposes, not a
This natural coloring is due to micro inclusions soluble stone, making it a desirable material for
or traces of other elements in the stone’s some difficult installations where exposure to
chemistry. However, not all quartz available water may be a problem.
on the market is naturally colored. Artificial
coloring processes are sometimes used in the 1.10 Metaquartzite. The metamorphic
gem industry to dye fractured crystalline equivalent of quartzite is metaquartzite. Often
quartz in colors not seen in nature, such as difficult to differentiate from its
bright pink and fluorescent shades of green, nonmetamorphosed parent stone,
yellow, and blue. metaquartzite has certain distinct features; for
example, thin “partings” of clear mica often
1.7.6 Electrical Properties. Quartz is separate layers or bands of pure metaquartzite.
“piezoelectric,” an unusual electrical property Some deposits of the stone occur in layers only
that has no effect on the performance of the 1/8" to ½" (3 mm to 12.5 mm) thick,
mineral in normal dimension stone separated by the micaceous parting that allows
applications. If squeezed, quartz generates an easy separation or cleaving characteristic of
electrical current proportional to the amount mica sheets, due to weak molecular bonds.
of pressure applied. When a small current is
generated on two opposing faces of a cut, 1.11 These mica partings should not be
ground quartz crystal, it vibrates electrically, confused with former bedding. The partings
acting as an oscillator at a frequency are a form of banding developed from the
determined by the exact thickness of the mineral segregation that occurs in the process
crystal. These were used in communications of metamorphism. Thin metaquartzite is
equipment from the 1920s to the 1950s to valued for use in flooring and decorative stone
control broadcast frequencies, but are now applications.
obsolete.
1.12 Quartz pebble conglomerates,
1.8 Sandstone is a nonmetamorphic unless silica-cemented, may tend to
sedimentary stone. When firmly cemented disaggregate rather easily, particularly if the
with silica, sandstone could be correctly quartz pebbles are highly rounded and smooth
identified as quartzite. However, it is and the cement is not strong, especially if the
suggested the name quartzite should be cementing agent and matrix is the soluble
restricted for sandstone tightly cemented with mineral calcite or limestone. If the
homogeneous crystalline silica (quartz conglomeratic matrix is silica, then the stone
crystals). will break through the quartz pebbles. A quartz
pebble conglomerate may occasionally consist

3 Crystalline Quartz can be deposited in a void against as a consequence of the atomic geometry of quartz.
an existing crystal face of another mineral. The The only true, flat quartz face is a crystal face.
resulting flat face on quartz is an artifact, not originating

Page 8-8 • Quartz-Based Stone © 2022 Natural Stone Institute

of a variety of colored quartz pebbles including 2.2 The purest Quartz-based stones are
white, yellows, reds, black, and sometimes nearly white. Colors are primarily due to iron
banded agate. A multicolored quartz pebble oxides. The presence of limonite usually yields
conglomerate with red siliceous cement is yellow, brown, and buff shades; the presence
found on the Iberian Peninsula and in the Atlas of hematite yields darker brown or red.
Mountains of North Africa. This type is a Oxidation of iron-bearing minerals upon
valuable dimension stone. exposure may cause some stones to change
color after installation.
1.13 Metaconglomerates. Metaquartz
pebble conglomerates, like metaquartzite, will 2.3 Since most Quartz-based stones are
break through and not around grains and formed in layers through centuries, each layer
pebbles. Other strongly metamorphosed may have considerable color variations. It is not
conglomerates have been squeezed under such uncommon that some may have a color range
high pressure that the quartz pebbles are of possibly up to 12 shade variations. If a
flattened. The plane of flattening is normal minimal amount of shade variation is desired,
(perpendicular to the direction of pressure), then additional quarrying time will be
and flattened pebbles of hard quartz are a required, as well as special, hand-selection
notable example of how high the pressures of costs.
metamorphism can be.

1.14 Chert, Agate, Flint. These are varietal 3.0 TEXTURE

names for hydrous silica deposits that can occur
in beds or nodules. Chert, the preferred 3.1 The term “texture,” as applied to
geological name, is classified as chemical Quartz-based stone, means size, degree of
sedimentary stone. Cherts are true chemical uniformity, and arrangement of constituent
precipitates emplaced within a sedimentary minerals. Quartz-based stones are essentially
sequence at some time after burial and perhaps quartz; some are nearly pure quartz.
before cementation.
3.2 Grains of quartz may be well-rounded
1.15 Some cherts, like red jasper, are or angular, depending upon the degree to
valuable as semiprecious stones sold and used which they were water-worn before
by gemstone hobbyists. Banded or lace agate consolidation. Some deposits show remarkable
can be valuable for jewelry or as an exceedingly uniformity in size of grains. This grain
rare and expensive dimension stone. Entire composition can affect the texture.
fireplace mantles and part of the surround have
been made from large, exquisite sheets of 3.3 Texture of Quartz-based stone is also
agate. Because it is softer than crystalline affected by the way that the grains of silica
quartz, Agate was often the material used to fracture. Sandstone fractures around the
carve mortars and pestles for use in 19th constituent grains. Quartzitic sandstone
century pharmacies. It was also used to make fractures around or through the constituent
marbles for the game popular with 19th and grains. Quartzite fractures conchoidally
early 20th century children. through the grains.

2.0 COLOR AND VEINING 3.4 Quartz-based stones are the most
variable type of dimension stone due to wide
2.1 The color, veinings, clouds, mottlings, variety in degree of cementation and type of
and shadings in Quartz-based stone are caused cementing material between the grains. There
by substances included during formation. are four common cementing materials: iron
oxides, clay, calcite, and quartz. All stages of

© 2022 Natural Stone Institute Quartz-Based Stone • Page 8-9

cementation are found in nature, from presents these varieties to us. Therefore, size
incoherent sandstones that may be crumbled may become a limiting factor to consider in the
between the fingers, to the most hardened selection of a particular Quartz-based stone.
quartzites. All types between these extremes
are used commercially. 6.2 A jointing scheme which permits the use
of appropriate sizes of Quartz-based stone
3.5 Sandstones may be relatively high yielded by the particular quarry will greatly
porosity stones. Quartzites, on the other hand, facilitate selection and delivery.
can have as little pore space as granites.

7.0 PRODUCT SAMPLING

4.0 FINISHES
7.1 Quartz-based stones are formed by
4.1 A common finish for Quartz-based stone nature; thus, there are variations in the tonal
is natural cleft finish. It should be noted that the qualities of the stones. However, it is these
face of natural-cleft stone is not necessarily a natural variations that make Quartz-based
true flat surface. This surface may vary from stone unique, valuable, and highly desirable.
flat to variations up to ¼" from true flat. This Because of these variations, selection of a stone
could result in a surface that is concave or should never be made on the basis of one
convex, or could also be warped or sample only. It is recommended that selection
“propellered” (corners tipping either down or be based on viewing sufficient samples to show
up). the complete range of color of the desired
stone. (See “2.0 Color and Veining” in this
4.2 Many of the standard finishes can be chapter section for additional information.)
applied to Quartz-based stones.

4.3 Some stone finishes can affect strength 8.0 PROPER USAGE TIPS
and durability. Examples are bush-hammered
and thermal finishes, which reduce a stone’s 8.1 Recommendation for commercial
thickness, making it more vulnerable to floors:
weakening from exposure to freeze and thaw
cycles. 8.1.1 Minimum ¾" (20 mm) thickness.

5.0 THICKNESS 8.1.2 A honed finish.

5.1 As these are split stones, standard 8.1.3 A minimum hardness value of 2
thicknesses are highly variable, e.g., ¾", 1½", (Sandstone), 8 (Quartzitic Sandstone), and 8
2", 4", or 8" (20 mm, 40 mm, 50 mm, 100 (Quartzite) as measured by ASTM
mm, or 200 mm). C241/C1353.

Note: As Quartz-based stone is cut thinner, its 8.2 Avoid the use of gypsum or molding
tensile strength is diminished. plaster setting spots for the installation of
exterior stone.
6.0 SIZES
9.0 TOLERANCES
6.1 Quartz-based stone is a product of
nature with many varieties available, each 9.1 Because of the many variances in
possessing varying characteristics. Little can be cementation and porosity, it is recommended
done to alter the condition in which nature that the Quartz-based Stone Quarrier or

Page 8-10 • Quartz-Based Stone © 2022 Natural Stone Institute

Fabricator be contacted regarding size and methods and specifications consistent with the
thickness tolerances. latest technology.

1.4 Final design should always be based on

10.0 FABRICATION
specific values for the stone variety ultimately
to be installed. These values may be obtained
10.1 One process after quarrying Quartz-
from the Stone Supplier. All materials are not
based stone is to guillotine the slabs to the
suitable for all uses. In order to avoid mistaken
desired length and thickness, thus the thick
selections, tests for material values should be
slabs can be split to the desired thicknesses of
made prior to final material selection.
2", 3", or 4" (50 mm, 75 mm, 100 mm).
1.5 Physical Properties of Quartz-
based Stone
TECHNICAL DATA – (These historical data and information are
Quartz-based Stone provided only as a guideline. Recommended
minimums or maximums are established and
provided by ASTM International.)*
1.0 PROPERTIES OF QUARTZ-
BASED DIMENSION STONE Property Range of Values
Compressive Strength (C170)
1.1 In centuries past, relatively little lbs/in² .............................. 2,000-37,000
importance was attached to the ultimate Recommended (min):
physical capabilities of most building materials. 4,000 (sandstone),
Rule of thumb was a common structural design 10,000 (quartzitic sandstone),
criterion. As a result, the widely used materials 20,000 (quartzite)
of the day, for the most part natural rather than
man-made materials, were seldom stressed to Flexural Strength (C880)
their ultimate limits. lbs/in² ...................................700-2,300
Modulus of Elasticity** (in millions)
1.2 In present-day construction, this is far lbs/in² ..................................... 1.0-1.75
from being true. Performance requirements
are daily become more demanding. In striving Density, lb/ft3 (C97) .................. 135-170
for taller structures, greater spans, firmer Recommended (min):
foundations, thinner walls and floors, stronger 125 (sandstone),
frames, and generally more efficient buildings 150 (quartzitic sandstone),
with more usable space, today’s Architects and 160 (quartzite)
Engineers must get the most out of the Modulus of Rupture (C99) lbs/in².300-2,500
materials with which they work. Recommended (min):
350 (sandstone),
1.3 Quartz-based stone is a product of 1,000 (quartzitic sandstone),
nature and not always subject to the rules of 2,000 (quartzite)
consistent behavior that may apply to
manufactured building materials. Physical Absorption (by weight) % (C97) …..1.0-20.0
property values of Quartz-based stone may, Recommended (max):
however, be measured using the standard test 8.0 (sandstone),
methods approved by the Dimension Stone 3.0 (quartzitic sandstone),
Committee C-18 of ASTM International. The 1.0 (quartzite)
NSI and Member companies are represented
on the ASTM committee and are active in its * Test methods described in current ASTM
technical work of establishing proper test standards. ** Also known as Young’s Modulus.

© 2022 Natural Stone Institute Quartz-Based Stone • Page 8-11

2.0 STRENGTH (ASTM C99, 4.0 ABRASION RESISTANCE
C170, C880) (ASTM C241/C1353)

2.1 Values for modulus of rupture, 4.1 Abrasion resistance is a property of

compressive strength, and flexural strength are stone that should be tested per ASTM
ascertained by testing specimens of Quartz- C241/C1353 to provide an indication of the
based stone under laboratory conditions until stone’s wearing qualities when exposed to foot
they fail. traffic.

2.2 Size and finish of test samples required 4.2 The hardness and uniform wearing
by the standard ASTM test methods may not qualities of most Quartz-based stones make
reflect the actual performance of stone when them extremely desirable and economically
used in lesser thicknesses or with other finishes practical for floors and stairs. Varieties with an
that affect strength. For this reason, the abrasive hardness (Ha/Iw) of 8 or more, as
Modulus of Rupture (C99) test is measured by ASTM C241/C1353 tests, are
recommended when the stone to be used will recommended for use as flooring exposed to
be two or more inches thick. The Flexural normal foot traffic. A minimum abrasive
Strength (C880) test is recommended when hardness of 12 is recommended for
the stone thickness will be less than two inches. commercial floors, stair treads, and platforms
subject to heavy foot traffic. If floors are
2.3 The strength of a Quartz-based stone is constructed with two or more stone varieties,
a measure of its ability to resist stresses. This the Ha/Iw values of the stones must not differ
strength depends on several factors: the by more than 5, or the floor surface will not
amount of free silica, degree of cementation, wear evenly and uniformly.
porosity, and whether the stone is
metamorphosed.
5.0 FACTORS AFFECTING
PROPERTIES
3.0 FIRE RESISTANCE
5.1 The ultimate test of a building material
3.1 Stone is not combustible according to is its ability to have and maintain the necessary
underwriters’ ratings, and therefore is structural strength, as well as beauty of
considered a fire-resistant material. Because of appearance and low cost of maintenance, over
its thermal conductivity, heat transfer is fairly the useful life of the structure. Experience has
rapid. Most stone is not considered a highly proven that stone meets this test as few other
rated thermal insulator. building materials can. Studies have shown that
the durability of most stones is little affected by
3.2 Underwriters’ fire-resistance ratings cycles of weather. This is because most have a
evaluate whether or not a material will burn, low rate of moisture absorption.
as well as how long it will keep surrounding
combustible materials from reaching
temperatures which will cause them to ignite. 6.0 SAFETY FACTORS
Methods of estimating fire-resistance periods
of masonry walls and partitions utilizing 6.1 Good engineering practice requires that
component laminae are given in “Fire allowable design stress must provide a margin
Resistance Classifications of Building of safety in any structural element. As a
Construction,” BMS92, National Bureau of necessary precaution against such conditions as
Standards. wind, ice, snow, impact, temperature changes,
and imperfect workmanship, these allowable

Page 8-12 • Quartz-Based Stone © 2022 Natural Stone Institute

stresses must be smaller than those which 67. The U.S. Army Corps of Engineers has also
produce failure. published TM 5-809-10, “Seismic Design for
Buildings.”
6.2 Within the accepted limits of safe design
practice, the closer the allowable load is to the
ultimate failure load, the more efficient is the 8.0 EFFLORESCENCE AND
use of the material and the less the cost of the STAINING
construction.
8.1 Efflorescence is a salt deposit, usually
6.3 Contemporary building design does not white in color that appears on exterior surfaces
usually employ stone as part of the structural of masonry walls. The efflorescence-producing
frame, but rather as an independent unit, a salts found in masonry are usually sulfates of
curtain wall, or veneer. Therefore, the sodium, potassium, magnesium, calcium, and
primary concern in such cases is with wind or iron. Salts which are chlorides of sodium,
seismic loads, and a safety factor of 8.0 is calcium, and potassium will sometimes appear,
recommended. Where the stone is to be but they are so highly soluble in water that they
subjected to concentrated loading, such as stair will be washed off by rain.
treads or lintels supported only at the ends, a
factor of 10.0 should be used. 8.2 The water-soluble salts causing
efflorescence come from other materials in the
6.4 These safety factors may be adjusted wall. The salts exist in small amounts and are
using sound engineering principles and leached to the surface by water percolating
judgment. through the walls. The most feasible means of
prevention is to stop the entrance of large
6.5 As buildings become taller and amounts of water. Absorption from the face
individual stone-slab veneer becomes larger in will not cause efflorescence unless there are
area, the lateral forces due to wind loads must open joints.
be considered. Wind tunnel tests are often
used on major structures to determine wind 8.3 Quartz-based stones are seldom injured
dynamics and force magnitude. Reinforcement by efflorescence. However, some of the salt
is sometimes necessary for large dimension- crystals may form in the stones' pores near the
slab veneer in critical areas. surface. Crystal growth (recrystallization) in
the pores can cause stress on the walls of the
pores and cause the stone to flake off. If the
7.0 SEISMIC CONSIDERATIONS conditions bringing about this action persist,
scaling may continue and flake off one layer
7.1 Seismic considerations generally require after another. For this to happen, large
that low buildings be stiff, and that tall amounts of water must enter the wall and must
buildings be relatively flexible. Design of contain large amounts of salts.
connections must account for seismically
induced horizontal loading. Local building 8.4 Research indicates that staining and
codes vary and must always be checked to discoloration occurring on new buildings are
determine specific requirements for each area. caused by the action of water percolating
The National Bureau of Standards has published through cement from which soluble alkali salts
two documents on the topic: “Earthquake are leached. The salts are then carried through
Resistant Masonry Construction,” NBS Science the stone, where partially oxidized organic
Series 106; and “Abnormal Loading on matter is picked up. This is then transported to
Buildings and Progressive Collapse: An the surface of the stone, where it is deposited
Annotated Bibliography,” NBS Science Series

© 2022 Natural Stone Institute Quartz-Based Stone • Page 8-13

as a stain as evaporation of the water takes from the Quarriers or Fabricator before
place. making a final selection.

8.5 This staining phenomenon is similar to

efflorescence except that it involves organic
material. It does not harm the stone other than
leaving an objectionable appearance during or
soon after erection. However, if left alone, the
stain is removed naturally by the action of the
elements, usually in the course of a few
months.

8.6 A considerable amount of water passing

through the stone is necessary to bring out
conspicuous discolorations. Proper pre-
cautions taken during construction of the walls
will usually prevent such troubles. A simple
and helpful expedient is to provide frequent
weep holes in the base course and above shelf
angles. These should be placed in the vertical
joints so they can be sloped upward from the
front to back.

8.7 Stains sometimes appear on the base

course when Quartz-based stone is in contact
with soil, due to the carrying of soluble salts
and some colored soil constituents up through
and to the surface of the stone by capillary
action. Almost all soils contain soluble salts.
Therefore, this staining phenomenon should
disappear when the source of moisture is
eliminated.

8.8 Avoid contact between soil and stone.

Damp-proofing treatments of either a
bituminous or cementitious nature may be
used as a barrier to the groundwater or
construction moisture causing these stains.

9.0 THERMAL EXPANSION

9.1 The thermal expansion of Quartz-based

stone is an important consideration when it is
used with dissimilar materials to form large
units which are rigidly fixed. The coefficient of
thermal expansion varies from one variety to
another; actual thermal characteristics of a
specific Quartz-based stone should be obtained

Page 8-14 • Quartz-Based Stone © 2022 Natural Stone Institute

Serpentine 1.2.3.1 Membership, Products, and Services
Directory
1.0 GENERAL 1.2.3.2 Dimension Stone Design Manual
1.1 Related Documents 1.2.3.3 Additional publications may be
available from the NSI Bookstore. Go online at
1.1.1 Drawings and general provisions, www.naturalstoneinstitute.org.
including General and Supplementary
Conditions of the Contract and Division I 1.3 Scope of Included Work
Specification sections, apply to this section.
1.3.1 The work to be completed under this
1.2 Applicable Publications contract includes all labor and materials
required for the furnishing and installation of
1.2.1 The following publications listed here all serpentine work shown or called for on the
and referred to thereafter by alphanumeric contract drawings, specifications, and
code designation only, form a part of this addenda.
specification to the extent indicated by the
references thereto: 1.4 Definition of Terms
1.2.2 ASTM International (ASTM): 1.4.1 The definitions of trade terms used in
this specification shall be those published by the
1.2.2.1 C1526, Standard Specification for NSI or ASTM International.
Serpentine Dimension Stone

1.2.2.2 C97, Standard Test Methods for

1.5 Source of Supply
Absorption and Bulk Specific Gravity of
Dimension Stone 1.5.1 All serpentine shall be obtained from
quarries having adequate capacity and facilities
1.2.2.3 C99, Standard Test Method for to meet the specified requirements, and by a
Modulus of Rupture of Dimension Stone firm equipped to process the material promptly
on order and in strict accord with
1.2.2.4 C170, Standard Test Method for specifications. The Specifying Authority
Compressive Strength of Dimension Stone (architect, designer, engineer, contracting
officer, end user, etc.) reserves the right to
1.2.2.5 C241, Standard Test Method for approve the Material Supplier prior to the
Abrasion Resistance of Stone Subjected to Foot award of this contract. Stone and workmanship
Traffic quality shall be in accordance with Industry
Standards and Practices as set forth by the NSI.
1.2.2.6 C880, Standard Test Method for
Flexural Strength of Dimension Stone 1.6 Samples

1.2.2.7 C1353, Standard Test Method for 1.6.1 The Serpentine Contractor shall submit
Abrasion Resistance of Dimension Stone through the General Contractor, for approval
Subjected to Foot Traffic Using a Rotary by the Specifying Authority, at least two sets of
Platform Abraser samples of the various kinds of serpentine
specified. The sample size shall be 1'-0" x 1'-0"
1.2.3 Natural Stone Institute (NSI): (300 mm x 300 mm) and shall represent
approximately the finish, texture, and
anticipated range of colors to be supplied.

© 2022 Natural Stone Institute Serpentine • Page 9-1

Where necessary to show variations in color SUCH DRAWINGS HAVE BEEN FULLY
and markings, larger samples or range sets of APPROVED AND MARKED AS SUCH. The
samples should be submitted. If serpentine is to General Contractor shall furnish all field
be matched, a minimum of two sets each dimensions necessary for fabrication. If
containing four matched samples showing measurements are not established and
proposed veining and range of colors in each set guaranteed in advance, the Serpentine
must be supplied. Samples designating finished Contractor shall obtain and verify
face shall be clearly labeled on the back with measurements at the building. The General
the name of the serpentine, and the use for Contractor shall be responsible for all
which the serpentine is intended. One set of reasonable assistance to the Serpentine
samples shall be retained by the Specifying Contractor, including the services of an
Authority, and one set shall be returned to the Engineer, if required, for the establishment of
Serpentine Supplier for their record and levels, benchmarks, and the like. The
guidance. It is noted herein that serpentine is a Serpentine Contractor shall not be responsible
natural material and will have intrinsic for determining, making, or verifying (1)
variations in color, markings, and other design, structural, wind, seismic, or other
characteristics. Depending on the serpentine design loads; (2) engineering estimates; (3)
selected and quantity required, a range plans or specifications; or (4) the types, sizes,
mockup may be used to further define the or locations of anchors, unless specifically
characteristics of the material. Cost of added to the scope of work.
mockup, if required, shall not be included in
this section. 1.8 Defective Work
1.6.2 Prior to fabrication, an inspection and 1.8.1 Any piece of serpentine showing flaws
approval by the Specifying Authority and/or or imperfections upon receipt at the storage
General Contractor and/or End User of the yard or building site shall be referred to the
finished slabs is recommended to understand Specifying Authority for determination as to
the finish and full range of the material. responsibility and decision as to whether it shall
be rejected, patched, or redressed for use.
1.7 Shop Drawings
1.9 Repairing Damaged Stone
1.7.1 The Serpentine Contractor shall submit
through the General Contractor, for approval 1.9.1 Patching during fabrication. Serpentines
by the Specifying Authority, sufficient sets of have some variation in working qualities.
shop drawings showing general layout, Veins and lines of separation are common. It is
jointing, anchoring, stock thickness, and such standard practice to repair these variations by
other pertinent information. These drawings use of reinforcing, liners, sticking1 together,
shall show all bedding, bonding, jointing and filling with resin or terrazzo, and doing all
anchoring details along with the net piece other work necessary to hold the stone
dimensions of each serpentine unit. One copy together to yield a finished product that is
of approved drawings shall be retained by the usable for architectural purposes. On
Specifying Authority, one copy shall be completion, most repair is visible, with
retained by the General Contractor, and one differences in light reflection. Unlike other
copy returned to the Serpentine Contractor for dimension stones, many varieties of serpentine
fabrication. NO FABRICATION OF that have been reinforced and repaired are
SERPENTINE SHALL BE STARTED UNTIL suitable for use in exterior environments,
1Sticking describes the butt edge repair of a broken piece,
now generally done with dowels, cements, or epoxies.
The pieces are “stuck” together; thus “sticking.”

Page 9-2 • Serpentine © 2022 Natural Stone Institute

though not in all situations. Where questions of 2.1.3.2 Provide information as in 2.1.3.1 for
suitability for use are encountered, NSI each different serpentine/finish combination
recommends that reliance on past performance on the project.
is the best guide for making decisions as to
future performance. 2.1.4 Asbestos Content. Most serpentine
stone contains a minor quantity of asbestos
1.9.2 Patching during installation. Small chips fibers as a constituent to the white calcite
at the edges and corners of serpentine may be veining common to the variety, and as such,
patched, provided the structural integrity of should be worked “wet” only. The asbestic
the stone is not affected and the patch matches content has no effect on the stone’s use and/or
the color and finish of the stone so that it does maintenance. (Refer also to the Geological
not detract from the appearance. Classification section within this chapter).

2.1.5 Finishes: Finishes listed in the schedule

2.0 MATERIALS shall conform with definitions by NSI or ASTM
International.
2.1 Serpentine
2.1.6 Polished: A mirrorlike, glossy surface
2.1.1 General: All serpentine shall be of kind which brings out the full color and character of
or kinds shown on the Specifying Authority’s the stone. This finish is not recommended for
drawing or as specified herein, conforming to exterior or commercial floor use.
or within the range of approved samples and in
accordance with the characteristics and 2.1.7 Honed: A velvety smooth surface with
working qualities. Care shall be taken in little or no gloss.
selection to produce as harmonious effects as
possible. Patching and waxing2, where 2.2 Setting Mortar (And
permitted under the Marble Institute of Adhesives)
America Group Classifications, shall be
carefully done to conform to the serpentine's 2.2.1 Portland cement shall conform to the
general character and finish. Texture and finish requirements of the Standard Specification for
shall be within the range of sample(s) approved Portland Cement, ASTM C150. White
by the Specifying Authority. portland cement is recommended for white or
light colored serpentine. Nonstaining cement
2.1.2 ASTM C1526 [C97] [C99] [C170] shall conform to the requirements of the
[C241/C1353] [C880] See the chart of Standard Specification for Masonry Cement,
applicable ASTM standards and tests in the ASTM C91. Molding Plaster (plaster of paris)
Appendix. shall conform to the requirements of the
Standard Specification for Gypsum Casting
2.1.3 Schedule: Serpentine shall be provided Plaster and Gypsum Molding Plaster, ASTM
as follows: C59/C59M.

2.1.3.1 For (state location on building) (state 2.2.2 Sand. All sand shall be clean, free from
name and color) serpentine with a (type) finish, organic and other deleterious matter likely to
supplied by (name company or list several approved stain the finished work, and shall be screened
suppliers). as required for the desired results.

2 Waxing refers to the practice of filling minor surface compounds. It does not refer to the application of past
imperfections such as voids or sand holds with melted wax to make surfaces shinier.
shellac, cabinetmaker’s wax or certain polyester

© 2022 Natural Stone Institute Serpentine • Page 9-3

2.2.3 Portland cement shrinkage- additional 8 square feet (0.75 m2) surface area.
reducing accelerator used with portland Shims used to maintain joints shall be plastic.
cement to give it the quick-setting
characteristics of plaster of paris, shall be a 2.5.1.3 Use of copper wire for anchors to be
nonstaining admixture that will not corrode installed over 12' (3.5 m) off the ground is not
anchors or dowels. recommended.

2.2.4 Nonstaining adhesive shall be of a type

that will not stain the serpentine, is not affected 3.0 FABRICATION
by temperature changes or moisture, and
adheres firmly to all clean surfaces. 3.1 Beds and Joints
2.3 Pointing Mortar 3.1.1 Bed and joint width shall be determined
by analysis of anticipated building movements
2.3.1 Mortar for pointing shall be Type N, as and designed to accommodate such
defined in ASTM C270 (Standard Specification movements without inducing undue stresses in
for Mortar for Unit Masonry). All mixing, the stone panels or joint filler materials.
handling, and pacing procedures shall be in Expansion joints shall be designed and located
accordance with ASTM C270. to accommodate larger movements.

2.4 Sealants and Backup 3.2 Backs of Pieces

Material (if Applicable)
3.2.1 Backs of pieces shall be sawn or roughly
2.4.1 Where specified (state type or name of dressed to approximately true planes. Back
sealant) shall be used for the pointing of joints. surfaces shall be free of any matter that may
The backup material used with the sealant shall create staining.
be (identify material).
3.3 Moldings, Washes, and Drips
2.4.2 Sealants used for pointing to exclude
moisture and to provide a joint that will remain 3.3.1 Moldings, washes, and drips shall be
plastic for many years, shall be nonstaining. constant in profile throughout their entire
length, in strict conformity with details shown
2.5 Anchors, Cramps, and on approved shop drawings. The finish quality
Dowels on these surfaces shall match the finish quality
of the flat surfaces on the building.
2.5.1 Anchors, cramps, and dowels shall be
made of corrosion-resistant metals. Special 3.4 Back-Checking and Fitting
cramps, dowels, and the like shall be used to Structure or Frame
where shown on shop drawings, but
elsewhere, #8 copper or stainless steel wire 3.4.1 Stone coming in contact with structural
anchors shall be used. It shall be the work shall be back-checked as indicated on the
responsibility of the Serpentine Contractor to approved shop drawings. Stones resting on
anchor all serpentine securely. For standing structural work shall have beds shaped to fit the
serpentine, the following practices usually supports as required.
prevail:
3.4.2 Maintain a minimum of 1" (25 mm)
2.5.1.2 A minimum of four anchors should between stone backs and adjacent structure.
be provided for pieces up to 12 square feet (1 Note: many bolted connections will require
m2), with two additional anchors for each

Page 9-4 • Serpentine © 2022 Natural Stone Institute

more space than this; 2" (50 mm) space may be strict accordance with the spirit and intent of
more desirable. Large-scale details should the approved shop drawing, or from models
illustrate and control these conditions. furnished or approved by the Specifying
Authority.
3.5 Cutting for Anchoring,
Supporting, and Lifting Devices 4.0 SHIPPING AND HANDLING

3.5.1 Holes and sinkages shall be cut in stones 4.1 Packing and Loading
for all anchors, cramps, dowels, and other
tieback and support devices per industry Finished serpentine shall be carefully packed
standard practice or approved shop drawings. and loaded for shipment using all reasonable
However, additional anchor holes shall be and customary precautions against damage in
drilled at job site by Serpentine Contractor to transit. No material which may cause staining
facilitate alignment. or discoloration shall be used for blocking or
packing.
3.5.2 No holes or sinkages will be provided
for Serpentine Contractor's handling devices 4.2 Site Storage
unless arrangement for this service is made by
the Serpentine Contractor with the Serpentine It shall be the responsibility of the Serpentine
Fabricator. Contractor to receive, store, and protect the
serpentine from damage by others after it is
[NOTE: It is not recommended that lewis pins delivered to the job site and prior to its
be used for stones less than 3½" (90 mm) erection in the building. All serpentine shall be
thick.] received and unloaded at the site with care in
handling to avoid damage or soiling. If
3.6 Cutting and Drilling for serpentine is stored outside, it shall be covered
Other Trades with non-staining waterproof paper, clean
canvas, or polyethylene.
3.6.1 Any miscellaneous cutting and drilling
of stone necessary to accommodate other
trades will be done by the Serpentine 5.0 INSTALLATION
Fabricator only when necessary information is
furnished in time to be shown on the shop
5.1 General Installation
drawings and details, and when work can be
executed before fabrication. Cutting and
5.1.1 Installation shall be accomplished with
fitting, due to job site conditions, will be the
competent, experienced Stone Setters, in
responsibility of the Serpentine Contractor.
accordance with the approved shop drawings.
3.6.2 Incidental cutting such as for window
5.1.2 All serpentine pieces shall be identified
frame clips, etc., which is normally not
with a unique piece number corresponding
considered to be the responsibility of the stone
with the number on the shop drawings.
supplier, will be provided only by arrangement
Interchanging of numbered pieces is not
by the General Contractor and Serpentine
permitted.
Contractor with the Serpentine Fabricator.
5.1.3 Serpentine shall be free of any ice or
3.7 Carving and Models frost at time of installation. Salt shall not be
used for the purpose of melting ice, frost, or
All carving shall be done by skilled Stone snow on the stone pieces.
Carvers in a correct and artistic manner, in

© 2022 Natural Stone Institute Serpentine • Page 9-5

5.1.4 Adequate protection measures shall be 5.3.3 Before being set, all serpentine shall be
taken to ensure that exposed surfaces of the clean and free of foreign matter of any kind.
stone shall be kept free of mortar at all times.
5.3.4 Cement Bed. The cement bed to
5.2 Mortar Setting receive the serpentine tile shall consist of 1 part
portland cement to not more than 3 to 5 parts
5.2.1 Caution with Serpentine Setting of clean, sharp sand mixed quite dry for
Beds. Water expands the intercrystalline tamping. White Portland cement is
space in serpentine dimension stone. When it recommended for light-colored serpentines.
is being installed in a mortar bed, techniques
should be employed that minimize the amount 5.3.5 Serpentine Tamped. The serpentine
of water at the back face of the stone, and/or shall be tamped with a suitable mallet until
employment of fogging on the face (to increase firmly bedded to the proper level of the floor.
the intercrystalline space at both surfaces
uniformly) should be considered. Absent of 5.3.6 Serpentine Removed. The
this, the stone could expand at the back face serpentine shall then be removed and the back
temporarily to a larger dimension than the top parged with wet cement or the bed sprinkled
face, causing warping and/or twisting. The with water and cement. In the latter
warped stone is difficult, if not impossible, to procedure, the back of the serpentine shall be
return to its original dimensions. wet. The method of fully buttering edges of the
serpentine as it is laid is equally approved.
5.2.2 Other methodologies suggest
employment of installation material that is not 5.3.7 Joints between the serpentine
water-soluble to avoid this potential problem. pieces shall show an even width when laid and
finished.
5.2.3 This is an installation condition, and
should not be construed as a limitation of the 5.3.8 Traffic after Installation. The
stone’s range of application. Most serpentine floor shall be roped off for 24 hours after
varieties perform well in wet work installation and then grouted with water and
applications. white portland cement grout or non-staining
dry set portland cement grout.
5.3 Floor Serpentine
5.3.9 Timeline for Additional
5.3.1 Floor Preparation. It is the General Cleaning. Cleaning or additional surfacing, if
Contractor’s responsibility to clean all subfloor required, shall not be undertaken until the new
surfaces to remove dirt, dust, debris, and loose floor is at least seven days old.
particles immediately prior to setting
serpentine floor and to ensure that the area to 5.3.10 Thin-Set Method. The thin set
receive the stone flooring meets the deflection method of installing serpentine tile employing
standards of the industry. the use of dry set portland cement mortars is
recommended for thin serpentine tiles
5.3.2 Curing compounds of any kind shall [nominal 3/8" (9.5 mm) thick] where
not be used on the slab on which floor optimum setting space is not available.
serpentine is to be directly set. If a curing Subfloor shall be clean, smooth finished, and
compound is present, it is the General level.
Contractor’s responsibility to remove it by
scarifying the slab. 5.3.11 Stone dust must be washed off the
back face of stone pavers prior to installation.
Apply mortar with flat side of trowel over an

Page 9-6 • Serpentine © 2022 Natural Stone Institute

area that can be covered with tile while mortar 5.6.2 For ceiling-hung units, metal supporting
remains plastic. Within ten minutes, and using members in ceiling are to be furnished and
a notched trowel sized to facilitate the proper installed by the General Contractor.
coverage, comb mortar to obtain an even-
setting bed without scraping the backing 5.7 Mortar Joints
material. Key the mortar into the substrate
with the flat side of the trowel. Comb with the 5.7.1 Mortar joints shall be raked out to a
notched side of the trowel in one direction. depth of ½" to ¾" (12.5 mm to 20 mm).
Firmly press stone tiles into the mortar and Apply pointing mortar in layers not exceeding
move them perpendicularly across the ridges, 3/8" (9.5 mm) and allow each layer to get hard
forward and back approximately 1/8" to ¼" (3 to the touch before the next layer is applied.
mm to 6.5 mm) to flatten the ridges and fill the Tool finished joints with a concave tool having
valleys. Ensure a maximum mortar thickness of a diameter approximately 1/8" (3 mm) greater
3/32" (2.5 mm) between stone tile and than the joint width.
backing after stone tile has been tamped into
place. Stone tile shall not be applied to skinned- 5.7.2 Care shall be taken to keep expansion
over mortar. Or alternatively, back butter the joints free of mortar, which would
stone tiles to ensure 100% contact. In either compromise their function.
method, ensure 100% contact on 3/8" (9.5)
tile; not less than 80% contact on ¾" (20 mm) 5.8 Anchorage
or thicker material, excepting that all corners
and edges of stone tiles must always be fully 5.8.1 All serpentine shall be anchored or
supported, and contact shall always be 100% in doweled in accordance with the approved shop
exterior and/or water-susceptible conditions. drawings.

5.4 Interior Veneer Serpentine 5.8.2 To the furthest extent possible, all
anchor preparations in the serpentine units
5.4.1 The serpentine shall be set by spotting shall be shop-applied.
with gypsum molding plaster or cement
mortar and the use of concealed anchors 5.8.3 All anchorage devices and anchor
secured in the wall backing. hole/slot fillers shall be in accordance with
ASTM C1242. Care must be taken to ensure
that any holes capable of retaining water are
5.5 Serpentine Wall Tile
filled after use to prevent water collection and
freezing.
5.5.1 Individually set thin tile [nominal 3/8"
(9.5 mm) thick] on vertical surfaces exceeding
8' (2.5 m) is not recommended. Where thin 5.9 Sealant Joints
serpentine tile is installed, non-staining
5.9.1 Where so specified, joints requiring
adhesives or dry set mortars may be used as
sealant shall be first filled with a closed-cell
setting beds.
ethafoam rope backer rod. The backer rod
shall be installed to a depth that provides
5.6 Toilet and Shower optimum sealant profile after tooling.
Compartments
5.9.2 If recommended by the Sealant
5.6.1 Stiles and partitions shall be assembled Manufacturer, primers shall be applied to the
with concealed dowel fastenings or corrosion substrate surfaces according to the
resistant angles, three in height of stall. manufacturer’s directions prior to application
of the joint sealant.

© 2022 Natural Stone Institute Serpentine • Page 9-7

5.10 Expansion Joints cause discoloration is expressly prohibited.
Fabricator should be contacted before cleaners
5.10.1 It is not the intent of this other than neutral detergents are used.
specification to make control and expansion-
joint recommendations for a specific project. 6.2 Protection of Finished Work
The Specifying Authority must specify control
and expansion joints and show locations and 6.2.1 After the serpentine work is installed, it
details on drawings. shall be the responsibility of the General
Contractor to see that it is properly and
5.11 Caulking adequately protected from damage and stains
until all trades are finished. This responsibility
5.11.1 Where so specified, joints shall be includes the stone cleaning costs prior to the
pointed with the sealant(s) specified in Section final inspection. The Serpentine Contractor
2.4 after first installing the specified backup will outline the needs for protection, in
material and applying a primer if required, all writing, to the General Contractor. For the
in strict accordance with the printed protection of projecting members, corners,
instructions of the Sealant Manufacturer. window stools and saddles, wood guards using
lumber that will not stain or deface serpentine
5.11.2 All sealants shall be tooled to ensure shall be supplied, installed, and maintained by
maximum adhesion to the contact surfaces. the General Contractor. All nails used shall be
galvanized or nonrusting. Damage to finished
serpentine by other trades shall be repaired or
5.12 Weep Tubes
replaced at the expense of the General
Contractor. Serpentine flooring shall be
5.12.1 Plastic or other weep tubes shall be
adequately protected by the General
placed in joints where moisture may
Contractor against traffic and other damage
accumulate within the wall, such as at base of
with non-staining materials, without cost to
cavity, continuous angles, flashing, etc., or as
the Serpentine Contractor.
shown on architectural drawings.
6.2.2 All serpentine work in progress shall be
protected at all times during construction by
6.0 CLEANING AND use of a suitably strong, impervious film or
PROTECTION fabric securely held in place.

6.1 Cleaning
PRODUCT
6.1.1 Serpentine shall be shop-cleaned at
the time of final fabrication. It shall also be
DESCRIPTION –
cleaned after installation and all pointing or Serpentine
caulking is completed. All dirt, excess mortar,
weld splatter, stains, and other defacements 1.0 GEOLOGICAL
shall be removed. CLASSIFICATION
6.1.2 All cleaning methods shall be in 1.1 Serpentine. These beautiful and
accordance with ASTM C1515. elegant green stones traditionally have been
grouped in the commercial marble category.
6.1.3 Stiff bristle fiber brushes may be used, However, they are not true marbles. Marble is
but the use of wire brushes or of acid type by geologic definition metamorphic limestone,
cleaning agents and other solutions that may calcium carbonate (CaCO3), and dolomite

Page 9-8 • Serpentine © 2022 Natural Stone Institute

CaMg(CO3)2. Geologically, the “green yellowish-green? Why is one provided with
marbles,” as they are informally known, are the reinforcing net epoxied to the back and another
low-level metamorphic stone “serpentinite,” of is not? The complex differences are all in the
which the dominant mineral is serpentine. chemistry of rocks, fluids, and variations in
When the mineral name is altered to end with parameters of the metamorphic process.
the suffix “-ite,” it becomes the name of the
stone in which it is the main chemical 1.4 A wide range in apparent quality and
constituent. Serpentinite is sometimes performance of these beautiful stones reflects
confused with “green schist,” an entirely the diversity of mineral content and
different rock generally not suitable as consequent variations in the physical properties
dimension stone and rarely seen in the market and durability between the many “green
in part because large, nonfractured blocks are marbles” or serpentinites on today’s market.
difficult to obtain and loose mineral grains This clearly points up the exceptional value of
often preclude achieving suitably polished and the experience and knowledge attained by
durable surfaces. skilled stone technicians.

1.2 The major parent rock of the serpentine 1.5 The geochemistry involved with these
mineral is dark, iron- and magnesium-rich rocks is complex; however, knowing
igneous rock of the oceanic type, with a lesser something about a few of the important
amount of lighter, continental-type rock chemical components of serpentine and their
admixed. When these are intruded with hot, properties greatly aids understanding this often
chemical-rich fluids, the mineral serpentine is perplexing stone group.
formed in belt-like rinds around larger blocks
of oceanic-type, seafloor rock bodies. This 1.6 Serpentine (Mg3Si2O5(OH)4) is only
action takes place when two large segments of formed as a metamorphic mineral. It has the
Earth’s crust crash together, causing regional sheeting habit of mica in that it is composed of
scale metamorphism with injection of thin sheets loosely bound together like pages in
chemical-rich fluids3. Serpentines are thought a poorly manufactured book. Unlike the well-
to be formed very deep, at temperatures up to known micas, biotite and muscovite,
around 500°C at a depth called the “Moho,” 4 serpentine sheets are not elastic, but they are
the border marking the transition between the flexible. Large chunks of the mineral have a
outer crust of the Earth and the underlying “soapy” appearance and luster, and feel slippery
upper mantle, at depths of less than 10 to more or “greasy.” The slippery surfaces act as a
than 60 km (6 to 40 miles). lubricant in faulting of the stone. Serpentinites
often occur in contorted and complex shapes
1.3 Slight variations of parent rock mineral because of the flexibility of the sheets, and that
content, the condition of the parent rock, is part of the attraction of the stone. Serpentine
variations in chemistry of the invading fluids, hardness varies from about H=2.5 to 5 on the
and changes in temperature, pressure, and Mohs Scale5, depending on specific parameters
time plus subsequent geologic history, all of its geologic history and other admixed
influence the formation of serpentine stone. minerals. Serpentine does not react to cold,
Frequently asked questions are: Why the great dilute acid.
differences between different shades of green?
Why does one fade and others do not? Why is 1.7 Asbestos. The normal, sheet-like
one very dark green and others light- or “habit” or occurrence of serpentine has been

3 Skinner, B. J. and S. C. Porter, 1992, The Dynamic by a contrast in the velocity of sound through the two
Earth, 2nd ed., John Wiley & Sons, New York, p. 455. chemically different rock compositions.
4 Moho is the accepted slang term for Mohorovicić 5 See Appendix for the Mohs Scale of mineral hardness.

Discontinuity, or the crust/mantle boundary identified

© 2022 Natural Stone Institute Serpentine • Page 9-9

described, but another form of serpentine is thickness in the figure of the stone. Both
fibrous, and when found in this form it is the carbonate minerals have several properties in
potentially dangerous mineral asbestos. common: they are both H=3 (soft), break in
Properly known as chrysotile serpentine or perfect little rhombohedrons due to inherent
chrysotile asbestos, it has a slightly different weakness in molecular structure, and both are
chemistry than normal serpentine. Additional generally white or sometimes slightly iron-
meta-morphism, and again slight changes in stained.
chemistry, produce the familiar mineral talc.
Since the three forms of serpentine often occur 1.10 The only characteristic that can be used
together, avoid cutting serpentinites dry and to differentiate the two is their reaction to
maintain absolutely meticulous dust control in cold, dilute acid: calcite will effervesce
the shop. vigorously while magnesite does not. Is this
important in dimension stone? Yes, if used as a
1.8 Chrysotile and Talc. The tabletop, one of the traditional uses of highly
transformation of serpentine to chrysotile figured “green marbles.” It will not be easily
(asbestos) to talc is a continuously variable etched by salad vinegar or wine if the carbonate
chemical series and the members are mineral is magnesite. The simple dilute acid
chemically quite similar, but have differing test can be done by anyone; however, if a
molecular geometry. Since they form in surface-masking sealer is used, the acid may not
response to slight differences in metamorphic reach the calcite and produce the typical
pressures and chemistry, all three minerals may reaction. If the sealing agent is trustworthy
be found together. Talc is the softest of over an extended time, the occurrence of one
minerals and used as the example for H=1 on or the other of these carbonates stones should
the Mohs Scale. Talc does not polish. not matter. Consulting with Sealing
Chrysotile may polish if highly compacted and Professionals is recommended.
cut normal to the fibers. Sometimes chrysotile
may become highly siliceous; that is, the 1.11 Carbonate minerals soluble in dilute
mineral is replaced by silica but retains a acids should be used with extreme care in
“ghost” of its fibrous structure. This altered exterior applications where an acid-polluted
variant is known in the semiprecious gem trade atmosphere exists. Likewise, magnesite-rich
as “tiger’s eye” for its striking optical “green marbles” should not be used in exterior
characteristics. Since both talc and asbestos can applications where atmospheric sulfate
be considered undesirable admixtures to a pollution occurs. Magnesite will react to very
commercial-grade “green marble,” they are not dilute sulfuric acid in the moisture and
generally found in more than small or trace recrystallize to water-soluble magnesium
amounts in the better-known serpentines used sulfate (milk of magnesia).
for decades. Their occurrence tends to weaken
the stone, allows moisture penetration, 1.12 Note: Thin-set, cementitious
weathers faster, and should be considered compounds will probably react with any
detrimental in some exterior applications carbonate mineral in the serpentinite stones
where moisture control is difficult. White yielding a failure in attaching thin sheets of
veins in serpentine indicate the presence of talc some green marble.
or asbestos; consequently, the use of such stone
should be minimized in external applications. 1.13 Siderite (FeCO3) is a semi-hard iron
carbonate (H=3.5 to 4.5 on the Mohs Scale)
1.9 Calcite and magnesite (calcium and not uncommon in serpentinites as pale- to
magnesium carbonates, (CaCO3) and (MgCo3) dark-brown masses or veins. It breaks easily
occur in serpentinites, usually as white to off- into parallelogram-shaped fragments, as do
white discrete masses or veins of varying other carbonates, and does not react with cold,

Page 9-10 • Serpentine © 2022 Natural Stone Institute

dilute acids. It will effervesce in hot, dilute and these two minerals do occur together.
acids, but trying to perform that test is strongly Rapid weathering or loss of the well-polished
discouraged due to the danger of eye damage surface of some “green marbles” may in fact be
when attempting to heat any acid. due to undetected chlorite that occurs as finely
disseminated or small pockets in the serpentine
1.14 Brucite (magnesium hydroxide or that are obscure except to close inspection by
Mg(OH)2) commonly occurs with serpentine, experienced Stone Technicians.
greenschists, chlorite schists, and with talc and
other low-grade metamorphic stone formed 1.18 Albite (NaAlSi3O8). This plagioclase
from dark, high iron- and magnesium-rich feldspar composed of sodium aluminum
igneous rock. Brucite is very soft, about H=2.5 silicate is found in some serpentinites, an
– the same hardness as a human fingernail – expectation given the dark, oceanic-type
thus it is not desirable to have large parent of serpentine. Albite is hard (H=6) and
accumulations or veins of brucite in “green durable, thus a vein of albite is in no way a
marbles.” Brucite is very soluble in cold, dilute detriment unless incipient fractures accompany
acids, but will not effervesce, becoming instead the vein – probably when the vein happens to
a mud-like slurry. be bordered by a very thin chlorite rind.

1.15 Note that since serpentine is formed in 1.19 Magnetite (Fe3O4) iron oxide is often
part from iron- and magnesium-rich parent present in serpentinites due to mineral
rock, the occurrence of other high-Mg segregation that occurs in metamorphic
minerals such as brucite or magnesite and the processes. Magnetite is very hard (H=5.5 to
carbonates of iron, Fe, Ca, and Mg are to be 6.5), harder than common glass. It is magnetic,
expected as minor constituents in black, and when polished, has a metallic luster.
serpentinites.
1.20 Limitations. As a final note to this
1.16 Chlorite [(Mg,Fe)5(Al,Fe)2Si3O10 section regarding the use of serpentine in
(OH) 8] is another green, very soft, sheet-like, building applications, remember that failures
metamorphic mineral. Chlorite, like with the “green marbles” can occur in some
serpentine, brucite, and magnesite, has flexible projects from the physical limitations of
but not elastic sheets loosely bound together. accessory minerals in the stone’s chemical
It has a greasy-feeling surface that facilitates composition. In addition, serpentine’s sheet-
internal slippage in the serpentinite and like, crystalline habits and slippery texture can
greenstone belts. Its color ranges from sometimes cause weakness in slabs, or allow
medium green to a light, yellowish-green, and accelerated surface oxidation in exterior uses
light to medium yellow. Chlorite hardness is where water, temperature extremes, and
H=2 to 2.5, or very soft. Although chlorite sunlight will rapidly degrade some minerals.
may polish, it does not retain polish and is The degree of compaction should always be
prone to rapid surface dulling. Veins of chlorite examined in any stone selection.
weaken the stone when sliced thin and may be
a likely reason to reinforce some slabs with 2.0 COLOR AND VEINING
backup netting and epoxy. Chlorite’s sheeting
habit acts as a plane of weakness along which 2.1 The color, veining, clouds, mottlings,
faulting, slippage, and fracturing will occur, and shadings in serpentine are caused by minor
further weakening a thinly sawn piece. inclusions during the formation or some prior
degradation or weathering of the stone to
1.17 Chlorite may be almost impossible to release staining color. Iron oxides make the
distinguish from serpentine except by pinks, yellows, browns, and reds. Most grays,
hardness, a very difficult distinction to make, blue grays, and blacks are of bituminous origin.

© 2022 Natural Stone Institute Serpentine • Page 9-11

Greens are caused by micas, chlorites, and 6.0 SIZES
silicates.
6.1 Serpentine is a product of nature with
hundreds of varieties available, each possessing
3.0 TEXTURE distinct characteristics. Little can be done to
alter the condition in which nature presents
3.1 The term “texture,” as applied to these varieties to us. Therefore, size may
serpentine, means size, degree of uniformity, become a limiting factor to consider in the
and arrangement of constituent minerals. selection of serpentine. Check with the Stone
Grains of calcite and other carbonates, the chief Supplier as to the sizes that are available for the
accessory mineral of most serpentines, are specific serpentine.
crystalline and have definite rhombohedral
cleavage which shows bright, reflecting faces 6.2 Selection and delivery can be greatly
on a broken surface. In most serpentines, facilitated by a jointing scheme which permits
however, the grains are elongated in one the use of smaller sizes. A final jointing scheme
direction by the plication (folding) of the beds. should be agreed upon after the serpentine has
been selected and the Serpentine Contractor
4.0 FINISHES has been consulted.

4.1 Serpentine’s surface may be finished in a

number of ways. In general, smooth finishes 7.0 PRODUCT SAMPLING
tend to emphasize color and veining, whereas
rough finishes tend to subdue the veining or 7.1 Serpentine is formed by nature; thus,
markings. there are variations in the tonal qualities of the
stones. However, it is these natural variations
4.2 Typical Finishes for Serpentine that make serpentines unique, valuable, and
Are: highly desirable. Because of these variations,
selection of serpentine should never be made
4.2.1 Polished: A glossy surface that brings on the basis of one sample only. It is
out the full color and character of the recommended that selection be based on
serpentine. It is not generally recommended viewing sufficient samples to show the
for exterior use or commercial floors. complete range of colors of the desired stone.

4.2.2 Honed: A satin-smooth surface with

little or no gloss, recommended for 8.0 PROPER USAGE TIPS
commercial floors.
Recommendation for commercial floors:
5.0 THICKNESS 1) Minimum ¾"(20 mm) thickness.
2) A honed finish.
5.1 Standard nominal thicknesses for 3) A minimum hardness value of 10 as
serpentine veneer are ¾", 7/8", 1¼", 1½", measured by ASTM C241/C1353.
and 2" (20 mm, 22 mm, 30 mm, 40 mm, and
50 mm). When a serpentine thinner than ¾" Avoid the use of gypsum or molding plaster
(20 mm) is specified, the ratio between setting spots for the installation of exterior
thickness and overall size and the use of stone.
reinforcing backup materials must be
considered. Serpentine thicker than 2" (50
mm) is usually regarded as cubic stock.

Page 9-12 • Serpentine © 2022 Natural Stone Institute

9.0 VENEER CUTTING building materials. It may not be proper for
certain applications.
9.1 Quarry blocks are reduced to slabs by
a gang saw. The gang saw consists of a series of 1.3 Physical property values of serpentine
steel blades set parallel in a frame that moves may, however, be measured using the standard
forward and backward. The most productive test methods approved by the Dimension Stone
and precision gang saws have diamond-tipped Committee C 18 of ASTM International. The
blades with individual hydraulic blade values found when stone is tested for
tensioners. absorption, density, compressive strength,
abrasion resistance, and flexural strength
9.2 Serpentine blocks can be sawn either should be useful for the Designer and Engineer
perpendicular or parallel to the bedding plane. when preliminary construction calculations are
The perpendicular cut is referred to as an being made. However, these tests should be
across-the-bed or vein cut. The parallel cut is made before the project specifications are
with-the-bed or fleuri cut. Some serpentines written, not after. Member companies of the
produce a pleasing surface when sawed in Marble Institute of America are represented on
either direction, and are available as either vein this committee and are active in its technical
or fleuri. Other serpentines produce a pleasing work of establishing proper test methods and
surface only when sawed in one direction, and specifications consistent with the latest
are generally available only in that variety. technology.

1.4 Physical Properties of Serpentine

TECHNICAL DATA - (This historical data and information is
Serpentine provided only as a guideline. Recommended
minimums or maximums are established and
1.0 PROPERTIES OF provided by ASTM International.)*
SERPENTINE DIMENSION STONE Property Range of Values
Compressive Strength (C170)
1.1 In centuries past, relatively little lbs/in²………………………9,000 27,000
importance was attached to the ultimate Recommended (min): 10,000
physical capabilities of most building materials.
Rule of thumb was a common structural design Flexural Strength (C880)
criterion. As a result, the widely used materials lbs/in² .................................. 900-5,000
of the day, for the most part natural rather than Recommended (min): 1,000
manmade materials, were seldom stressed to Modulus of Elasticity** (in millions)
their ultimate limits. lbs/in² ..................................... 2.0-15.0
In present-day construction, however, this is
far from being true. Performance Density, lb/ft3 (C97) .................. 155-180
requirements are daily becoming more Recommended (min): 168
demanding. In striving for taller structures, Modulus of Rupture (C99) lbs/in².500-2,500
greater spans, firmer foundations, thinner Recommended (min): 1,000
walls and floors, stronger frames, and generally
more efficient buildings with more usable Absorption, by weight % (C97). ..... 0.09-1.2
space, today’s Architects and Engineers must Recommended (max): 0.20 exterior, 0.60
get the most out of the materials with which interior
they work. Abrasion Resistance (Ha) (C241) ..... 25-110
1.2 Serpentine is a product of nature and not Recommended (min): 10
always subject to the rules of consistent * Test methods described in current ASTM
behavior that may apply to manufactured standards. ** Also known as Young’s Modulus.

© 2022 Natural Stone Institute Serpentine • Page 9-13

2.0 STRENGTH (ASTM C170, 4.0 ABRASION RESISTANCE
ASTM C880) (ASTM C241/C1353)

2.1 The strength of a serpentine is a measure 4.1 Abrasion resistance is a property of

of its ability to resist stresses. This strength stone that should be tested per ASTM
depends on several factors: the rift and cleavage C241/C1353 to provide an indication of the
of the crystals, the degree of cohesion, the stone’s wearing qualities when exposed to foot
interlocking of the crystals, and the nature of traffic.
any cementing materials present.
4.2 The hardness and uniform wearing
qualities of most serpentine varieties make
3.0 FIRE RESISTANCE them extremely desirable and economically
practical for floors and stairs. Varieties with an
3.1 Serpentine is not combustible according ASTM C241/1353 abrasive hardness rating
to underwriters’ ratings, and so is considered a (Ha/Iw) of 10 or more are recommended for
fire-resistant material. Because of its thermal use as flooring. A minimum abrasive hardness
conductivity, however, the heat transfer of 12.0 is recommended for commercial
through serpentine is fairly rapid. Serpentine is floors, stair treads, and platforms subject to
not considered a highly rated thermal insulator. heavy foot traffic. Surfaces of floors
constructed with two or more varieties, with
3.2 Underwriters’ fire-resistance ratings Ha/Iw differences more than 5, will not wear
evaluate whether or not a material will burn, evenly and uniformly.
as well as how long it will keep surrounding
combustible materials from reaching
temperatures which will cause them to ignite. 5.0 FACTORS AFFECTING
Pilot plant tests at The Ohio State University PHYSICAL PROPERTIES
Pyrotechnics Laboratory indicate that a 10
minute rating could be expected from 7/8" 5.1 The ultimate test of a building material
(22 mm) thick serpentine. is its ability to have and maintain the necessary
structural strength, as well as beauty of
3.3 The use of an insulating material with appearance and low cost of maintenance, over
serpentine substantially improves the fire the useful life of the structure. Experience has
rating, as shown in the following: proven that serpentine meets this test as few
other building materials can.
7/8" (22 mm) serpentine with 1" (25 mm)
core of: 5.2 Illinois Institute of Technology Research
Paper Honeycomb…………….…..½ hour Institute’s studies have shown that the
Cement-Bonded Wood Excelsior…...1 hour durability of serpentine is little affected by
Autoclaved Cellular Concrete……..1½ hour cycles of weather. This is because of
serpentine’s low rate of absorption. The rates
3.4 Methods of estimating fire-resistance of moisture absorption of all the serpentines
periods of masonry walls and partitions studied were less than 1 percent by weight.
utilizing component laminae are given in “Fire Other masonry materials range upward from 4
Resistance Classifications of Building to 12 percent.
Construction,” BMS92, National Bureau of
Standards. 6.0 SAFETY FACTORS
6.1 Good engineering practice requires that
allowable design stress must provide a margin

Page 9-14 • Serpentine © 2022 Natural Stone Institute

of safety in any structural element. As a 6.6 This span for each thickness is the
necessary precaution against such conditions as maximum for panels that are supported on two
wind, ice, snow, impact, temperature changes, sides only.
and imperfect workmanship, these allowable
stresses must be smaller than those which 6.7 If the panel is supported on all four sides
produce failure. and the long side of the panel exceeds twice the
short side, use the short span from the table.
6.2 Within the accepted limits of safe design
practice, the closer the allowable load is to the 7.0 SEISMIC CONSIDERATIONS
ultimate failure load in a structure, the more
efficient is the use of the material and the less 7.1 Seismic considerations generally require
the cost of the construction. that low buildings be stiff, and that tall
buildings be relatively flexible. Design of
6.3 Contemporary design of buildings, connections must account for seismically
exclusive of the monumental type, does not induced horizontal loading. Local building
usually employ serpentine as part of the codes vary and must always be checked to
structural frame, but rather as an independent determine specific requirements for each area.
unit, a curtain wall, or veneer. Therefore, the
primary concern in such cases is with wind 7.2 Additional Readings:
load, and a safety factor of 5.0 is
recommended. Where the serpentine is to be 7.2.1 The National Bureau of Standards has
subjected to concentrated loading, such as stair published two documents on the topic:
treads or lintels supported only at the ends, a “Earthquake Resistant Masonry Construction,”
factor of 10.0 should be used. NBS Science Series 106; and “Abnormal
Loading on Buildings and Progressive Collapse:
6.4 As buildings become taller and An Annotated Bibliography,” NBS Science
individual stone slab veneer becomes larger in Series 67.
area, the lateral forces due to wind loads must
be considered. Wind tunnel tests are often 7.2.2 The U.S. Army Corps of Engineers has
used on major structures to determine wind also published TM 5-809-10, “Seismic Design
dynamics and force magnitude. Reinforcement for Buildings.”
is sometimes necessary for large-dimension
slab veneer in critical areas.
8.0 EFFLORESCENCE AND
6.5 To determine the thickness and size of
panel required: STAINING

6.5.1 Determine the design and wind load. 8.1 Efflorescence is a salt deposit, usually
white in color that appears on exterior surfaces
6.5.2 Obtain the flexural strength of the of masonry walls. The efflorescence producing
serpentine under consideration using the salts found in masonry are usually sulfates of
ASTM C880 test method. This information sodium, potassium, magnesium, calcium, and
may be available from the Serpentine Supplier. iron. Salts which are chlorides of sodium,
calcium, and potassium will sometimes appear,
6.5.3 Select the unsupported span for each but are so highly soluble in water that they will
thickness for which the stress is below the be washed off by rain.
flexural strength of the serpentine from the
appropriate table. 8.2 The water-soluble salts causing
efflorescence come from other materials in the
wall. The salts exist in small amounts and are

© 2022 Natural Stone Institute Serpentine • Page 9-15

leached to the surface by water percolating the vertical joints so they can be sloped upward
through the walls. The most feasible means of from the front to the back.
prevention is to stop the entrance of large
amounts of water. Absorption from the face 8.7 Stains sometimes appear on the base
will not cause efflorescence unless there are course when serpentine is in contact with soil,
open joints. or on interior and exterior horizontal surfaces,
due to the carrying of soluble salts and some
8.3 Serpentine is not injured by colored soil constituents up through and to the
efflorescence. However, some of the salt surface of the stone by capillary action. Almost
crystals may form in the pores near the surface. all soils and most of the veining in serpentine
Crystal growth (recrystallization) in the pores contain soluble salts. Therefore, this staining
can cause stress on the walls of the pores and phenomenon is similar to the discoloration
cause the stone to flake off. If the conditions described previously, and will disappear when
bringing about this action persist, scaling may the source of moisture is eliminated. However,
continue and flake off one layer after another. materials from the veining may remain on the
For this to happen, large amounts of water stone’s surface. In walls, provide venting so
must enter the wall and must contain large that moisture can escape through the vents
amounts of salts. rather than through the stone. On horizontal
surfaces, the use of a vapor barrier between the
8.4 Research indicates that staining or setting bed and the concrete slab, or between
discoloration occurring on new buildings is the setting bed and the ground, is
caused by the action of water percolating recommended.
through cement from which soluble alkali salts
are leached. The salts are then carried by the Additional Resources: Refer to Veneer
water through the serpentine, where partially Cutting and Veneer Patterns drawings at the
oxidized organic matter is picked up. This is close of Chapter 7 (Marble and Onyx).
then transported to the surface of the stone,
where it is deposited as a stain as the water
evaporates.

8.5 This staining phenomenon is similar to

efflorescence, except that it involves organic
material. It does not harm the stone other than
leaving an objectionable appearance during or
soon after erection. However, if left alone, the
stain is removed naturally by the action of the
elements, usually in the course of a few
months.

8.6 A considerable amount of water passing

through the stone is necessary to bring out
conspicuous discolorations. Proper
precautions taken during construction of the
walls will usually prevent such troubles. A
simple and helpful expedient is to provide
frequent weep holes in the base course and
above shelf angles. These should be placed in

Page 9-16 • Serpentine © 2022 Natural Stone Institute

SLATE 1.2.3.1 Membership, Products, and Services
Directory

1.0 GENERAL 1.2.3.2 Dimension Stone Design Manual

1.1 Related Documents 1.2.3.3 Additional publications may be

available from the NSI Bookstore. Go online at
1.1.1 Drawings and general provisions, www.naturalstoneinstitute.org.
including General and Supplementary
Conditions of the Contract and Division I 1.3 Scope of Included Work
Specification sections, apply to this section.
1.3.1 The work to be completed under this
1.2 Applicable Publications contract includes all labor and materials
required for the furnishing and installation of
1.2.1 The following publications listed here all slate work shown or called for on the
and referred to thereafter by alphanumeric contract drawings, specifications, and
code designation only, form a part of this addenda.
specification to the extent indicated by the
references thereto: 1.4 Definition of Terms

1.2.2 ASTM International (ASTM): 1.4.1 The definitions of trade terms used in
this specification shall be those published by the
1.2.2.1 C629, Standard Specification for NSI or ASTM International.
Slate Dimension Stone
1.5 Source of Supply
1.2.2.2 C120, Standard Test Methods of
Flexure Testing of Slate (Modulus of Rupture, 1.5.1 All slate shall be obtained from quarries
Modulus of Elasticity) having adequate capacity and facilities to meet
the specified requirements, and by a firm
1.2.2.3 C121, Standard Test Method for equipped to process the material promptly on
Water Absorption of Slate order and in strict accord with specifications.
The Specifying Authority (architect, designer,
1.2.2.4 C217, Standard Test Method for engineer, contracting officer, end user, etc.)
Weather Resistance of Slate reserves the right to approve the Material
Supplier for slate prior to the award of this
1.2.2.5 C241, Standard Test Method for contract. Stone and workmanship quality shall
Abrasion Resistance of Stone Subjected to Foot be in accordance with Industry Standards and
Traffic Practices as set forth by the NSI.

1.2.2.6 C880, Standard Test Method for 1.6 Samples

Flexural Strength of Dimension Stone
1.6.1 The Slate Contractor shall submit
1.2.2.7 C1353, Standard Test Method Using through the General Contractor, for approval
the Taber Abraser for Abrasion Resistance of by the Specifying Authority, at least two sets of
Dimension Stone Subjected to Foot Traffic samples of the various kinds of slate specified.
The sample size shall be 1'-0" x 1'-0" and shall
1.2.3 Natural Stone Institute (NSI): represent approximately the finish, texture,
and anticipated range of color to be supplied.

© 2022 Natural Stone Institute Slate • Page 10-1

One set of samples shall be retained by the 1.8 Defective Work
Specifying Authority, and one set shall be
returned to the Slate Supplier for his/her 1.8.1 Any piece of slate showing flaws or
record and guidance. It is noted herein that imperfections upon receipt at the storage yard
slate is a natural material and will have intrinsic or building site shall be referred to the
variations in color, markings, and other Specifying Authority for determination as to
characteristics. Color variation range is to be responsibility and decision as to whether it shall
only from natural markings in the slate or from be rejected, patched, or redressed for use. Any
the reflective sheen and shadow value of the material in question should not be installed
graining of the natural-cleft textures and prior to inspection and approval.
cleavage planes. Depending on slate selected
and quantity required, a range mockup may be 1.9 Repairing Damaged Stone
used to further define the characteristics of the
material. Cost of mockup, if required, shall not 1.9.1 Chips at the edges or corners may be
be included in this section. patched, provided the structural integrity of
the stone is not affected and the patch matches
1.6.2 Prior to fabrication, an inspection and the color and finish of the natural stone so that
approval by the Specifying Authority and/or it does not detract from the stone’s
General Contractor and/or End User of the appearance.
finished slabs is recommended to understand
the finish and full range of the material.
2.0 MATERIALS
1.7 Shop Drawings
2.1 Slate
1.7.1 The Slate Contractor shall submit
through the General Contractor, for approval
2.1.1 General: All slate shall be of standard
by the Specifying Authority, sufficient sets of
architectural grade, free of cracks, seams,
shop drawings showing general layout,
starts, or other traits which may impair its
jointing, anchoring, stock thickness, and other
structural integrity or function. Inherent color
pertinent information. These drawings shall
variations characteristic of the quarry from
show all bedding, bonding, jointing, and
which it is obtained will be acceptable. Texture
anchoring details along with the net piece
and finish shall be as shown in the sample(s)
dimensions of each slate unit. One copy of the
approved by the Specifying Authority.
approved shop drawings shall be retained by
the Specifying Authority, one copy shall be
2.1.2 ASTM C629 [C120] [C121] [C217]
retained by the General Contractor, and one
[C241/1353] See the chart of applicable
copy returned to the Slate Contractor for
ASTM standards and tests in the Appendix.
fabrication. NO FABRICATION OF SLATE
SHALL BE STARTED UNTIL SUCH
2.1.3 Schedule: Slate shall be provided as
DRAWINGS HAVE BEEN FULLY
follows:
APPROVED AND MARKED AS SUCH. The
Slate Contractor shall not be responsible for 2.1.3.1 For (state location on building) (state
determining, making, or verifying (1) design, name and color) slate with a (type) finish,
structural, wind, seismic, or other design supplied by (name company or list several approved
loads; (2) engineering estimates; (3) plans or suppliers).
specifications; (4) the types, sizes, or locations
of anchors; or (5) verification of field 2.1.3.2 Provide information as in 2.1.3.1 for
dimensions, unless specifically added to the each different slate/finish combination in the
scope of work. project.

Page 10-2 • Slate © 2022 Natural Stone Institute

2.1.4 Finishes: Face finish of all exterior 3.0 FABRICATION
panels should be natural cleft. Sand-rubbed,
honed and other finishes are available, 3.1 Dimensional Limitations
depending on the Slate Supplier. All exposed
edges should be honed to remove saw marks 3.1.1 Slate spandrels, panels, and wall facings
and darken the edge color. are recommended in thicknesses of 1", 1¼",
and sometimes 1½" (25, 30, and 40 mm).
2.1.4.1 Finishes listed in the schedule shall Standard economical lengths are up to 6'-6" (2
conform with definitions by NSI or ASTM m) and widths up to 4'-0" (1.2 m). Special
International. larger sizes are available to meet design and job
conditions on special request. No single piece
2.2 Setting Mortar is recommended to be over 9'-6" ((3 m) in
length or 5'-0" 1.5 m) in width. Larger sizes
2.2.1 Mortar for setting and pointing shall be may be available only under special conditions
one part portland cement and one part plastic and limited production.
lime hydrate to three to five parts of clean,
nonstaining sand. It shall be mixed in small 3.2 Beds and Joints
batches, using potable, non-alkaline water with
a pH of 7, until it is thoroughly homogeneous, 3.2.1 Bed and joint width shall be determined
stiff, and plastic. After mixing, the mortar shall by analysis of anticipated building movements
set for not less than one hour or more than two and designed to accommodate such
hours before being used. movements without inducing undue stresses in
the stone panels or joint filler materials.
Expansion joints shall be designed and located
2.3 Pointing Mortar
to accommodate larger movements.
2.3.1 Mortar for pointing shall be Type N, as 3.2.2 Some slight lippage and variation is
defined in ASTM C270 (Standard Specification natural and unavoidable where the natural-cleft
for Mortar for Unit Masonry). All mixing, face comes together at the sawed joints.
handling, and placing procedures shall be in
accordance with ASTM C270. 3.2.3 Joints 3/8" or ½" (9.5 or 12.5 mm) are
recommended between standard size panels,
2.4 Sealants and Backup and ¼" and 3/8" (6.5 and 9.5 mm) joints at
Material (if Applicable) abutting masonry. All joints are to be water-
and moisture-tight and caulked with a proper
2.4.1 Where specified, (state type or name of sealant.
sealant) shall be used for the pointing of joints.
The backup material used with the sealant shall 3.3 Backs of Pieces
be (identify material)
3.3.1 Backs of pieces shall be sawn or roughly
dressed to approximately true planes. Back
2.5 Anchors, Cramps, and surfaces shall be free of any matter that may
Dowels create staining.

2.5.1 All wire anchors, cramps, dowels, and 3.4 Moldings, Washes, and Drips
other anchoring devices shall be nonferrous
metal of the types and sizes shown on approved 3.4.1 Moldings, washes, and drips shall be
shop drawings. Doweling natural-cleft slate to constant in profile throughout their entire
slate is not acceptable. length, in strict conformity with details shown

© 2022 Natural Stone Institute Slate • Page 10-3

on approved shop drawings. The finish quality details, and when work can be executed before
on these surfaces shall match the finish quality fabrication. Cutting and fitting, due to job site
of the flat surfaces on the building. conditions, will be the responsibility of the
Slate Contractor.
3.5 Back-checking and Fitting to
3.7.2 Incidental cutting such as for window
Structure or Frame
frame clips, etc., which is normally not
considered to be the responsibility of the Stone
3.5.1 Stone coming in contact with structural
Supplier, will be provided only by arrangement
work shall be back-checked as indicated on the
by the General Contractor and Slate
approved shop drawings. Stones resting on
Contractor with the Slate Fabricator.
structural work shall have beds shaped to fit the
supports as required.
4.0 SHIPPING AND HANDLING
3.5.2 Maintain a minimum of 1" (25 mm)
between stone backs and adjacent structure. 4.1 Packing and Loading
Note: many bolted connections will require
more space than this; 2" (50 mm) space may be 4.1.1 Finished slate shall be carefully packed
more desirable. Large-scale details should and loaded for shipment using all reasonable
illustrate and control these conditions. and customary precautions against damage in
transit. No material which may cause staining
3.6 Cutting for Anchoring, or discoloration shall be used for blocking or
packing.
Supporting, and Lifting Devices
4.2 Site Storage
3.6.1 Holes and sinkages shall be cut in stones
for all anchors, cramps, dowels, and other 4.2.1 Upon receipt at the building site, the
tieback and support devices per industry slate shall remain in the factory-prepared
standard practice or approved shop drawings. bundles until beginning of the installation.
However, additional anchor holes shall be Bundles shall be staged in an area which is least
drilled at job site by Slate Contractor to susceptible to damage from ongoing
facilitate alignment. construction activity. Once unbundled, the
slate shall be stacked on timber or platforms at
3.6.2 No holes or sinkages will be provided least 2" (50 mm) above the ground, and the
for Slate Contractor’s handling devices unless utmost care shall be taken to prevent staining
arrangement for this service is made by the or impact damage of the slate. If storage is to
Slate Contractor with the Slate Fabricator. be prolonged, polyethylene or other suitable,
nonstaining film shall be placed between any
[NOTE: It is not recommended that lewis pins wood and finished surfaces of the slate.
be used for stones less than 3½" (90 mm) Polyethylene or other suitable, nonstaining
thick.] film may also be required as protective
covering.
3.7 Cutting and Drilling for
Other Trades 5.0 INSTALLATION
3.7.1 Any miscellaneous cutting and drilling 5.1 General Installation
of stone necessary to accommodate other
trades will be done by the Slate Fabricator only 5.1.1 Installation shall be accomplished with
when necessary information is furnished in competent, experienced Stone Setters, in
time to be shown on the shop drawings and accordance with the approved shop drawings.

Page 10-4 • Slate © 2022 Natural Stone Institute

5.1.2 All slate stone pieces shall be identified Round anchor holes in the edge of the slate to
with a unique piece number corresponding receive nonferrous wire anchors are the least
with the number on the shop drawings. expensive and the strongest system. Slots for
Interchanging of numbered pieces is not strap anchors are sometimes acceptable.
permitted.
5.2.4 Rear face of slabs should be at least 1"
5.1.3 Slate stone shall be free of any ice or (25 mm) from the face of the backup wall.
frost at time of installation. Salt shall not be Gauged backs are frequently required where
used for the purpose of melting ice, frost, or fitting is tight. Space between back of slate and
snow on the stone pieces. wall should not be filled in completely, but
instead spotted with approved nonstick mastic
5.1.4 Adequate protection measures shall be compound or portland cement in spots
taken to ensure that exposed surfaces of the approximately 6" x 6" (150 x 150 mm) located
stone shall be kept free of mortar at all times. every 18" (450 mm) apart. All shims and
blocks must be removed.
5.2 Mortar Setting and Interior panels are set and anchored similarly
to exterior work.
Anchorage
5.2.5 Panels set in metal frames shall have
5.2.1 All setting shall be done by competent rabbeted edges and a sealant for all joints to
Stone Setters, in accordance with approved prevent moisture seepage. Hairpin-spring
shop drawings. anchors in the back of the panels make slate
easily adaptable to slate-faced precast units and
5.2.2 Exterior panels shall be anchored to the systems.
masonry wall or framing by at least four bronze
wire or other nonferrous metal anchors for 5.2.6 In some selected interior work, small 1'-
each piece. Standard size anchor is 1/8" to ¼" 0" x 1'-0" (300 x 300 mm) or less ¼" (6.5 mm)
(3 to 6.5 mm)wire (depending on the thickness thick gauged panels can be applied with a
of the stone) turned down 1" (25 mm) into a proper adhesive without anchors. Some
3/8" (9.5 mm) round, 1½" (40 mm) deep hole interior work may be set with narrow joints
in the edge of the slate. Each piece must be without grout.
anchored individually for proper adjustment.
Slabs over 12 square feet (1 m2) in surface area 5.2.7 Individually set thin slate tile [¼" or
shall have at least two additional anchors every 3/8" (6.5 or 9.5 mm)] on vertical surfaces
6 square feet (0.5 m2). Relief angles and liners exceeding 15'-0" (4.5 m) is not recommended.
may be required at normal floor-line distances.
5.3 Mortar Joints
5.2.3 The larger the panel, the more
pronounced and rustic will be the textured 5.3.1 Mortar joints shall be raked out to a
face. Generous tolerance allowances of this depth of ½" to ¾" (12.5 to 20 mm). Apply
natural-textured material will give more speed pointing mortar in layers not exceeding 3/8"
and ease in installation and a better general (9.5 mm) and allow each layer to get hard to
appearance. Anchoring and setting methods the touch before the next layer is applied. Tool
should allow for slight adjustments of each finished joints with a concave tool having a
individual panel. Careful piece-to-piece diameter approximately 1/8" (3 mm) greater
selection should be exercised by the Slate than the joint width.
Contractor at the job. Individual anchoring
allows proper adjustment and alignment of
each piece in relation to surrounding pieces.

© 2022 Natural Stone Institute Slate • Page 10-5

5.3.2 Care shall be taken to keep expansion in strict accordance with the printed
joints free of mortar, which would instructions of the Sealant Manufacturer.
compromise their function.
5.7.2 All sealants shall be tooled to ensure
5.4 Anchorage maximum adhesion to the contact surfaces.

5.4.1 All slate shall be anchored or doweled in 5.8 Weep Tubes

accordance with the approved shop drawings.
5.8.1 Plastic or other weep tubes shall be
5.4.2 To the furthest extent possible, all placed in joints where moisture may
anchor preparations in the slate units shall be accumulate within the wall, such as at base of
shop-applied. cavity, continuous angles, flashing, etc., or as
shown on architectural drawings.
5.4.3 All anchorage devices and anchor
hole/slot fillers shall be in accordance with
ASTM C1242. Care must be taken to ensure
6.0 CLEANING AND
that any holes capable of retaining water are
filled after use to prevent water collection and PROTECTION
freezing.
6.1 Cleaning
5.5 Sealant Joints
6.1.1 The Slate Contractor shall keep the slate
5.5.1 Where so specified, joints requiring clean with a sponge and clean water. No
sealant shall be first filled with a closed-cell mortar drippings shall be allowed to dry on the
ethafoam rope backer rod. The backer rod face of the slate. Upon completion of various
shall be installed to a depth that provides portions of work, all mortar stains, grease
optimum sealant profile after tooling. marks, and dirt should be removed by washing
with a good grade of cleaner. Flush and clean
5.5.2 If recommended by the Sealant with clear water.
Manufacturer, primers shall be applied to the
substrate surfaces according to the 6.2 Protection of Finished Work
manufacturer’s directions prior to application
of the joint sealant. 6.2.1 After the slate work has been installed,
it shall be the responsibility of the General
5.6 Expansion Joints Contractor to see that it is properly and
adequately protected from damage or stains
5.6.1 It is not the intent of this specification to until all trades are finished. This responsibility
make control or expansion joint includes the stone cleaning costs prior to final
recommendations for a specific project. The inspection. The Slate Contractor will outline
Specifying Authority must specify control or the needs for protection, in writing, to the
expansion joints and show location and details General Contractor.
on drawings.

5.7 Caulking PRODUCT

DESCRIPTION - Slate
5.7.1 Where so specified, joints shall be
pointed with the sealant(s) specified in Section
2.4, after first installing the specified backup
1.0 GEOLOGICAL
material and applying a primer if required, all CLASSIFICATION

Page 10-6 • Slate © 2022 Natural Stone Institute

 direction and may have no relation to former
1.1 Slate is a fine-grained, metamorphic bedding, only coinciding with bedding as an
rock exhibiting “slaty” cleavage, which allows accident of fold geometry.
it to be split into thin sheets.1 It is a low-grade
metamorphic rock formed from shale, which is 1.4 This realignment and added
a thin-bedded, fine-grained, clastic compression develops the “slaty” cleavage or
sedimentary rock compacted from mud of cleavability, one of the defining and most useful
clay-sized silicate clay minerals.2 properties of slate. Because of the realignment
of the microscopic sheets of clay minerals, the
1.2 How Slate Is Formed. Clay minerals new cleavage is independent of the former
are often suspended in the turbid waters of bedding, which can no longer function as a
rivers, lakes, and ponds following heavy rains parting plane even though it may still be
and their consequent flooding. When turbidity perfectly visible as a color demarcation. A fresh
ceases, clay particles settle to the bottom of the cleavage surface on slate has a silvery sheen
still water, descending with a rocking, back- from the microscopic sheets of muscovite and
and-forth motion, like falling leaves. Over chlorite mica that typically develop on cleavage
time, the clay accumulates in thin, flat layers surfaces in low-grade metamorphism. Time,
on the bottom. Additional layers are deposited oxidation, freezing and thawing, rain, and hail
with each heavy rain or flood event until ultimately fade colors and degrade the stone’s
gradually many thin layers build up multiple sheen. This is not a fault–just the normal
beds of clay sequences with a water saturation consequence of weathering and not
of about 60%. If undisturbed through continual detrimental in most cases unless water
sedimentation, compaction occurs, squeezing penetrates to allow frost heaving.
out ±95% of the water. With increased burial
to thousands of feet, additional compaction and 1.5 Slate colors are caused by small
cementation occurs, and shale is formed. Shale amounts of iron (red-brown), organic carbon
readily splits apart at bedding planes, (black), and other additives, minerals, or
sometimes into very thin sheets or thick units. mixtures that yield violet, green, gray, and
other colors.
1.3 If the resulting shale sequence, a clastic
sedimentary stone, is subjected to regional 1.6 Slate quality has been commonly
compression at a high enough pressure- related to how long it lasts on a roof. Some
temperature-time cycle, then metamorphism slates from northern New England are known
occurs. Regional pressure at this level usually to endure at least 250 years. Slate roofs from
folds the entire sedimentary sequence, thus the Vermont dwellings constructed circa 1740
bedding surfaces will generally, but not always, have been recycled to new homes and remain
be at some angle to the pressure. Pressure in good condition, exhibiting only some fading
causes the small, flat sheets of clay minerals in from surface oxidation of carbonaceous matter
the shale to always realign normal that once gave the slate its dark gray hue. Slate
(perpendicular to the direction of pressure). from areas of less intense metamorphism or
The metamorphic pressure can be from any slightly less optimal parent rock composition

1 Ref: American Geological Institute. The Glossary of same structure as mica. Clay mineral sheets are carried
Geology, 2nd ed., 1980, Bates and Jackson, eds. in suspension by water, and deposition from suspension
2 Clay, the word, has two distinct meanings: Clay when turbidity ends. Clay is also a size term defined as
minerals are complex silicates, the products of chemical particles less than 1/256 mm or 0.00016" in size.
weathering of feldspar and other silicate minerals. Clay Particles can also be ground-up mineral crystals, rock
minerals have a sheet-like molecular structure, the fragments, and colloidal lithic material, as well as clay
minerals.

© 2022 Natural Stone Institute Slate • Page 10-7

several states to the south of Vermont are location, and the pressure-temperature-time
reported to be good for 75 to 100 years. cycle, the products are a continuum from one
extreme to another–from insufficiently
1.7 Phyllite. If the metamorphic pressures metamorphosed to highly metamorphosed–
are more intense, the time under pressure is both extremes being unsuitable for building
longer, or the parent shale composition is silty, purposes. A stone that cannot be used isn’t
sandy, or contains other foreign matter and “bad,” but there is simply a lot of stone
entrained chemicals, the resulting meta- unsatisfactory for commercial applications.
morphic stone may develop into phyllite, the
next higher metamorphic grade. Phyllite tends
2.0 COLOR AND VEINING
to have nonuniform, undulating cleavage
surfaces and often large cubes or crystals of 2.1 The color of a slate is determined by its
pyrite (FeS2) that quickly oxidize and bleed chemical and mineralogical composition. The
ugly iron stain, or superhard garnet “knots” that gray and bluish-gray colors are due chiefly to
occur as lumps and bumps on the wavy the presence of carbonaceous material; many
cleavage. Phyllite develops more muscovite other colors are due to iron compounds. Slates
mica (a hydrous potassium aluminum silicate) containing large proportions of finely divided
and sericite (iron carbonate or FeCO3) on the carbonaceous matter are black. Other colors
cleavages than slate, thus phyllite has an even that are found are blue-black, red, green,
more silky silver sheen than ordinary slate. purple, mottled, yellow, brown, and buff.
1.8 Schist. If the variables in 2.2 Permanence of color has considerable
metamorphism already mentioned are carried importance, for although some slates maintain
to the next step, then schist is developed. In their original color for many years, others
schist, secondarily developed minerals from change to new shades within a comparatively
intense metamorphism such as muscovite or short time.
biotite mica occur in compact masses and
usually do not have the well-defined, flat 2.3 Some slates tend to fade under the
cleavage characteristic of slate, thus schist is influences of the elements. Such changes may
unsuitable for most traditional uses of slate. be due to the presence of small quantities of
The mica flakes do not lie in flat planes and are iron-lime-magnesia carbonates which
loose enough to easily flake off. Schist is named decompose readily and form a yellow hydrous
for the major, flat mineral in its composition; iron oxide, limonite. Therefore, slates are of
for example, muscovite schist, biotite schist, two types: unfading and fading. Unfading color
hornblende schist, etc. is not a quality verifiable by any current ASTM
or other test method.
1.9 Unfortunately, some schists and
phyllites are sold as slate and when used in
3.0 TEXTURE
exterior applications result in sheets sloughing
off, iron stains bleeding out of the stone, or 3.1 Differences in conditions of deposition
actual disintegration of tiles and slabs. Some of often result in variations in texture of
these “marginal slates” are highly colored and successive strata, and such variations make it
have interesting textures, but are best reserved possible to trace folds and contortions within
for interior, decorative applications and not in the quarry. “Ribbons” are dark bands, a fraction
places where there is potential moisture or of an inch to several inches in width,
where falling stone is a safety hazard. intersecting blocks of slate at various angles.
Cleavage and grain are other characteristics of
1.10 Because the metamorphic process and
slate that can affect its texture. Cleavage is the
resulting stone is so dependent on the right
tendency for stone split with ease in one
combination of parent stone composition,
direction. However, many slates have a second

Page 10-8 • Slate © 2022 Natural Stone Institute

direction of splitting that is less pronounced Use Thickness
called the grain. Residential Commercial
Foot Traffic Foot Traffic
4.0 FINISHES Flagging (exterior) ¾" 1"
Thresholds ¾" –7/8" 1" – 1 ¼"
4.1 Slate’s surface may be finished in a Tile ¼" – 5/8" ¾" – 1"
number of ways. Typical finishes for slate are: Treads 1" – 1 ¼" 1 ½" – 2"

4.1.1 Natural Cleft: A cleavage face formed 6.0 SIZES

when the slate is split into any thickness.
6.1 Slate is a product of nature with many
4.1.2 Honed: A satin smooth surface with no varieties available, each possessing varying
gloss. characteristics. Little can be done to alter the
condition in which nature presents these
4.1.3 Sand Rubbed: A flat, nonreflective varieties to us. Therefore, size may become a
surface. limiting factor to consider in the selection of a
particular slate. The following table represents
4.1.4 Tumbled: A weathered, aging finish. approximate recommended sizes for selected
slate applications.
4.1.5 Machine Gauged (Diamond
Gauged): Surface is a level plane with swirl Use Length (max) Width (max)
marks noticeable. Flagging (exterior) 1"-6" 2'-0"
Thresholds 4'-0" 8"
4.2 The type of finish desired bears some Tile 2'-0" 1'-6"
relationship to final cost, as the smoother Treads 5'-6" 1'-6"
surfaces require more finishing, and
consequently, more time. The most 6.2 A jointing scheme which permits the use
economical finish is the natural cleft. of smaller sizes of slate will greatly facilitate
selection and delivery. The NSI
4.3 Other finishes, such as bush- Member/Supplier can assist with approval of
hammered, sandblasted, and planed, the final scheme.
may also be available. Some stone finishes can
affect strength and durability. For example,
bush-hammered and thermal finishes reduce a
stone’s thickness, making it more vulnerable to
7.0 PRODUCT SAMPLING
weakening from exposure to freeze and thaw
7.1 Slate is formed by nature; thus, there are
cycles.
variations in the tonal qualities of the stones.
However, it is these natural variations that
5.0 THICKNESS make slate unique, valuable, and highly
desirable. Because of these variations, selection
5.1 Standard thicknesses for slate veneers of a particular slate should never be made on
are ¾", 1", 1¼", 1½", and 2" (20 mm, 25 the basis of one sample only. It is
mm, 30 mm, 40 mm, and 50 mm). Slate tiles recommended that selection be based on
are available in a variety of thicknesses ranging viewing sufficient samples to show the
from ¼" to 1" (6.5 mm to 25 mm). The complete range of colors of the desired stone.
following table represents approximate NSI Members can provide these range samples.
recommended thicknesses for selected slate
applications:

© 2022 Natural Stone Institute Slate • Page 10-9

8.0 PROPER USAGE TIPS 1.2 In present-day construction, however,
this is far from being true. Performance
8.1 Recommendation for commercial requirements are daily becoming more
floors: demanding. In striving for taller structures,
greater spans, firmer foundations, thinner
8.1.1 Minimum ¾" (20 mm) thickness. walls and floors, stronger frames, and generally
more efficient buildings with more usable
8.1.2 A honed or cleft finish. space, today’s Architects and Engineers must
get the most out of the materials with which
8.1.3 A minimum hardness value of 8 as they work.
measured by ASTM C241/C1353.
1.3 Slate is a product of nature and not
8.2 Avoid the use of gypsum or molding always subject to the rules of consistent
plaster setting spots for the installation of behavior that may apply to manufactured
stone. building materials.

1.4 Physical property values of slate may,

9.0 TOLERANCES however, be measured using the standard test
methods approved by the Dimension Stone
9.1 Because of the variances in natural cleft Committee C-18 of ASTM International. The
or cleavage, it is recommended that the Slate NSI and Member companies are represented
Quarrier or Fabricator be contacted regarding on the ASTM committee and are active in its
size and thickness tolerances. technical work of establishing proper test
methods and specifications consistent with the
latest technology.
10.0 SOUNDNESS
1.5 Final design should always be based on
specific values for the slate variety ultimately to
10.1 Slate, consisting as it does chiefly of very
be installed. These values may be obtained
small overlapping flakes consolidated under
from the Slate Supplier. All materials are not
pressure, is a strong rock. Most mica slates of
suitable for all uses. In order to avoid mistaken
good commercial quality are highly impervious
selections, tests for material values should be
to moisture.
made prior to final material selection.

1.6 Physical Properties of Slate.

TECHNICAL DATA - Slate (This historical data and information is
provided only as a guideline. Recommended
1.0 PROPERTIES OF SLATE minimums or maximums are established and
DIMENSION STONE provided by ASTM International.)*

1.1 In centuries past, relatively little Property Range of Values

importance was attached to the ultimate Compressive Strength (C170)
physical capabilities of most building materials. lbs/in² ............................ 10,000-15,000
Rule of thumb was a common structural design
criterion. As a result, the widely used materials Flexural Strength (C880)
of the day, for the most part natural rather than lbs/in² ................................ 6,000-5,000
manmade materials, were seldom stressed to
Density, lb/ft3 (C97) .................. 170-190
their ultimate limits.

Page 10-10 • Slate © 2022 Natural Stone Institute

Property Range of Values combustible materials from reaching
Modulus of Rupture (C120) temperatures which will cause them to ignite.
lbs/in² ............................... 5,500-9,000 Methods of estimating fire-resistance periods
Recommended (min): of masonry walls and partitions utilizing
7,200 along grain, component laminae are given in “Fire
9,000 across grain Resistance Classifications of Building
Construction,” BMS92, National Bureau of
Absorption, by Weight % (C121)….0.1-0.45 Standards.
Recommended (max):
0.25 interior,
0.45 exterior
4.0 ABRASION RESISTANCE
Abrasion Resistance (C241/C1353) (ASTM C241/C1353)
(Ha) 6.0-10 ……6.0-10.0
Recommended (min): 8 4.1 Abrasion resistance is a property of slate
that should be tested per ASTM C241/C1353
* Test methods described in current ASTM to provide an indication of the slate’s wearing
standards. qualities when exposed to foot traffic.

4.2 The hardness and uniform wearing

2.0 STRENGTH (ASTM C120, qualities of most slate makes it extremely
C880) desirable and economically practical for floors
and stairs. Varieties with an abrasive hardness
(Ha) of 8 or more as measured by ASTM
2.1 Values for modulus of rupture and
C241/C1353 tests are recommended for use
flexural strength are determined by testing
as flooring exposed to normal foot traffic. A
specimens of slate under laboratory conditions
minimum abrasive hardness of 10 is
until they fail.
recommended for commercial floors, stair
treads, and platforms subject to heavy foot
2.2 The strength of slate is a measure of its
traffic. The abrasion resistance hardness values
ability to resist stresses. This strength depends
pertain to foot traffic only. If floors are
on several factors: the amount of mica flakes
constructed with two or more stone varieties,
and quartz grains present, the degree of
the Ha values of the stones must not differ by
cohesion, and the nature of any cementing
more than 5 or the floor surface will not wear
materials present.
evenly and uniformly.

3.0 FIRE RESISTANCE 5.0 FACTORS AFFECTING

PROPERTIES (ASTM C121, C217)
3.1 Slate is not combustible according to
underwriters’ ratings, and therefore is 5.1 The ultimate test of a building material
considered a fire-resistant material. Because of is its ability to have and maintain the necessary
its thermal conductivity, heat transfer is fairly structural strength, as well as beauty of
rapid. Most slate is not considered a highly appearance and low cost of maintenance, over
rated thermal insulator. the useful life of the structure. Experience has
proven that slate meets this test as few other
3.2 Underwriters’ fire-resistance ratings building materials can. Studies have shown that
evaluate whether or not a material will burn, the durability of most slates is little affected by
as well as how long it will keep surrounding

© 2022 Natural Stone Institute Slate • Page 10-11

cycles of weather. This is because of slate’s low area, the lateral forces due to wind loads must
rate of water absorption. be considered. Wind tunnel tests are often
used on major structures to determine wind
5.2 Currently, two ASTM test methods are dynamics and force magnitude. Reinforcement
unique to slate. ASTM C217 “Standard Test is sometimes necessary for large-dimension
Method for Weather Resistance of Slate,” is a slab veneer in critical areas.
method that is useful in indicating the
differences in weather resistance between
various slates, and should be used to correlate 7.0 SEISMIC CONSIDERATIONS
their durability. ASTM C121 “Standard Test
Method for Water Absorption of Slate,” 7.1 Seismic considerations generally require
provides another element in the comparison of that low buildings be stiff, and that tall
slates. Water absorption testing can be helpful buildings be relatively flexible. Design of
in determining the porosity of a particular connections must account for seismically
slate. induced horizontal loading. Local building
codes vary and must always be checked to
determine specific requirements for each area.
6.0 SAFETY FACTORS The National Bureau of Standards has published
two documents on the topic: “Earthquake
6.1 Good engineering practice requires that Resistant Masonry Construction,” NBS Science
allowable design stress must provide a margin Series 106; and “Abnormal Loading on
of safety in any structural element. As a Buildings and Progressive Collapse: An
necessary precaution against such conditions as Annotated Bibliography,” NBS Science Series
wind, ice, snow, impact, temperature changes, 67. The U.S. Army Corps of Engineers has also
and imperfect workmanship, these allowable published TM 5-809-10, “Seismic Design for
stresses must be smaller than those which Buildings.”
produce failure.

6.2 Within the accepted limits of safe design 8.0 EFFLORESCENCE AND
practice, the closer the allowable load is to the STAINING
ultimate failure load, the more efficient is the
use of the material and the less the cost of the 8.1 Efflorescence is a salt deposit, usually
construction. white in color that appears on exterior surfaces
of masonry walls. The efflorescence-producing
6.3 Contemporary building design does not salts found in masonry are usually sulfates of
usually employ slate as part of the structural sodium, potassium, magnesium, calcium, and
frame, but rather as an independent unit, a iron. Salts which are chlorides of sodium,
curtain wall, or veneer. Therefore, the calcium, and potassium will sometimes appear,
primary concern in such cases is with wind or but they are so highly soluble in water that they
seismic loads, and a safety factor of 5.0 is will be washed off by rain.
recommended. Where the slate is to be
subjected to concentrated loading, such as stair 8.2 The water-soluble salts causing
treads or lintels supported only at the ends, a efflorescence come from other materials in the
factor of 10.0 should be used. These safety wall. The salts exist in small amounts and are
factors may be adjusted using sound leached to the surface by water percolating
engineering principles and judgment. through the walls. The most feasible means of
prevention is to stop the entrance of large
6.4 As buildings become taller and amounts of water. Absorption from the face
individual slate slab veneer becomes larger in

Page 10-12 • Slate © 2022 Natural Stone Institute

will not cause efflorescence unless there are
open joints.

8.3 Slate is seldom injured by efflorescence.

However, some of the salt crystals may form in
the pores near the surface. Crystal growth
(recrystallization) in the pores can cause stress
on the walls of the pores and cause the stone to
flake off. If the conditions bringing about this
action persist, scaling may continue and flake
off one layer after another. For this to happen,
large amounts of water must enter the wall and
must contain large amounts of salts.

8.4 Calcium carbonate is the least resistant

constituent of slates to long weather exposure,
especially to sulfur fumes, for sulfur trioxide
acting on calcium carbonate forms calcium
sulfate, or gypsum, a mineral which expands
greatly with disruptive effects during
crystallization. Iron carbonate is sometimes
present, and its decomposition not only affects
the slate, but the resulting iron oxides may
cause stains. Iron sulfides may oxidize and form
spots and stains. The oxidation of iron-bearing
minerals, especially ferrous carbonate, often
causes color changes.

© 2022 Natural Stone Institute Slate • Page 10-13

NOTES:

Page 10-14 • Slate © 2022 Natural Stone Institute

SOAPSTONE 1.2.3 Natural Stone Institute (NSI):

1.2.3.1 Membership, Products, and Services

1.0 GENERAL Directory

1.2.3.2 Dimension Stone Design Manual

1.1 Related Documents
1.2.3.3 Additional publications may be
1.1.1 Drawings and general provisions, available from the NSI Bookstore. Go online at
including General and Supplementary www.naturalstoneinstitute.org.
Conditions of the Contract and Division I
Specification sections, apply to this section.
1.3 Scope of Included Work
1.2 Applicable Publications 1.3.1 The work to be completed under this
contract includes all labor and materials
1.2.1 The following publications listed here required for the furnishing and installation of
and referred to thereafter by alphanumeric all slate work shown or called for on the
code designation only, form a part of this contract drawings, specifications, and
specification to the extent indicated by the addenda.
references thereto:

1.2.2 ASTM International (ASTM):

1.4 Definition of Terms

1.2.2.1 There currently is no ASTM 1.4.1 The definitions of trade terms used in
Standard Specification for Soapstone this specification shall be those published by
Dimension Stone. NSI or ASTM International.

1.2.2.2 C97, Standard Test Methods for 1.5 Source of Supply

Absorption and Bulk Specific Gravity of
Dimension Stone 1.5.1 All soapstone shall be obtained from
quarries having adequate capacity and facilities
1.2.2.3 C99, Standard Test Method for to meet the specified requirements, and by a
Modulus of Rupture of Dimension Stone firm equipped to process the material promptly
on order and in strict accord with
1.2.2.4 C170, Standard Test Method for specifications. The Specifying Authority
Compressive Strength of Dimension Stone (architect, designer, engineer, contracting
officer, end user, etc.) reserves the right to
1.2.2.5 C241, Standard Test Method for approve the Material Supplier for slate prior to
Abrasion Resistance of Stone Subjected to Foot the award of this contract. Stone and
Traffic workmanship quality shall be in accordance
with Industry Standards and Practices as set
1.2.2.6 C880, Standard Test Method for forth by NSI.
Flexural Strength of Dimension Stone
1.6 Samples
1.2.2.7 C1353, Standard Test Method Using
the Taber Abraser for Abrasion Resistance of 1.6.1 The Soapstone Contractor shall submit
Dimension Stone Subjected to Foot Traffic through the General Contractor, for approval
by the Specifying Authority, at least two sets of
samples of the various kinds of Soapstone
specified. The sample size shall be 1'-0" x 1'-0"
(300 x 300 mm) and shall represent
© 2022 Natural Stone Institute Soapstone • Page 11-1
approximately the finish, texture, and dimensions, unless specifically added to the
anticipated range of color to be supplied. One scope of work.
set of samples shall be retained by the
Specifying Authority, and one set shall be 1.8 Defective Work
returned to the Soapstone Supplier for his/her
record and guidance. It is noted herein that 1.8.1 Any piece of Soapstone showing flaws or
Soapstone is a natural material and will have imperfections upon receipt at the storage yard
intrinsic variations in color, markings, and or building site shall be referred to the
other characteristics. Color variation range is Specifying Authority for determination as to
to be only from natural markings in the responsibility and decision as to whether it shall
Soapstone or from the reflective sheen and be rejected, patched, or redressed for use. Any
shadow value of the graining of the natural- material in question should not be installed
cleft textures and cleavage planes. Depending prior to inspection and approval.
on Soapstone selected and quantity required, a
range mockup may be used to further define
1.9 Repairing Damaged Stone
the characteristics of the material. Cost of
mockup, if required, shall not be included in
1.9.1 Chips at the edges or corners may be
this section.
patched, provided the structural integrity of
the stone is not affected and the patch matches
1.6.2 Prior to fabrication, an inspection and
the color and finish of the natural stone so that
approval by the Specifying Authority and/or
it does not detract from the stone’s
General Contractor and/or End User of the
appearance. Scratches may be hand-sanded
finished slabs is recommended to understand
after which mineral oil shall be re-applied to
the finish and full range of the material.
achieve uniform color.

1.7 Shop Drawings

2.0 MATERIALS
1.7.1 The Soapstone Contractor shall submit
through the General Contractor, for approval
2.1 Soapstone
by the Specifying Authority, sufficient sets of
shop drawings showing general layout,
2.1.1 General: All Soapstone shall be of
jointing, anchoring, stock thickness, and other
standard architectural grade, free of cracks,
pertinent information. These drawings shall
seams, starts, or other traits which may impair
show all bedding, bonding, jointing, and
its structural integrity or function. Inherent
anchoring details along with the net piece
color variations characteristic of the quarry
dimensions of each Soapstone unit. One copy
from which it is obtained will be acceptable.
of the approved shop drawings shall be retained
Texture and finish shall be as shown in the
by the Specifying Authority, one copy shall be
sample(s) approved by the Specifying
retained by the General Contractor, and one
Authority.
copy returned to the Soapstone Contractor for
fabrication. NO FABRICATION OF
2.1.2 Currently there is no ASTM Standard
SOAPSTONE SHALL BE STARTED UNTIL
Specification for Soapstone Dimension Stone.
SUCH DRAWINGS HAVE BEEN FULLY
APPROVED AND MARKED AS SUCH. The
2.1.3 Schedule: Soapstone shall be provided
Soapstone Contractor shall not be responsible
as follows:
for determining, making, or verifying (1)
design, structural, wind, seismic, or other
2.1.3.1 For (state location on building) (state
design loads; (2) engineering estimates; (3)
name and color) Soapstone with a (type) finish,
plans or specifications; (4) the types, sizes, or
locations of anchors; or (5) verification of field
Page 11-2 • Soapstone © 2022 Natural Stone Institute
supplied by (name company or list several approved 4.0 SHIPPING AND HANDLING
suppliers).
4.1 Packing and Loading
2.1.3.2 Provide information as in 2.1.3.1 for
each different Soapstone/finish combination in 4.1.1 Finished Soapstone shall be carefully
the project. packed and loaded for shipment using all
reasonable and customary precautions against
2.1.4 Finishes: Face finish of exterior panels damage in transit. No material which may
should be a fine honed finish. All exposed edges cause staining or discoloration shall be used for
should be honed to remove saw marks and blocking or packing.
darken the edge color. Finished surfaces
should be treated with mineral oil to achieve a
uniform, dark, rich color. 5.0 INSTALLATION

2.1.5 Finishes listed in the schedule shall 5.1 General Installation

conform with definitions by the NSI or ASTM
International. 5.1.1 Installation shall be accomplished with
competent, experienced Stone Setters, in
accordance with the approved shop drawings.
3.0 FABRICATION
5.1.2 All Soapstone stone pieces shall be
3.1 Moldings, Washes, and Drips identified with a unique piece number
corresponding with the number on the shop
3.1.1 Moldings, washes, and drips shall be drawings. Interchanging of numbered pieces is
constant in profile throughout their entire not permitted.
length, in strict conformity with details shown
on approved shop drawings. The finish quality 5.1.3 Soapstone stone shall be free of any ice
on these surfaces shall match the finish quality or frost at time of installation. Salt shall not be
of the flat surfaces on the project. used for the purpose of melting ice, frost, or
snow on the stone pieces.
3.2 Cutting and Drilling For
Other Trades 5.1.4 Adequate protection measures shall be
taken to ensure that exposed surfaces of the
3.2.1 Any miscellaneous cutting and drilling stone shall be kept free of mortar at all times.
of stone necessary to accommodate other
trades will be done by the Soapstone Fabricator 5.2 Expansion Joints
only when necessary information is furnished
in time to be shown on the shop drawings and 5.2.1 It is not the intent of this specification to
details, and when work can be executed before make control or expansion joint
fabrication. Cutting and fitting, due to job site
recommendations for a specific project. The
conditions, will be the responsibility of the
Soapstone Contractor. Specifying Authority must specify control or
expansion joints and show location and details
3.2.2 Incidental cutting, such as for window on drawings.
frame clips, etc., which is normally not
considered to be the responsibility of the Stone 5.3 Caulking
Supplier, will be provided only by arrangement
by the General Contractor and Soapstone 5.3.1 Where so specified, joints shall be
Contractor with the Soapstone Fabricator. pointed with the sealant(s) after first installing
the specified backup material and applying a

© 2022 Natural Stone Institute Soapstone • Page 11-3

primer if required, all in strict accordance with PRODUCT
the printed instructions of the Sealant
Manufacturer. DESCRIPTION –
Soapstone
5.3.2 All sealants shall be tooled to ensure
maximum adhesion to the contact surfaces. 1.0 GEOLOGICAL
CLASSIFICATION
1.1 Soapstone currently enjoys a resurgence
6.0 CLEANING AND of popularity for surfaces, kitchenware,
PROTECTION traditional decorative uses, industrial
applications and artistic carvings. The long-
6.1 Cleaning known, unique physical properties and wide
range of colors are once again driving forces in
this recent interest.
6.1.1 The Soapstone Contractor shall keep the
Soapstone clean with a sponge and clean water, 1.2 Soapstone is a metamorphic1 stone or rock
utilizing a neutral detergent if necessary. composed of one or more minerals; however,
in most industrial applications it is almost
6.2 Protection of Finished Work always a mixture of minerals because the
mixture is somewhat harder than single-
6.2.1 After the Soapstone work has been mineral soapstone and mineral mixtures in
installed, it shall be the responsibility of the nature are common, while single mineral
purity is much less common.
General Contractor to see that it is properly
and adequately protected from damage or
1.3 Soapstone texture can vary from
stains until all trades are finished. This massive2 to fibrous or flaky. The best
responsibility includes the stone cleaning costs commercial grades are highly compacted and
prior to final inspection. The Soapstone are not absorbent. It commonly has a “soapy”
Contractor will outline the needs for to slippery and soft feel when the surface is
protection, in writing, to the General unaltered by long use or treated with chemicals
Contractor. or oils.

1.4 Soapstone of commercial value is

quarried in many places around the world: in
far Arctic areas of Canada, Scandinavia, Siberia
and Russia, as well as in Brazil and northeastern
United States.

1.5 Soapstone has been used for thousands

of years by the Inuit people (“Eskimo”) and
others as a medium for carving highly valued
sculpture.

1
Soapstone is always of metamorphic origin, formed by 2
Massive in metamorphic stone means a stone whose
very high pressures and generally from light-colored, constituents are neither oriented in parallel position
low specific gravity, highly silicic (> 60% SiO2; or nor arranged in layers; that is, a stone that does not
quartz) igneous rock. have layering, schistosity, foliation or similar structure.
Page 11-4 • Soapstone © 2022 Natural Stone Institute
2.0 MINERALOGY amphibole (hornblende etc.) derived from the
alteration of ferromagnesian silicates in igneous
2.1 Minerals commonly found in soapstone rock that, because of the Fe and Mg, may yield
- in general order of abundance: “disfiguring” coloration or blemishes.

2.1.1 Talc: Hydrous magnesium silicate 2.2 Steatite (a.k.a. “steatite talc”): A nearly
Mg3Si4O10(OH)2 is the most abundant mineral obsolete term for soapstone or very pure talc-
component and thus dictates some of the rich rock used for talcum powder and formerly
stone’s characteristic properties like hardness for electrical insulators. Since the term is used
and feel. Since talc defines the Mohs hardness in some older definitions of soapstone, it has
of 1, the softest level of the Mohs scale, found its way into the literature of some
soapstone dominantly composed of talc may be quarries and distributors of soapstone. It is
a bit soft for use as a surface material since it recommended the use of this term be
could easily be scratched by even a fingernail. discontinued as it demands a definition that at
Soapstone is somewhat harder if its best is often vague and confusing. Almost
composition includes one or more of the everyone is familiar with talcum powder (talc),
minerals below. its softness and feel.

2.1.2 Magnesite: Magnesium carbonate

(MgCO3) moderately hard Mohs 3.5 – 4.5, not 3.0 PHYSICAL PROPERTIES OF
soluble in cold, dilute hydrochloric acid, SOAPSTONE
generally the second most abundant soapstone
mineral. Exhibits excellent rhombohedral 3.1 Hardness: Soapstone used for surfaces
cleavage that is microscopic and not is a soft dimension stone. Mohs hardness 1-4,
detrimental in massive soapstone. Is generally depending on mineral content. The softness is
the white mineral filling “veins” in soapstone a plus: It can be worked with ordinary tooling,
scratches and dings can be eliminated or
and may be responsible for much of the
minimized with ordinary sandpaper, and it is
mottled appearance. forgiving of china–much more so than granite.
It does not have a bothersome preferential
2.1.3 Dolomite: A calcium and magnesium breakage or fracture direction.
carbonate (CaMg(CO3), Mohs hardness of
~3.5, does not react with dilute hydrochloric 3.2 Chemical reactivity: Soapstone is
acid. very inert. It does not react with strong acids
or alkali (basic) solutions. It is non-poisonous
2.1.4 Micas: Muscovite is inert, colorless, and safe to cook in or use around food.
elastic and flaky mica. Less common in
3.3 Heat retention is very high. Soapstone is
soapstone is the dark mica biotite which
unaffected by temperatures from well below
contains iron and magnesium, H=2.5 - 4.
zero to above ±2,000°F (±1,100ºC). Thus it
is very useful as refractory material and is
2.1.5 Chlorite is a metamorphic greenish frequently used for wood burning stoves that
mica that is soft, non-flexible; and non- use both of these properties. It is dimensionally
reactive. It is responsible for the greenish color very stable through a wide range of
of some soapstone. temperature. The ancient Nordic Vikings used
flat soapstone pebbles for pocket hand
2.1.6 Rare Accessory Minerals: minor to warmers.
trace amounts of pyroxene (augite, etc.) and
© 2022 Natural Stone Institute Soapstone • Page 11-5
3.4 Absorbency: Since soapstone is a
metamorphic stone formed under high
pressure, it is highly compacted and dense; thus
absorbency is zero or so close to zero that it is
inconsequential, making this stone exceedingly
sanitary as a food preparation surface, as well-
maintained surfaces resist harboring bacterial
growth.

3.5 Color: Usually in the gray to gray-

bluish ranges to mottled white or lighter gray
and greenish hues and/or streaked with
irregular veins of white that may be talc,
magnesite, chlorite, dolomite or again, a
mixture.

3.6 Electrical: Soapstone is non-

conductive and thus is ultra safe for kitchen
counter surfaces. Formerly used for high
voltage electrical insulation.

4.0 FIRE RESISTANCE

4.1 Soapstone is not combustible according
to underwriters’ ratings, and therefore is
considered a fire-resistant material. Because of
its thermal conductivity, heat transfer is fairly
rapid. Most soapstone is not considered a
highly rated thermal insulator.

4.2 Underwriters’ fire-resistance ratings

evaluate whether or not a material will burn,
as well as how long it will keep surrounding
combustible materials from reaching
temperatures which will cause them to ignite.
Methods of estimating fire-resistance periods
of masonry walls and partitions utilizing
component laminae are given in “Fire
Resistance Classifications of Building
Construction,” BMS92, National Bureau of
Standards.

Page 11-6 • Soapstone © 2022 Natural Stone Institute

TRAVERTINE 1.2.3.2 Dimension Stone Design Manual
1.0 GENERAL 1.2.3.3 Additional publications may be
available from the NSI Bookstore. Go online at
1.1 Related Documents www.naturalstoneinstitute.org.
1.1.1 Drawings and general provisions,
including General and Supplementary
1.3 Scope of Included Work
Conditions of the Contract and Division I The work to be completed under this contract
Specification sections, apply to this section. includes all labor and materials required for the
furnishing and installation of all travertine
1.2 Applicable Publications work shown or called for on the contract
drawings, specifications, and addenda.
1.2.1 The following publications listed here
and referred to thereafter by alphanumeric 1.4 Definition of Terms
code designation only, form a part of this
specification to the extent indicated by the 1.4.1 The definitions of trade terms used in
references thereto: this specification shall be those published by
NSI or ASTM International.
1.2.2 ASTM International (ASTM):

1.2.2.1 C1527, Standard Specification for

1.5 Source of Supply
Travertine Dimension Stone
1.5.1 All travertine shall be obtained from
1.2.2.2 C97, Standard Test Methods for quarries having adequate capacity and facilities
Absorption and Bulk Specific Gravity of to meet the specified requirements, and from a
Dimension Stone firm equipped to process the material promptly
on order and in strict accord with
1.2.3.3 C99, Standard Test Method for specifications.
Modulus of Rupture of Dimension Stone
1.5.2 The Specifying Authority (architect,
1.2.2.4 C170, Standard Test Method for designer, engineer, contracting officer, end
Compressive Strength of Dimension Stone user, etc.) reserves the right to approve the
Material Supplier for travertine prior to the
1.2.2.5 C241, Standard Test Method for award of this contract.
Abrasion Resistance of Stone Subjected to
Foot Traffic 1.6 Samples
1.2.2.6 C880, Standard Test Method for 1.6.1 The Travertine Contractor shall submit
Flexural Strength of Dimension Stone through the General Contractor, for approval
by the Specifying Authority, at least two sets of
1.2.2.7 C1353, Standard Test Method for
samples of the various kinds of travertine
Abrasion Resistance of Dimension Stone
specified. The sample size shall be 1'-0" x 1'-0"
Subjected to Foot Traffic Using a Rotary
(300 x 300 mm) and shall represent
Platform Abraser
approximately the vein trend, finish, texture,
1.2.3 Natural Stone Institute (NSI): direction of cut (vein or fleuri), incidence of
holes, color of fill (if applicable), and
1.2.3.1 Membership, Products, and Services anticipated range of color to be supplied. One
Directory set of samples shall be retained by the

© 2022 Natural Stone Institute Travertine • Page 12-1

Specifying Authority, and one set shall be size details prepared by the Specifying
returned to the Travertine Supplier for his/her Authority, except where it is agreed in writing
record and guidance. It is noted herein that or shown on the approved shop drawings that
travertine is a natural material and will have changes be made. Each stone indicated on the
intrinsic variations in color, markings, and setting drawings shall bear the corresponding
other characteristics. Depending on travertine number marked on an unexposed surface.
selected and quantity required, a range Provisions for the anchoring, doweling, and
mockup may be used to further define the handling of the material, and for the support of
characteristics of the material. (NSI stone by shelf angles and mechanical anchors,
recommends the use of mockups.) Wherever when required, shall be clearly indicated on the
possible, mockups should remain as a shop drawings. NO FABRICATION OF
completed portion of the project. Where that TRAVERTINE SHALL BE STARTED UNTIL
is not possible, cost of mockup shall not be SUCH DRAWINGS HAVE BEEN FULLY
included in this section. APPROVED AND MARKED AS SUCH. The
Travertine Contractor, unless specifically
1.6.2 Prior to fabrication, an inspection and directed to do so, shall not be responsible for
approval by the Specifying Authority and/or determining, making, or verifying (1) design,
General Contractor and/or End User of the structural, wind, seismic, or other design
finished slabs is recommended to understand loads; (2) engineering estimates; (3) plans or
the finish and full range of the material specifications; or (4) the types, sizes, or
locations of anchors, unless specifically added
1.7 Shop Drawings to the scope of work.

1.7.1 The Travertine Contractor shall submit 1.8 Defective Work

through the General Contractor, for approval
by the Specifying Authority, sufficient sets of 1.8.1 Any piece of travertine showing flaws or
shop drawings showing general layout, imperfections upon receipt at the storage yard
jointing, anchoring, stock thickness, and other or building site shall be referred to the
pertinent information. These drawings shall Specifying Authority for determination as to
show all bedding, bonding, jointing, and responsibility and decision as to whether it shall
anchoring details along with the net piece be rejected, patched, or redressed for use.
dimensions of each travertine unit. One copy
of the approved shop drawings shall be retained 1.9 Repairing Damaged
by the Specifying Authority, one copy shall be Travertine
retained by the General Contractor, and one
copy returned to the Travertine Contractor for 1.9.1 Repair of travertine is an accepted
fabrication. All jointing as shown by the practice and will be permitted. Some chipping
Specifying Authority on the contract drawings is expected; repair of small chips is not
shall be followed, unless modifications are required if it does not detract from the overall
agreed upon in writing, or indicated upon the appearance of the work, or impair the
approved shop drawings. If the contract effectiveness of the mortar or sealant. The
drawings do not show the intent of the jointing, criteria for acceptance of chips and repairs will
it will be the Travertine Contractor’s be per the Natural Stone Institute Dimension
responsibility to establish the jointing to meet Stone Design Manual standards unless other
the Specifying Authority’s design intent within criteria are mutually agreed upon in writing by
the limitations of the material selected. the Travertine Contractor and the Specifying
Authority.
1.7.2 The cutting and setting drawings shall be
based upon and follow the drawings and full

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2.0 MATERIALS 2.2.2 Travertine should be installed with
white cement. Hydrated lime should conform
2.1 Travertine to ASTM C207 Type S.

2.1.1 General: All travertine shall be of 2.2.3 Sand should comply with ASTM C144.
standard architectural grade, free from cracks,
seams, starts, or other traits which may impair 2.2.4 Mixing water must be potable quality.
its structural integrity or function. Inherent
color variations characteristic of the quarry 2.2.5 Mortar mixes vary in proportions from
from which it is obtained will be acceptable, a hard mixture (1:1:4) to a flexible mixture
providing such is demonstrated in the approved (1:1:9). Hard mixes can be expected to set up
samples. Texture and finish shall be approved stress conditions between the stone and mortar
by the Specifying Authority as shown in the in joints because the thermal coefficient of
samples. mortar expansion is greater than that of stone.
In paving installations, stress is often sufficient
2.1.1.1 If travertine is supplied unfilled, to break the bond between the stone and the
careful attention must be made to the size of substrate. Flexible mortars are not suitable for
any holes present. Holes larger than 2 cm in exterior work.
diameter and/or holes that go through the
stone should be filled with a travertine chip 2.3 Pointing Mortar
cemented below the surface of the stone.
2.3.1 Pointing mortar shall be composed of
2.1.1.2 ASTM C1527 [C97] [C99] [C170] one part white portland cement, one part
[C241/C1353] [C880] See the chart of hydrated lime, and six parts white sand passing
applicable ASTM standards and tests in the a #16 sieve.
Appendix.
2.4 Sealants and Backup
2.1.2 Schedule: Travertine shall be Material (if Applicable)
provided as follows:
2.4.1 Where specified (state type or name of
2.1.2.1 For (state location on building) (state sealant) shall be used for the pointing of joints.
name and color) travertine with a (type) finish, The backup material used with the sealant shall
supplied by (name company or list several approved be (identify material).
suppliers).
2.5 Anchors, Dowels, Fastenings
2.1.2.2 Provide information as in 2.1.2.1 for
each different travertine/finish combination in 2.5.1 The Travertine Contractor shall furnish
the project. and set all anchors shown on approved shop
drawings unless otherwise specified. All
2.1.3 Finishes: Finishes listed in the anchors shall be fabricated from Type 304 or
schedule shall conform with definitions by NSI 316 stainless steel or other suitable nonferrous
or ASTM International. metal. Multipart anchors may contain metal
other than stainless steel, provided such metal
2.2 Setting Mortar is not embedded in linkages in the travertine.

2.2.1 Cement used with travertine shall be 2.6 Stain Prevention

white portland cement, ASTM C150, or white
masonry cement, ASTM C91. 2.6.1 Where necessary, specify one or
both of the following systems:

© 2022 Natural Stone Institute Travertine • Page 12-3

2.6.1.1 Damp-proof unexposed stone 3.4.1 Stone coming in contact with structural
surfaces. Joint surfaces should be damp- work shall be back-checked as indicated on the
proofed only to 1" (25 mm) of finished surface approved shop drawings. Stones resting on
when using non-staining emulsion. structural work shall have beds shaped to fit the
supports as required.
2.6.1.2 Damp-proof all concrete surfaces on
which travertine will rest. Damp-proof 3.4.2 Maintain a minimum of 1" (25 mm)
adjacent concrete structure, haunches, etc. between stone backs and adjacent structure;
however, many bolted connections will
2.7 Adjacent To Water require more space – 2" (50 mm) may be
preferable. Large-scale details should illustrate
2.7.1 Travertine used in areas adjacent to and determine these conditions.
water that is chemically purified should be
tested to ensure that there is no reaction 3.5 Cutting for Anchoring,
between the stone and the purification Supporting, and Lifting Devices
chemicals (see Exterior Horizontal Surfaces
chapter for more information). 3.5.1 Holes and sinkages shall be cut in stones
for all anchors, cramps, dowels, and other
3.0 FABRICATION tieback and support devices per industry
standard practice or approved shop drawings.
3.1 Beds and Joints However, additional anchor holes shall be
drilled at job site by Travertine Contractor to
3.1.1 Bed and joint width shall be determined facilitate alignment.
by analysis of anticipated building movements
and designed to accommodate such 3.5.2 No holes or sinkages will be provided
movements without inducing undue stresses in for Travertine Contractor’s handling devices
the stone panels or joint filler materials. unless arrangement for this service is made by
Expansion joints shall be designed and located the Travertine Contractor with the Travertine
to accommodate larger movements. Fabricator.

3.2 Backs of Pieces [NOTE: It is not recommended that lewis pins

be used for stones less than 3½" (90 mm)
3.2.1 Backs of pieces shall be sawn or roughly thick.]
dressed to approximately true planes. Back
surfaces shall be free of any matter that may 3.6 Cutting and Drilling for
create staining Other Trades
3.3 Moldings, Washes, and Drips 3.6.1 Any miscellaneous cutting and drilling
of stone necessary to accommodate other
3.3.1 Moldings, washes, and drips shall be trades will be done by the Travertine
constant in profile throughout their entire Fabricator only when necessary information is
length, in strict conformity with details shown furnished in time to be shown on the shop
on approved shop drawings. The finish quality drawings and details, and when work can be
on these surfaces shall match the finish quality executed before fabrication. Cutting and
of the flat surfaces on the building. fitting, due to job site conditions, will be the
responsibility of the Travertine Contractor.
3.4 Back-Checking and Fitting
to Structure or Frame 3.6.2 Incidental cutting such as for window
frame clips, etc., which is normally not

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considered to be the responsibility of the Stone 5.0 INSTALLATION
Supplier, will be provided only by arrangement
by the General Contractor and Travertine 5.1 General Installation
Contractor with the Travertine Fabricator.
5.1.1 Installation shall be accomplished with
3.7 Carving and Models competent, experienced Stone Setters, in
accordance with the approved shop drawings.
3.7.1 All carving shall be done by skilled Stone
Carvers in a correct and artistic manner, in 5.1.2 All travertine pieces shall be identified
strict accordance with the spirit and intent of with a unique piece number corresponding
the approved shop drawing, or from models with the number on the shop drawings.
furnished or approved by the Specifying Interchanging of numbered pieces is not
Authority. permitted.

4.0 SHIPPING AND HANDLING 5.1.3 Travertine shall be free of any ice or
frost at time of installation. Salt shall not be
4.1 Packing and Loading used for the purpose of melting ice, frost, or
snow on the stone pieces.
4.1.1 The cut travertine shall be carefully
packed for transportation with exercise of all 5.1.4 Adequate protection measures shall be
customary and reasonable precautions against taken to ensure that exposed surfaces of the
damage in transit. All travertine under this stone shall be kept free of mortar at all times.
contract shall be loaded and shipped in the
sequence and quantities mutually agreed upon 5.2 Setting Mortar
by the General Contractor, Travertine
Contractor, and the Travertine Fabricator. 5.2.1 All travertine shall be set accurately in
strict accordance with the contract, approved
4.2 Site Storage shop drawings, and specifications. White
portland cement with a low-alkali content is
4.2.1 Receipt, storage, and protection of recommended.
travertine prior to and during installation shall
be the responsibility of the Travertine 5.2.2 When necessary, before setting in the
Contractor. wall, all stones shall be thoroughly cleaned on
all exposed surfaces by washing with a fiber
4.2.2 All travertine shall be received and brush and soap powder, followed by a
unloaded at the site with all necessary care in thorough rinsing with clear water.
handling to avoid damaging and soiling.
5.2.3 All stone joint surfaces not thoroughly
4.2.3 Stones shall be stored above the ground wet shall be saturated with clear water just
on non-staining skids made of cypress, white prior to setting.
pine, poplar, or yellow pine without an
excessive amount of resin. Chemically treated 5.2.4 Except as otherwise specially noted,
wood should not be used. DO NOT USE paving stone shall be set in full beds of mortar
CHESTNUT, WALNUT, OAK, FIR, AND with all vertical joints flushed full. For vertical
OTHER WOODS CONTAINING TANNIN. panels, completely fill all anchor, dowel, and
Completely dry travertine shall be covered similar holes, as well as first-course panels in
with non-staining waterproof paper, clean traffic areas up to 36" (900 mm) of finished
canvas, or polyethylene. floor. All bed and vertical joints shall be 3/8"
(9.5 mm) unless otherwise noted.

© 2022 Natural Stone Institute Travertine • Page 12-5

5.2.5 Plastic setting pads shall be placed under the touch before the next layer is applied. Tool
heavy stones, column drums, etc., in the same finished joints with a concave tool having a
thickness as the joint, and in sufficient quantity diameter approximately 1/8" (3 mm) greater
to avoid squeezing mortar out. If anchor than the joint width.
system requires lower stones to carry the
weight of upper stone, then any heavy stones Care shall be taken to keep expansion joints
or projecting courses shall not be set until free of mortar, which would compromise their
mortar in courses below has hardened function.
sufficiently to avoid squeezing.
5.4 Anchorage
5.2.6 Joints can be tooled when initial set has
occurred, or raked out 1" (25 mm) and pointed 5.4.1 All travertine shall be anchored or
later. If pointed with sealant, the raked depth doweled in accordance with the approved shop
and sealant applications shall conform to drawings.
manufacturer’s instructions.
5.4.2 To the furthest extent possible, all
5.2.7 Projecting stones shall be securely anchor preparations in the travertine units shall
propped or anchored until the wall above is set. be shop-applied.
5.2.8 Only the ends of lugged sills and steps 5.4.3 All anchorage devices and anchor
shall be embedded in mortar. Balance of joint hole/slot fillers shall be in accordance with
shall be left open until finally pointed. ASTM C1242. Care must be taken to ensure
that any holes capable of retaining water are
5.2.9 All cornice, copings, projecting belt filled after use to prevent water collection and
courses, other projecting courses, steps, and freezing.
platforms (in general, all stone areas either
partially or totally horizontal) should be set
5.5 Sealant Joints
with unfilled vertical joints. After setting,
insert properly sized backup material or backer
5.5.1 Where so specified, joints requiring
rod to proper depth, and gun in sealant.
sealant shall be first filled with a closed-cell
ethafoam rope backer rod. The backer rod
5.2.10 In cold weather, International
shall be installed to a depth that provides
Masonry Industry All Weather Council
optimum sealant profile after tooling.
recommendations for setting from 40ºF to
20ºF (4ºC to -6ºC) shall be followed, except
5.5.2 If recommended by the Sealant
that no additives shall be used in the setting
Manufacturer, primers shall be applied to the
mortar, and below 20ºF (-6ºC), all work shall
substrate surfaces according to the
be done in heated enclosures.
manufacturer’s directions prior to application
of the joint sealant.
5.2.11 Individually set thin tile [nominal
3/8" (9.5 mm)] on vertical surfaces exceeding
8' (2.5 m) is not recommended. 5.6 Expansion Joints
5.6.1 Joints shall be adequate to allow for
5.3 Mortar Joints
thermal and structural differential movement.
Filler material for these joints shall be non-
5.3.1 Mortar joints shall be raked out to a
staining.
depth of ½" to ¾" (12.5 to 20 mm). Apply
pointing mortar in layers not exceeding 3/8"
5.6.2 It is not the intent of this specification to
(9.5 mm) and allow each layer to get hard to
make control or expansion-joint

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recommendations for a specific project. The 6.2 Protection of Finished Work
Specifying Authority must specify expansion
and control joints and show locations and 6.2.1 During construction, tops of walls shall
details on the drawings. be carefully covered at night and especially
during any precipitation or other inclement
5.7 Caulking weather.

5.7.1 Where so specified, joints shall be 6.2.2 At all times, walls shall be adequately
pointed with the sealant(s) specified in Section protected from droppings.
2.4, after first installing the specified backup
material and applying a primer if required, all 6.2.3 Whenever necessary, substantial
in strict accordance with the printed wooden covering shall be placed to protect the
instructions of the Sealant Manufacturer. stonework. Non-staining building paper or
membrane shall be used under the wood.
5.7.2 All sealants shall be tooled to ensure Maintain all covering until removed to permit
maximum adhesion to the contact surfaces. the final cleaning of the stonework.

5.8 Weep Tubes 6.2.4 The Travertine Contractor will outline

the needs for protection in writing to the
5.8.1 Plastic or other types of weep tubes shall General Contractor. The General Contractor
be placed in joints where moisture may shall be responsible for protection of the
accumulate within the wall, such as at the base finished work until all trades are finished. This
of a cavity, continuous angles, flashing, etc., or responsibility includes the stone cleaning costs
as shown on architectural drawings. prior to the final inspection.

6.2.5 Finishes commonly available are

6.0 CLEANING AND defined as follows:
PROTECTION
6.2.5.1 Polished: Glossy.
6.1 Cleaning
6.2.5.2 Honed: Dull sheen.
6.1.1 The stone shall be washed with fiber
brushes, mild soap powder or detergent, and 6.2.5.3 Smooth: Smooth with minimum of
clean water, or approved mechanical cleaning surface interruption.
process.
6.2.5.4 Plucked: Rough texture.
6.1.2 Special consideration and protection 6.2.5.5 Machine Tooled: Parallel grooves
shall be provided when brickwork or other cut in the stone. Available with 4, 6, or 8
masonry is cleaned above the travertine. grooves to the inch.
Strong acid compounds used for cleaning brick
will burn and discolor the travertine. 6.2.5.6 Tumbled: A weathered, aging
finish.
6.1.3 Use of sandblasting, wire brushes, or
acids will only be permitted under special 6.2.5.7 Diamond Gang Sawn:
circumstances approved by Specifying Comparatively smooth surface with some
Authority (architect, engineer, contracting parallel markings and scratches.
officer, etc.).

© 2022 Natural Stone Institute Travertine • Page 12-7

PRODUCT materials, especially if used on floors to avoid
snagging high heel shoes.
DESCRIPTION –
Travertine 1.3 The etymology of its name is from the
Italian word “travertino,” derived from the
1.0 GEOLOGICAL ancient Roman name Tibur (now Tivoli), a
town near Rome where travertine forms an
CLASSIFICATION extensive deposit that has been worked for
many centuries. At Tivoli, travertine formed
1.1 Travertine is a varietal name for a kind around hot springs heated by volcanic activity
limestone formed under special conditions of associated with Mt. Vesuvius.
deposition. It is classed as chemical
sedimentary rock and is deposited as 1.4 In a strict sense, travertine is most often1
precipitates in terrestrial (land) environments, considered a precipitate of calcium carbonate2
as opposed to limestone, which is the cemented from saturated, generally warm or hot, fresh,
or recrystallized accumulation of calcareous mineral-laden waters in and around the mouth
organic debris deposited on the sea bottom, of conducting fractures or conduits. One of
then compacted and later cemented. Some several alternative modes of formation can be
marine limestone textures are altered to have wind-agitated pools or ponds saturated with
travertine-like voids before or after deposition calcium carbonate, thus causing precipitates to
and cementation. Marine limestone may or form in concretionary deposits found with
may not have fossils visible to the unaided eye. true, Tivoli-type travertine. Although
If not, then fossil marine microorganisms are travertine often contains plant fragments or
probably present in great abundance together fossils of land animals such as rodents or deer,
with some spores and pollen from terrestrial it will not have marine fossils as do other
plants, algae, and fungi. Because marine travertine-like limestones or marine
limestone fossils are chitinous (the material of limestone.
fingernails), they are preserved even if the
limestone is recrystallized, which obliterates 1.5 Limestone is developed by compaction
calcareous fossils. and cementation of debris from sea shells,
algae, and other marine organisms that extract
1.2 Travertine is valuable in the dimension calcium carbonate from seawater. Subsequent
stone industry because of its striking textural geologic forces can act upon these formations
character—very porous, often cavernous on a to produce travertine-like limestone with
scale of inches, with a diverse palette of light abundant voids and high porosity that mimics
hues and soft earth tones. In part because it is travertine texture. These are marketed as
soft and easily worked, travertine has been a travertine, although they are not the chemical
favorite building and decorative stone from precipitate, Tivoli-type travertine formed
preclassical times to the present. While void around springs. Postdepositional and post-
spaces are distinctive features of travertine, so cementation dissolution, mineral replacement,
too is the character of the stone itself. Void and other chemical changes3 are called
spaces are sometimes filled with waterproof “diagenesis,” and include weathering effects or

1 The American Geological Institute definition of with a slightly different physical geometry of atoms in
travertine allows inclusion of onyx and other its molecules than the more stable molecular geometry
travertine-like limestone. of calcite.
2 The mineral calcite (CaCO ) has several metastable 3 Diagenetic chemical changes can include introduction
3
relatives, minerals that exist for only a short time and of other minerals by invading solutions. Some of these
then revert to the most stable form of CaCO3, which is minerals are chert (hydrous silica), the sulfide minerals
calcite. One such example is aragonite, still CaCO3, but of iron, lead, zinc, and strontium; pyrite (FeS2), galena
(PbS), sphalerite (ZnS), and celestite (SrSO4).

Page 12-8 • Travertine © 2022 Natural Stone Institute

metamorphic changes caused by pressure, easily dissolved or converted to calcite over
heat, or time at depth together with regional time. Other voids can also be traced to
crustal movement. dissolution of aragonite shell debris in central
Texas travertine.
1.6 Diagenetically altered limestone may
have high porosity, often up to 40% or more. 1.9 Clay Balls. Not uncommon, and
The stone itself may have been formed in very usually undesirable, clay balls are occasionally
shallow waters like tidal flats or near-shore found in travertine. These are lumps of clay
reefs where deposits are exposed at low tide to tumbled by currents until more or less round,
dry in hot sunlight. That drying tends to and deposited in the sedimentation of the
preserve and enhance high porosity, or at least limestone. Clay balls are generally not
provide a well-cemented framework that cemented, will not polish, are soft, and wash
persists even though the void space may be out.
filled with carbonate muds (from tidal flats) or
land-derived mud. Fillings may be washed out 1.10 Tufa. A stone often mistaken for
later or dissolved, leaving voids. This kind of travertine is calcareous tufa. Tufa is a very
limestone is sometimes included in the porous, punky stone that precipitates around
travertine category because its texture having the vents of freshwater springs saturated with
voids resembles that of travertine. However, calcium carbonate that occur on the bottoms of
the mode and environment of formation is salty, landlocked lakes such as Mono Lake in
entirely different than the terrestrial, Tivoli- California and the Dead Sea in Israel.
type travertine.
1.10.1 Calcareous precipitation from fresh-
1.7 Other limestone that ends up with an water occurs when CO3-laden springwater
open travertine texture may be formed by mixes with the saturated salt water of the lake.
secondary solution of the calcium carbonate at Often precipitation is aided by the presence of
great depth—even in formerly dense algal and fungal activity in or around the lake
limestone of low porosity. In this case, void bottom springs. Tufa deposits can take the
space is again developed by dissolution due to form of mounds or spires, giving them, if the
the influx of slightly acidic water that lake level is low enough that they can be seen,
differentially dissolves some of the calcium a crenellated, castle-like appearance with
carbonate. multiple hollow spires that springwater flowed
up through. Spires can be 10 feet high. Tufa is
1.8 A good example is Upper Cretaceous- usually so soft, spongy, irregular, and badly
age (≈70-100 million years old) travertine colored that it generally does not make a usable
limestone from central Texas. This limestone dimension stone. When occasional, rare
was a shallow-water deposit containing deposits are usable, they are marketed as
abundant large marine clams and coiled snails. travertine.
The shells filled with carbonate mud from
marine grasses, and the surrounding matrix and 1.11 Tuff. Another stone, tuff, is frequently
filling was then cemented; later and at depth, confused with tufa. Tuff is a pyroclastic deposit
the calcium carbonate shell was dissolved, (volcanic ash) is not the same as, nor related to,
leaving a “steinkern” (derived from the German, Tufa.
literally meaning “stone nut”) or casting of the
internal shape of the shell cavity plus void space 1.11.1 The primary composition of travertine-
formerly occupied by shells. Differential type stones, except the volcanic tuff, is calcite
solution occurs because these large, heavy or calcium carbonate (CaCO3), with a few
mollusk shells are composed of the mineral having the mineralogical variation of aragonite.
aragonite, a reactive, unstable form of calcite When water precipitates one soluble mineral,

© 2022 Natural Stone Institute Travertine • Page 12-9

it may also precipitate other minerals or even 4.1.4 Sawn: A comparatively rough surface;
replace calcium carbonate if the chemical can be chat, shot, sand, or diamond sawn.
building blocks are available. Thus most
travertine may contain some hydrous silica 4.1.5 Filled or Unfilled. Travertine for
(chert or flint) or any other soluble salt, other horizontal applications is usually filled with a
minerals, and occasional terrigenous grains of cementitious fill or an epoxy fill similar in color
clastic sediments—clays, quartz silt, or even a to the background color of the travertine.
few grains of quartz sand.
5.0 THICKNESS
2.0 COLOR AND VEINING
5.1 Standard thicknesses for travertine are
2.1 As with most sedimentary rocks, generally ¾", 1¼", 2", and 2-3/8" (20, 30,
travertine colors range from light buff through 50, and 60 mm). The recommended
tan to brown and into shades of red, due to thicknesses vary depending on the type of
varying amounts of iron oxides in the stone. travertine used.
Many rocks are colored by iron staining that
leached out of rock units above or 5.2 Cutting can be made to exact metric
superimposed on top of the travertine or measurements through conversion of U.S.
limestone deposit. Conventional System values to SI International
System equivalents. Note that as travertine,
2.2 Other colors are due to inclusion of like all other natural stone, is cut thinner, its
minerals other than iron and variations in tensile strength diminishes.
colors of banding that reflect changes in the
volume or chemistry of invading fluids, 6.0 SIZES
changes in conduits, and alternating wet and
dry climatic cycles. 6.1 Travertine is a product of nature with
many varieties available, each possessing
3.0 TEXTURE varying characteristics. Little can be done to
alter the condition in which nature presents
3.1 The term “texture,” as applied to these varieties to us. Therefore, size may
travertine, means size, degree of uniformity, become a limiting factor to consider in the
and arrangement of constituent materials. selection of a particular travertine.

4.0 FINISHES 6.2 NSI Members should be consulted for

specific size information for a particular stone
4.1 Travertine surfaces may be finished in a and its desired use. A jointing scheme that
number of ways. Typical finishes are: permits the use of smaller sizes of travertine
may greatly facilitate selection and delivery.
4.1.1 Polished: A glossy surface which NSI Member/Supplier should assist in the final
brings out the full color and character of the scheme approval.
travertine.
7.0 PRODUCT SAMPLING
4.1.2 Honed: A satin smooth surface with
little or no gloss. 7.1 Travertine is formed by nature; thus,
there are variations in the tonal qualities of the
4.1.3 Smooth: An even, flat, level finish, stones. However, it is these natural variations
with no surface bumps or roughness. that make travertine unique, valuable, and
highly desirable. Because of these variations,
selection of a travertine should never be made

Page 12-10 • Travertine © 2022 Natural Stone Institute

on the basis of one sample only. It is method, use in high-traffic paving areas may be
recommended that selection be based on problematic. Holes may appear after
viewing sufficient samples to show the general installation due to thin wall cavities at or near
range of color of the desired stone. NSI the exposed surface of the stone. These cavity
Members can provide these range samples. holes may open because of heavy foot traffic. It
is acceptable practice to fill holes that appear
8.0 PROPER USAGE TIPS after installation.

8.1 Recommendation for commercial 11.0 FILLING OF TRAVERTINE

floors:
11.1 Travertine may be obtained with its
8.1.1 Minimum ¾" (20 mm) thickness. normal voids unfilled or filled. Although some
finish travertine floors by grinding in place
8.1.2 A honed finish. after installation, this practice is less desirable
than filling by a Stone Finisher in his shop under
8.1.3 A minimum hardness value of 10 as controlled conditions.
measured by ASTM C241/C1353.
11.2 Filler. Common materials used for
8.2 Avoid the use of gypsum or molding filling are natural (gray colored) or tinted
plaster setting spots for the installation of portland cement, and clear or colored epoxy
exterior stone. or polyester resins. Unless otherwise specified,
matching colored portland cement is used as
filler.
9.0 TOLERANCES
9.1 Because of the many variations in types TECHNICAL DATA –
of travertine, it is recommended that the Travertine
Travertine Quarrier or Fabricator be contacted
regarding size and thickness availability.
Tolerances for fabrication and installation are
1.0 PROPERTIES OF
the same as for marble dimension stones. TRAVERTINE DIMENSION
STONE

10.0 CUT TYPES 1.1 In centuries past, relatively little

importance was attached to the ultimate
10.1 Due to the bedding planes inherent in physical capabilities of most building materials.
most travertine, there are two ways to cut the Rule of thumb was a common structural design
material that will give dramatically different criterion. As a result, the widely used materials
patterns and color ranges: of the day, for the most part natural rather than
manmade materials, were seldom stressed to
10.1.1 Vein Cut: Vein-cut travertine is cut their ultimate limits.
against the bedding planes, exposing the edge
of the formation and giving a very linear 1.2 In present-day construction, this is far
pattern. from being true. Performance requirements
are daily becoming more demanding. In
10.1.2 Fleuri Cut: Sometimes called “cross striving for taller structures, greater spans,
cut,” the fleuri cut is parallel to the bedding firmer foundations, thinner walls and floors,
plane, exposing a “flowery,” random pattern. stronger frames, and generally more efficient
Although the stone is strong when cut in this buildings with more usable space, today’s

© 2022 Natural Stone Institute Travertine • Page 12-11

Architects and Engineers must get the most out Property Range of Values
of the materials with which they work.
Modulus of Rupture (C99)
1.3 Travertine is a product of nature and not lbs/in² .............................. 500-1,500
always subject to the rules of consistent Recommended (min):
behavior that may apply to manufactured 700 (interior),
building materials. 700 (exterior)
Absorption, by weight % (C97) .... 0.10-2.5
1.4 Physical property values of travertine Recommended (max): 2.5
may, however, be measured using the standard
test methods approved by the Dimension Stone Abrasion Resistance (C241) (Ha) .........7-25
Committee C18 of the ASTM International. Recommended (min): 10
The NSI and Member companies are
represented on the ASTM committee and are * Test methods described in current ASTM
active in its technical work of establishing standards.
proper test methods and specifications
consistent with the latest technology.
2.0 STRENGTH (ASTM C99,
1.5 Final design should always be based on C170, C880)
specific values for the stone variety ultimately
to be installed. These values may be obtained 2.1 Values for modulus of rupture,
from the Stone Supplier. All materials are not compressive strength, and flexural strength are
suitable for all uses. In order to avoid mistaken ascertained by testing specimens of travertine
selections, tests for material values should be under laboratory conditions until they fail.
made prior to final material selection.
2.2 Size and finish of test samples required
1.6 Physical Properties of Travertine by the standard ASTM test methods may not
(This historical data and information is reflect the actual performance of stone when
provided only as a guideline. Recommended used in lesser thicknesses or with other finishes
minimums or maximums are established and that affect strength. For this reason, the
provided by ASTM International.)* Modulus of Rupture (C99) test is
recommended when the stone to be used will
Property Range of Values be two or more inches thick. The Flexural
Compressive Strength (C170) Strength (C880) test is recommended when
lbs/in² .......................... 5,000 -10,500 the stone thickness will be less than two inches.
Recommended (min):
5,000 (interior), 2.3 The strength of a travertine is a measure
7,500 (exterior) of its ability to resist stresses. The two “cuts” of
travertine will exhibit different strength
Flexural Strength (C880) characteristics and must be tested for the type
lbs/in² ............................. 600-1,500 of cut being used on the project. Travertine’s
Recommended (min): strength depends on several factors, such as the
500 (interior), rift and cleavage of the calcite crystals, the
500 (exterior) degree of cementation, the interlocking of the
calcite crystals, and the nature of any
Modulus of Elasticity (in millions)
cementing materials present.
lbs/in² ............................... 2.0-15.0
Density, lb/ft3 (C97) ................ 140-165
Recommended (min): 144

Page 12-12 • Travertine © 2022 Natural Stone Institute

3.0 FIRE RESISTANCE 5.0 FACTORS AFFECTING
PROPERTIES
3.1 Stone is not combustible according to
underwriters’ ratings, and therefore is 5.1 The ultimate test of a building material
considered a fire-resistant material. Because of is its ability to have and maintain the necessary
its thermal conductivity, heat transfer is fairly structural strength, as well as beauty of
rapid. Most stone is not considered a highly appearance and low cost of maintenance, over
rated thermal insulator. the useful life of the structure. Experience has
proven that stone meets this test as few other
3.2 Underwriters’ fire-resistance ratings building materials can. Studies have shown that
evaluate whether or not a material will burn, the durability of most stones is little affected by
as well as how long it will keep surrounding cycles of weather. This is because most have a
combustible materials from reaching low rate of moisture absorption.
temperatures which will cause them to ignite.
Methods of estimating fire-resistance periods 5.2 Exterior travertine paving is not re-
of masonry walls and partitions utilizing commended for environments where deicing
component laminae are given in “Fire chemicals may be used to melt ice and snow,
Resistance Classifications of Building because these chemicals will damage most
Construction,” BMS92, National Bureau of travertine.
Standards.
6.0 SAFETY FACTORS
4.0 ABRASION RESISTANCE 6.1 Good engineering practice requires that
(ASTM C241/C1353) allowable design stress must provide a margin
of safety in any structural element. As a
4.1 Abrasion resistance is a property of necessary precaution against such conditions as
stone that should be tested per ASTM wind, ice, snow, impact, temperature changes,
C241/C1353 to provide an indication of the and imperfect workmanship, these allowable
stone’s wearing qualities when exposed to foot stresses must be smaller than those which
traffic. produce failure.

4.2 The hardness and uniform wearing 6.2 Within the accepted limits of safe design
qualities of most varieties of travertine make practice, the closer the allowable load is to the
them extremely desirable and economically ultimate failure load, the more efficient is the
practical for floors and stairs. Varieties with an use of the material and the less the cost of the
abrasive hardness (Ha/Iw) of 10 or more as construction.
measured by ASTM C241/C1353 tests are
recommended for use as flooring exposed to 6.3 Contemporary building design does not
normal foot traffic. A minimum abrasive usually employ stone as part of the structural
hardness of 12 is recommended for frame, but rather as an independent unit, a
commercial floors, stair treads, and platforms curtain wall, or veneer. Therefore, the
subject to heavy foot traffic. If floors are primary concern in such cases is with wind or
constructed with two or more stone varieties, seismic loads, and a safety factor of 8.0 is
the Ha/Iw values of the stones must not differ recommended. Where the stone is to be
by more than 5 or the floor surface will not subjected to concentrated loading, such as stair
wear evenly and uniformly. treads or lintels supported only at the ends, a
factor of 10.0 should be used. These safety
factors may be adjusted using sound
engineering principles and judgment.

© 2022 Natural Stone Institute Travertine • Page 12-13

6.4 As buildings become taller and 8.3 The most feasible means of prevention is
individual stone slab veneers becomes larger in to stop the entrance of large amounts of water.
area, the lateral forces due to wind loads must Absorption from the face will not cause
be considered. Wind tunnel tests are often efflorescence unless there are open joints.
used on major structures to determine wind
dynamics and force magnitude. Reinforcement 8.4 However, some of the salt crystals may
is sometimes necessary for large-dimension form in the pores near the surface. Crystal
slab veneer in critical areas. growth (recrystallization) in the pores can put
stress on the walls of the pores and cause the
stone to flake off. If the conditions bringing
7.0 SEISMIC CONSIDERATIONS about this action persist, scaling may continue
and flake off one layer after another. For this to
7.1 Seismic considerations generally require happen, large amounts of water must enter the
that low buildings be stiff, and that tall wall and must contain large amounts of salts.
buildings be relatively flexible. Design of
connections must account for seismically 8.5 Avoid contact between soil and stone.
induced horizontal loading. Local building Damp-proofing treatments of either a
codes vary and must always be checked to bituminous or cementitious nature may be
determine specific requirements for each area. used as a barrier to the ground water or
The National Bureau of Standards has published construction moisture causing these stains.
two documents on the topic: “Earthquake
Resistant Masonry Construction,” NBS Science
Series 106; and “Abnormal Loading on
Buildings and Progressive Collapse: An
Annotated Bibliography,” NBS Science Series
67. The U.S. Army Corps of Engineers has also
published TM 5-809-10, “Seismic Design for
Buildings.”

8.0 EFFLORESCENCE AND

STAINING

8.1 Efflorescence is a salt deposit, usually

white in color that occasionally appears on
exterior surfaces of masonry walls. The
efflorescence-producing salts found in masonry
are usually sulfates of sodium, potassium,
magnesium, calcium, and iron. Salts which are
chlorides of sodium, calcium, and potassium
will sometimes appear, but they are so highly
soluble in water that they will be washed off by
rain.

8.2 The water-soluble salts causing

efflorescence come from other materials in the
wall. The salts exist in small amounts and are
leached to the surface by water percolating
through the walls.

Page 12-14 • Travertine © 2022 Natural Stone Institute

HORIZONTAL texture, and marking that the stone supplied to
the project will have. Samples must be
SURFACES reviewed as a complete set and approved or
rejected in their entirety, without stipulation.
1. DESIGN CRITERIA
1.1.2.1. Pending the scope of the installation
1.1. STONE SELECTION and the variability of the stone product, a
mockup of a specified size and extent, may be
1.1.1. STONE PRODUCT DEFINITIONS required to adequately demonstrate the range
of the material’s color and character. Mockups
1.1.1.1. TILE: A stone tile is a thin, flat piece are intended to demonstrate the full range of
of natural stone used as finishing material, with color tones and natural characteristics of the
a thickness ranging from ¼" to ⅝" (6 to 16 stone to be expected across the entire project
mm) inclusive and having no dimension greater yet condensed into the much smaller surface
than 2’ 0” (610 mm). Tiles are normally area of the mockup. Therefore, the effects of
supplied in typical sizes, with atypical pieces the variation and characteristics of the stone
being field cut to fit, although in some cases will be more concentrated, and appear more
when detailed shop drawings are prepared, extreme, than the actual project since the
factory cutting of atypical pieces can occur. actual project will have less frequent
occurrences of these elements.
1.1.1.2. CUT-TO SIZE: Cut-to-size stone
products, also referred to as “slab stock” stone 1.1.2.2. Pending the scope of the installation
products, are custom fabricated pieces of and the variability of the stone product, a “dry-
natural stone. Fabrication of these products lay” may be required to adequately
normally occurs in a factory setting, where demonstrate the range of the material’s color
each piece is custom fabricated to fit, but character, and finish, with the advantage of
partial fabrication may also occur in the field at predetermining the actual position and
the time of installation. orientation of each stone panel. The dry-lay
allows the design professional to see the actual
1.1.1.3. Natural stone tiles and cut-to-size blend of the finished floor, and also allows the
products may have different fabrication arrangement of pieces to be adjusted per
tolerances due to their different methods of his/her desires. Since each stone panel is
fabrication. Refer to the specific stone dedicated to a specific location, crating and
description chapter for fabrication tolerances. handling must be skillfully executed to prevent
damage as there may or may not be a suitable
1.1.1.4. LABOR ASSIGNMENT: The replacement available for a given stone. A dry
successful installation of both dimension stone lay is generally considered to be a wise
and stone tile is dependent upon the investment for decorative interior office lobby,
experience and craft knowledge of the firm floor and wall projects. It provides a beneficial
contracted to install the stone. The Natural team building experience and the formal
Stone Institute endorses the use of NSI approval of all stone prior to shipment helps
Accredited Natural Stone companies. See eliminate jobsite anxiety and rejections.
www.naturalstoneinstitute.org for a directory
of installation companies accredited by the 1.1.2.3. Inspection of supplied material to
NSI. evaluate compliance with approved
samples/mockups/dry-lays shall be done at a
1.1.2. SAMPLES: The Dimension Stone viewing distance of not less than 6’-0” (2 m),
Contractor shall furnish samples of the various with natural lighting, and an angle
dimension stones to be used. Samples shall perpendicular to the face of the stone.
indicate the extremes of color, veining,

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-1

1.1.3. THICKNESS Suggested minimum 1.1.4.6. Identification of mortar, adhesive, and
thicknesses for Horizontal stone surfaces: grout types.

1.1.3.1. Exterior Stone Pavers, Pedestrian 1.1.4.7. Relationship to adjacent building

Traffic: 1¼" (30 mm). materials, cavities, and placement tolerances of
support systems.
1.1.3.2. Exterior Stone Pavers, Vehicular
Traffic: Is best determined by engineering 1.1.4.8. Details of mechanical anchorage,
analysis, but is generally 3” (75 mm) or thicker. including anchor devices and metallurgy of
same.
1.1.3.3. Interior Residential Stone Flooring:
⅜” (10 mm). 1.1.5. FABRICATION: Stone paving units
are precut and prefinished to dimensions
1.1.3.4. Interior Commercial Flooring, light specified on shop drawings and are usually
duty (e.g., retail shops, tenant areas of office delivered to the job site ready to install.
buildings): ⅜” (10 mm).
1.1.6. CARVING: All carving shall be
1.1.3.5. Interior Commercial Flooring, Heavy performed by stone carvers in strict accordance
Duty/High Traffic: ¾”, or 1¼” (20 or 30 mm) with approved full-size details or models, with
pending stone variety selection and level of allowance for documented industry tolerances.
traffic loading. Architectural drawings shall show approximate
depth and relief of carving. Carving shall be
1.1.3.6. Note: Large stone unit sizes and/or left as it comes from the tool, unless otherwise
specific loading/traffic requirements may specified.
dictate the use of greater thicknesses than those
listed above. 1.1.7. FIELD REPAIR: Shop fabrication is
generally preferred over field fabrication as
1.1.3.7. Note: Regardless of the stone quality control is more easily monitored in the
thickness, loading as a result of building controlled environment of a shop setting.
maintenance equipment oftentimes requires When field fabrication is necessary, it shall be
protection of the stonework to prevent damage accomplished by skilled, experienced
from the equipment. mechanics. Conditions or occurrences that
may exist which would necessitate field
1.1.4. SHOP DRAWINGS: Detailed, scale fabrication:
shop drawings which include elevations, plan
views and section details shall be provided by 1.1.7.1. Inability to verify field dimensions or
the stone contractor. Shop drawings shall conditions prior to stone being in transit to the
address: installation site.

1.1.4.1. Stone Type and Finish 1.1.7.2. Requirement to coordinate with

1.1.4.2. Stone sizes, thicknesses, joinery and related components that are being installed
patterning concurrently with the stone.
1.1.4.3. Reference to building column grid
lines 1.1.7.3. Changes in the scope or design of the
1.1.4.4. Vein and Rift directions, if appropriate installation.
1.1.4.5. Joint sizes and treatments
1.1.4.5.1. Typical Joints 1.1.7.4. Repair or patching is sometimes
1.1.4.5.2. Expansion Joints necessary due to damage of material either on-
1.1.4.5.3. Movement Joints site or in transit. By allowing these repairs to
be made on-site, progress of the job can be

Page 13-2 • Horizontal Surfaces © 2022 Natural Stone Institute

maintained, thus aiding the successful 1.1.10.2. Interior stone flooring finishes
completion of the work. Repairs should not may include honed, polished, sanded, flamed
detract from the desired appearance or (a.k.a. “thermal”), sawn, sanded, and natural
strength of the completed installation. The cleft, and other finishes.
means and methods or examples should be
discussed and/or demonstrated for approval 1.1.10.3. Many proprietary finishes are
prior to performing the repair. offered from suppliers which may be suitable
but are not included in the above, generic lists.
1.1.8. STONE COLORS and VARIETIES:
Pending the material successfully meeting the 1.2. TECHNICAL DATA
specified performance requirements, most of
the commercially available varieties are 1.2.1. PHYSICAL PROPERTY VALUES.
suitable provided they meet or exceed the Final design should always be based on the
necessary performance specifications of the specific property values of the stone to be used.
project. These values may be obtained from the Stone
Supplier. When current (≤3 years, per ASTM
1.1.9. SIZES and THICKNESSES may need C1799) reliable physical property data is not
to be determined by engineering analyses. The available from the supplier, re-testing of the
following properties should be considered stone should be considered.
when determining size and thickness of stone
paving units: 1.2.2. Each stone variety used for exterior
stone paving should conform to the applicable
1.1.9.1. Flexural Strength (Ref: ASTM C880) ASTM standard specification and the physical
of the stone requirements contained therein. The
specification for each stone type follows:
1.1.9.2. The unsupported span or anticipated
deformation of the bedding system. 1.2.2.1. Granite: ASTM C615, Standard
Specification for Granite Dimension Stone
1.1.9.3. The anticipated loads.
1.2.2.2. Limestone: ASTM C568, Standard
1.1.9.4. Stone thickness tolerances. Specification for Limestone Dimension Stone

1.1.9.5. Size and availability limitations of 1.2.2.3. Marble: ASTM C503, Standard
stone blocks and/or slabs Specification for Marble Dimension Stone

1.1.9.6. Compatibility of the chemical 1.2.2.4. Onyx: No ASTM Standard exists at

composition of setting bed and the stone this time
material’s reaction to the chosen setting bed
materials. (Pre-construction testing for 1.2.2.5. Quartz-Based Stone: ASTM C616,
compatibility is recommended). Standard Specification for Quartz-Based
Dimension Stone
1.1.9.7. Factors of Safety
1.2.2.6. Serpentine: ASTM C1526, Standard
1.1.10. STONE FINISHES Specification for Serpentine Dimension Stone

1.1.10.1. Exterior stone pavements 1.2.2.7. Slate: ASTM C629, Standard

shall have textured surfaces such as flamed Specification for Slate Dimension Stone
(a.k.a. “thermal”), sanded, bush-hammered,
cleft, or other suitably textured finishes. 1.2.2.8. Soapstone: No ASTM Standard exists
at this time

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-3

1.2.2.9. Travertine: ASTM C1527, Standard 1.3.4. Exterior paving should have a
Specification for Travertine Dimension Stone minimum Ha or Iw of 12.0.

1.3. ABRASION RESISTANCE 1.3.5. Thresholds: Ha or Iw of the varieties

Class of usage establishes the minimum selected should be a minimum of 12.0.
abrasion resistance that a stone requires to
withstand the foot traffic requirements of the 1.3.6. Stairs: Thresholds: Ha or Iw of the
project. This is determined according to the varieties selected should be a minimum of
ASTM C241 or C1353 test methods for 12.0. Higher abrasion resistance should be
abrasion resistance and is reported as Ha when considered for stairs that experience abrasive
tested per ASTM C241 or Iw when tested per grits from streets or snowmelting applications.
ASTM C1353. The two scales correlate well in
the range of values contained within this 1.3.7. These classifications are for the
section and are considered to be stone’s abrasion resistance only. The stone’s
interchangeable. Extremely hard stone finish (polished, honed, thermal, etc.) will
varieties will produce vastly different values wear with traffic. Polished finish on stones with
between the two test methods, but this is low abrasion indices (generally ≤ 20.0,
insignificant since the requirements of this although exceptions exist) are not suitable for
section will easily be satisfied. There are three most moderate and any heavy-traffic areas as
recognized classes of usage for interior stone the gloss will be reduced by the abrasion of the
flooring, plus additional classifications for foot traffic. Stone with high abrasion resistance
thresholds, steps, and exterior surfaces: will generally maintain a polished surface in
foot traffic areas. Stones with lesser abrasive
1.3.1. Light Traffic class is reserved for indices are likely to abrade in service, and
interior residential use where there is relatively generally perform better if supplied in honed
little traffic and/or shoes are not always worn. finish. While a polished finish in softer stone
Stone must have a minimum Ha or Iw of 6.0. varieties will be dulled by foot traffic, a honed
finish on a soft stone will oftentimes become
1.3.2. Moderate Traffic class is reserved for glossier due to foot traffic.
residential entranceways and small commercial
installations where pedestrian traffic is less than 1.3.8. Limitations. If several varieties of
50 persons per minute. Stone must have a stone are used together, the abrasive resistance
minimum Ha or Iw of 7.0 (Ha or Iw) of the stones should be similar.
Proper testing (ASTM C241 or ASTM C1353)
1.3.3. Heavy Traffic class is reserved for should be performed on each stone variety. If
commercial installations (banks, shopping the abrasion resistance of either stone is <20.0,
malls, train or bus stations, etc.) where then the difference in abrasion resistance
pedestrian traffic is greater than 50 persons per between the stones shall be ≤5.0. This can be
minute. Minimum Ha or Iw is 10.0 for general ignored when using stones with higher abrasion
areas, increasing to 12.0 for elevator lobbies, resistance indices (generally ≥20.0, although
halls, and other areas of traffic concentration. exceptions exist), since the resultant wear will
generally be minimal.
1.3.3.1. Consider higher abrasion resistance
than listed above for those areas immediately 1.4. FRICTION
accessible from outdoors. Solid contaminants Slips and falls may be caused by inadequate
(grit) that collects on the shoes of pedestrians available friction or due to a sudden change in
will be carried into the interior walking surface available friction. For example, a spilled
and act as an abrasive. beverage or other contaminant may reduce
available friction in a given area. Because of
this, the maintenance of a floor is an important

Page 13-4 • Horizontal Surfaces © 2022 Natural Stone Institute

factor in its ability to provide a safe walking recommended to limit differential deflection
surface. Local building codes normally take between adjacent framing members.
precedence over other regulatory agencies.
Natural stone used for paving provides an 1.5.4. Impact loading and rolling loads shall
adequate available static coefficient of friction be considered when designing substrate floor
for human ambulation when supplied with an assemblies.
appropriate finish and properly maintained.
Proper maintenance includes prompt cleanup 1.5.5. Preloading the floor prior to
of spills and correcting other conditions that installation may be required to lessen the
can cause a sudden reduction in a floor’s static effects of the deformation due to the dead load
or dynamic coefficient of friction. Aftermarket of the stone and other components.
products are available for application on
natural stones to increase available friction if 1.5.6. MATERIAL WEIGHTS: For
required. Such products must be applied and estimating purposes, mortar bed weight can be
maintained according to the manufacturer’s approximated as 0.75 lb per square foot per
recommendations. each 1/16” of thickness (2.3 kg/m² per each
mm of thickness). Stone weight can be
1.4.1. Testing of frictional properties to approximated as 1 lb per square foot per each
ascertain appropriate traction levels per ANSI 1/16” of thickness (3 kg/m² per each mm of
326.3 (American National Standard Test thickness).
Method for Measuring Dynamic Coefficient of
Friction of Hard Surface Flooring Materials) is 1.5.7. SELF-LEVELING
recommended. UNDERLAYMENTS. Gypsum-based and self-
leveling underlayments are not recommended
1.5. SUBSTRATES for use with stone paving, except in
conjunction with an approved primer and
1.5.1. DEFLECTION. Deflection must be waterproofing or crack isolation membrane
limited in the substrate for installation of stone (See ANSI A118.10-118.12). If using this
finishes. Stone thickness of less than ¾” (20 method, careful adherence to the
mm) is considered to contribute no flexural manufacturer’s recommended procedure is
strength to the assembly, providing decorative required.
and abrasion resistance properties only. Stone
of ¾” (20 mm) or greater thickness may be 1.6. JOINTS
considered to be part of the structural assembly Width of Joints between Stones. Joints
provided its suitability has been verified by between stones should be of sufficient width to
comprehensive engineering analysis. ensure that the grout being used can be placed
throughout the full depth of the stone and
1.5.2. CAST-IN-PLACE CONCRETE properly compacted within the joint.
FLOORS. The substrate shall be designed for
a total load deflection not exceeding L/360, as 1.6.1. Typical joint widths for stone
measured between control or expansion joints. installation:

1.5.3. FRAME CONSTRUCTION. The 1.6.1.1. EXTERIOR STONE PAVEMENT:

subfloor areas over which stone finishes are to Minimum ¼" (6 mm), preferably ⅜"
be installed must be designed to have a total (10 mm). Joints of ½” (12 mm) or larger are
load deflection not exceeding L/720. frequently required for large unit size
installation.
1.5.3.1. The use of strongbacks, cross-
bridging or other means of reinforcement is 1.6.1.2. INTERIOR STONE FLOORING
INSTALLATION: Minimum 1/16”

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-5

(1.5 mm), preferably ⅛” (3 mm). Joints of ¼” installed, the Specifying Authority shall show
(6 mm) or larger are frequently required for locations and details of expansion joints on
large unit size installation. project drawings.

1.6.2. Joints of ½” to 1” (12 to 25 mm) are 1.6.6.1. FINAL DESIGN. It is not the intent of
frequently required for installing stones with this manual to make movement and expansion
split, or “snapped” edges. joint recommendations for a specific project.
The Architect must specify expansion and
1.6.3. Stone units with “cleft” or other non- movement joints and show location and details
planar surface finishes generally require larger on drawings.
joints to minimize perceived lippage. Joint
widths of ¾” or 1” (20 to 25 mm) are not 1.6.6.2. Movement Joints are also required in
uncommon with these material finishes. fields of paving. Movement joints extend
through the finish layer only and provide an
1.6.4. An arris, or chamfer is commonly interruption to the accumulation of shear stress
used on stone edges to reduce the vulnerability resulting from differential in expansion
of chipping during handling and transport. between the finish layer and substrate layers of
Joints between stone units having an arris or the paving assembly. Reference ANSI A108.01
chamfer will appear wider than the actual section 3.7 and ANSI A108.02 section 4.4 for
dimension when filled. guidance on movement joint location and
design.
Installation of natural stone with tight joints is
not recommended.
1.6.6.3. Expansion, isolation, or construction
joints in the substrate must continue through
1.6.5. Where vertical surfaces meet
the entire stone installation assembly.
horizontal paving, the joint should be filled
with an elastomeric sealant in lieu of grout.
1.7. LIPPAGE
These joints should be at least ⅜" (10 mm) in
width and continue through the stone assembly 1.7.1. Tolerances for allowable lippage can
to the substrate or backing (membranes may be found in Chapter 22 on Tolerances.
remain continuous). Follow the sealant
manufacturer’s recommendation to determine 1.7.2. Allowable lippage is an installation
if primer or backer rod is required. tolerance and is additive to the inherent
warpage of the stone unit.
1.6.5.1. Installation sequencing is generally
easier if the walls are installed first and the floor
1.7.3. Industry lippage tolerances will not be
material abuts the wall face, although some
attainable in heavily textured surfaces,
designers prefer to have the horizontal surface
including flamed coarse-grained stones, cleft,
extend under the vertical surface, for aesthetic or water-jet finishes. In those installations,
reasons. In either case, protection of
joint width should be increased to limit
completed work must be provided.
perceived lippage, and in some cases joints as
wide as ¾” (20 mm) may be required.
1.6.6. EXPANSION AND MOVEMENT
JOINTS: Expansion and/or movement joints 1.7.4. Industry lippage tolerances may not be
are essential for the success of stone
achievable with extremely large format stone
installations. Various methods require proper
pavers, in which case larger than typical joint
design and location of expansion joints as
widths are recommended to minimize
shown in “Method EJ171,” from the Tile
perceived lippage.
Council of North America Installation
Handbook. Because of the limitless conditions
and structural systems in which stone can be
Page 13-6 • Horizontal Surfaces © 2022 Natural Stone Institute
2. RELATED MATERIALS waterproofing membranes also function as
crack isolation membranes.
2.1. MEMBRANES
2.1.3.5. SOUND ATTENUATION
2.1.1. The use of membranes to improve MEMBRANES: Sound attenuation membranes
system performance is common in the design are used to reduce audible transmission from
of stone walking surface installations. one level to the level below in multi-story
construction. These membranes are most
2.1.2. Comply with the membrane commonly used in condominium and office
manufacturer’s written instructions regarding buildings.
the applicability and installation of the
membrane product. 2.1.3.6. MEMBRANE SPECIFICATIONS:
Specifications for various membranes can be
2.1.3. Common types of membranes and found in ANSI A118:
their intended contribution to the system
performance are discussed below: 2.1.3.6.1. A118.10 American
National Standard Specifications for Load
2.1.3.1. CLEAVAGE MEMBRANES: Bearing, Bonded, Waterproof Membranes for
Cleavage membranes are used in thick-bed Thin-set Ceramic Tile and Dimension Stone
installations below a reinforced mortar bed to Installation
intentionally prevent the bond between the
stone setting system and the substrate slab, 2.1.3.6.2. A118.12 American
allowing independent movement (free National Standard Specifications for Crack
floating) of the stone and setting system. Isolation Membranes for Thin-Set Ceramic
Tile and Dimension Stone Installation
2.1.3.2. CRACK ISOLATION
MEMBRANES: Crack Isolation membranes 2.1.3.6.3. A118.13 American
are used to isolate the stone from minor in- National Standard Specification for Bonded
plane cracking of the substrate surface in thin- Sound Reduction Membranes for Thin-set
set applications. Crack Isolation membranes Ceramic tile Installation
are used in thin-set applications and can be
sheet applied, trowel applied, or liquid 2.2. SURFACE SEALERS
applied.
2.2.1. Sealing the Face of the Stone: This
2.1.3.3. UNCOUPLING MEMBRANES: section does not imply that sealing the face of
Uncoupling membranes are sheet applied, and the stone is a necessary practice. Application of
geometrically configured to provide a small sealers is a common practice in certain
airspace which accommodates lateral flexibility instances, such as when extremely high
between the tile and the substrate, reducing the porosity stone is installed or when the stone
transfer of stresses to thin-set stone installation floor is installed in a food or beverage service
systems. Uncoupling membranes are most area. If any sealer coating is specified for any
frequently used on wood frame support natural stone material, advice should be sought
systems. in detail from qualified sealer manufacturers,
stone suppliers or installers (See Ch 3, pg. 3-5,
2.1.3.4. WATERPROOF MEMBRANES: section 5.10).
Waterproof membranes are used to prevent
the migration of liquid water. These 2.2.1.1. While commonly referred to as
membranes are most commonly liquid applied, “sealers” the products used to treat stone
although sheet products are available. Some surfaces are typically an “impregnating
repellent” rather than a true sealer. These

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-7

products, when properly applied, are designed 2.2.3.3. Dry-Pack mortars are commonly used
to preserve the ability of the stone to transmit in exterior or other wet exposure areas. The
water vapor (“breathe”). absence of hydrated lime in this mixture
eliminates the possibility of lime solids leaching
2.2.2. MORTARS AND ADHESIVES to the surface.
Portland Cement Mortar: Portland cement
mortar is a mixture of portland cement and 2.2.4. THIN-SET MORTAR: Thin-set
washed sand, roughly in proportions of 1:3 (by mortar, oftentimes called “dry-set mortar”, is a
volume) for floors. Hydrated lime may also be mixture of portland cement (although a few are
added in the mortar mixture up to ⅛ of the not cement-based) with sand and additives
total volume. Additional additives, typically providing water retention. Thin-set mortars
latex or acrylic, may be included in this mortar are also frequently used as a bond coat for
recipe. The stone is typically set with this setting stone.
mortar while the mortar bed is still in a plastic
state. 2.2.4.1. Thin-set mortar is available as a
factory-sanded mortar to which only water
2.2.2.1. Portland cement mortars may be need be added. Cured thin set mortar is
reinforced with metal lath or welded wire generally tolerant of prolonged contact with
mesh for thick set setting bed systems, water but does not form a water barrier.
especially when a slip sheet is used
2.2.4.2. Thin-set mortar is not intended to be
2.2.2.2. Portland cement mortars are used in trueing or leveling the substrate
structurally strong, generally resistant to surfaces as tile is being installed.
prolonged contact with water, and can be used
to plumb and square surfaces installed by 2.2.4.3. Specifications for various thin-set
others. mortar varieties can be found in ASNI A118 as
below:
2.2.3. DRY-PACK MORTAR: Contrary to
its name, “Dry-Pack” mortar isn’t actually dry, 2.2.4.3.1. A118.1: American National
but rather it is simply under-hydrated Standard Specifications for Dry-Set Cement
compared to mortar mixes that are placed in a Mortar
plastic state. The mortar is a mixture of
portland cement and water, typically 2.2.4.3.2. A118.3: American National
containing 1 part portland cement to 3 to 4 Standard Specifications for Chemical Resistant,
parts (by volume) clean washed sand. Water Cleanable Tile-Setting and -Grouting
Epoxy and Water Cleanable Tile-Setting
2.2.3.1. A simple field test for the level of Epoxy Adhesive
hydration of the dry-pack is that one should be 2.2.4.3.3. A118.4: American National
able compact it into a “ball” in one’s hand. If Standard Specifications for Modified Dry-Set
the mortar can be extruded between one’s Cement Mortar
fingers when squeezing the ball of mortar, it is
over-hydrated. 2.2.4.3.4. A118.5: American National
Standard Specifications for Chemical Resistant
2.2.3.2. Despite being under-hydrated at the Furan Mortars and Grouts for Tile Installation
time of installation, dry-pack mortar will
eventually achieve full cure due to reaction 2.2.4.3.5. A118.8: American National
between the portland cement and water of Standard Specifications for Modified Epoxy
opportunity. Emulsion Mortar/Grout

Page 13-8 • Horizontal Surfaces © 2022 Natural Stone Institute

2.2.4.3.6. A118.11: American graded sand (per ASTM C144) used for joints
National Standard Specifications for EGP up to ¼" (6 mm) wide; 1:2 for joints up to ½"
(Exterior Glue Plywood) Latex-Portland (12 mm) wide; and 1:3 for joints over ½"
Cement Mortar (12 mm) wide. Hydrated lime, not exceeding
1/5 part, may be added. Damp curing is
2.2.4.3.7. A118.15: American preferable.
National Standard Specifications for Improved
Modified Dry-Set Cement Mortar 2.3.2.1. Sanded portland cement grout should
be applied with caution over softer varieties of
2.2.5. LIMESTONE (or other light-colored stone with honed or polished finishes because
stones) SETTING MORTAR. Cement used in it may scratch the stone surface. Masking of
mortars for setting limestone and other light- the stone may be necessary.
colored stones shall be white portland cement
per ASTM C150, or white masonry cement per 2.3.3. Unsanded Grout portland cement
ASTM C91. Nonstaining cement shall not grout is a commercially available mixture of
contain more than 0.03% of water-soluble portland cement and other ingredients,
alkali when determined in accordance with producing a water-resistant, dense, uniformly
procedure 15, calculation 16 of ASTM C91 or colored material, and is normally available in
Federal Specification SS-C181C. However, if white or gray colors. Damp curing is
a large amount of standard cement has been advantageous for this material. Unsanded
used in the backup material and an effective grout is commonly used for narrow joint
water barrier has not been provided between widths (≤⅛” [≤3 mm]) or with soft varieties of
the stone and the backup, the use of stones with polished finish which can be
nonstaining cement may not prevent scratched by the aggregate contained in a
discoloration. Discoloration will reduce or sanded grout.
disappear as the stone dries. The Indiana
Limestone Institute recommends a 1:1:6 2.3.4. Polymer Modified Portland Cement
(portland: lime: sand) or Type N mortar be Grout is a mixture of any of the preceding
used with Indiana Limestone. At the present grouts with polymer admixtures. The common
time, there are few masonry cement mortars polymer types are latex and acrylic. This grout
produced labeled “nonstaining.” is suitable for all installations subject to
ordinary use and for most commercial
2.3. GROUTS installations. The use of polymer additives in
Cementitious grouts used as joint fillers can be portland cement grout increases the flexibility
sanded or unsanded as required. Sanded grouts and reduces the permeability of the grout.
tend to have greater strength and durability Consult the grout and polymer manufacturers
than unsanded grouts but can introduce the risk for specific instructions.
of surface scratching when installed in stone
varieties that are softer than the aggregate in 2.3.4.1. Specifications for polymer modified
the grout and may be difficult or impossible to portland cement grouts can be found in A118.7
install in narrow width joints. American National Standard Specifications for
High Performance Cement Grouts for Tile
2.3.1. Pigments used in colored grouts can be Installation.
difficult to blend in an even manner. This may
cause color spotting and shading in the finished 2.3.5. COLORING OF GROUTS: Many
product. manufacturers offer grouting materials in
colors. Architects and Designers find them
2.3.2. Sanded portland cement grout is pleasing for aesthetic reasons. Since some
normally field-mixed in proportions of one stones are more porous than others, test to
part portland cement to one part clean, fine- determine the stability of the relationship
© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-9
between the colored joint filler and the stone (patios, decks, traffic surfaces) should be
before proceeding. Make certain pigments caulked with materials having sufficient
contained in the colored grout do not stain the abrasion resistance. Consult the Sealant
stone. Manufacturer’s technical recommendations for
sealants in these areas.
2.4. JOINT SEALANTS
2.4.3.7. Oil based organic sealants should not
2.4.1. Unlike grouting, which is commonly be used in conjunction with natural stone
specified in the stone specification, building products because they may stain the stone.
sealants are normally covered in a separate
specification section. 2.4.3.8. Some sealants contain plasticizers
which may wick into the stone perimeter and
2.4.2. Sealants should comply with the cause staining. If exemplar applications are not
requirements documented in ASTM C920 available to verify that the sealant does not
Standard Specification for Elastomeric Joint contain staining plasticizers, testing per ASTM
Sealants. C1248 or ASTM D2203 is highly
recommended.
2.4.3. Common joint sealant chemistries
include silicone, urethane, polysulfide and 2.4.4. BACKER RODS: Proper selection of
latex. the backer rod can greatly influence the
performance of the joint sealant.
2.4.3.1. Urethane sealants are commonly
preferred for horizontal stone surfaces because 2.4.4.1. The backer rod performs three
their typically higher modulus provides greater functions:
resistance to abrasion and penetration. 2.4.4.1.1. Controls the depth and shape
of the sealant profile.
2.4.3.2. Strict adherence to the written
instructions of sealant manufacturer is 2.4.4.1.2. Provides support for the
required. sealant when it is being compressed during
tooling.
2.4.3.3. Primers may be required for some
sealant/substrate combinations. Refer to the 2.4.4.1.3. Acts as a bond breaker for the
manufacturer’s requirements. sealant to prevent three-sided adhesion.
(Three-sided adhesion can result in failure of
2.4.3.4. Some grades of silicone sealants are the sealant.)
not recommended by their manufacturers for
application on high calcite content materials. 2.4.4.2. Backer rods are available as either
Consult the Sealant Manufacturer’s technical “open cell” or “closed cell” type. Closed cell
recommendation before applying a given backer rods are generally preferred as they do
sealant to calcite materials. not absorb water like an open cell rod. Caution
is necessary when installing closed cell rods to
2.4.3.5. All sealants shall be tooled to ensure avoid puncturing the rods. A punctured rod,
proper adhesion to the contact surfaces. during periods of increasing temperature, will
exhaust air as the air trapped within the rod
2.4.3.6. Specialty sealants exist for specific in- expands. This can produce bubbles in the
service conditions. For example, mildew- sealant or breach of the sealant joint.
resistant silicone sealants formulated with
fungicide are often used for sealing interior 2.4.4.3. Consult the Sealant, Waterproofing,
joints in showers and around tubs, sinks, and and Restoration Institute guidelines for further
plumbing fixtures. Severe service areas

Page 13-10 • Horizontal Surfaces © 2022 Natural Stone Institute

information on proper joint sealant design, 2.5.10. A crack suppression membrane is
selection, and installation. recommended when installing stone over
frame construction.
2.4.4.4. Consult sealant manufacturer to
verify warranties are compliant with project 2.5.11. Follow directions of manufacturers of
specifications. all system components.

2.5. PLYWOOD SUBFLOORS 2.6. CEMENTITIOUS BACKER UNITS

2.5.1. Refer to APA form No. E30W for 2.6.1. Cementitious backer units are
plywood installation methods. normally considered to be a bonding layer
only, without providing a significant
2.5.2. Plywood subfloors, including tongue- contribution to the flexural rigidity of the floor
and-groove plywood, must be installed with a assembly.
gap (generally ⅛ inch [3 mm]) between the
sheets to allow for expansion. Stagger all seam. 2.6.2. Comply with manufacturer’s
All subfloor seams should occur over framing, instructions as to installation, bedding, taping,
with underlayment seams occurring and fastening of cementitious backer units.
approximately 25% into the span between
framing members. Plywood should have the 2.6.3. Specifications for cementitious backer
strength axis running perpendicular to the units can be found in A118.9 American
joist. National Standard Specifications for Test
Methods and Specifications for Cementitious
2.5.3. Plywood shall be APA underlayment, Backer Units.
C-C plugged or plugged crossband grade.
2.7. METAL EDGES AND
2.5.4. Inner surfaces must be clean. Remove TRANSITION STRIPS
all sawdust and dirt before applying adhesive.
2.7.1. Metal edges and/or transition strips of
2.5.5. Use a construction adhesive in a different material are recommended required
accordance with manufacturer’s written wherever stone flooring abuts a dissimilar
directions. flooring material.

2.5.6. Allow adhesive to cure per 2.7.2. Comply with manufacturer’s

manufacturer’s recommendations before instructions as to installation and fastening of
beginning stone installation. preformed metal edge strips.

2.5.7. Place screws 6" (150 mm) on center in

both directions or per manufacturer’s 3. PAVEMENT SYSTEMS
directions, whichever is less.
3.1. EXTERIOR INSTALLATION
2.5.8. Align strength axis of both subfloor METHODS:
and underlayment layers.
3.1.1. MORTAR BED BONDED TO
2.5.9. A double layer (subfloor plus CONCRETE SUBSURFACE
underlayment) is recommended for natural
stone installations depending on joist spacing. 3.1.1.1. Preparatory Work. Concrete slabs to
receive bonded mortar beds, shall fulfill the
following requirements:

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-11

3.1.1.2. Substrate slab shall be sloped toward 3.1.2.3. Capillary moisture issues exist.
drains to maintain a uniform depth of the
mortar bed. 3.1.2.4. Where cold or control joints in slab
do not align with stone grid modules.
3.1.1.3. Concrete Slab shall have a textured
surface similar to a fine broom finish and shall 3.1.2.5. Where an unbondable membrane
be free of curing compounds, dust, or any exists.
other foreign materials that would inhibit the
bond of the mortar bed to the slab. 3.1.2.6. In these situations, the slab will
require remedial treatment commensurate
3.1.1.4. Concrete Slabs that require additional with the severity of the problem. These
work to achieve these requirements such as options usually involve a membrane of some
grinding, feathering, patching or scarifying are type and as such the mortar bed cannot be
considered as non-compliant with Industry bonded to the substrate. As with the bonded
Standards for stonework until remedial work mortar bed systems, slope and tolerance of the
has been completed by others. slab shall be such so as to maintain an even
thickness of the bed. Movement joint
3.1.1.5. METHOD. Stone paving should be requirements will also remain the same;
installed in a full mortar bed consisting of one however, the membrane may remain
part portland cement and from three to four continuous.
parts clean washed sand by volume. Minimum
thickness of a mortar bed is 1¼" (30 mm). The 3.1.2.7. The mortar bed must be reinforced in
recommended thickness is 2" (50 mm). any unbonded installation system as specified
Application of a bond coat of portland cement by the design professional.
paste or other approved material (slurry) to
both the paver and the substrate slab is 3.1.3. DRY-PACK MORTAR SYSTEMS
required.
3.1.3.1. Contrary to its name, “Dry-Pack”
3.1.1.6. JOINTS. The joints may be pointed mortar isn’t actually dry, but rather it is simply
with suitable mortar or grout or filled with a under-hydrated compared to mortar mixes
resilient filler strip and approved sealant. that are placed in a plastic state.

3.1.1.6.1. REINFORCING. Reinforcing 3.1.3.2. The rough concrete substrate below

of the mortar bed is recommended for beds of the stone paving installation shall be installed
2” (50 mm) depth or greater and shall be by others. The concrete elevation shall be low
specified by the design professional. enough to provide a minimum bed depth of 2”
(50 mm) between the stone and the concrete.
3.1.2. MORTAR BED SEPARATED FROM The concrete shall be allowed to cure for a
CONCRETE SLAB. This method is used minimum of 28 days.
where the concrete slab may be problematic
such as anticipated differential movement 3.1.3.3. A crack isolation membrane shall be
between the slab and the stone assembly. placed over the concrete slab to prevent
Other factors which favor selection of this bonding of the dry-pack mortar to the
installation method include: concrete. (Six mil polyethylene sheeting has
been found to be effective and economical for
3.1.2.1. Cracks in the slab that may transfer this purpose.)
through a bonded system.
3.1.3.4. The mortar bed to receive the stone
3.1.2.2. Contamination of the slab that may be paving shall consist of dry-pack mortar,
impractical to remove. containing 1 part Portland cement to

Page 13-12 • Horizontal Surfaces © 2022 Natural Stone Institute

approximately three to four parts clean washed 3.1.3.11. Traffic shall be prevented
sand by volume. A simple field test for the from traversing the floor for a minimum of 24
level of hydration of the dry-pack is that one hours after which it shall be grouted with the
should be able to compact it into a “ball” in specified grout material. Grout shall not be
one’s hand. If the mortar can be extruded over-hydrated, and the stiff grout mixture is to
between one’s fingers when squeezing the ball be compacted into the joints until level with
of mortar, it is over-hydrated. the stone surface, then tooled to a slight
concave profile.
3.1.3.5. The dry-pack mortar bed shall be
reinforced by 2” x 2” (50 mm x 50 mm) 16 3.1.4. PEDESTAL SUPPORTED SYSTEMS
gauge (1.5 mm) galvanized welded wire mesh
or as specified by the design authority. The 3.1.4.1. PREPARATORY WORK: Adequate
placement of the mesh shall be within the slope for surface drainage must be provided in
center one-third of the mortar bed. rough concrete slab. Waterproofing and
drainage system must be completed by other
3.1.3.6. The mortar should be spread evenly trades prior to installation of the stone.
over the substrate and screeded flat to the
desired elevation, then loosened or “fluffed up” 3.1.4.2. Stone-supporting pedestals may be
with a shallow toothed rake to assist in cast-in-place concrete, mortar, or plastic.
compression of the dry-pack when tamping the Careful shimming is required to maintain the
stone paver into position. plane of the stone surface at the specified
elevation and to prevent rocking of the finished
3.1.3.7. Before positioning a stone paver onto stone paver. Commercially available threaded
the mortar bed, the back of the paver should be plastic shims are available to efficiently
sponged clean, then dried, after which it shall accomplish the elevation adjustment. (See
be parged with either thinset, or a thick layer illustration at the close of this section).
of neat cement paste. This process is often
referred to as “back buttering”. 3.1.4.2.1. FLEXURAL STRENGTH. In
3.1.3.8. Immediately before placing the stone a pedestal supported pavement system, the
paver on the mortar bed, the dry pack mortar stone unit is a structural member that carries
should be sprinkled with water using a the live and dead loads back to the pedestals.
watering can with multiple small (≤ 1/16” [1.5 Required thickness and pedestal spacing should
mm]) perforations. be determined by a P.E. and must consider
design loads, stone properties, intended traffic
3.1.3.9. The stone paver shall be placed on the and appropriate safety factors. Atypical
mortar bed and tamped with a non-marring loading, such as maintenance vehicles,
mallet until firmly bedded to the proper level emergency vehicles, or performance structures
of the floor. Several iterations of removal and must be considered when determining the
replacement of the stone paver may be anticipated loads.
required to facilitate adding or removing
bedding material before the proper level is 3.1.4.3. OPEN JOINTS. The joints in this
achieved. system are left open, allowing water to flow
below the stone units to be collected and
3.1.3.10. The specified joint width shall transported by the drainage system.
be maintained within documented tolerances
between the paver units. Expansion and 3.1.4.4. Advantages of this system include the
movement joints shall be included per industry elimination of the requirement to slope the
recommendations in the pavement design. stone surface to a drain, since the drainage is
accomplished below the pedestrian deck, and
the ease of removal and replacement of the

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-13

pavers to facilitate maintenance or repair of the exert pressure at the top edge of the stone as
drainage system and waterproofing membranes the pavers displace vertically under load.
below the stone pavers. An additional
advantage is that because the joints are left 3.2. INTERIOR INSTALLATION
open, the edges of the stone pavers are METHODS
ventilated which prevents moisture from
wicking into the stone edges (edge wicking of 3.2.1. TCNA HANDBOOK DETAILS.
moisture can produce “picture framing” Since 2012, the Handbook for Ceramic, Glass,
staining). and Stone Tile Installation” by the Tile Council
of North America has included a section
3.1.5. GRANULAR (SAND) BED dedicated to stone tile installation. The
METHOD Natural Stone Institute has participated in the
Tile Council of North America’s (TCNA)
3.1.5.1. PREPARATORY WORK. Excavate development of this handbook and continues to
unsuitable, unstable, or unconsolidated participate in updates to the document. This
subgrade material and compact the area that document is reprinted every year, although the
has been cleared. Fill and level with densely handbook committee meets only biennially, so
graded crushed stone aggregate suitable for substantial revisions are likely to appear only
subbase material, or as otherwise directed by biennially. The details are not duplicated in the
Specifying Authority. Natural Stone Institute publications. Contact
the TCNA (www.tcnatile.com) or the Natural
3.1.5.2. METHOD. Place bedding course of Stone Institute’s Book Store to obtain a copy of
sharp, normal weight limestone screening or the handbook.
concrete sand to a depth of approximately 1½"
(40 mm) leveled to grade. Compact bedding 3.2.2. MORTAR BED BONDED TO
course parallel to finish grade and tamp. CONCRETE SUBFLOOR. This method is
used where the concrete sub-floor is not
3.1.5.3. Stone pavers shall be laid upon the subject to excessive movement or deflection
bedding course in successive courses. Every (Recommended for installation of larger pieces
course of pavers shall be laid true and even and [slabs]).
brought to grade by the use of non-marring
mallets or similar tools, and shall be laid 3.2.2.1. Concrete to receive bonded mortar
parallel to the base line. After the pavers are beds or direct bond of stone shall fulfill the
laid, the surface shall be swept and inspected. following requirements:
Cover surface with a wood board
approximately 3" (75 mm) thick, 12" 3.2.2.2. Slope if required, shall occur in the
(300 mm) wide, and 6' (2 m) long, and tamp concrete substrate to maintain an even depth or
to intended position. Do all tamping thickness of the mortar bed and/or bond
immediately after laying pavers and do not mortar.
allow tamper to come in contact with pavers.
Broom sand into joints, tamping sand in joints 3.2.2.3. Concrete shall have a textured surface
to ensure full bedding around perimeter of similar to a fine broom finish and shall be free
stone. of curing of curing compounds or any other
foreign materials that would inhibit the bond of
3.1.5.3.1. Joints in granular bedded the mortar bed or bond mortar to the concrete.
systems are typically “hand-tight” to prevent
lateral migration of stone units. Some spalling 3.2.2.4. Undersides and edges of concrete slabs
at the stone surface can be expected as grains of on grade shall have a suitable vapor barrier so
sand get wedged into the nearly tight joints and as to prevent moisture intrusion into concrete.

Page 13-14 • Horizontal Surfaces © 2022 Natural Stone Institute

3.2.2.5. Concrete that requires additional 3.2.3.6. In these situations, the slab will require
work to achieve these requirements such as remedial treatment commensurate with the
grinding, feathering, patching or scarifying are severity of the problem. These options usually
considered to be non-compliant with Industry involve a membrane of some type and as such
Standards for stonework until remedial work is the mortar bed cannot be bonded to the
completed. substrate. The requirement for unbonded
mortar beds is that they be reinforced as
3.2.2.6. Limits of moisture vapor transmission specified by the design professional; usually
shall be established by the stone supplier. with wire at the approximate center of the bed.
Testing and certification of compliance is the As with the bonded mortar bed systems, slope
responsibility of the specifying authority. and tolerance of the slab shall be such as to
maintain an even thickness of the bed.
3.2.2.7. Wash and dry backs and edges of Movement joint requirements will also remain
pavers or tiles prior to installation. the same; however, the membrane may remain
continuous.
3.2.2.8. A mortar bed consisting of one part
portland cement to three to four parts clean 3.2.4. MORTAR BED SEPARATED FROM
washed sand by volume is laid over the WOOD SUBFLOOR. This method is used
concrete subfloor to a nominal thickness of where subfloor is subject to movement and
1¼" (30 mm). Stone is back-buttered deflection.
uniformly with a cement paste bond coat, laid
over the mortar bed and tamped into a true and 3.2.4.1. The mortar bed floats over subfloor
level plane. Joints are grouted with a portland and minimizes possibility of stone cracking
cement based grout or other approved from structural movement. An isolation
material. (See Detail at the close of this membrane is laid over the sub-floor. A mortar
section). bed consisting of one part portland cement to
three to four parts clean washed sand by
3.2.3. MORTAR BED SEPARATED FROM volume with reinforcement specified by the
CONCRETE SUBFLOOR. This method is design professional. Stone tiles are laid over the
used where the concrete slab may be mortar bed and tamped into proper plane.
problematic such as anticipated differential Joints are later grouted with a portland
movement between the slab and the stone cement-based grout or other approved
assembly. Other factors that would favor the material.
selection of this installation system include:
3.2.5. THIN BED OVER PLYWOOD
3.2.3.1. Cracks in the slab that may transfer SUBFLOOR
through a bonded system.
3.2.5.1. This method should be used only in
3.2.3.2. Contamination of the slab that may be residential construction. The subfloor must be
impractical to remove. adequately designed to carry loads without
excessive deflection. Subfloor must be level
3.2.3.3. Capillary moisture issues exist. with a maximum variation of ⅛" in 10'-0"
(3 mm in 3 m), with a deflection not exceeding
3.2.3.4. Where cold or control joints in slab do L/720. Strongbacks, cross-bridging or other
not align with stone grid modules. reinforcement shall be used to limit differential
deflection between adjacent framing members.
3.2.3.5. Where an unbondable membrane Comply with all manufacturers’ written
exists. installation instructions. Apply mortar with flat
side of trowel over an area that can be covered
with tile while mortar remains plastic. Within

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-15

ten minutes and using a notched trowel sized portland cement-based grout or other
to facilitate the proper coverage, comb mortar approved material. (See Detail at the close of
to obtain an even setting bed without scraping this section).
the backing material. Key the mortar into the
substrate with the flat side of the trowel. Back 3.2.7. THIN-BED MORTAR OVER
butter the stone tiles to ensure 95% contact CEMENTITIOUS BACKER UNITS
with no voids exceeding 2 in² (1300 mm²) and
no voids within 2” (50 mm) of tile corners on 3.2.7.1. This method should be used only in
⅜" (10 mm) tile. Back butter the stone tiles to residential construction and per
ensure 80% contact with no voids exceeding 4 manufacturers’ instructions. The subfloor
in² (2600 mm²) and no voids within 2” must be adequately designed to carry loads
(50 mm) of tile corners on ¾" (20 mm) or without excessive deflection. The
thicker material. All corners and edges of stone cementitious backer unit is considered to be a
tiles must be fully supported and contact area bonding layer only and provides negligible
shall always be 95% or greater in water- structural contribution to the flooring system.
susceptible conditions. Joints are later grouted Subfloor must be level with a maximum
with a portland cement-based grout or other variation of 1/16" in 3'-0" (1.5 mm in 1 m),
approved material. with a deflection not exceeding L/720. Cross-
bridging or other reinforcement shall be used
3.2.6. THIN-BED PORTLAND CEMENT to limit differential deflection between
MORTAR OVER CONCRETE SUBSTRATE adjacent framing members. Apply mortar with
flat side of trowel over an area that can be
3.2.6.1. This method is used when space for covered with tile while mortar remains plastic.
full mortar bed is not possible. Concrete Within ten minutes and using a notched trowel
subfloor should not be subject to excessive sized to facilitate the proper coverage, comb
movement or excessive deflection. Subfloor mortar to obtain an even setting bed without
must be level with maximum variation of ¼" scraping the backing material. Key the mortar
in 10'-0" (6 mm in 3 m). Mortar bed is laid into the substrate with the flat side of the
using a notched trowel over subfloor to a trowel. Back butter the stone tiles to ensure a
thickness of not greater than 3/32" (2.5 mm) . minimum of 95% contact with no voids
Apply mortar with flat side of trowel over an exceeding 2 in² (1300 mm²) and no voids
area that can be covered with tile while mortar within 2” (50 mm) of tile corners on ⅜"
remains plastic. Within ten minutes and using (10 mm) tile. Back butter the stone tiles to
a notched trowel sized to facilitate the proper ensure a minimum of 80% contact with no
coverage, comb mortar to obtain an even voids exceeding 4 in² (2600 mm²) and no voids
setting bed without scraping the backing within 2” (50 mm) of tile corners on ¾"
material. Key the mortar into the substrate (20 mm) or thicker material. All corners and
with the flat side of the trowel. Back butter the edges of stone tiles must be fully supported and
stone tiles to ensure a minimum of 95% contact shall always be a minimum of 95% in
contact with no voids exceeding 2 in² water-susceptible conditions. Joints are later
(1300 mm²) and no voids within 2” (50 mm) of grouted with a portland cement-based grout or
tile corners on ⅜" (10 mm) tile. Back butter other approved material.
the stone tiles to ensure a minimum of 80%
contact with no voids exceeding 4 in² 3.3. HEATED FLOOR SYSTEMS
(2600 mm²) and no voids within 2” (50 mm) of
tile corners on ¾" (20 mm) or thicker 3.3.1. In frame construction, the plywood
material. All corners and edges of stone tiles portion of the substrate must be a minimum of
must be fully supported and contact shall be a 1½" (40 mm) exterior glue plywood. Leave a
minimum of 95% in water-susceptible gap between the plywood sheets for expansion.
conditions. Joints are later grouted with a Install a cleavage membrane over the plywood.

Page 13-16 • Horizontal Surfaces © 2022 Natural Stone Institute

3.3.2. Frame and Mortar Bed. Heated floor subtread, or supported by stringers. (See detail
systems are generally proprietary in nature, illustrations at the close of this section).
and the manufacturer’s installation guidelines
shall be closely followed. Consider using a heat 3.5.3. 100% coverage of mortar bed material
deflector on top of the membrane. The heating between tread and subtread is desirable.
contractor should install the heating system per
manufacturer’s recommendation. Fill cavity 3.5.4. Risers ¾" (20 mm) or thicker must be
with a wire or portland mix so that the mortar anchored with wire or stainless steel strap
bed covers pipes and is at least ¾" (20 mm) anchors. If risers thinner than ¾" are used,
over the top of heating pipes, with a minimum they may be adhered using the thin-bed
bed thickness of 2½" (65 mm). Allow to cure portland cement mortar method.
for at least 30 days. This mortar bed thickness
is necessary to dissipate heat to avoid damaging
the stone by uneven heating.
4. TROUBLESHOOTING
3.4. THRESHOLDS AND CAUTIONS

3.4.1. Exposed edges may be eased, 4.1. INSTALLATION METHODS

rounded, arrised or beveled. If instructions are Stone paving can be installed by several
not given as to type of edge required, Supplier methods. Consideration should be given to the
will furnish according to industry standards. various features of each method in making a
selection for a specific installation. See
3.4.2. Thicknesses of ½", ¾", and 1¼" (12, illustrations of installation examples at the
20, and 30 mm), or as specified. close of this section.
3.5. STAIRS
4.2. GEOGRAPHIC METHODS
3.5.1. SIZES: Tread thicknesses of ¾", 1¼", Some installation methods and materials are
and 1½" (20, 30, or 40 mm) are commonly not recognized and may not be suitable in some
used for interior stairs. Thicknesses of 1¼", 2" geographic areas because of local trade
(30, 50 mm) and cubic (greater than 2" [50 practices, building codes, climatic conditions,
mm]) are commonly used for exterior stairs. or construction methods. Therefore, while
Risers may be ¾" or 1¼" (20 or 30 mm) thick, every effort has been made to produce accurate
or in the case of cubic treads, the riser face is guidelines, they should be used only with the
integral with the tread surface stone. independent approval of technically qualified
persons. Some installation methods and
3.5.1.1. In residential applications, thin stone materials are not recognized and may not be
(less than ¾” [20 mm] treads and risers may be suitable in some geographical areas because of
installed using a thin-set portland cement local trade practices, building codes, climatic
mortar bed over clean and level concrete conditions, or construction methods.
subtreads or double layers of ¾" (20 mm) Therefore, while every effort has been made to
plywood installed in opposite directions with produce accurate guidelines, they should be
⅛" (3 mm) gaps between sheets. These types used only with the independent approval of
of applications will not withstand high impact technically qualified persons.
or wheel loads. Overhang is not permitted
when stones of this thickness are used. 4.3. PROTECTION OF FINISHED
WORK
3.5.2. METHODS. Stone stair treads may be During construction, the General Contractor
installed in a cement mortar bed, or in a thin- shall protect all stone from staining and
set cement or epoxy mortar bed, over a damage. After the stone paving has been
installed, the General Contractor must keep all

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-17

traffic off the floors for at least 48 hours. No 4.8.4. Separation or crack-isolation
rolling or heavy (greater than pedestrian) membranes installed between a slab and the
traffic should be permitted on newly installed setting bed may alter the acoustical report.
stone surfaces for at least two weeks after the
floor has been grouted or caulked. 4.8.5. The elevation or composition of the
subsurface may be irregular, causing one part
4.4. PREPARATION OF STONE of the floor to sound differently than another.
UNITS
Wash and dry backs and edges of all pavers 4.9. MOISTURE PENETRATION
prior to installation in any installation method The performance of a properly installed stone
other than pedestal supported pavers. installation is dependent upon the durability
and dimensional stability of the substrate to
4.5. MOISTURE AND ALKALINITY which it is bonded. The user is cautioned that
SENSITIVITY certain substrate materials used in wet areas
Stone suppliers shall identify stones that are may be subject to deterioration from moisture
adversely affected by moisture and alkalinity. penetration.

4.6. SETTING BEDS FOR LIGHT 4.10. WET AREAS

COLORED STONES “Wet areas” are stone surfaces that are either
White Portland cement with low alkali content soaked, saturated, or subjected to moisture or
is recommended for light colored stone. liquids (usually water), e.g., gang showers, tub
enclosures, showers, laundries, saunas, steam
4.7. TRANSITIONS FROM STONE TO rooms, swimming pools, hot tubs, and exterior
SOFT FLOORING areas.
Where stone abuts softer flooring materials, a
stone threshold or metal edge protection strip 4.11. FIBERGLASS MESH BACKING
is recommended. This will help prevent edge Producers frequently apply a fiber mesh
chipping caused by impact. reinforcement to the back surfaces of stone
tiles and slabs to reduce breakage and also to
4.8. HOLLOW SOUND increase safety when handling large slabs.
Because of the weight and consequent Caution should be used when using a stone that
difficulties in handling large-sized pavers, it is has a fiberglass mesh backing applied on the
impossible to avoid an occasional “hollow” back face. The fiberglass, having been bonded
sound found in some stone units after to the stone with a resinous (commonly epoxy,
installation. Reasons for hollow sounds although sometimes polyester or other
include: adhesive chemistries) adhesive, will not bond
adequately with cementitious products. Only
4.8.1. A hollow sound may indicate that epoxy products, or products specifically made
insufficient bonding of the paver exists, for fiberglass by the manufacture should be
although it is not necessarily a reliable test. used when installing stone with fiberglass mesh
Other influences can cause a hollow sound backing.
from a properly bonded paver.
4.12. GREEN COLORED STONE
4.8.2. Hollow sounds may be acoustical Avoid the use of water-based adhesive when
effects rather than bonding problems. installing certain green marbles and/or
serpentines. Some of these stones may warp
4.8.3. Air may be entrapped in either the through absorption of water from the setting
setting bed or slab, causing one part of the floor bed. (Water drawn into the stone is held to the
to sound differently than another. crystals by surface energy. This force tends to

Page 13-18 • Horizontal Surfaces © 2022 Natural Stone Institute

widen the intercrystalline space and thereby occur and flake off successive layers. For this to
expand the wet side.) happen, large amounts of water must continue
to enter behind the stone and must contain
4.13. VOIDS IN TRAVERTINE large amounts of salts.
Travertine flooring, particularly fleuri cut (also
called “cross-cut) will have voids occurring just 4.16. LIGHTING OF HIGH
below the finished surface of the material. ANGLES OF INCIDENCE
Since these voids are concealed by a thin shell Lighting with a high angle of incidence, in
of stone material, they do not get filled in the which the path of light is nearly parallel to the
factory filling process. Once in service, face of the wall surface, is a popular choice in
concentrated loads (e.g., loads from wheels or both interior and exterior designs. This
spike heels) will fracture the thin shell of stone, lighting style will exaggerate lippage, textural
exposing the void below. Several iterations of surface variation, and even warpage due to the
re-filling travertine floors in place can be extremely elongated shadow lines caused by
expected until these voids are all discovered. the angle of incidence. Material and
This is essentially a “break-in” process for this installation which are within industry
particular material and is not considered a tolerances may appear to be outside of
defect in the stone. tolerances due to the accentuation of the
lighting technique. Inspection of areas
4.14. SEALANT STAINING receiving such lighting shall be done with the
Some elastomeric sealants contain oil-based lighting turned off or otherwise blocked.
plasticizers to reduce their modulus and
increase their extension/compression 4.17. VARIATION IN GLOSS
capability. The plasticizers can wick into stone It is almost impossible to uniformly read light
perimeters, causing darkening of the edge reflection on a polished or high-honed-finish
(picture framing) and accelerated dirt installation due to the natural characteristics of
collection on the stone face. Caution should be dimension stone. Due to the heterogeneous
used in specifying sealants to ensure composition of natural stones, variable mineral
compatibility with stone. It is recommended hardness exists within the stone, producing
that either an exemplar project be identified variable reflectivity of light energy. Most
using the same stone and sealant components stones, especially travertine marbles and
with satisfactory results, or a testing regimen limestones, will appear to reflect light
(per ASTM C1248 or ASTM D2203) be unevenly.
employed to verify compatibility.
4.18. POLISHING WHEEL MARKS
4.14.1. Some sealant manufactures maintain a Polishing wheel marks or other scratches
database of stone projects using joint sealers caused during fabrication are unacceptable on
from that manufacturer to aid in identifying honed or polished stone.
exemplar projects for evaluation.
4.19. SNOW MELTING CHEMICALS
4.15. EFFLORESCENCE Many stones, especially limestones, are
Efflorescence is a salt deposit, usually white in vulnerable to attack from snow melting
color that appears on exterior surfaces of stone chemicals, particularly salt. The attack is
walls and floors. The efflorescence is produced actually mechanical, rather than chemical. In
by salts leached to the surface of the stone by solution, the salt can penetrate the pores of the
water percolating through the stone backup stone, but when the water evaporates, the salt
and joints. The most feasible means of recrystallizes within the pore. The resultant
prevention is to stop the entrance of large recrystallization pressure can exfoliate the
amounts of water. If the conditions bringing surface of the stone.
about the efflorescence continue, scaling may

© 2022 Natural Stone Institute Horizontal Surfaces • Page 13-19

NOTES:

Page 13-20 • Horizontal Surfaces © 2022 Natural Stone Institute

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

GROUT OR STONE PAVER

ELASTOMERIC SEALANT

BOND COAT

MORTAR OR DRY-PACK
MORTAR BED AS SPEC'D

MORTAR BED
BOND COAT

CONCRETE
SUB-SLAB

MORTAR BED WITH BOND COAT

1
ELASTOMERIC
SEALANT &
GROUT OR THINSET STONE PAVER BACKER ROD
ELASTOMERIC SEALANT

CONCRETE
SUB-SLAB

GRAVEL BED

MORTAR BED WITH THINSET MOVEMENT JOINT

2 2A

ELASTOMERIC SEALANT & STONE PAVER

COMPRESSIBLE BACKER
ROD OR FILLER STRIP
SLOPE TO DRAIN

REINFORCING AS REQ'D

EXPANSION MATERIAL MORTAR OR DRY-PACK

MORTAR BED AS SPEC'D

CONCRETE
CRACK ISOLATION SUB-SLAB
MEMBRANE

FULL MORTAR BED WITH MEMBRANE AND EXPANSION JOINT

3

NOTE: IT IS NOT THE INTENT OF THIS MANUAL TO MAKE EXPANSION, CONTROL, OR MOVEMENT JOINT
RECOMMENDATIONS FOR A SPECIFIC PROJECT. THE SPECIFYING AUTHORITY MUST DESIGN AND LOCATE
EXPANSION, CONTROL, AND MOVEMENT JOINTS ON THE CONSTRUCTION DOCUMENTS.

REV DATE
EXTERIOR STONE PAVING
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-1
3" = 1'-0"

© 2022 Natural Stone Institute 13-D-1

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SAND SWEPT JOINT STONE PAVER

1 1/2" THICK LIMESTONE

SCREENING

4" CRUSHED STONE BASE

SUB SOIL

STONE PAVERS SET IN SAND BED

1 Scale: 3" = 1'-0"

OPEN JOINTS TO ALLOW PAVER THICKNESS TO BE WATERPROOFING

DRAINAGE TO BELOW ENGINEERED BASED ON MEMBRANE
STONE STRENGTH, SPAN
AND LOADS

SLOPE TO DRAIN

PEDESTAL SUPPORTED STONE PAVERS

2
Scale: 112" = 1'-0"
(GRAPHIC COURTESY OF BISON INNOVATIVE PRODUCTS)

REV DATE
EXTERIOR STONE PAVING
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-2
As Noted
13-D-2 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

GROUT STONE TILE

BOND COAT

MORTAR BED

STONE TILE
MORTAR BED
BOND COAT

CONCRETE THIN SET

SUB-SLAB MORTAR

STONE TILE SET IN MORTAR BED CONCRETE

1 SUB-SLAB

REINFORCING STONE TILE

STONE TILE SET IN THIN-SET
AS REQ'D
4 BED OVER CONCRETE SLAB
BOND COAT

MORTAR BED

CRACK ISOLATION
MEMBRANE

CONCRETE
SUB-SLAB
STONE TILE

STONE TILE SET IN

2 REINFORCED MORTAR BED THIN SET
MORTAR BED

UNCOUPLING
REINFORCING STONE TILE MEMBRANE
AS REQ'D
DOUBLE LAYER
PLYWOOD SUB FLOOR

BOND COAT

MORTAR BED

STONE TILE SET IN THIN-SET BED

CRACK ISOLATION
MEMBRANE 5 WITH UNCOUPLING MEMBRANE
OVER WOOD FRAME
DOUBLE LAYER
PLYWOOD SUBFLOOR

STONE TILE SET IN

3 REINFORCED MORTAR BED
OVER WOOD FRAME

REV DATE
INTERIOR STONE FLOORING
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-3
3" = 1'-0"

© 2022 Natural Stone Institute 13-D-3

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

STONE TILE

REINFORCING
MESH

HEATING PIPES

MORTAR BED
3/4" MIN OF COVERAGE AROUND PIPES

HEAT REFLECTOR (OPTIONAL)

MEMBRANE

CONCRETE SUBSTRATE

STONE TILE OVER HYDRONIC RADIANT HEAT

1 SYSTEM WITH CONCRETE SUBSTRATE

STONE TILE

HEATING PIPES

MORTAR BED
3/4" MIN OF COVERAGE AROUND PIPES

HEAT REFLECTOR (OPTIONAL)

MEMBRANE

DOUBLE LAYER PLYWOOD

FLOOR FRAME SYSTEM

STONE TILE OVER HYDRONIC RADIANT HEAT

2 SYSTEM WITH WOOD FRAME SUBSTRATE

REV DATE
INTERIOR STONE FLOORING
0 MAR 2022 RADIANT HEAT DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-4
3" = 1'-0"
13-D-4 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

DOOR

MORTAR BED TILE FLOORING STONE TILE FLOORING

THRESHOLD

VARYING BED DEPTH MORTAR METHOD

1

STONE
THRESHOLD DOOR STONE FLOORING

NON-STONE MORTAR BED

FLOORING

FULL MORTAR BED METHOD

2

EASED EDGE DOOR

TILE FLOORING STONE ADJACENT FLOOR
THRESHOLD COVERING
MORTAR BED
THINSET
MORTAR BED

THIN-SET METHOD
3

NOTES: 1. USE 100% COVERAGE OF BOND COAT MATERIAL BETWEEN THRESHOLD AND SUB-SLAB
2. MINIMUM ABRASIVE HARDNESS OF THRESHOLD MATERIAL SHOULD BE 12.0 (ASTM C241 OR C1353)

REV DATE
STONE THRESHOLDS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-5
3" = 1'-0"

© 2022 Natural Stone Institute 13-D-5

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

STAINLESS
STEEL DOWEL

SOLID MORTAR
SETTING BED

STEEL PAN
SOLID MORTAR
SETTING BED

CUBIC STEP DETAIL STEP DETAIL ON METAL PAN

1 SCALE: 1½" = 1'-0" 2 SCALE: 3" = 1'-0"

STAINLESS
STEEL DOWEL

SOLID MORTAR
SETTING BED

STEEL PAN
SOLID MORTAR
SETTING BED

CUBIC STEP DETAIL STEP DETAIL ON METAL PAN

3 SCALE: 1½" = 1'-0" 4 SCALE: 3" = 1'-0"

NOTES: 1. USE 100% COVERAGE OF BOND COAT MATERIAL BETWEEN THRESHOLD AND SUB-SLAB
2. MINIMUM ABRASIVE HARDNESS OF THRESHOLD MATERIAL SHOULD BE 12.0 (ASTM C241 OR C1353)

REV DATE
STONE STAIR DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-6
As Noted
13-D-6 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

STRAP ANCHOR

STAINLESS
STEEL DOWEL

SOLID MORTAR
SETTING BED

CONCRETE
SUB SLAB

VENEERED STEP DETAIL

5

STAINLESS
STEEL DOWEL

SOLID MORTAR
SETTING BED

CONCRETE
SUB SLAB

HOOKED STEP DETAIL

6

NOTES: 1. A ROUGH OR TEXTURED FINISH IS RECOMMENDED FOR EXTERIOR USAGE

2. MINIMUM ABRASIVE RESISTANCE OF STONE TREAD MATERIAL SHOULD BE 12.0 (ASTM C241 OR C1353)
3. FABRICATION LABOR REQUIREMENTS COMMONLY MAKE DETAIL 6 A HIGHER COST ALTERNATIVE

REV DATE
STONE STAIR DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-7
1 1/2" = 1'-0"

© 2022 Natural Stone Institute 13-D-7

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

ABRASIVE
(SLIP-RESTRAINT)
INSERT
COPPER OR STAINLESS STEEL
WIRE ANCHOR (OR STAINLESS
ABRASIVE 1/16" JOINT
STEEL STRAP ANCHOR)
(SLIP-RESTRAINT)
INSERT SOLID MORTAR
SETTING BED

NON-CORROSIVE
METAL RISER
STONE RISER

SOLID MORTAR
SETTING BED

STEEL STRINGERS

STEP DETAIL ON METAL PAN STEP DETAIL ON METAL PAN

1 2
CL FOR STONE
BALUSTERS ABOVE

SOLID MORTAR
ALT: CLIP
SETTING BED
ANGLE WITH
LINER PLATE

STEEL STRINGER
COPPER OR STAINLESS
STEEL WIRE ANCHOR
(OR STAINLESS STEEL
STRAP ANCHOR)
STONE RISER
STEEL PAN
STONE LINER
WITH DOWEL

EYE BOLT @
EACH JOINT

STAINLESS
STEEL PIN
SOLID MORTAR
SETTING BED

VENEERED STEP DETAIL STEP DETAIL ON METAL PAN

3 4
REV DATE
STONE STAIR DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 13-D-8
3" = 1'-0"
13-D-8 © 2022 Natural Stone Institute
VERTICAL SURFACES 1.1.3. LABOR ASSIGNMENT: The
successful installation of both dimension stone
and stone tile is dependent upon the
1. DESIGN CRITERIA experience and craft knowledge of the firm
Design of vertical surfaces, particularly in contracted to install the stone. The Natural
exterior applications, require several factors to Stone Institute endorses the use of NSI
be taken into account. Amongst others, these Accredited Natural Stone companies. See
include climatic conditions such as wind, www.naturalstoneinstitute.org for a directory
seismic, freeze-thaw cycles; material of installation companies accredited by the
properties of the stone selected and the NSI.
structural back up provided by the building 1.1.4. ASTM C119 outlines the terminology
engineer. The building classification, local relating to dimension stone and provides a brief
building codes and material selected will description of some of the stone groups. There
dictate the appropriate minimum factors of are numerous suitable materials available for
safety, preferred method of installation and cladding in each group, however one must be
optimal anchoring system. These may vary aware that stone, being a natural material, may
from state to state and/or specified building have significantly varying properties within
classification. It is for these reasons that we each group. Additionally, physical and
strongly recommend a qualified stone engineer mechanical properties of the stone, panel size,
and accredited installer be engaged from panel thickness, design loads, and climatic
preconstruction through final construction conditions can determine whether a stone is
phases to ensure a successful project delivery. suitable for a given application.
1.1. STONE SELECTION AND SUPPLY 1.1.5. As a general rule, stone panel thickness
should be a minimum of 1¼" (30 mm) for
1.1.1. STONE PRODUCT DEFINITIONS exterior installations and a minimum of ¾”
(20 mm) for interior installations, but in many
1.1.1.1. TILE. A stone tile is a thin, flat piece cases heavier thicknesses are necessitated.
of natural stone used as finishing material, with Panel sizes and thicknesses may also be dictated
a gauged thickness ranging from ¼" to ⅝" (6 by local codes, wind load requirements, areas
to 16 mm) inclusive and having no dimension of usage, and material performance as
greater than 2’ 0” (610 mm). Tiles are determined by ASTM standard specifications.
normally supplied in typical sizes, with all Refer to ASTM C1528 for recommendations
atypical pieces being field cut to fit. of minimum stone thickness.
1.1.1.2. CUT-TO SIZE. Cut-to-size stone 1.1.6. SHOP DRAWINGS: Detailed shop
products, also referred to as “slab stock” stone drawings shall be provided by the stone
products, are custom fabricated pieces of contractor. Shop drawings shall address:
natural stone. Fabrication of these products
normally occurs in a shop setting, where each 1.1.6.1. Stone type and finish
piece is custom fabricated to specific sizes, but
partial fabrication may also occur in the field at 1.1.6.2. Stone sizes, thicknesses, joinery and
the time of installation. patterning
1.1.2. TOLERANCES. Natural stone tiles 1.1.6.3. Vein and rift directions, if appropriate
and cut-to-size products may have different
fabrication tolerances due to their different 1.1.6.4. Joint sizes and treatments
methods of fabrication. Refer to the Chapter
22 on Tolerances of this manual for fabrication 1.1.6.5. Identification of mortar, adhesive, and
and installation tolerances. grout types.
© 2022 Natural Stone Institute Vertical Surfaces • Page 14-1
1.1.6.6. Details of mechanical anchorage, 1.1.10.2. The anticipated loads
including anchor devices and metallurgy of
same. 1.1.10.3. Required factors of safety

1.1.6.7. Structural Backup 1.1.10.4. Generally, large panel

dimensions can create supply and/or
1.1.6.8. Flashing and/or other means of water anchorage difficulties. The designer is
management encouraged to verify obtainable dimensions
with the quarrier of the material prior to
1.1.6.9. Relationship/interface between stone finalizing the design.
and adjacent building materials
1.1.11. Each stone variety used for exterior
1.1.7. FABRICATION: Exterior veneer veneer should conform to the applicable ASTM
units are precut and prefinished to dimensions standard specification and the physical
specified on shop drawings and are typically requirements contained therein. The
delivered to the job site ready to install. specification for each stone type follows:

1.1.7.1. All required carving shall be 1.1.11.1. Granite: ASTM C615,

performed by skilled tradespeople in strict Standard Specification for Granite Dimension
accordance with approved full-size details or Stone
models. Architectural drawings will show
approximate depth and relief of carving. 1.1.11.2. Limestone: ASTM C568,
Carved surfaces shall be left as produced by the Standard Specification for Limestone
carving tool(s), unless otherwise specified. Dimension Stone

1.1.8. FINISHES: Most commercially 1.1.11.3. Marble: ASTM C503,

available stone finishes are suitable for exterior Standard Specification for Marble Dimension
veneer, however, some stones, notably calcitic Stone
materials such as marbles and limestones, will
not retain a polished finish in exterior 1.1.11.3.1. Soundness Classifications:
environments. Refer to Chapter 7 for a complete discussion of
Marble Soundness Classifications.
1.1.8.1. Some fabricator applied treatments,
such as resin, may have inadequate resistance 1.1.11.4. Onyx: No ASTM Standard
to weathering. exists at this time.

1.1.9. COLORS: A wide variety of color 1.1.11.5. Quartz-based Stone: ASTM

options are available, provided they meet or C616, Standard Specification for Quartz-based
exceed the necessary performance Dimension Stone
specifications of the project.
1.1.11.6. Serpentine: ASTM C1526,
1.1.10. Panel Sizes and Thicknesses may need Standard Specification for Serpentine
to be determined by engineering analyses. The Dimension Stone
following properties should be considered
when determining size and thickness of stone 1.1.11.7. Slate: ASTM C629, Standard
veneer units: Specification for Slate Dimension Stone

1.1.10.1. Flexural Strength (Ref: ASTM 1.1.11.8. Soapstone: No ASTM

C880) or Modulus of Rupture (Ref: ASTM Standard exists at this time.
C99) of the stone

Page 14-2 • Vertical Surfaces © 2022 Natural Stone Institute

1.1.11.9. Travertine: ASTM C1527, damage as there may or may not be a suitable
Standard Specification for Travertine replacement available for a given stone. A dry
Dimension Stone lay is generally considered to be a wise
investment for decorative interior office lobby,
1.1.12. Caution is advised when using floor and wall projects. It provides a beneficial
historical test data for natural stones. It is team building experience and the formal
preferable to use data obtained from test approval of all stone prior to shipment helps
specimens from current quarry production that eliminate jobsite anxiety and rejections.
is representative of the actual product being
supplied. Test data should be obtained from 1.2.3. A performance mockup may also be
testing agencies specializing in natural stone required to verify the structural and/or
testing. weatherproofing capabilities of the designed
system.
1.2. SAMPLES AND MOCKUPS
The stone supplier shall provide samples of the 1.3. INSPECTION
various dimension stones to be used per the Inspection of supplied material to evaluate
requirements of the project specifications. compliance with approved samples or mockups
Samples shall indicate the extremes of color, shall be done at a viewing distance of not less
veining, and marking that the stone supplied to than 6’-0” (2 m) with natural lighting, from a
the project will have. vantage point that is perpendicular to the face
of the stone.
1.2.1. Pending the scope of the installation
and the variability of the stone product, a full- 1.4. FIELD REPAIR
sized visual mockup may be required to
adequately demonstrate the range of the 1.4.1. During the progress of construction,
material’s color and character. Mockups are changes are often necessary to accommodate
intended to demonstrate the full range of color other trade and design revisions. These changes
tones and natural characteristics of the stone to may require job site cutting and some finishing
be expected across the entire project yet of stone, and this can be satisfactorily executed
condensed into the much smaller surface area by qualified mechanics.
of the mockup. Therefore, the effects of the
variation and characteristics of the stone will be 1.4.2. Repair or patching is sometimes
more concentrated and appear more extreme necessary due to damage of material either on-
than the actual project since the actual project site or in transit. By allowing these repairs to
will have less frequent occurrences of these be made on-site, progress of the job can be
elements. maintained, thus aiding the successful
completion of the work. Repairs should not
1.2.2. Pending the scope of the installation detract from the desired appearance or
and the variability of the stone product, a “dry- strength of the completed installation.
lay” may be required to adequately
demonstrate the range of the material’s color 1.5. CAVITIES
character, and finish, with the advantage of Cavities behind stone facades are commonly
predetermining the actual position and used to provide space for anchorage,
orientation of each stone panel. The dry-lay insulation, and other components in addition
allows the design professional to see the actual to accommodating fabrication and construction
blend of the finished wall, and also allows the tolerances of both the stone and backup
arrangement of pieces to be adjusted per system.
his/her desires. Since each stone panel is
dedicated to a specific location, crating and 1.5.1. Cavities shall have weeps, commonly
handling must be skillfully executed to prevent at intervals of 3 to 4 ft (1 to 1.5 m) at their

© 2022 Natural Stone Institute Vertical Surfaces • Page 14-3

lowest point and at any level where water Most anchors will fall under one of the
cannot freely travel vertically within the cavity following categories:
(such as where continuous shelf angles or
flashings exist). 1.7.1. STRAP ANCHORS: Anchors formed
from light gauge (≤ 3/16”, ≤5 mm) metal,
1.5.2. Cavities shall be vented to provide usually stainless steel, and feature a “tab” that
additional evacuation opportunities for water engages a slot penetration or “kerf” in the
vapor and to reduce possible pressure perimeter of the stone, are commonly referred
differentials between the cavity and the to as “strap anchors”. Strap anchors carry
ambient pressure. lateral loads only, with the gravity loads carried
by other means.
1.5.3. ADDITIONAL TECHNIQUES. With
today’s improved construction techniques, it is 1.7.2. PIN ANCHORS: Pin anchors consist
possible to produce structures that are highly of a pin swaged into a strap, with the strap
resistant to natural weather conditions. Joints attached to the backup structure and the pin
can be sealed with resilient sealants and the penetrating a drilled hole in the edge of the
building interiors can be temperature- and stone. Pin anchors are more challenging to
humidity-controlled. Venting of the cavity is align between successive courses than strap
recommended to prevent moisture problems. anchors, but are sometimes preferable to strap
It is recommended that a vapor barrier be anchors since the penetration required in the
installed at the exterior face of the backup wall. stone removes less material and in some cases
In most cases, the back face of the stone should results in greater lateral capacity for the
not be sealed. anchor.

1.5.4. VENEER CAVITIES: Solid grouting of 1.7.3. DOWEL ANCHORS: Anchors

stone veneer cavities that would permit the consisting of a simple section of dowel, usually
capillary transmission of moisture through the stainless steel, are referred to as dowel
wall from exterior to interior, and interior to anchors. These anchors engage a drilled hole
exterior, is generally considered inadvisable. in the edge of the stone, with the opposite end
However in some cases, particularly rubble of the dowel penetrating a rigid material,
stone construction, solid-filled collar joints are oftentimes concrete, to provide the necessary
used. connection. Dowel anchors typically carry
lateral loads, but in some cases (i.e.: liner
1.6. FLASHING blocks) are responsible for gravity loads.
Condensate is expected to form within cavities
and will travel downward within the cavity 1.7.4. SHELF ANCHORS: Shelf anchors are
until it reaches a location where it is directed usually a section of extruded angle or bent
out. Flashing is required at any location where plates, either stainless steel or corrosion
water must be prevented from seeping behind protected mild steel, that carry gravity loads.
attached elements and at any location where
water must be prevented from contacting the 1.7.5. BENT PLATE ANCHORS: Bent
area below. Flashing can be either membrane plates, either formed from one metal section or
or sheet metal. welded from multiple sections, carry
bidirectional loads (lateral and gravity).
1.7. ANCHORS Essentially, they are a hybrid combination of a
Anchorage systems must be securely attached strap and shelf anchor. They are usually made
and located as shown on the approved shop of stainless steel since a portion of the anchor
drawings and shall be plumb and in true plane. penetrates and/or is in contact with the stone.
Numerous types of mechanical anchorage
devices have been developed over decades.

Page 14-4 • Vertical Surfaces © 2022 Natural Stone Institute

1.7.6. BACK ANCHORS: Back anchors work hardening. Excessive work hardening of
include any of several devices that penetrate the wire can lead to embrittlement of the
the back surface of a stone panel with a metal. Care must be taken to ensure that the
positive, mechanical locking feature. Most physical properties of the wire have been
back anchors are capable of providing improved and not degraded by this process.
bidirectional load carrying capacity and can
therefore be used to address both lateral and 1.7.9. OTHER ANCHORAGE DEVICES:
gravity loads. Standard, custom, and proprietary anchorage
devices are available for stone panel
1.7.7. MASONRY BED ANCHORS: These attachments. A representation of many of the
anchors do not penetrate the stone but are commonly used devices can be found in the
merely embedded in the mortar joints of split- graphics section of this chapter. Additional
face ashlar or similar installations. They can be information can also be found in the Natural
wire loops or corrugated metal. These types Stone Institute’s Technical Bulletin on
of anchors are only recommended for stone Dimension Stone Anchorage.
greater than 3” (75 mm) in thickness.
1.7.10. THIN STONE ANCHORAGE:
1.7.8. WIRE TIE ANCHORAGE: Wire tie Natural stone in thicknesses of less than ¾” (20
anchorage is a historically effective method of mm) are usually not capable of accommodating
anchoring stone panels and has been used mechanical anchors and must be secured by
successfully for centuries. However, this adhesive attachment.
installation must be carried out by a qualified
and trained marble or stone mason. Additional 1.7.11. ANCHOR SIZE: Anchor sizing is
considerations when using wire tie anchorage dependent upon materials, codes, physical
are listed below: conditions of the structure, wind and seismic
requirements, thermal properties, etc.
1.7.8.1. Wire anchors are not generally Anchors should be engineered separately for
recommended for installations exceeding 15’- each condition.
0” (4.5 m) vertically.
1.7.12. METALLURGY: Anchors shall be of
1.7.8.2. Copper is the most commonly used non-staining, corrosion resistant metals.
wire, although stainless steel wire (¼ Hard Stainless steel, aluminum, bronze, brass, and
Series 304 stainless steel wire is often specified copper wire are commonly used for their
as it provides a reasonable balance between corrosion resistance. (See illustrations of
workability and strength) is recommended in typical anchors and accessories at the close of
lieu of copper wire for exterior or wet area this chapter). In exterior cladding systems,
interior applications. stainless steel and aluminum are the most
common, and series 304 stainless is the most
1.7.8.3. A plaster or cementitious dollop, or common alloy of stainless steel used for
“spot” is used in conjunction with the wire tie. anchorage. Copper, bronze and brass are
When wire tie anchorage is used for exterior normally limited to interior applications.
or wet areas the spot material shall be of a
portland cement based compound. Setting 1.7.13. ANCHOR QUANTITY: Weight,
plaster, moulding plaster, or other gypsum size, shape, and type of stone along with
based products are strictly limited to interior, loading requirements will determine the
dry environments. number, spacing and size of the anchors . Four
anchors per panel is generally considered to be
1.7.8.4. When copper wire is used, it is both minimum and optimum, although certain
common in some geographical regions to twist conditions may mandate additional anchor
the wire to stiffen the wire via metallurgical locations. IBC currently prescribes minimum

© 2022 Natural Stone Institute Vertical Surfaces • Page 14-5

anchorage quantities for non-engineered “stone 1.7.15.1.3. Verify that the elastomeric
veneer” and “slab type veneer” based on the material is non-staining.
surface area of the stone panels. Due to varying
loads, stone properties, and anchor capacities, 1.7.15.2. Elastomeric fillers of high
this may not necessarily be adequate, modulus sealants are commonly used to allow
particularly when public or occupant safety greater flexibility to accommodate building
may be compromised. It is recommended that movements.
exterior stone cladding systems be reviewed by
an experienced stone cladding engineer to 1.7.15.3. Extremely rigid fillers, such as
verify anchor and panel capacities. In all cases, epoxy are generally not recommended,
anchorage shall be compliant with the project although there are some instances where they
specifications, requirements of the engineer of are appropriate.
record, and/or applicable codes.
1.7.15.4. The use of gypsum plaster
1.7.14. ANCHOR PLACEMENT: Anchors (molding plaster) setting spots or gypsum
shall be placed per the locations indicated on based compounds for anchor preps fillers for
the approved shop drawings and engineer’s exterior stone is not an acceptable practice.
calculations.
1.7.15.5. Some anchors, specifically
1.7.14.1. When possible, it is preferred back-anchors, are designed to be used without
to reduce flexural stresses in stone panels by filler in the anchor prep. Consult the anchor
positioning anchors at optimum locations in the manufacturer’s directions regarding the use, or
panel. nonuse, of filler for these anchors.

1.7.14.2. In some cases, for instance 1.8. MORTARS AND ADHESIVES

anchoring highly decorative stones with limited
soundness in interior installations, it is 1.8.1. PORTLAND CEMENT MORTAR:
preferred to allow the field mechanics to Portland cement mortar is a mixture of
determine the anchor placement so that portland cement, sand, and lime in proportions
unsound regions of the stone panel can be of 1:3:½ to 1:4:½ for walls. Additional
avoided. additives may be included in this mortar recipe.
The stone is set with this mortar while the
1.7.15. FILLING OF ANCHOR PREPS: mortar bed is still in a plastic state.
Anchor preps in stone panels shall be filled to
prevent rattling of the stone panel and to 1.8.1.1. Portland cement mortars can be
prevent moisture collection in the anchor prep reinforced with metal lath or mesh, backed
in wet area installations. with membranes, and applied on metal lath
over sheathed studding.
1.7.15.1. Fillers may be cementitious or
elastomeric and must be non-expanding. 1.8.1.2. Portland cement mortars are
structurally strong, generally resistant to
1.7.15.1.1. Only flexible filler materials prolonged contact with water, and can be used
are recommended for continuous kerf to plumb and square surfaces installed by
anchorage. others.

1.7.15.1.2. Cementitious fillers are 1.8.2. THIN-SET MORTAR: Thin-set

generally used for stone that are fully bedded mortar, often times called “dry-set mortar”, is
in mortar, while elastomeric fillers are a mixture of portland cement (although a few
commonly used for thin cladding which will are not cement-based) with sand and additives
have caulked joints. providing water retention. Thin-set mortars

Page 14-6 • Vertical Surfaces © 2022 Natural Stone Institute

are used both as bedding/adhesive layers and mortars for setting limestone and other light
also as a bond coat for setting stone with other colored stones shall be of white portland
mortar systems. cement per ASTM C150, or white masonry
cement per ASTM C91. Nonstaining cement
1.8.2.1. Thin-set mortar is available as a shall contain not more than 0.03% of water-
factory-sanded mortar to which only water soluble alkali when determined in accordance
need be added. Cured thin set mortar is with procedure 15, calculation 16 of ASTM
generally tolerant of prolonged contact with C91 or Federal Specification SS-C181C.
water but does not form a water barrier. However, if a large amount of standard cement
has been used in the backup material and an
1.8.2.2. Thin-set mortar is not intended to be effective water barrier has not been provided
used in trueing or leveling the substrate between the stone and the backup, the use of
surfaces as tile is being installed. nonstaining cement may not prevent
discoloration. Discoloration will reduce or
1.8.2.3. Specifications for various thin-set disappear as the stone dries. The Indiana
mortar varieties can be found in ASNI A118 as Limestone Institute recommends a 1:1:6
below: (portland: lime: sand) or Type N mortar be
used with Indiana Limestone. At the present
1.8.2.3.1. A118.1: American National time, there are few masonry cement mortars
Standard Specifications for Dry-Set Cement produced labeled “nonstaining.”
Mortar
1.9. GROUTS
1.8.2.3.2. A118.3: American National Cementitious grouts used as joint fillers can be
Standard Specifications for Chemical Resistant, sanded or unsanded as required. Sanded grouts
Water Cleanable Tile-Setting and -Grouting tend to have greater strength and durability
Epoxy and Water Cleanable Tile-Setting than unsanded grouts, but can introduce the
Epoxy Adhesive risk of surface scratching when installed in
stone varieties that are softer than the
1.8.2.3.3. A118.4: American National aggregate in the grout, and can be difficult or
Standard Specifications for Modified Dry-Set impossible to install in narrow (≤⅛”, ≤3 mm)
Cement Mortar width joints.

1.8.2.3.4. A118.5: American National 1.9.1. Sanded portland cement grout is

Standard Specifications for Chemical Resistant normally field-mixed in proportions of one
Furan Mortars and Grouts for Tile Installation part portland cement to one part clean, fine-
graded sand (per ASTM C144) used for joints
1.8.2.3.5. A118.8: American National up to ⅛" wide; 1:2 for joints up to ½" wide;
Standard Specifications for Modified Epoxy and 1:3 for joints over ½" wide. Hydrated lime
Emulsion Mortar/Grout may be added, not exceeding 1/5 part. Damp
curing is preferable.
1.8.2.3.6. A118.11: American
National Standard Specifications for EGP 1.9.1.1. Sanded-portland cement grout should
(Exterior Glue Plywood) Latex-Portland be applied with caution with softer varieties of
Cement Mortar stone with honed or polished finishes because
1.8.2.3.7. A118.15: American it may scratch the stone surface. Masking of
National Standard Specifications for Improved the stone may be necessary.
Modified Dry-Set Cement Mortar
1.9.2. Unsanded portland cement grout is a
1.8.3. Limestone (or other light-colored commercially available mixture of portland
stones) Setting Mortar: Cement used in cement and other ingredients, producing a
© 2022 Natural Stone Institute Vertical Surfaces • Page 14-7
water-resistant, dense, uniformly colored 1.10.2. Sealants should comply with the
material, and is normally available in white or requirements documented in ASTM C920
gray colors. Damp curing is advantageous for Standard Specification for Elastomeric Joint
this material. Unsanded grout is typically used Sealants.
for joints of ⅛” (3 mm) or less, or when soft
varieties of stone are used with polished finish 1.10.3. Common joint sealant chemistries
which could be scratched by the aggregate in include silicone, urethane, and polysulfide.
sanded grout.
1.10.3.1. Strict adherence to the
1.9.3. Polymer Modified Portland Cement written instructions of sealant manufacturer is
Grout is a mixture of any of the preceding required.
grouts with polymer admixtures. The common
polymer types are latex and acrylic. This grout 1.10.3.2. Primers may be required for
is suitable for all installations subject to some sealant/substrate combinations. Check
ordinary use and for most commercial manufacturer’s requirements.
installations. The use of polymer additives in
portland cement grout increases the flexibility 1.10.3.3. Some grades of silicone
of the grout and reduces the permeability. sealants are not recommended by their
Consult the grout and polymer manufacturers manufacturers for application on high calcite
for specific instructions. content materials. Consult the Sealant
Manufacturer’s technical recommendation
1.9.3.1.1. Specifications for polymer before applying a given sealant to calcite
modified portland cement grouts can be found materials.
in A118.7 American National Standard
Specifications for High Performance Cement 1.10.3.4. All sealants shall be tooled to
Grouts for Tile Installation. ensure maximum adhesion to the contact
surfaces.
1.9.4. Coloring of Grouts: Many
manufacturers offer grouting materials in 1.10.3.5. Specialty sealants exist for
colors. Architects and Designers find them specific in-service conditions. For example,
pleasing for aesthetic reasons. Since some mildew-resistant silicone sealants formulated
stones are more porous than others, test to with fungicide are often used for sealing
determine the stability of the relationship interior joints in showers and around tubs,
between the colored joint filler and the stone sinks, and plumbing fixtures.
before proceeding. Make certain pigments
contained in the colored grout do not stain the 1.10.3.6. Oil based organic sealants
stone. A mockup to test for staining and color should not be used in conjunction with natural
consistency should be performed. stone products because they may stain the
stone.
1.10. JOINT SEALANTS
1.10.3.7. It is recommended that
1.10.1. Unlike grouting, which is almost exemplar projects of the same stone type and
always in the stone specification section, sealant type be reviewed, or a mockup be
building sealants are normally covered in a prepared to ensure the sealant is non-staining
separate specification section. While grouting and compatible with the stone.
is nearly always performed by stone setters, in
most trade areas the installation of sealants is 1.10.3.8. Some sealants contain
not in the trade jurisdiction of Marble plasticizers which may wick into the stone
Mechanics or Stonemasons. perimeter and cause staining. If exemplar
applications are not available to verify that the

Page 14-8 • Vertical Surfaces © 2022 Natural Stone Institute

sealant does not contain staining plasticizers, seismic displacement, and other applicable
testing per ASTM C1248 or ASTM D2203 is movements based on project conditions and
recommended. An adhesion test may also be material properties. Because of the many
required. conditions and structural systems in which
stone can be installed, the Specifying Authority
1.10.4. BACKER RODS: An important or engineer of record shall show locations and
feature in the determination of the joint sealant details of expansion joints on project drawings
is the selection of the backer rod. and/or calculations.

1.10.4.1. The backer rod performs 1.11.1.2. Movement Joints are also
three functions: required in fields of paving. Movement joints
extend through the finish layer only, and
1.10.4.1.1. Controls the depth and shape provide an interruption to the accumulation of
of the sealant profile. shear stress resulting from differential in
expansion between the finish layer and
1.10.4.1.2. Provides support for the substrate layers of the paving assembly.
caulking sealant when it is being compressed Reference ANSI A108.01 section 3.7 and ANSI
during tooling. A108.02 section 4.4 and TCNA EJ 171 for
guidance on movement joint location and
1.10.4.1.3. Acts as a bond breaker for the design.
sealant to prevent three-sided adhesion.
(Three-sided adhesion can result in failure of 1.11.2. Joint Size: Typical joint widths are:
the sealant.)
1.11.2.1. Exterior Stone Cladding:
1.10.4.2. Backer rods are available as Minimum ¼" (6 mm), preferably ⅜"
either “open cell” or “closed cell” type. Closed (10 mm). Joints of ½” (12 mm) or larger are
cell backer rods are generally preferred as they frequently required for large unit size
do not absorb water like an open cell rod. installation.
Caution is necessary when installing closed cell
rods to avoid puncturing the closed cell rods. 1.11.2.2. Interior Stone Cladding:
A punctured rod, during periods of increasing Minimum 1/16” (1.5 mm), preferably ⅛”
temperature will exhaust air as the air trapped (3 mm). Joints of ¼” (6 mm) or larger are
within the rod expands. This leads to a possible frequently required for large unit size
bubble or breach of the sealant joint. installation.

1.10.4.3. Consult the Sealant, 1.11.2.3. Tight or “hand-butted” joints

Waterproofing, and Restoration Institute are not recommended.
guidelines for further information on proper
joint sealant design, selection, and installation. 1.11.3. Shims: Shims shall be stainless steel or
high-impact plastic or approved equal. Shim
1.11. JOINTS size shall distribute the loads to ensure that
point loading does not affect stones
1.11.1. EXPANSION, AND MOVEMENT performance.
JOINTS
1.11.3.1. Where permanent setting
1.11.1.1. Expansion Joints. In exterior pads (shims) are required, 90 durometer
stone walls, expansion joints may be provided neoprene or high-impact plastic is
to reduce the damaging effect of building recommended. Placement of setting pads
and/or veneer movements due to thermal (shims) shall be positioned to accommodate
expansion, structural live load deflection,

© 2022 Natural Stone Institute Vertical Surfaces • Page 14-9

effective load transfer and avoid interference stone suppliers or installers (See Chapter 3, pg.
with joint filler materials. 3-5, Section 5.10).

1.11.3.2. Shims used in joints of 1.13.1.1. While commonly referred to

“stacked” veneer systems remain in the joint as “sealers” the products used to treat stone
permanently to transfer load from course to surfaces are typically an “impregnating
course. Shims may be used to temporarily repellent”, which when properly applied will
maintain joint width in other joint conditions preserve the ability of the stone to transmit
but are to be removed prior to application of water vapor (“breathe”).
joint filler material.
1.14. THERMAL INSULATION
1.12. LIPPAGE
1.14.1. Because heat is easily transmitted
1.12.1. Tolerances for allowable lippage can through stone when stone is part of a system
be found in Chapter 22 on Tolerances. assembly, insulation should be provided by
other contractors. A minimum 1” (25 mm)
1.12.2. Allowable lippage is an installation cavity shall be maintained between the stone
tolerance and is additive to the inherent and the insulation to prevent contact between
warpage of the stone unit. the two materials.

1.12.3. Lippage tolerances may not be 1.14.2. To comply with regional energy
attainable in flamed, cleft, or otherwise codes, stone anchorage may require a thermal
textured finishes. In those installations, joint isolator to reduce the conductivity of the
width should be increased to limit perceived anchorage assembly.
lippage, and in some cases joints as wide as ¾”
(20 mm) may be required. 1.15. FIRE RATINGS

1.12.4. Lippage tolerances may not be Stone is not combustible according to

achievable in extremely large stone panels, in underwriters’ ratings, and therefore is
which case larger than typical joint widths are considered a fire-resistant material. Because of
recommended to minimize perceived lippage. its thermal conductivity, heat transfer is fairly
rapid. Most stone is not considered a highly
1.12.4.1. It is recommended that rated thermal insulator.
exposed stone edges be gauged to the precise
thickness specified, particularly when the 1.15.1. Underwriters’ fire-resistance ratings
condition includes multiple pieces in a evaluate whether or not a material will burn,
continuous run. as well as how long it will keep surrounding
combustible materials from reaching
1.13. SURFACE SEALERS temperatures that will cause them to ignite.
Methods of estimating fire-resistance periods
1.13.1. Sealing the Face of the Stone: This of masonry walls and partitions utilizing
section does not imply that sealing the face of component laminae are given in “Fire
the stone is a necessary practice. Application of Resistance Classifications of Building
sealers is a common practice in certain Construction,” BMS92, National Bureau of
instances, such as when high porosity stone is Standards.
installed or when the stone is installed in a food
or beverage service area. If any sealer coating 1.15.2. Fire resistance of a material does not
is specified for any natural stone material, constitute a “fire rating”. Fire ratings are
advice should be sought in detail from qualified established for construction assemblies, of
which the stone would be only one

Page 14-10 • Vertical Surfaces © 2022 Natural Stone Institute

component. Because changing the stone 2.1.1. The stone panels and associated
variety would nullify the fire rating of the anchorage are designed to accommodate
assembly, it is cost prohibitive to provide the vertical loads (stone unit self-weight) and
testing and documentation required to include lateral loads (wind and seismic forces) as
the benefit of the stone’s fire resistance to a fire required by governing codes and/or project
rated wall. Therefore, when a fire rating is specifications. Each of these loads is transferred
required, it is normally achieved by directly to the backup wall substrate through
construction of a fully fire rated wall behind the the stone anchorage. Joints between each stone
stone face, typically with multiple layers of are designed to accommodate thermal
gypsum board. expansion and differential movement between
stone units, and therefore, must remain free of
1.16. ENGINEERING shims, mortar, or any other rigid material that
The attachment systems for many interior and would transfer load from one stone to another.
low-rise stone installations of limited scope are The joints are typically filled with a non-
designed by empirical methods and are not staining sealant that possesses extension and
reviewed by a registered or licensed engineer. compressive capacities adequate to meet the
As the scope and complexity of installation performance requirements for the project. A
increases, or the complexity of the project minimum joint width of ⅜" (10 mm) is
environment increases (e.g.: special wind or recommended for exterior stone veneer.
seismic regions), having the design completed Larger joints may be required to accommodate
and/or reviewed by a registered, licensed specific project demands. Note: This system
professional experienced in stone attachment can also be installed as a rainscreen or open-
system designs becomes necessary. joint façade omitting joint sealant between
stone veneer units.
1.16.1. A knowledgeable and experienced
Installer must provide an engineered and 2.1.1.1. Concrete/CMU Substrates:
fabricated system that will satisfy functional Independently Supported veneer systems can
and aesthetic requirements. However, be anchored directly to cast-in-pace concrete
determining which performance requirements or Concrete Masonry Unit (CMU) backup
and the criteria under each must be made by walls. In most cases, the cores of CMU wall
the Specifying Authority in consultation with require filling to provide adequate capacity for
the Structural Engineer. the drilled anchors.

2.1.1.2. Metal Frame Substrates:

2. EXTERIOR Independently Supported veneer systems can
INSTALLATION SYSTEMS be anchored to miscellaneous metal framework
by either welding or bolting, or a combination
Vertical Stone Surfaces are installed with a of the two. All elements must have adequate
variety of conventional and proprietary corrosion protection.
systems. A brief discussion of the more
common types is below: 2.1.1.3. Stud Walls: Independently Supported
veneer systems can be anchored to stud frame
2.1. INDEPENDENTLY SUPPORTED walls.
VENEER
Each stone panel is independently supported 2.1.1.3.1. Metal studs placed behind
(relieved and restrained) by mechanical stone wall installations to support the stone
anchorage attached to the backup wall must be engineered and sized to accommodate
substrate (building structure, masonry backup, loads. Stud wall thickness must provide
stud framing assembly, miscellaneous steel adequate pull-out capacity for fasteners (16
etc.). gauge or heavier is often required).

© 2022 Natural Stone Institute Vertical Surfaces • Page 14-11

2.1.1.3.2. Continuous horizontal commonly done with a proprietary attachment
channels are frequently required to provide for system available from the panel manufacturer.
more flexibility in attachment locations and to
distribute loads uniformly over multiple studs. 2.1.5.2. Other backing materials are used in
addition to aluminum, including carbon fiber,
2.1.1.3.3. Walls and partitions fiberglass, stone, and concrete.
constructed of metal studs should be designed
for a maximum deflection of L/720 for 2.2. STACKED VENEER
conditions utilizing thick-set or thin-set mortar Restraint and relief are achieved by using a
installation methods. combination of lateral ties (straps, split-tail
anchors, welded tees, or other positively
2.1.2. Grid Systems, commonly composed of engaged mechanical anchorage approved by a
vertical and horizontal support framing of qualified design professional) and gravity relief
varying corrosion-resistant materials, such as supports.
aluminum, mild steel, cold-formed steel, or
stainless steel. The framing is typically pre- 2.2.1. Each stone panel is restrained by
installed in the stone setting cavity to the mechanical anchorage attached to the backup
substrate or support wall. Stone supports are wall substrate (building structure, masonry
typically integrated in the system design. backup, stud framing assembly, miscellaneous
steel, etc.). The stone panels and associated
2.1.3. Strut Systems are commonly anchorage are designed to accommodate lateral
composed of vertical support framing of loads only (wind and seismic forces) as
varying corrosion-resistant materials such as required by governing codes and/or project
aluminum, mild steel, cold-formed steel or specifications. These loads are transferred
stainless steel. The framing is typically pre- directly to the backup wall substrate through
installed in the stone setting cavity to the the stone anchorage. Relieving supports (e.g.,
substrate or support wall. Non-integrated continuous angles or clips) are designed to
stone supports are typically attached in a accommodate the cumulative vertical load of
method similar to Independently Supported the stone veneer units “stacked” between the
Veneer or “Stacked” Veneer with Relieving relief support and expansion or control joint
Supports. above, typically a live load joint at a floor/slab
line. Relief supports are typically provided
2.1.4. Integrated Curtainwall Stone veneer over all openings and at each story height (or
installed in glazing channels of glazed curtain maximum vertical spacing of 20' [6 m]).
wall members or mechanically fastened to Within a “stack”, vertical loads are typically
mullions in similar manner to metal spandrel transferred from one stone to another using
panels in a manner similar to glass or load-bearing shims or mortar. The joints are
curtainwall spandrel panels. typically filled with a non-staining sealant or
mortar adequate to meet the performance
2.1.5. Bi-Material Composite Panels requirements for the project.

2.1.5.1. Lightweight Natural Stone Veneer 2.2.2. Consideration of weeps and flashing is
Panels Definition: This product is a bi-material recommended when continuous relief angles
panel using a thin (±5 mm) stone face are utilized. Relieving angles should be
adhesively bonded to a lightweight aluminum provided over all openings and at each story
backer. Most stone varieties and finishes are height (or maximum vertical spacing of 20'
available, although each manufacturer has [6 m]). Angles should have ¼" (6 mm) weep
several preferred stones available in their holes every 2'-0” (600 mm). Refer to local
offerings. Attachment of these systems is codes for variance.

Page 14-12 • Vertical Surfaces © 2022 Natural Stone Institute

2.3. THICK BED, COURSED ASHLAR with a secondary drainage system is required in
INSTALLATION lieu of a vented cavity.

2.3.1. Coursed splitface ashlar veneers are 2.3.5. Dead load should be relieved at every
anchored to the substrate wall to address lateral floor line, and in no case shall the vertical
loads only. Dead loads (gravity loads) are dimension between relieving points exceed
carried downward through successive courses 20’-0” (6 m). Shelf angles used to relieve
and ultimately borne by concrete corbels, shelf deadload may be mild steel with appropriate
angles, or other means of transferring the load corrosion protection.
to the building frame.
2.3.6. Lateral loads must be accommodated
2.3.2. The substrate wall may be cast in place by anchors within the stone bed joints.
concrete, concrete masonry units, or sheathed Corrugated “brick ties” are not recommended.
stud frame walls. In all cases appropriate Masonry “loop” anchors, or anchors that
waterproofing shall be applied to the substrate penetrate the stone such as pin or bent strap
wall. anchors are preferred. These anchors shall be
stainless steel. Anchor quantity and placement
2.3.3. The stone product is typically split in a is governed by local codes, but typically
hydraulic guillotine, and will have irregular, requires one anchor for every 3 ft² (~4
cleft surfaces on both the front and back faces. anchors/m²). In some cases, for instance
The degree of this irregularity and depth of seismic regions, continuous rodding within the
relief will vary pending the mineral structure, mortar bed may be required.
rift direction and intensity, and course height.
The surfaces resulting from the guillotine will 2.3.7. The stones shall be fully bedded in
be both convex and concave. In many cases, mortar. Type S mortar is typically used for
the stone will be hand pitched in the field to harder stones (e.g., granite) and type N mortar
create convex surfaces on all pieces yielding a is typically used for softer stones (e.g.,
“pillowed” look to each course of the wall. limestone).

2.3.4. When installing stone with a relatively 2.4. ADHERED VENEER

uniform bedding thickness, an open cavity is
usually maintained between the stone and the 2.4.1. Thinset Adhered installation is
substrate wall. This cavity varies, pending generally limited to thin stone (¼" to ½" [6 to
construction tolerances and irregularity of the 12 mm] thickness) of heights not exceeding
back surface of the stone, and can be anywhere 15’-0” (4.5 m).
from 1” to 4” (25 to 100 mm), and sometimes
larger to accommodate insulation or other 2.4.1.1. Units shall not exceed 36 inches (914
building envelope components. The cavity mm) in the greatest dimension nor more than
must be ventilated, and weeps must occur at 720 square inches (0.46 m²) in total area and
the bottom course and at any course where shall not weigh more than 15 pounds per
water cannot travel vertically within the cavity square foot (73 kg/m²) unless approved by the
(such as at a shelf angle location). Weeps must local governing officials and the engineer of
occur frequently, with lateral spacing typically record.
every 3’-0” to 4’-0” (1.0 to 1.2 m) as joint
pattern allows. 2.4.1.2. Recommended substrate materials are
masonry and cementitious backer board.
2.3.4.1. In some instances, for example field or
rubble stone construction or other stone wall 2.4.1.3. Exterior Vertical Surfaces. When
constructions using stone units of varying adhesive installation methods are used for
bedding thicknesses, a mortar-filled collar joint exterior vertical surfaces, the stone shall be

© 2022 Natural Stone Institute Vertical Surfaces • Page 14-13

back buttered to achieve, as close as practical, 2.5. STONE SOFFITS
100% adhesive contact between the stone and Stone soffits may be anchored with back
the backup. Remove freshly installed tiles anchors, or edge anchors. In some cases soffits
periodically during installation to verify may be edge-supported.
adhesion level.
2.5.1. When thinner stone panels are used
2.4.1.4. When thin stone tiles are installed on for exterior soffits in high wind load
exterior vertical surfaces, they are fully reliant environments and are only edge supported,
upon the backup and substrate for additional measures to prevent uplift may be
performance. Use of unstable backup materials required.
should be avoided.
2.5.2. Factors of Safety may need to be
2.4.2. Thin-Bed Stone Adhered Systems are increased for soffit design to address the
stone installation of ¾” to 1” (20 to 25 mm) continuous loading condition of this
stone units which are design to portray the look application.
of thicker (±4” / 100 mm) stone veneers.

2.4.2.1. Thin-bed stone units shall not exceed 3. INTERIOR

36 inches (914 mm) in the greatest dimension
nor more than 720 square inches (0.46 m²) in
INSTALLATION SYSTEMS
total area and shall not weigh more than 15
pounds per square foot (73 kg/m²) unless Stone wall facing panels may be installed either
approved by the local governing officials and by conventionally set method using nonstaining
the engineer of record. anchors, dowels, pins, cramps, wire, and
mortar or plaster spots; nonstaining adhesive in
2.4.2.2. Cast-in-place concrete, concrete securing thin tile units to interior vertical
masonry unit, and sheathed stud frame backup surfaces; or by one of the several mechanical
walls are suitable substrates for thin-bed stone methods.
installation.
3.1. ANCHORED SYSTEMS
2.4.2.3. An appropriate waterproofing
membrane, either liquid or sheet applied, is 3.1.1. Concrete/CMU Backup
required at the face of the substrate wall.
3.1.1.1. Masonry Backup: May be poured-in-
2.4.2.4. Thin-bed stone systems have limited place concrete, hollow concrete block, brick,
adjustment capability, so concrete and CMU or other solid masonry surface. Normally,
walls frequently require a metal lath with a stone installation with this substrate will be set
scratch coat to provide for a more accurate with a cavity.
plane to which the stone can be adhered.
Sheathed stud frame walls always require metal 3.1.2. STUD WALLS
lath with a scratch coat.
3.1.2.1. Metal Studs: Must be engineered to
2.4.2.5. Corner units are often fabricated as an accommodate all loads and be of adequate
“L” shape to create the appearance of a thicker thickness to provide required fastener pullout
stone wythe. values (16 gauge is generally recommended ).
Stone anchors may attach directly to the studs,
2.4.2.6. Thin bed stone systems are adhered to or a horizontal track component may be used
the scratch coat with standard portland cement to carry the load of the anchor uniformly across
mortars or latex modified mortars. several studs. Plywood, cementitious backer

Page 14-14 • Vertical Surfaces © 2022 Natural Stone Institute

board, or gypsum board may be used as a non- 3.2.2.2. Tile patterns shall be laid out so that no
loadbearing sheathing. perimeter tile is less than ½ the width of the
typical stone tile, except at the front of cutouts.
3.1.2.2. Wood Studs: Stone anchors may attach
directly to the studs, or a horizontal track 3.2.2.3. Suitable substrates for stone tile are
component may be used to carry the load of the masonry, cementitious backer board, and
anchor uniformly across several studs. gypsum board. Do not use gypsum-based
Plywood, cementitious backer board, or products in wet areas.
gypsum board may be used as a non-
loadbearing sheathing. The use of natural 3.3. STONE BASE
wood studs may require additional bracing, Stone Base not exceeding 1-0” (300 mm) in
bridging, blocking or other provisions to height is most often adhesively attached. Stone
prevent rotation or other deformation in the base of greater heights generally requires
studs over time. When engineered studs are mechanical anchorage.
used, follow manufacturer’s instructions for
fastening and bracing requirements. 3.4. STONE SOFFITS
Stone soffits are either edge supported,
3.2. ADHERED SYSTEMS anchored with back anchors, or anchored with
In all conditions, the substrate must be installed edge anchors. In some cases, thin (≤½”,
sufficiently true and level so that the stone ≤12 mm) stone soffits in interior applications
panels or tiles may be installed true and level can be adhesively attached without mechanical
and sufficiently rigid to ensure a satisfactory anchorage. Consult the adhesive manufacturer
backup surface to the stone installation. for guidance in installation methodology and
(Industry standard: ⅛" in 10'-0" with no more substrate recommendations.
than 1/32" between individual stones.)
3.4.1. Factors of Safety may need to be
3.2.1. For all applications, the stone tile shall increased for soffit design to address the
be back buttered to achieve, as close as continuous loading condition of this
practical, 100% adhesive contact between the application.
stone and the backup.
3.5. STONE FIREPLACE FACES
3.2.2. STONE TILE SYSTEMS Anchorage of stone fireplace surrounds is
accomplished similarly to other interior
3.2.2.1. Stone Tile Installation installations.
References. The Natural Stone Institute has
participated in the Tile Council of North 3.5.1. Provide adequate accommodations for
America’s (TCNA) development of the expansion due to thermal effects, including
Handbook for Ceramic, Glass, and Stone absolute temperature and thermal gradients.
Installation. This document is reprinted every
year, although the handbook committee meets 3.5.2. Caution is required in selecting joint
only biennially, so substantial revisions are sealer, anchor fillers, and/or adhesive
likely to appear only biennially. This materials that may be exposed to elevated
handbook includes a section dedicated to the temperatures. Consult the product
installation of stone tile products. The details manufacturer for recommendations.
are not duplicated in the Natural Stone
Institute publications. Contact the TCNA
(www.tcnatile.com) or the Natural Stone
Institute’s Book Store to obtain a copy of the
handbook.

© 2022 Natural Stone Institute Vertical Surfaces • Page 14-15

4. TROUBLESHOOTING than the sum of the volumes of the two parent
components. Therefore, if portland cement
AND CAUTIONS and gypsum are mixed in a confined space (as
in an anchor slot), extreme expansive forces
4.1. WET AREAS
will occur as the ettringite is formed, typically
Avoid the use of plywood or gypsum board as
causing rupture of the anchor slot.
substrate materials. Provide a moisture
barrier. Suitable substrates are masonry
4.6. FIBERGLASS MESH BACKING
backup and cementitious backer board on
Producers frequently apply a fiber mesh
metal or wood studs. Apply appropriate water
reinforcement to the back surfaces of stone
proofing membranes to all substrates.
tiles and slabs to reduce breakage and also
increase safety when handling large slabs.
4.2. PROTECTION OF FINISHED
Caution should be used when using a stone that
WORK: During construction, the General
has a fiberglass mesh backing applied on the
Contractor shall protect all stone from staining
back face. The fiberglass, having been bonded
and damage.
to the stone with a resinous (commonly epoxy)
adhesive, will not bond adequately with
4.3. TOLERANCES
cementitious products. Only epoxy products,
Fabrication and installation tolerances can be
or products specifically made for fiberglass by
found is a separate chapter of this manual.
the manufacture, should be used when
installing stone with fiberglass mesh backing.
4.4. HYSTERESIS
Hysteresis is a phenomenon that affects certain
4.6.1. Regardless of the tenacity of the bond
“true” marbles. Unlike most stones, which
of the installation adhesive to the fiberglass
return to their original volume after exposure
mesh, the overall performance of the
to higher or lower temperatures, these marbles
attachment system can be no greater than the
show small permanent increases in volume
bond between the fiberglass and the stone, of
after each thermal cycle. This can result in
which the installer has no control. Testing of
differential expansion within the stone, which
the bond at this interface is recommended.
is more likely to be accommodated or
restrained in thick veneers than in thin ones. If
4.7. GREEN COLORED STONE
it is not restrained, bowing of the marble
Avoid the use of water-based adhesive when
panels ensues. Bowing also stretches the face,
installing certain green marbles and/or
which makes stones more porous and increases
serpentines. Some of these stones may warp
the vulnerability to corrosion from acids in the
through absorption of water from the setting
atmosphere and deterioration from freezing
bed. (Water drawn into the stone is held to the
and thawing effects. If marbles with this
crystals by surface energy. This force tends to
tendency are selected, research shall be
widen the intercrystalline space and thereby
performed to determine the minimum
expand the wet side.)
thickness needed to overcome effects of
hysteresis.
4.8. SEALANT STAINING
Some elastomeric sealants contain oil-based
4.5. GYPSUM
plasticizers to reduce their modulus and
The use of gypsum-based products as fillers in
increase their extension/compression
anchor preparations is not recommended in
capability. The plasticizers can wick into stone
any environment and is specifically prohibited
perimeters, causing darkening of the edge
for any wet or potentially wet environment.
(picture framing) and accelerated dirt
collection on the stone face. Caution should be
4.5.1. Ettringite: Ettringite can be formed
used in specifying sealants to ensure
by the combination of gypsum and portland
compatibility with stone. It is recommended
cement. Ettringite has a volume that is greater
Page 14-16 • Vertical Surfaces © 2022 Natural Stone Institute
that either an exemplar project be identified 4.12. POLISHING WHEEL MARKS
using the same stone and sealant components Polishing wheel marks or other scratches
with satisfactory results, or a testing regimen caused during fabrication are unacceptable on
per ASTM C1248 or ASTM D2203 be honed or polished stone.
performed.
4.13. GEOGRAPHICAL VARIATION
4.9. EFFLORESCENCE IN PRACTICE
Efflorescence is a salt deposit, usually white in Some installation methods and materials are
color that appears on exterior surfaces of stone not recognized and may not be suitable in some
walls and floors. The efflorescence is produced geographic areas because of local trade
by salts leached to the surface of the stone by practices, building codes, climatic conditions,
water percolating through the stone backup or construction methods. Therefore, while
and joints. The most feasible means of every effort has been made to produce accurate
prevention is to stop the entrance of large guidelines, they should be used only with the
amounts of water. If the conditions bringing independent approval of technically qualified
about the efflorescence continue, scaling may persons.
occur and flake off successive layers. For this to
happen, large amounts of water must continue
to enter behind the stone and must contain
large amounts of salts.

4.10. DOWN WASHED LIGHTING

The use of down washed lighting and/or
lighting of high angles of incidence, in which
the path of light is nearly parallel to the face of
the wall surface, is a popular choice in both
interior and exterior designs. This lighting
style will exaggerate lippage, textural surface
variation, and even warpage due to the
extremely elongated shadow lines caused by
the slight angle of incidence. Material and
installation which are within industry
tolerances may appear to be outside of
tolerances due to the accentuation of the
lighting technique. Inspection of areas
receiving down washed lighting shall be done
with the down washed lighting turned off.

4.11. VARIATION IN GLOSS

It is almost impossible to uniformly read light
reflection on a polished or high-honed-finish
installation due to the natural characteristics of
dimension stone. Due to the heterogeneous
composition of natural stones, variable mineral
hardness exists within the stone, producing
variable reflectivity of light energy. Most
stones, and especially travertine marbles and
honed-finish surfaces, will appear to reflect
light unevenly.

© 2022 Natural Stone Institute Vertical Surfaces • Page 14-17

Notes:

Page 14-18 • Vertical Surfaces © 2022 Natural Stone Institute

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

FULL BEARING HIGH

IMPACT PLASTIC SHIMS

SEAL PENETRATIONS IN
WATERPROOFING
WITH COMPATIBLE SEALANT

EXPANSION BOLT OR ANCHOR

EXTRUDED ALUMINUM CLIP

(OR S.S. WELDED T ANCHOR)

HIGH IMPACT PLASTIC SHIMS

SEALANT & BACKER ROD

FILL KERF CONTINUOUS WITH

NON STAINING ELASTOMERIC
SEALANT TOP AND BOTTOM

CONCRETE (SHOWN) OR
GROUT FILLED CMU WALL

STONE TYPE & THICKNESS

VARIES PER SPECIFICATION

EXTRUDED ALUMINUM OR WELDED STAINLESS STEEL "T" ON CMU BACKUP

1

SEAL PENETRATIONS IN
WATERPROOFING
WITH COMPATIBLE SEALANT

EXTRUDED ALUMINUM CLIP

(OR S.S. WELDED T ANCHOR)
EXPANSION BOLT
FILL KERF WITH NON STAINING OR ANCHOR
ELASTOMERIC SEALANT, FULL LENGTH OF CLIP

HIGH IMPACT PLASTIC SHIMS

FULL BEARING HIGH

IMPACT PLASTIC
SHIMS

SEALANT & BACKER ROD

FILL KERF CONTINUOUS WITH

NON STAINING ELASTOMERIC SEALANT

CONCRETE (SHOWN) OR
GROUT FILLED CMU WALL

STONE TYPE & THICKNESS VARIES PER SPECIFICATION

EXTRUDED ALUMINUM OR WELDED ST. STEEL "T" ON CONCRETE BACKUP

2
REV DATE
EXTERIOR STONE ATTACHMENT DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

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www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-1
3" = 1'-0"

© 2022 Natural Stone Institute 14-D-1

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

MINIMUM 16 GA. MTL. STUDS

MIN. 14 GA. STUD TRACK

W/ (2) SCREWS AT EACH
VERT. STUD

HIGH IMPACT
PLASTIC SHIMS
EXTRUDED ALUMINUM CLIP
(OR S.S. WELDED T ANCHOR)

FILL KERF WITH NON-STAINING

ELASTOMERIC SEALANT FULL LENGTH OF
ANCHOR CLIP

HIGH IMPACT PLASTIC SHIMS

SEALANT & BACKER ROD

FILL KERF CONTINUOUS WITH NON-STAINING

ELASTOMERIC SEALANT

STONE TYPE & THICKNESS VARIES

PER SPECIFICATION

SHEATHING

EXTRUDED ALUMINUM OR WELDED ST. STEEL "T" ON METAL STUD BACKUP

1

MINIMUM 16 GA. MTL. STUDS

MIN. 14 GA. STUD TRACK

W/ (2) SCREWS AT EACH
VERT. STUD
HIGH IMPACT
PLASTIC SHIMS

S.S. SPLIT TAIL ANCHOR

FILL KERF WITH NON-STAINING

ELASTOMERIC SEALANT FULL
LENGTH OF ANCHOR CLIP

HIGH IMPACT PLASTIC SHIMS

SEALANT & BACKER ROD

FILL KERF CONTINUOUS

WITH NON-STAINING
ELASTOMERIC SEALANT
STONE TYPE & THICKNESS VARIES
PER SPECIFICATION

SHEATHING

STAINLESS STEEL SPLIT-TAIL ANCHOR ON METAL STUD BACKUP

2

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DIMENSION STONE DESIGN MANUAL 2022

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www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-2
3" = 1'-0"
14-D-2 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

MISC. STEEL FRAMING

HIGH IMPACT PLASTIC SHIMS

S.S. SPLIT TAIL ANCHOR

FILL KERF WITH NON-STAINING

ELASTOMERIC SEALANT FULL
LENGTH OF ANCHOR CLIP

HIGH IMPACT PLASTIC SHIMS

SEALANT & BACKER ROD

FILL KERF CONTINUOUS

WITH NON-STAINING
ELASTOMERIC SEALANT

STONE TYPE & THICKNESS VARIES

PER SPECIFICATION

STAINLESS STEEL SPLIT-TAIL ANCHOR ON MISC. METAL BACKUP

1

MISC. STEEL FRAMING

HIGH IMPACT PLASTIC SHIMS

EXTRUDED ALUMINUM CLIP

(OR S.S. WELDED T ANCHOR)

FILL KERF WITH NON-STAINING

ELASTOMERIC SEALANT FULL
LENGTH OF ANCHOR CLIP

HIGH IMPACT PLASTIC SHIMS

SEALANT & BACKER ROD

FILL KERF CONTINUOUS

WITH NON-STAINING
ELASTOMERIC SEALANT

STONE TYPE & THICKNESS

VARIES PER SPECIFICATION

EXTRUDED ALUMINUM OR WELDED ST. STEEL "T" ON MISC. METAL BACKUP

2

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DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-3
3" = 1'-0"

© 2022 Natural Stone Institute 14-D-3

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

CONCRETE (SHOWN) OR
GROUT FILLED CMU WALL

EXPANSION BOLT OR ANCHOR

S.S. BENT PLATE AT 1/5

POINTS OF STONE

FILL KERF WITH NON-STAINING

ELASTOMERIC SEALANT FULL LENGTH
OF ANCHOR CLIP

SEALANT & BACKER ROD

FULL BEARING HARD PLASTIC SHIMS

CONTINUOUS RELIEF ANGLE

RELIEF ANGLE CONNECTION ON CMU/CONCRETE BACKUP

1

MINIMUM 16 GA. MTL. STUDS

HIGH IMPACT
PLASTIC SHIMS

SEALANT & BACKER ROD

LEVELING SCREW

LOCAL INTERLOCKING CLIP

UNDERCUT ANCHOR

CONTINUOUS INTERLOCKING
CHANNEL

INTERLOCKING GRID SYSTEM CONNECTION ON METAL STUD BACKUP

2

REV DATE
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0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-4
3" = 1'-0"
14-D-4 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

MINIMUM 16 GA. METAL STUDS

MIN. 14 GA. STUD TRACK

W/ (2) SCREWS AT EACH
VERTICAL STUD

HIGH IMPACT PLASTIC

SHIMS

S.S. BENT PLATE

S.S. LINER PLATE AT STONE

1/5 PTS

FILL KERF WITH NON-STAINING

SILICONE SEALANT, FULL
LENGTH OF KERF PLATE

HIGH IMPACT PLASTIC SHIM

SHEATHING

BACK ANCHOR & ST. STL. CLIP FOR "BLIND" CONNECTION ON METAL STUDS
1

WATERPROOFING
MEMBRANE

EXPANSION ANCHOR

HIGH IMPACT
PLASTIC SHIMS

S.S. BENT PLATE

S.S. KERF PLATE AT

STONE 1/5 PTS

FILL KERF WITH NON-STAINING

SILICONE SEALANT, FULL
LENGTH OF KERF PLATE

HIGH IMPACT PLASTIC SHIM

BACK ANCHOR & ST. STL. CLIP FOR "BLIND" CONNECTION ON CMU/COMCRETE
2
REV DATE
EXTERIOR STONE ATTACHMENT DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-5
3" = 1'-0"

© 2022 Natural Stone Institute 14-D-5

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SHIMS

MASONRY
ANCHOR ATTACHED TO FASTENER
BEARING ANGLE IN FIELD

PRESSURE
RELIEVING
JOINT

CLIP ANGLE

DETAIL
1
SHIMS MASONRY
FASTENER

CLIP ANGLE
WITH DOWEL

PRESSURE
RELIEVING JOINT

OFFSET STRAP
ANCHOR BEYOND

DETAIL
2

STRUT
STONE LINER
WITH DOWEL

CLIP ANGLE

SHIMS
DETAIL
3 DRIP

NOTE: 1. ALLOW ADEQUATE SPACE FOR ANCHOR BOLT HEADS.

2. NEVER ANCHOR THROUGH A PRESSURE RELIEVING JOINT.
3. ALL METALS IN DIRECT CONTACT WITH THE STONE MUST BE STAINLESS STEEL.

REV DATE
EXTERIOR STONE RELIEF DETAILS
0 MAR 2022 WITH REBATED BEARING
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-6
3" = 1'-0"
14-D-6 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SHIM MASONRY
FASTENER

MASONRY
STRAP ANCHOR FASTENER

L-STRAP WITH DOWEL

DETAIL
1
DETAIL
A OPTION TO ANCHOR STRAP, Z BAR OR
MASONRY
IN VERTICAL JOINT WIRE ANCHOR
FASTENER

BENT STRAP ANCHOR

DETAIL
2

MASONRY
FASTENER

SPLIT TAIL STRAP

ANCHOR

DETAIL
3

NOTE: 1. ALLOW ADEQUATE SPACE FOR ANCHOR BOLT HEADS.

2. NEVER ANCHOR THROUGH A PRESSURE RELIEVING JOINT.
3. ALL METALS IN DIRECT CONTACT WITH THE STONE MUST BE STAINLESS STEEL.

REV DATE
EXTERIOR STONE VENEER
0 MAR 2022 RESTRAINT ANCHORAGE DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-7
3" = 1'-0"

© 2022 Natural Stone Institute 14-D-7

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

STONE WASHER

WIRE ANCHOR

SELF- DRILLING
SELF-TAPPING
SCREW
SEALANT
CONTINUOUS
PLATE. 4" WIDE
SECURED TO
STUDS BY G.C.

LINE OF STUDS
SHEETROCK (INTERIOR)
OR FACE OF
CEMENT BACKER BOARD (EXTERIOR)
EXISTING WALL

DETAIL
1

GYPSUM WALL BOARD

(INTERIOR) - ATTACHED TO METAL STUDS
CEMENT BACKER BOARD (EXTERIOR)

NON-FERROUS WIRE (TYP.)

MORTAR SPOT

DETAIL
2

WIRE TIE BACK WITH DOWEL

NOTES:
1. EXPANSION BOLTS SHOULD ONLY BE USED IN BRICK,
CONCRETE, OR FILLED CORE CMU BACK-UP.
2. ALL METALS IN DIRECT CONTACT WITH STONE MUST BE
STAINLESS STEEL DETAIL
3. ALLOW ADEQUATE SPACE FOR ANCHOR BOLT HEADS 3
REV DATE
INTERIOR STONE VENEER
0 MAR 2022 RESTRAINT ANCHORAGE DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-8
3" = 1'-0"
14-D-8 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

BENT STRAP ANCHORED

TO STONE VENEER WITH
EXPANSION SHIELD & BOLT

CONCRETE (SHOWN) OR
GROUT FILLED CMU WALL
U BAR CRAMP IN
HORIZONTAL JOINT

BUTT JOINT OFFSET BUTT JOINT

1 2

MORTAR SPOTS

CONCRETE (SHOWN)
OR GROUT FILLED
CMU WALL
U BAR CRAMP IN
HORIZONTAL JOINT

NON-FERROUS WIRE
ANCHORS (TYP.)

QUIRK MITER JOINT QUIRK MITER JOINT

3 4

SPLINE TYPE
WATER STOP
NON-FERROUS
WIRE (TYP.)

MORTAR SPOTS

SEALANT

COMPRESSIBLE
BACKING ROD

U BAR CRAMP IN
HORIZONTAL JOINT

SEALANT

TYPICAL EXPANSION JOINTS RABBETED JOINT

5 6

NOTE: ALL METALS IN DIRECT CONTACT WITH THE STONE MUST BE STAINLESS STEEL.

REV DATE
EXTERIOR STONE VENEER
0 MAR 2022 CORNERS, EXPANSION JOINTS, REGLETS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-9
3" = 1'-0"

© 2022 Natural Stone Institute 14-D-9

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

STONE FACING

S.S SPLIT - TAIL SELF-DRILLING,

STRAP ANCHOR SELF-TAPPING
SCREW

HAT CHANNEL

GYPSUM WALL METAL STUD

BOARD

STRAP ANCHORED TO METAL STUDS

1
STONE FACING
MORTAR SPOT SELF-DRILLING,
SELF-TAPPING SCREW
COPPER WIRE @ EACH STUD
ANCHOR

HORIZ. COLD
ROLLED CHANEL

VERT. COLD ROLLED SELF-DRILLING,

CHANEL @ EA. STUD SELF-TAPPING SCREW

WIRE ANCHORED TO CHANNEL

2

HEAVY GUAGE
METAL STUD
SEALANT JOINT

GYPSUM WALL BOARD

STONE FACING

MORTAR SPOT

COPPER WIRE

DOWEL

STONE LINER EPOXIED &

DOWELED TO BACK OF
STONE FACING

SUPPORT ANGLE
FASTENED TO
METAL STUDS
NOTE: THIS CONDITION CAN
ONLY BE USED IF THE OPPOSITE WIRE ANCHORED TO METAL STUDS
SIDE OF STUDS ARE EXPOSED AT 3
THE TIME OF STONE INSTALLATION.

REV DATE
INTERIOR STONE CLADDING
0 MAR 2022 WALL FACING DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-10
3" = 1'-0"
14-D-10 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

CEILING BOX ANCHOR

(FILL WITH MORTAR)

AIR SPACE COPPER WIRE

GYPSUM
BOARD

STONE PANEL
2-LAYERS
GYPSUM BD. STONE
METAL STUDS

METAL STUDS

BOX
2-LAYERS ANCHOR
GYPSUM BD.
(STAGGER
JOINTS)

FINISH
FLOOR

SECTION AT FIRE-RATED WALL

(CHECK APPLICABLE CODES)
1

1
NOTE: 1 2" SETTING SPACE REQUIRED WHEN MARBLE LINERS ARE NOT EMPLOYED.

REV DATE
INTERIOR STONE CLADDING
0 MAR 2022 WALL FACING DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-11
3" = 1'-0"

© 2022 Natural Stone Institute 14-D-11

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

S.S OR COPPER
WIRE ANCHOR

WIRE LACE ANCHOR

1 (TO BE USED ONLY WHERE EDGE CONDITION
IS NOT AVAILABLE FOR ANCHORING)

STONE FACING

WIRE ANCHOR INTO EDGE

OF STONE FACING PANEL

MORTAR SPOT

CONCRETE (SHOWN) OR
GROUT FILLED CMU WALL

WIRE ANCHOR IN MASONRY

2

STONE FACING

MOLDED STONE TRIM

WIRE ANCHOR

CONCRETE (SHOWN)
OR GROUT FILLED
CMU WALL

WIRE ANCHORED MOULDED TRIM

3
NOTE: 1-1/2 INCH SETTING SPACE REQUIRED WHEN MARBLE LINERS ARE NOT EMPLOYED.

REV DATE
INTERIOR STONE CLADDING
0 MAR 2022 COLUMN CLADDING DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-12
3" = 1'-0"
14-D-12 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT
4"
BOTT. OF
41 4" SLAB.
JOINT
7" (TYP.)
812"

3"
1'-13 4" B
FIN. CLG.

2'-0"

3'-1"
C

TWO THIRDS ENTASIS

2'-0"
2'-0"

JOINTS
2'-0"

3'-1"
33'-6"

12'-9"
2'-1"
2'-1"

ONE THIRD STRAIGHT

2'-1"

4'-4" DIAMETER
2'-1"

A
3'-1"

2'-3"
1'-10"

8"

JOINTS

1'-712" JOINT
(TYP.) D
6"

312"

ELEVATION ELEVATION
1/4"=1'-0" (1:48) 1/2"=1'-0" (1:24)

REIF. CONC.
COL.

PLAN A PLAN B PLAN C PLAN D

1/4"=1'-0" (1:48) 1/4"=1'-0" (1:48) 1/2"=1'-0" (1:24) 1/2"=1'-0" (1:24)

REV DATE
INTERIOR STONE CLADDING
0 MAR 2022 COLUMN CLADDING DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-13
As Noted

© 2022 Natural Stone Institute 14-D-13

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

JOINTS

11"
JOINTS

4"
1 "
2
F
REVEAL
B
E

BATTERED
JOINTS SPLAY

JOINTS
12'-9"

12'-9"
A D

4" 2'-0" 4" 5" 1'-10" 5"

JOINTS
JOINTS
2" 4"

112" C
8"

8"

ELEVATION ELEVATION
1/2"=1'-0" (1:24) 1/2"=1'-0" (1:24)
4"

PLAN C PLAN F
1/2"=1'-0" (1:24) 1/2"=1'-0" (1:24)
2'-0"
4"

PLAN A PLAN B PLAN D PLAN E

1/2"=1'-0" (1:24) 1/2"=1'-0" (1:24) 1/2"=1'-0" (1:24) 1/2"=1'-0" (1:24)

REV DATE
INTERIOR STONE CLADDING
0 MAR 2022 COLUMN CLADDING DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-14
As Noted
14-D-14 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

3'-0" [914] 3'-0" [914] 3'-0" [914] 3'-0" [914]

2'-6" [762]
2'-6" [762]
2'-6" [762]
2

NOTE: DIMENSIONS ARE TO

2'-6" [762]
1 CENTER OF 1/8" JOINTS.
3 TOP, BOTTOM AND SIDE
TRIM PIECE WIDTH VARIES.

ELEVATION
1/4"=1'-0"(1:48)
1
5 8" [3] 5
16" [8] 16" [8]
[8]

2" [51]
16"
5

[3]
8"

STONE
[8]

1
16"
5

"H"ANCHOR CAST INTO

CLIPPED CONC. CRYPT WALL 1/4" DIA. THREADED
CORNERS BRASS ROD STABILIZER
LINE OF
DETAIL 1 ROSETTE
STONE
6"=1'-0"(1:2) BRACKET

ANCHOR INSERT
CAST INTO CONC.
CRYPT WALL 3/4"x3/4" RABBET ROSETTE

FACE OF STONE BRACKET

CONC.

FACE OF
CONC
2" [51]

SECTION 3
STONE
STONE SLIDE 3"=1'-0"(1:4)
ROSETTE
1
8" [3]
PLAN 2
3"=1'-0"(1:4)
REV DATE
CRYPT COVER ATTACHMENTS
0 MAR 2022 WITH BRACKET & ROSETTE
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-15
As Noted

© 2022 Natural Stone Institute 14-D-15

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

WIRE ANCHOR
(TYPICAL)

"U" CRAMP
BUTT JOINT
(TYPICAL)
7 INTERNAL CORNER
BUTT JOINT
1 EXTERNAL CORNER

QUIRK MITER JOINT

2 EXTERNAL CORNER
CORNER COVE JOINT
8 INTERNAL CORNER

CORNER BLOCK JOINT

3 EXTERNAL CORNER

112" [38]

CORNER BLOCK JOINT

9 INTERNAL CORNER

RABBETTED JOINT
5 EXTERNAL CORNER
112" [38]

BEVELED BLOCK JOINT

112" [38]

10 INTERNAL CORNER
[3]
8"
1

MOLDED JOINT
6 EXTERNAL CORNER 112" [38]

REV DATE
INTERIOR STONE ATTACHMENT
0 MAR 2022 CORNER DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-16
3" = 1'-0"
14-D-16 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

NOTES:
1. SECTION 1: STONE BASE AND WALL
FACING ANCHORED TO MASONRY
BACK-UP WITH NON-STAINING ADHESIVE.
PLASTIC SHIM
2. SECTION 4: STONE BASE AND WALL
FACING ANCHORED TO MASONRY
BACK-UP WITH COPPER WIRE TIE- BACK
ANCHORS OR STRAP ANCHORS.
COPPER WIRE TIE GROUT
BACK ANCHORS

NON-STAINING MORTAR
ADHESIVE SPOTS (TYP.)
LONG DOWEL

SECTION SECTION
1 4
NOTES:
1. SECTION 2: STONE BASE ANCHORED
TO WOOD STUD WITH WIRE TIE BACK
ANCHORS. INTERIOR BASE 6" HIGH OR
LESS DOES NOT REQUIRE ANCHORS.

2. SECTION 5: STONE BASE ANCHORED

TO PLASTERED PARTITION WITH WIRE TIE
BACK ANCHORS. INTERIOR BASE 6" HIGH
OR LESS DOES NOT REQUIRE ANCHORS.

WIRE TIE BACK ANCHORS

MORTAR SPOTS

PLASTIC SPACER SHIMS (TYP.)

SECTION SECTION
2 5
NOTES:
SECTION 3: STONE BASE ANCHORED
TO GYPSUM BOARD PARTITION
WITH NON-STAINING ADHESIVE.
BASE 6" HIGH OR LESS DOES NOT
REQUIRE WIRE TIE ANCHORS. METAL FEATURE STRIP

MORTAR FILL

WIRE ANCHOR

NON-STAINING
ADHESIVE

PLASTIC SPACER
SHIMS (TYP.)

SECTION SECTION
3 6

NOTE: ALL METALS IN DIRECT CONTACT WITH THE STONE MUST BE STAINLESS STEEL.

REV DATE
INTERIOR STONE ATTACHMENT
0 MAR 2022 BASE DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-17
3" = 1'-0"

© 2022 Natural Stone Institute 14-D-17

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SCREW TO STEEL FRAMING,

CONCRETE INSERTS OR TO
FACE OF CONCRETE
SCREW TO STEEL FRAMING,
BEAMS, CLIP ANGLES,
CONCRETE INSERTS, ETC.

JOINT SEALANT ONLY VERTICAL SURFACE

MUST BE WEEPED

SECTION THROUGH FLAT STRAP ANCHORS

1
NOTE: 1. BOLT ANCHORS TO STEEL FRAMING, BEAMS, CLIP ANGLES OR
CONCRETE INSERTS. USE EXPANSION BOLTS TO FASTEN
TO VERTICAL CONCRETE SURFACES ONLY.
2. SPACER REQUIRED. 16 GA. STAINLESS STEEL OR AS SPECIFIED.
NON-STAINLESS SUPPORT STEEL MUST NOT BE IN DIRECT
CONTACT WITH STONE.

ANGLE ATTACHED TO
FURRING CHANNEL OR
EQUIVALENT

SPACER

SECTION THROUGH BACK ANCHORS

2
SUPPORT
ANGLE L-SPLINE ANCHOR

SECTION THROUGH DISC & L-SPLINE ANCHORS

3
NOTE: CONSIDERATION SHOULD BE GIVEN TO ANCHORING EACH STONE SOFFIT
PIECE INDEPENDENTLY FROM OTHER SOFFIT AND VERTICAL PIECES.

REV DATE
STONE SOFFIT ATTACHMENT DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-18
3" = 1'-0"
14-D-18 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

MASONRY
FIREPLACE

STONE
SURROUND

PLAN DETAIL STONE

PLAN DETAIL
1 2
HEARTH
1 1
Scale: 2" = 1'-0" Scale: 2" = 1'-0"

STONE
MANTEL

STONE
HEADER

STONE
SURROUND

STONE
HEARTH

FIN.
FLR.

STONE
ELEVATION A ELEVATION
3
B
4
BASE
1 1
Scale: 2" = 1'-0" Scale: 2" = 1'-0"

STONE MANTEL
MASONRY
DOWEL FIREPLACE
STONE HEADER

STONE HEADER MORTAR

SPOT
STONE SURROUND WIRE
STONE HEARTH ANCHOR STONE SURROUND
(TYP.)
STONE HEARTH
NOTE: 100% COVERAGE OF
MORTAR BED BETWEEN STONE
HEARTH & SUB-FLOOR IS FIN. FLR.
RECOMMENDED
STONE BASE
FIN. FLR.

SECTION SECTION
A Scale:
1
1 2" = 1'-0"
B 1
Scale: 1 2" = 1'-0"

REV DATE
STONE FIREPLACE FACING
0 MAR 2022 ATTACHMENT DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-19
As Noted

© 2022 Natural Stone Institute 14-D-19

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

MASONRY FIREPLACE

WOOD SURROUND

PLAN DETAIL
1 1
Scale: 2" = 1'-0"
STONE LEG
STONE HEARTH

WOOD MANTEL

STONE HEARTH

WOOD SURROUND

STONE LEG

ELEVATION STONE HEARTH

2 1
Scale: 2" = 1'-0"
FIN. FLR.

MASONRY
FIREPLACE WOOD MANTEL

WIRE ANCHOR
STONE HEADER
MORTAR SPOT

NOTE: 100% COVERAGE OF

MORTAR BED BETWEEN STONE
HEARTH & SUB-FLOOR IS
RECOMMENDED

STONE HEARTH
STONE LEG
FINISH FLOOR

SECTION
A 1
Scale: 1 2" = 1'-0"

REV DATE
STONE FIREPLACE FACING
0 MAR 2022 ATTACHMENT DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-20
As Noted
14-D-20 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

MOISTURE BARRIER

CONCRETE SUBSTRATE

MORTAR JOINT

SPLITFACE STONE

VENTILATED CAVITY

MASONRY
FASTENER
WIRE LOOP ANCHOR

SPLITFACE ASHLAR ON CONCRETE BACKUP

1

MORTAR JOINT

THIN STONE

MORTAR SETTING BED

METAL LATHE W/ SCRATCH COAT

MOISTURE BARRIER

SHEATHING ON METAL BACKUP

THIN STONE VENEER ON MISC. METAL BACKUP

2
REV DATE
SPLIT FACE ASHLAR AND THIN STONE VENEER
0 MAR 2022 ATTACHMENT DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-21
As Noted

© 2022 Natural Stone Institute 14-D-21

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

DEEP RAKED MORTAR JOINT.

JOINT SIZE TO BE DOUBLE THE THICKNESS
OF WALL TIE
i.e. 1/8" WALL TIE = 1/4" JOINT

RUBBLE STONE
MINIMUM
MORTAR COVER 5/8" ENGAGEMENT
[16]
1 1/2"
[38]

WALL TIE

MOISTURE BARRIER

SHEATHING ON METAL BACKUP

DRY STACK VENEER ON MISC. METAL BACKUP

1

REV DATE
DRY-STACK VENEER ATTACHMENT DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-22
As Noted
14-D-22 © 2022 Natural Stone Institute
 TWISTED STRAP
"Z" STRAP (FOR VERTICAL EDGE ANCHORS) "U" CRAMP STRAP

"L" STRAP DOVETAIL STRAP

SPLIT-TAIL STRAP (HOLE FOR DOWEL) (HOLE FOR DOWEL)

DOVETAIL STRAP DOVETAIL "L" STRAP DOVETAIL SPLIT-TAIL STRAP

SMOOTH

THREADED

SHIM DOWELS DOVETAIL TWISTED

(PLASTIC OR ST. STEEL) (TWO WAY STRAP)

NOTE: ALL ANCHORS AND ACCESSORIES TO BE CORROSION RESISTANT METALS

REV DATE
COMMON ANCHORS AND ACCESSORIES
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-23
Not to Scale

© 2022 Natural Stone Institute 14-D-23

 PLUG ANCHOR T-31 BACK ANCHOR

30°

BENT ROD UNDERCUT BACK ANCHOR UNDERCUT BACK ANCHOR

(GRAPHIC COURTESY OF (GRAPHIC COURTESY OF
KEIL BEFESTIGUNGSTECHNIK GMBH) FISCHER FIXINGS LLC)

SOFFIT HANGER "L" STUD AND DISC RELIEVING ANGLE-CLIP

NOTE: ALL ANCHORS AND ACCESSORIES TO BE CORROSION RESISTANT METALS

REV DATE
COMMON ANCHORS AND ACCESSORIES
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-24
Not to Scale

© 2022 Natural Stone Institute 14-D-24

 WIRE TIEBACK WIRE TIEBACK
WIRE LACE ANCHOR
(WITH DOWEL)

"L" BAR OR EYE ROD AND DOWEL WIRE "GOOSE NECK"

HOOKED BOLT ANCHOR

"U" CLAMP BAR "HAIRPIN" PRECAST SPRING CLIP

ANCHOR (WITH COLLAR)

"Z" BAR

NOTE: ALL ANCHORS AND ACCESSORIES TO BE CORROSION RESISTANT METALS

REV DATE
COMMON ANCHORS AND ACCESSORIES
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 14-D-25
Not to Scale

© 2022 Natural Stone Institute 14-D-25

NOTES:

Dimension Stone Design Manual Ó 2022 Natural Stone Institute

WET AREAS – products are acceptable. Moisture sensitive
stones should not be used in wet areas.
GENERAL INFORMATION
2.2.1 Avoid use of stones that are flawed.
1.0 INSTALLATION OF DIMEN- Moisture can travel through the flaw to the
SION STONE IN WET AREAS back face of the stone. Do not use Marble
Soundness Classifications “C” or “D” stones, or
This chapter of Natural Stone Institute’s stones that have adhered fiberglass mesh
Dimension Stone Design Manual includes general reinforcement.
notes and references that apply to the
installation of natural stone in wet areas 2.2.2 Steam Showers. Soundness
(urinal, toilet and shower partitions, slab and Classifications C and D marbles used in steam
tile showers, steam rooms and steam showers). showers and around whirlpool tubs have a
This chapter should be used in conjunction tendency to lose their fillings due to moisture,
with chapters 13 and 14, Horizontal and heat, and vibration. Stone tile with adhered
Vertical Installation, respectively. fiberglass mesh reinforcement on their back
surfaces are not to be used for steam shower
1.1 Installation Methods. There are applications.
several methods by which stone partitions and
showers can be installed.1 Consideration 2.2.3 Mesh Backing. Producers frequently
should be given to the various features of each apply fiber mesh reinforcement to the back
method in making a selection for a specific surfaces of stone tiles and slabs to reduce
installation. For more information about breakage and also increase safety when
installation methods, see the detail drawings at handling large slabs. Caution should be used
the end of the chapter. when handling these stones. Mesh and resin
backing require special consideration when
1.2 Labor Assignment. In most regions of adhesives are chosen. Confirm compatibility of
the United States, the labor body responsible adhesive prior to setting units of this type. Slabs
for installing a stone product will change with mesh backing should not be used in free
pending if the stone product is a tile or a cut- standing vertical applications.
to-size product. Labor jurisdiction practices
vary regionally and locally, so research is 2.3 Anchors. An alternate system that may
encouraged to ascertain the labor group be used is non-staining, corrosion-resistant
assigned to the field installation of a given dowels, pins, and wire anchors in lieu of
product. standard commercial hardware. The design of
these systems must provide for the transfer of
2.0 DESIGN CRITERIA loads from the stone through the anchor to the
2.1 Oil-based putty and plumbing building structure.
sealants should never be used in contact with
stone. 2.4 White portland cement is
recommended for most light-colored natural
2.2 Sound Stones. Only sound stones, stone. White portland cement with a low alkali
free of any cracks, defects, geological flaws, content is recommended for limestone.
and voids should be used. Variations in natural

1 Natural Stone Institute endorses the use of a partial the “Natural Stone Tile Installation Methods” section in
list of details published by the Tile Council of North the current edition of the TCNA Handbook for Ceramic,
America. For additional installation information, see Glass, and Stone Tile Installation.

© 2022 Natural Stone Institute Wet Areas/General Information • Page 16-1

2.5 Use cement backer board instead of 3.1.6 Serpentine: ASTM C1526, Standard
water-resistant drywall board (green board). Specification for Serpentine Dimension Stone.
Drywall will degrade and the paper on it will
become a food source for mold and mildew 3.1.7 Slate: ASTM C629, Standard
when subjected to moisture. Do not use Specification for Slate Dimension Stone.
“green board” or any gypsum-based product 3.1.8 Soapstone: No ASTM Standard exists
unless a waterproof membrane completely at this time.
protects the surface from moisture infiltration.
3.1.9 Travertine: ASTM C1527, Standard
2.6 Positive water movement. All Specification for Travertine Dimension Stone.
horizontal surfaces (e.g., seats, sills, curbs,
etc.) must slope toward drain or toward other 4.0 TERMINOLOGY
surfaces sloped toward a drain.
4.1 Definitions.
2.7 Geographic Methods. Some 4.1.1 Hot mop. A substrate employing layers
installation methods and materials are not of asphalt applied while hot to create a
recognized and may not be suitable in some waterproof barrier.
geographic areas because of local trade
practices, building codes, climatic conditions, 4.1.2 Cold applied membrane. A liquid
or construction methods. Therefore, while applied bonded membrane, impervious to
every effort has been made to produce accurate water.
guidelines, they should be used only with the
independent approval of technically qualified 4.1.3 Wet set. Tile installation method
persons. prescribed by ANSI A108.1A.
4.1.4 Dry pack. A mortar mixed with
3.0 TECHNICAL DATA inadequate water component to facilitate
3.1 Each stone variety used for stone complete hydration, thereby dependent upon
partitions or shower rooms described in this water of opportunity to complete chemical
chapter should conform to the applicable cure. Dry packs are used due to their
ASTM standard specification and the physical compatibility and greater ability to allow
requirements contained therein. The lateral transfer of water. Dry packs frequently
specification for each stone type follows: include aggregates coarser than sand.

3.1.1 Granite: ASTM C615, Standard 4.1.5 Positive flow. To move along in the
Specification for Granite Dimension Stone. direction of a drain or other planar surfaces
sloped towards a drain.
3.1.2 Limestone: ASTM C568, Standard
Specification for Limestone Dimension Stone. 4.1.6 Negative flow. To move along in the
direction away from a drain or other planar
3.1.3 Marble: ASTM C503, Standard surfaces sloped towards a drain.
Specification for Marble Dimension Stone,
Soundness Classification “A.” 4.1.7 Sheet applied bonded membrane.
A waterproof membrane providing a barrier to
3.1.4 Onyx: No ASTM Standard exists at this positive liquid migration per ANSI A118.10.
time.
4.1.8 Shower pan (membrane or liner).
3.1.5 Quartz-based Stone: ASTM C616, Water containment sheeting per ASTM D4551
Standard Specification for Quartz-based PVC or ASTM D4068 CPE.
Dimension Stone.

Page 16-2 • Wet Areas/General Information © 2022 Natural Stone Institute

WET AREAS – 1.8.1 The deflection of the material under
maximum anticipated load shall not exceed
STONE TOILET PARTITIONS L/720.

1.0 PRODUCT DESCRIPTION

2.0 INSTALLATION
1.1 Basic Use. Toilet partitions for all
building types. 2.1 Preparatory Work. A solid substrate
and a structurally adequate plumbing wall
1.2 Fabrication. Stone toilet partitions are should be provided for proper installation.
precut, predrilled, and prefinished to
dimensions specified on the shop drawings and 2.2 Methods. Partitions are assembled
delivered to the job site ready to install. using corrosion resistant hardware. Ceiling-
Certain job conditions make it necessary to suspended units are fastened to structural steel
perform some fabrication steps at the job site. supports in the ceiling. Ceiling-suspended
units may require a metal spline. Floor-
1.4 Types. Partitions may be designed as supported units require concrete floor
floor-supported or ceiling-suspended. construction to secure anchor bolts. Anchorage
methods are to comply with applicable codes.
1.5 Finishes. Polished finish is most
common due to ease of maintenance. See 2.2.1 All joints are filled with non-staining
chapter 3, Stone Selection, for other sealants or grout. Where so specified, joints
commonly available finishes. requiring sealant shall be first filled with an
approved rope backer rod. The backer rod shall
1.6 Colors. Some of the commercially be installed to a depth that provides optimum
available varieties are unsuitable due to sealant profile after tooling.
reduced soundness of the material or
susceptibility to acid attack. 2.3 General Precautions. During
construction, the General Contractor shall
1.7 Sizes. Stone size is limited by the stone protect all stone from staining or damage.
deposit and quarrying method of the selected
stone and design requirements of the specific 2.4 The ceiling channel to which the stile
project. Appropriate stone thickness will be should be attached shall be furnished and
determined by many factors including installed by others.
soundness of the stone, anchorage capacity and
placement, span between supporting 2.5 Unless otherwise noted, channels,
members, etc. head rails, splines, pilasters, threaded pipe and
other fittings are to be supplied by others.
1.8 Technical Information. Every
construction condition requires engineering
based on specific factors for each project–
panel weight, backup material, stone
mechanical and physical properties, etc. The
most stringent code documents always take
precedence. Contact the engineer or
manufacturer of each anchoring system for its
particular technical information and
engineering formulas.

© 2022 Natural Stone Institute Wet Areas/Stone Toilet Partitions • Page 16-3
WET AREAS – particular technical information and
engineering formulas.
STONE URINAL PARTITIONS
1.7.1 The deflection of the material under
1.0 PRODUCT DESCRIPTION maximum anticipated load shall not exceed
L/720.
1.1 Basic Use. Urinal partitions (or as
junior toilet partitions where doors are not
desired) for all building types. 2.0 INSTALLATION
1.2 Fabrication. Stone urinal partitions 2.1 Preparatory Work. A solid substrate
are precut, predrilled, and prefinished to not more than two inches below finish floor
dimensions specified on the shop drawings and and a plumbing wall should be provided for
are delivered to the job site ready to install. proper installation.
For certain job conditions it is preferable to
finish the stone at the job site. 2.2 Methods. Partitions are available
floor-supported or ceiling-hung. If ceiling-
1.3 Types. Partitions may be designed as hung, the General Contractor shall furnish and
wall hung or floor-supported (with or without install the ceiling channel. Unless otherwise
overhead brace). noted, channels, head rails, splines, pilasters,
threaded pipe and other fittings are to be
1.4 Finishes. Polished finish is most supplied by others
common due to ease of maintenance. See
chapter 3, Stone Selection, for other 2.2.1 Partitions are assembled using
commonly available finishes. corrosion resistant hardware. Floor-supported
units are set on dowels into the finished floor.
1.5 Colors. Some of the commercially Ceiling-hung units are bolted to overhead
available varieties are unsuitable due to support. All ceiling-hung units must have a
reduced soundness of the material or metal spline. Wall-mounted urinal partitions
susceptibility to acid attack. must be attached to the wall at a minimum of
three locations.
1.6 Sizes. Stone size is limited by the stone
deposit and quarrying method of the selected 2.2.2 All joints are filled with non-staining
stone and the design requirements of the sealants or grout. Where so specified, joints
specific project. Appropriate stone thickness requiring sealant shall be first filled with an
will be determined by many factors including approved rope backer rod. The backer rod shall
soundness of the stone, anchorage capacity and be installed to a depth that provides optimum
placement, span between supporting sealant profile after tooling.
members, etc.
2.3 General Precautions. During
1.7 Technical Information. Every construction, the General Contractor shall
construction condition requires engineering protect all stone from staining and damage.
based on specific factors for each project–
panel weight, backup material, stone physical
and mechanical properties, etc. The most
stringent code documents always take
precedence. Contact the engineer or
manufacturer of each anchoring system for its

Page 16-4 • Wet Areas/Stone Urinal Partitions © 2022 Natural Stone Institute
WET AREAS – manufacturer of each anchoring system for its
particular technical information and
STONE SLAB SHOWER engineering formulas.
PARTITIONS
1.7.1 The deflection of the material under
1.0 PRODUCT DESCRIPTION maximum anticipated load shall not exceed
L/720.
1.1 Basic Use. Shower partitions for all
building types.
2.0 INSTALLATION
1.2 Fabrication. Stone shower partitions
are precut, predrilled, and prefinished to 2.1 Preparatory Work. A solid substrate
dimensions specified on the shop drawings and and a plumbing wall should be provided for
are delivered to the job site ready to install. proper installation.
For certain job conditions it is preferable to
finish the stone at the job site. 2.1.1 Waterproofing (ANSI A118.10) is
typically the responsibility of other trades prior
1.3 Types. Partitions may be designed as to installation of stone. Shower pan or
wall hung or floor-supported (with or without waterproof membrane (ANSI A118.10) must
overhead brace). Partitions are also available as be installed to turn up vertical wall surface at
free-standing units with precast terrazzo least 3" (75 mm) above the finished surface of
receptors. the shower curb. The integrity of the
waterproof membrane of the floor up to the
1.4 Finishes. Polished finish is most curb height should be verified by the contractor
common due to ease of maintenance. See before commencing work by flood test per
chapter 3, Stone Selection, for other building and plumbing code requirements per
commonly available finishes. ASTM D5957, “Standard Guide for Flood
Testing Horizontal Waterproofing
1.5 Colors. Some of the commercially Installations.” Test shower pan or waterproof
available varieties are unsuitable due to the lack membrane and drainage fitting for leaks before
of soundness of the material or its susceptibility beginning stone work.
to acid attack.
2.1.2 Shower pan or moisture proofing
1.6 Sizes. Stone size is limited by the stone must be pre-sloped at a minimum pitch of ¼"
deposit and quarrying method of the selected per foot (20 mm per m) to the weep holes of
stone and the design requirements of the he shower drain assembly. Surround the drain
specific project. Appropriate stone thickness with pea gravel or other weep protection to
will be determined by many factors including prevent mortar from blocking weep holes.
soundness of the stone, anchorage capacity and
placement, span between supporting 2.1.3 Partitions are assembled using
members, etc. corrosion resistant hardware. All joints are
sealed with non-staining sealants or grout.
1.7 Technical Information. Every Where so specified, joints requiring sealant
construction condition requires engineering shall be first filled with an approved rope
based on specific factors for each project– backer rod. The backer rod shall be installed to
panel weight, backup material, stone physical a depth that provides optimum sealant profile
and mechanical properties, etc. The most after tooling.
stringent code documents always take
precedence. Contact the engineer or
© 2022 Natural Stone Institute Wet Areas/Stone Shower Partitions • Page 16-5
2.2 Methods. Stone shower partitions are
to be installed to allow service or replacement
of the partition without damaging adjacent
finished surfaces. Stone shower partitions can
be installed by one of the following methods:

2.2.1 Free-standing units. Partitions are

assembled using corrosion resistant hardware.
All joints are filled with non-staining sealants
or grout.

2.2.2 Floor-supported units. Partitions

are to be set on top of substrate. Floor-
supported units are set on dowels into the
finished floor.

2.3 General Precautions. During

construction, the General Contractor shall
protect all stone from staining and damage.

NOTES:

Page 16-6 • Wet Areas/Stone Slab Residential © 2022 Natural Stone Institute
WET AREAS – particular technical information and
engineering formulas.
STONE SLAB RESIDENTIAL
SHOWERS, STEAM ROOMS, 1.7.1 Construction of walls and partitions
AND STEAM SHOWERS should be designed to maximum deflection of
L/720 for conditions utilizing thick-set or thin-
set mortar installation methods.
1.0 PRODUCT DESCRIPTION
2.0 INSTALLATION –
1.1 Basic Use. Shower stalls, steam rooms,
and steam showers for residential use.
SLAB SHOWER STALLS

1.2 Fabrication. Parts are precut and 2.1 Preparatory Work. Shower pan or
prefinished to dimensions specified on the shop waterproof membrane (ANSI A118.10) must
drawings and are delivered to the job site ready be installed to turn up vertical wall surface at
to install. For certain job conditions it is least 3" (75 mm) above the finished surface of
preferable to finish the stone at the job site. the shower curb. The integrity of the
waterproof membrane of the floor up to the
1.3 Limitations. Only sound stone curb height should be verified by the contractor
varieties should be used. Marble selection is before commencing work by flood test per
limited to Soundness Classifications “A” and building and plumbing code requirements per
“B”. ASTM D5957, “Standard Guide for Flood
Testing Horizontal Waterproofing
1.4 Finishes. Polished finish is most Installations.” Test shower pan or waterproof
common due to ease of maintenance. See membrane and drainage fitting for leaks before
chapter 3, Stone Selection, for other beginning stone work.
commonly available finishes.
2.1.1 Shower pan or waterproofing must
1.5 Colors. Some of the commercially be pre-sloped to a minimum pitch of ¼" per
available varieties are unsuitable due to the lack foot (20 mm per m) to the weep holes of the
of soundness of the material or its susceptibility shower drain. Surround the drain with pea
to acid attack. gravel or other weep protection to prevent
mortar from blocking weep holes.
1.6 Sizes. Stone size is limited by the stone
deposit and quarrying method of the selected 2.2 Method. Shower stall floor should be
stone and the design requirements of the installed in a dry-pack mortar bed consisting of
specific project. Appropriate stone thickness one part portland cement to four to five parts
will be determined by many factors including sand, 100% coverage of mortar bed material
soundness of the stone, anchorage capacity and between floor and substrate is recommended.
placement, span between supporting Moisture must be able to freely migrate
members, etc. laterally through the mortar bed and discharge
via the weep holes in the shower drain
1.7 Technical Information. Every assembly.
construction condition requires engineering
based on specific factors for each project– 2.3 Stone wall panels are set firmly
panel weight, backup material, stone physical against masonry walls or waterproofed
and mechanical properties, etc. The most surfaces.
stringent code documents always take
precedence. Contact the engineer or 2.4 Joint width can be maintained by
manufacturer of each anchoring system for its using plastic shims. Joints should be at least
© 2022 Natural Stone Institute Wet Areas/Stone Slab Residential • Page 16-7
1/16" (1.5 mm) wide and pointed with white Professional design and installation are critical
cement, grout, or non-staining sealant. Joint to avoid damage to adjacent material due to
width must be specified. vapor migration and heat transfer.

2.5 Anchors that contact the stone should 3.1 Waterproofing. A waterproofing
be corrosion resistant metal (stainless steel, membrane (ANSI A118.10) must extend a
copper, bronze, brass, aluminum) and should minimum of 3" above the top of the finished
be securely attached to the structure and the surface of the curb. All backup surfaces must
stone. be waterproofed with a membrane authorized
by the Manufacturer for steam room
2.6 Exposed stone edges must be gauged applications. All horizontal surfaces shall be
to the precise thickness specified. pre-sloped to a minimum pitch of ¼" per foot
(20 mm per m) toward the shower drain
2.7 Face Sealing. Stone residential shower assembly. The integrity of the waterproof
stalls may be sealed or unsealed. membrane on the floor up to the height of the
curb should be verified by the contractor
2.7.1 If sealed, follow Manufacturer’s before commencing work by flood test per
written recommendations for cleaning, building and plumbing code requirements per
stripping, and resealing. The chemicals used ASTM D5957, “Standard Guide for Flood
should contain no acids or harshly alkaline Testing Horizontal Waterproofing
ingredients. Both types destroy the polished Installations.”
finishes on some stone varieties.
3.2 Methods. Stone may be installed by
2.7.2 Sealing does not eliminate the need using any of the approved methods. Exterior
for frequent cleaning of the wall or floor methods must be used in the shower. Avoid
surfaces. A neutral detergent (pH of 7) is the use of gypsum board in shower areas.
recommended cleaning agent.
3.3 Ceilings are to be sloped ½” per foot
2.8 Stone Ceilings. For details and (40 mm per m) up to 2” per foot (170 mm per
information regarding stone ceilings in m) for textured finishes to bring moisture to
residential showers, refer to the “Stone Soffits” the face of the wall opposite the shower head,
section of this Manual in Chapter 14, Vertical or the principal wall(s) of the room. For
Surfaces. example, consider sloping the ceiling away
from the wall including a bench or doorway.
2.9 General Precautions. During Sloping ceiling from the center can minimize
construction, the General Contractor shall rundown on the walls. Large, one-piece
protect all stone from staining and damage. shower ceilings should be supported by the
shower walls. An additional anchor should be
3.0 INSTALLATION – installed at the cutout for the fan or fan/light
SLAB STEAM ROOMS AND combination.
STEAM SHOWERS 3.4 Finished surface must be sloped
Steam rooms are highly specialized toward the shower drain assembly at a
applications. All electrical and plumbing minimum pitch of ¼" per linear foot (20 mm
fixtures should be rated for steam rooms. per m) and a maximum pitch of ½" per linear
Steam rooms for continuous use require a foot (40 mm per m).
membrane (ANSI A118.10) with a water vapor
permeance (perm rating) of 0.5 or less.

Page 16-8 • Wet Areas/Stone Slab Residential © 2022 Natural Stone Institute
3.5 Grout is to be full stone depth. Cured moisture at the back face. Weep holes should
grout should not be easily penetrated with a be provided to evacuate moisture from any
pocket knife blade. voids which may have developed between the
back face of the stone and the substrate.
3.6 Installation materials must be
authorized by the Manufacturer for steam 3.10 Provision for Steam Generator.
room applications. Water should be potable Oversize the diameter of the hole in the stone
and free of any staining agents. Stone tiles may for the steam pipe a minimum of ¼” (6 mm).
be used. Center the steam line in the hole and use high
temperature silicone or insulation to act as a
3.7 Stone may be installed using any heat barrier between the steam and the stone
of the following methods: material.

3.7.1 A thin-set method on a mortar bed or 3.10.1 Install steam shower controller per
cementitious backer board for tile only. Setting Manufacturer’s installation instructions. When
material suitability may be affected by the size installing on cleft or irregular surfaced stone,
of stone units to be installed. Consult with ensure control is sealed to wall.
adhesive manufacturer for specific
recommendations.
NOTES:
3.7.2 Mortar bed (wet set) method. The
method (ANSI A108.1A) that requires that the
stone be set on a mortar bed that is still plastic.

3.7.3 Mechanically anchored. An

installation system over a waterproofed
backing of scratch coat or cementitious backer
board for pieces greater than 2’ x 2’ (600 x 600
mm). Weep holes should be provided at the
base of the cavity or as shown on architectural
drawings, to evacuate accumulated
condensation from the air space between the
back face of the stone and the substrate.
Additionally, openings should be provided at
the top of the installation to accommodate
ventilation of the cavity

3.8 Effects of Steam on Stone and

Anchorage. Steam is a catalyst. Many stones
contain elements and metallic compounds that
will react with steam and form other elements
not common to the stone’s variety. Color
change in background and veining could result,
and the stone’s structural integrity may be
compromised. Use non-corroding hardware in
all conditions where in contact with stone.

3.9 Additional Moisture Control.

Adhered stone should be solid-set to avoid

© 2022 Natural Stone Institute Wet Areas/Stone Slab Residential • Page 16-9
WET AREAS – 1.7 Technical Information. Every
construction condition requires engineering
STONE TILE RESIDENTIAL based on specific factors for each project–
SHOWERS, STEAM ROOMS, panel weight, backup material, stone physical
AND STEAM SHOWERS and mechanical properties, etc. The most
stringent code documents always take
precedence. Contact the engineer or
1.0 PRODUCT DESCRIPTION manufacturer of each anchoring system for its
particular technical information and
1.1 Basic Use. Shower stalls, steam rooms, engineering formulas.
and steam showers for residential use.
1.7.1 The deflection of the material under
1.2 Fabrication. Parts are precut and pre- maximum anticipated load shall not exceed
finished to dimensions specified on the shop L/720.
drawings and are delivered to the job site ready
to install. 1.8 Exposed stone edges must be gauged
to the precise thickness specified.
1.3 Limitations. Only sound stone
varieties, including Soundness Classification 2.0 INSTALLATION –
Groups A and B marbles, should be used. Stone
tile with adhered fiberglass mesh
TILE SHOWER STALLS
reinforcement on their back surfaces are not to
be used for shower applications. Due to the 2.1 Preparatory Work. Shower pan,
nature of stone tile production, it can be waterproof membrane (ANSI A118.10), or
expected that wide ranges in color and veining vapor retarder membrane (ANSI A108.02-
will occur. It is unreasonable to expect the 3.8) must be specified (see current TCNA
Installer to produce specific matching patterns B414 STONE for details). Turn shower pan
or strict adherence to a specific range of colors membrane up vertical wall surface at least 3"
from tiles pulled one by one out of a carton (75 mm) above the finished surface of the
unless specific instructions are given and shower curb [6” (150 mm) above floor in
agreed to before the installation is begun. showers without curbs]. The integrity of the
waterproof membrane up to the height of the
1.4 Finishes. Polished finish is standard. curb should be verified by the contractor
See chapter 3, Stone Selection, for other before commencing work by flood test per
commonly available finishes. building and plumbing code requirements per
ASTM D5957, “Standard Guide for Flood
1.5 Colors. Most of the commercially Testing Horizontal Waterproofing
available varieties are suitable. However, some Installations.”
varieties are unsuitable due to the reduced
soundness of the material or susceptibility to 2.2 Method. Shower stall floor should be
acid attack. installed in a dry-packed mortar bed consisting
of one part portland cement to four to five
1.6 Sizes. Stone size is limited by the stone parts sand. 100% coverage of mortar bed
deposit and quarrying method of the selected material between floor and sub-slab is
stone and the design requirements of the recommended.
specific project. Appropriate stone thickness
will be determined by many factors including 2.2.1 Shower pan membrane must be
soundness of the stone, anchorage capacity and sloped toward the shower drain assembly at a
placement, span between supporting minimum pitch of ¼" per linear foot. Finished
members, etc. surface must be sloped toward the shower
Page 16-10 • Wet Areas/Stone Tile Residential © 2022 Natural Stone Institute
drain assembly at a minimum pitch of ¼" per Steam rooms are highly specialized
linear foot (20 mm per m) and a maximum applications. All electrical and plumbing
pitch of ½" per linear foot (40 mm per m). fixtures should be rated for steam rooms.
Steam rooms for continuous use require a
2.2.2 A plumb, properly waterproofed membrane (ANSI A118.10) with a water vapor
backup wall with a maximum variation of 1/8” permeance (perm rating) of 0.5 or less.
in 8'-0" (3mm per 2.5 m) must be provided. Professional design and installation are critical
Thinset adhesive is spread over the substrate to avoid damage to adjacent material due to
with a notched trowel, and the stone tile is put vapor migration and heat transfer.
into place with a slight twisting motion. For all
applications, the stone tile shall be back 3.1 Installation materials must be
buttered to achieve, as close as practical, 100% authorized by the Manufacturer for steam
adhesive contact between the stone and the room applications. Water must be free of
backup. metals and should be potable.

2.3 Joint width can be maintained by 3.2 Preparatory Work. Shower pan
using plastic shims. Joints should be at least (ANSI A118.10, ASTM D4068 or D4551 and
1/16" (6.5) wide. Joint width must be meeting applicable building codes) must be
specified. specified (see current TCNA SR613 or SR614
for details). Turn shower pan membrane up
2.4 Movement Joints (Architect must vertical wall surface at least 3" (75 mm) above
specify type of joint and show location and the finished surface of the shower curb [6” (150
details on drawings). Movement joints are mm) above floor in showers without curbs].
mandatory according to TCNA EJ171. The integrity of the waterproof membrane up
to the height of the curb should be verified by
2.5 Sealing. Stone tiles installed in the contractor before commencing work by
residential showers may be sealed or unsealed, flood test per building and plumbing code
according to the Owner’s preference. requirements per ASTM D5957, “Standard
Guide for Flood Testing Horizontal
2.5.1 If sealed, follow Manufacturer's Waterproofing Installations.”
written recommendations for cleaning,
stripping, and resealing. The chemicals used 3.3 Stone tile may be installed using
should contain no acids or harshly alkaline any of the following methods:
ingredients. Both types destroy the polished
finishes on some stone varieties. 3.3.1 Thin-set method on a mortar bed or
cementitious backer board.
2.5.2 Sealing does not eliminate the need
for frequent cleaning of the wall or floor 3.3.2 A full mortar bed. A full mortar bed
surfaces. A neutral detergent (pH of 7) is the or wet set method (ANSI A108.1A) that
recommended cleaning agent. requires that the stone be set on a mortar bed
that is still plastic.
2.6 General Precautions. During
construction, the General Contractor shall 3.3.3 Tiles as thin as 3/8" may be used.
protect all stone from staining and damage. Reference current edition of TCNA Handbook
for Ceramic, Glass, and Stone Tile Installation for
3.0 INSTALLATION – TILE additional details.
STEAM ROOMS AND STEAM
3.4 Effects of Steam on Stone. Steam is
SHOWERS
a catalyst. Many stones contain elements and

© 2022 Natural Stone Institute Wet Areas/Stone Tile Residential • Page 16-11
metallic compounds that will react with steam WET AREAS –
and form other elements not common to the
stone’s variety. Color change in background ACCESSORIES AND STONE
and veining could result, and the stone’s PENETRATIONS
structural integrity may be compromised. Use
non-corroding hardware in all conditions
where in contact with stone. 1.0 ACCESSORIES
1.1 Accessories must meet all
3.5 Moisture Proofing. Stone should be applicable building codes and be
solid-set to avoid creating a moisture collection installed per Manufacture’s recom-
cavity at the back face. mendations.
3.6 Ceilings are to be sloped ½” per foot 1.2 Manufacturer's standard design
(40 mm per m) up to 2” per foot (170 mm per hardware and accessories shall be made of non-
m) for textured finishes to bring moisture to corroding materials.
the face of the wall opposite the shower head,
or the principal wall(s) of the room. For 1.3 All built-in seats, sills, curbs, etc., shall
be waterproof and installed over a pre-sloped,
example, consider sloping the ceiling away
flashed, waterproof membrane. Finish surface
from the wall including a bench or doorway.
and substrate should have a minimum slope of
Sloping ceiling from the center can minimize
¼” per foot (20 mm per m) toward the drain.
rundown on the walls.
1.4 All built-in seats, sills, curbs, etc., must
3.7 Slope shower pan membrane a be dimensionally stable when moist and
minimum of ¼" per foot (20 mm per m) to structurally sound.
weep holes in drain.

3.8 Grout is to be full stone depth. 2.0 PENETRATIONS

2.1 Penetrating the waterproof system or
3.9 Provision for Steam Generator.
the stone is often necessitated for the
Oversize the diameter of the hole in the stone
installation of recessed niches, all features of
for the steam pipe a minimum of ¼” (6 mm).
niches (e.g., shelves, lights), and corner seats,
Center the steam line in the hole and use high
grab bars, fans or fan/light combinations, etc.
temperature silicone or insulation to act as a
heat barrier between the steam and the stone 2.2 All openings, cut-outs or protrusions
material. through the waterproofing system should be
sealed with a suitable flexible sealant.
3.9.1 Install steam shower controller per
Manufacturer’s installation instructions. When 2.3 Any opening penetrating the water-
installing on cleft or irregular surfaced stone, proof envelope must be flashed and sealed to
ensure control is sealed to wall. become an integral part of the system.
2.4 Any penetrations through the stone shall
be made waterproof with a non-staining
flexible sealant.

Page 16-12 • Wet Areas/Stone Tile Residential © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

1,2,6,12,13,15 7

PLAN
TYPICAL LAYOUT

11

3 1,2,6,7

4,5

ELEVATION A ELEVATION B
HARDWARE MOUNTED HARDWARE MOUNTED

FLOOR SUPPORTED STALL

REV DATE STONE TOILET PARTITIONS
0 MAR 2022 (FLOOR-SUPPORTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-1
¼" = 1'-0"

© 2022 Natural Stone Institute 16-D-1

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

8,9,10

3 1,2,6

ELEVATION A ELEVATION B
HARDWARE MOUNTED HARDWARE MOUNTED

CEILING MOUNTED STALL

REV DATE STONE TOILET PARTITIONS

0 MAR 2022 (CEILING-MOUNTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-2
¼" = 1'-0"
16-D-2 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

PLAN 1 PLAN 2 PLAN 3

HARDWARE MOUNTED HARDWARE MOUNTED HARDWARE MOUNTED

SECTION 4 SECTION 5
FLOOR SUPPORTED FLOOR SUPPORTED

PLAN 6 PLAN 7
HARDWARE MOUNTED HARDWARE MOUNTED

REV DATE STONE TOILET PARTITIONS

0 MAR 2022 (FLOOR-SUPPORTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-3
1½" = 1'-0"

© 2022 Natural Stone Institute 16-D-3

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

DETAIL 8 DETAIL 9
CEILING MOUNTED CEILING MOUNTED

DETAIL 10 DETAIL 11
CEILING MOUNTED FLOOR MOUNTED

REV DATE STONE TOILET PARTITIONS

0 MAR 2022 (CEILING-MOUNTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-4
1½" = 1'-0"
16-D-4 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

PLAN 12 PLAN 13
DOWEL MOUNTED DOWEL MOUNTED

SECTION 14 SECTION 15
DOWEL MOUNTED DOWEL MOUNTED

REV DATE STONE TOILET PARTITIONS

0 MAR 2022 (DOWEL-MOUNTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-5
1½" = 1'-0"

© 2022 Natural Stone Institute 16-D-5

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

3,4,5

1,2

SIDE END

URINAL SCREEN ELEVATIONS - FLOOR SUPPORTED 3/4"=1'-0"

DETAIL 1 DETAIL 2
LEG PENETRATING FLOOR LEG RESTING ON FLOOR

1 1/2"=1'-0"

REV DATE STONE URINAL PARTITIONS

0 MAR 2022 (FLOOR-SUPPORTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-6
AS NOTED
16-D-6 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

3,4,5,6

SIDE END

URINAL SCREEN ELEVATIONS - WALL MOUNTED 3/4"=1'-0"

PLAN 3 PLAN 4
HARDWARE MOUNTED HARDWARE MOUNTED

PLAN 5 PLAN 6
HARDWARE MOUNTED HARDWARE MOUNTED 1 1/2"=1'-0"

REV DATE STONE URINAL PARTITIONS

0 MAR 2022 (WALL-MOUNTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-7
AS NOTED

© 2022 Natural Stone Institute 16-D-7

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

6 16 SIM 16 SIM
6
23,24,25
23,24,25

8 8

16

16 SIM.
16 SIM.
7 7

13,14,15 5 6

5
13,14,15

PLAN
WATERPROOF PAN RECEPTOR TYPE 3/8"=1'-0"

8
6 6 6 6

12 12

PLAN PLAN
PRECAST RECEPTOR TYPE PRECAST RECEPTOR TYPE
REV DATE
STONE SHOWER PARTITIONS - PLANS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-8 3
8" = 1'-0"

16-D-8 © 2022 Natural Stone Institute

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

OPEN OPEN

13, 14, 15

7 7

ELEVATION A
WATERPROOF PAN RECEPTOR TYPE 3/8"=1'-0"

OPEN

12

ELEVATION B
PRECAST RECEPTOR TYPE
REV DATE
STONE SHOWER PARTITIONS - ELEVATIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-9 3
8" = 1'-0"

© 2022 Natural Stone Institute 16-D-9

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

PLAN 1 PLAN 2
DOWEL MOUNTED DOWEL MOUNTED

SECTION 3 SECTION 4
DOWEL MOUNTED DOWEL MOUNTED

PLAN 5 PLAN 6
HARDWARE MOUNTED CORNER

REV DATE
STONE SHOWER PARTITIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-10
1½" = 1'-0"
16-D-10 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SECTION 7 SECTION 8
SHOWER STALL CURB SHOWER STALL DRAIN

SECTION 9 SECTION 10
BOTTOM OF STONE AT CMU BOTTOM OF STONE AT METAL STUDS

SECTION 11 SECTION 12
BOTTOM OF STONE AT WOOD STUDS BOTTOM OF STONE AT PRECAST RECEPTOR
NOTE: REFER TO TCNA HANDBOOK FOR CERAMIC, GLASS, AND STONE TILE INSTALLATION FOR ADDITOINAL DETAILS
REV DATE
STONE SHOWER PARTITIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-11
1½" = 1'-0"

© 2022 Natural Stone Institute 16-D-11

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SECTION 13
STONE SEAT AT CMU WALL

SECTION 14
STONE SEAT AT METAL STUD WALL
REV DATE
STONE SHOWER PARTITIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-12
1½" = 1'-0"
16-D-12 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SECTION 15
STONE SEAT AT WOOD STUD WALL

SECTION 16
STONE CLAD SHOWER DIVIDER WALL

REV DATE
STONE SHOWER PARTITIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-13
1½" = 1'-0"

© 2022 Natural Stone Institute 16-D-13

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SECTION 17 SECTION 18
TOP OF STONE AT CMU TOP OF STONE AT METAL STUDS

SECTION 19
TOP OF STONE AT WOOD STUDS

REV DATE
STONE SHOWER PARTITIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-14
1½" = 1'-0"
16-D-14 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SECTION 20 SECTION 21
SLOPING STONE CEILING AT CMU SLOPING STONE CEILING AT METAL STUDS

SECTION 22
SLOPING STONE CEILING AT WOOD STUDS

REV DATE
STONE SHOWER CELINGS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-15
1½" = 1'-0"

© 2022 Natural Stone Institute 16-D-15

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

DN DN

SECTION 23 SECTION 24
ACCESSORY NICHE AT CMU ACCESSORY NICHE AT METAL STUDS

DN

SECTION 25
ACCESSORY NICHE AT WOOD STUDS
REV DATE
STONE SHOWER ACCESSORY NICHE
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-16
1½" = 1'-0"
16-D-16 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SECTION 26
MACHINED SHOWER FLOOR

SECTION 27
BARRIER FREE SHOWER FLOOR

REV DATE
STONE SHOWER PARTITIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-17
1½" = 1'-0"

© 2022 Natural Stone Institute 16-D-17

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

PLAN SECTION 28 PLAN SECTION 29

JAMB AT SHOWER DOOR HINGE JAMB AT SHOWER DOOR HINGE

PLAN SECTION 30
JAMB AT SHOWER DOOR HINGE

REV DATE
STONE SHOWER DOOR JAMBS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-18
3" = 1'-0"
16-D-18 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SECTION 31
PLUMBING CONTROL VALVE

SECTION 32

REV DATE
STONE SHOWER PARTITIONS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 16-D-19
3" = 1'-0"

© 2022 Natural Stone Institute 16-D-19

NOTES:

Dimension Stone Design Manual Ó 2022 Natural Stone Institute

RESIDENTIAL STONE 2.3 Marbles are traditionally prized for
their aesthetic appeal, accentuated by
COUNTERTOP pronounced veining trends and often bold
INSTALLATION colors. These stones are calcium carbonate-
based, made up principally of the calcite
crystal. Due to their mineralogical makeup, all
1.0 INTRODUCTION marbles are vulnerable to either abrasion or
chemical attack. Abrasive attack occurs most
commonly from common kitchen utensils, and
1.1 The beauty and permanence of natural
can be prevented with the judicious use of
stone countertops are enjoyed by many. The
protective cutting boards and similar measures.
full potential of these installations is realized
The use of cleaners containing abrasives must
only when the selection, design, fabrication,
be avoided. Chemical attack is most
and installation are completed by, or with the
commonly brought about by exposure to acidic
consultation of, qualified and experienced
solutions, such as lemon juice, tomatoes,
individuals. This document has been prepared
vinegar, etc. The use of inappropriate cleaning
and published by the Natural Stone Institute to
agents may also trigger acidic attack. Acidic
guide the user in the correct means and
solutions can permanently etch the surface of
methods of using natural stone as a countertop
the material. The application of an
surface.
impregnating sealer may reduce the
vulnerability to acidic attack, but it will not
eliminate it.
2.0 STONE MATERIALS
2.1 Varieties. All varieties of dimension 2.4 Serpentines are similarly prized for
stone have been used successfully for their veining and color. Historically, this rock
countertop surfaces. Different types of stone type had been commercially grouped with
have specific properties that offer advantages or marble. However, serpentine is not true
disadvantages in various applications. The marble geologically. See Chapter 9, Geological
following is a brief overview of the common Classification, for distinguishing characteristics
varieties of dimension stone. of serpentine. Due to their mineralogical
difference, serpentines generally have
2.2 Granites are undoubtedly the most improved abrasion and chemical resistance
popular stone type used in countertop over true marbles.
applications today. This group of stones, in a
commercial sense, includes many stone 2.5 Onyx, also prized for its color and
materials that are not true granites by veining, is perhaps best known for its
geological definition. For example, gabbro, translucent properties allowing for stunning
anorthosite, gneiss, diabase, and diorite would effects when backlit in the application. Like
be commercially sold as granite due to similar several other rock varieties, onyx was
working and performance properties. These traditionally commercialized as marble,
are some of the hardest of the common despite its notable differences. Refer to section
dimension stones, offering high levels of 1.2 of the Geological Classification section in
resistance to abrasion and scratching. The Chapter 7 for further discussion of onyx
primary minerals in granite materials are mineralogy. Due to its cryptocrystalline grain
resistant to virtually all chemicals commonly structure, when compared to true marbles,
found in a residential setting; however, there onyx tends to have lower levels of resistance to
may be trace minerals present in some granites both chemical and abrasive exposures.
and granite-like stones that are vulnerable to
some acids.

© 2022 Natural Stone Institute Countertops • Page 17-1

2.6 Soapstone is a metamorphic rock that Follow the recommendations of the
is comprised primarily of talc with varying Manufacturer of the material.
amounts of dolomite, magnesite, and other
minerals. Soapstone generally has a smooth
feel to the touch. It is used for countertops and 3.0 STONE FINISHES
other various building aspects such as sinks and There are several finishes available for natural
heaters. Soapstone is a very popular choice for stone countertops and new finishes appear in
countertops in laboratories and classrooms due the market regularly keeping pace with
to its high resistance to chemicals. Soapstone consumer demands. A description of a few of
has limited hardness and is vulnerable to the finishes commonly available follows:
scratches from abrasives. Soapstone is typically
top treated with a food grade mineral oil to 3.1 Polished: A high gloss, mirror like
retain its luster and to mask small scratches that finish with sharp reflections. This finish is
are often common because of its talc content. achieved using multiple grinding heads and
progressively finer abrasives. A polished finish
2.7 Slates, when referring to true slates, intensifies the color and pattern of natural
have high resistance to chemicals. stone.
Traditionally slates were frequently used as
chemistry laboratory tops due to this chemical 3.2 Honed: A non-reflective, satin-like
resistance. Caution is advised, however, in finish. This finish is achieved using multiple
that not all materials marketed as slates are in grinding heads and progressively finer abrasives
fact true slate, and therefore may not stopping short of a polish. A honed finish shows
demonstrate the superior chemical resistance fewer scratches.
that has been associated with this stone variety.
Being of metamorphic origin, slates are of 3.3 Brushed / Antique / Leather: The
limited hardness and therefore the use of this series of names is not fully
vulnerability to scratching or other abrasive standardized within the industry. From some
attack should be noted. The same precautions sources, they are used interchangeably, while
applying to marbles with regard to abrasive from other sources, they are distinctly different
damage should be applied to slates. processes. Most commonly, they describe a
finish that has been achieved by abrading a
2.8 Limestones and travertines used in smooth (or honed) surface with an abrasive,
countertop applications, being of calcium- often diamond, brush. The resultant finish can
based makeup, will have the same chemical have varying levels of sheen and relief. The
attack vulnerabilities as marbles. Abrasion hardness of the mineral matrix within the stone
damage is also a concern, particularly if the to which it is applied will also affect the final
stone is provided with a polished finish. Many product.
varieties of these stone types have high
absorption rates, and commonly, a sealer will
be applied to retard the rate of water 4.0 CUSTOMER
absorption into the stone.
COMMUNICATION
2.9 Stone tiles can be used as a countertop 4.1 Documentation. As dictated by
surface material, and the finished surface will standard practices of good business,
carry the same precautions as the particular communications with the customer should be
stone type from which it is made. The joint documented in writing.
filler, whether grout, elastomeric sealant,
epoxy or polyester resin, may have specific 4.1.1 As all natural stones are unique, with
requirements for protection and maintenance. pits, fissures, cracks, corrosive minerals, or

Page 17-2 • Countertops © 2022 Natural Stone Institute

other features that the customer may find 6.0 CABINET AND SUBSTRATE
objectionable, these should be acknowledged REQUIREMENTS
when samples and/or slabs are being viewed.
The customer must be made aware that some Cabinets to receive stone countertops must be
of these features may become more or less permanently affixed in their final position prior
noticeable when the position (vertical or to field measuring for countertops.
horizontal) of the slab is changed, or when the
lighting intensity is changed. 6.1 Measurement Tolerances. Refer to
Chapter 22 for allowable substrate tolerances.
4.2 Customer and Subcontractor When cabinets are not within these tolerances,
Responsibilities. Those items that are a notice to proceed with the installation shall
required to be completed by the customer, or be obtained from the customer (or authorized
by subcontractors coordinated by the representative). Installations done on cabinetry
customer, should be specifically addressed that is outside of these tolerances will have
(e.g., cabinetry installation, plumbing rough- excessive shim spaces and wide regions of filler
in and electrical rough-in). material. Any required aesthetic improvement
to conceal this condition (e.g., additional wood
4.3 Shop Drawings (or facsimile) can trim) is the responsibility of others.
effectively communicate exact cutting
information to the customer. A shop drawing 6.2 Subtops. Fragile stone varieties may
is a highly detailed document that will identify require a full subtop to support the stone.
all aspects of the finished product installation. Generally, sound varieties of granites and
The shop drawing is to be prepared by the marbles falling within soundness classifications
fabricator, showing the layout of the stone A or B can be used in thicknesses of 20 mm or
pieces, location and size of all seams, and greater without the use of a subtop. The
details clarifying all corner and edge treatment presence of unsound veins, cracks, or excessive
conditions. This document can be reviewed by fissuring will mandate the use of a subtop,
the customer prior to commencement of regardless of thickness. Appropriate materials
fabrication. Time constraints of some projects, for subtops are marine-grade plywood,
particularly multi-unit projects, may not allow exterior-grade plywood, waterproofed
for the formal shop drawing preparation and medium-density particle board, or furring
approval processes. In such cases, a copy of the strips. Excessive load-carrying requirements,
field measuring technician’s sketch and notes such as the use of heavy cast-iron sinks, may
may be used in place of the shop drawing. This require the use of either a subtop or auxiliary
document shall be signed by the field measurer framing to carry the weight of the sink and its
upon completion of the field measurement. contents.

4.4 Stone Slab Layout. When working 6.3 Cabinet doors, end panels, and
with highly variegated materials, it may be hardware shall be installed when the field
necessary to invite the customer to participate measurements are made.
in the layout of the actual stone slabs.
7.0 FIELD MEASUREMENTS
7.1 Cabinet Components. Field
5.0 CONTRACTS measurements are to be taken once all cabinets
5.1 Examples of residential supply contracts have been installed in their permanent
can be found in the Introduction of this Manual positions. The following related components
and Customer & Sales Forms in the NSI must be available to the technician at the time
Management Tool Kit Series. of measurement:

© 2022 Natural Stone Institute Countertops • Page 17-3

7.1.1 Cabinet Doors cantilevered portion represent more than 1/3
of the width of the countertop. Cantilevered
7.1.2 End Panels countertops exceeding these dimensions will
require corbelled supports beneath the stone.
7.1.3 Cabinet Hardware The exposed underside of cantilevered
portions of countertops will be sawn or
7.1.4 Sinks (and manufacturer-supplied otherwise unfinished surfaces. NOTE: Stones
templates) of lesser soundness may require corbelled
supports for cantilevers that are less than those
7.1.5 Plumbing Fixtures specified herein.

7.1.6 Cook Tops 8.3 Sink Mounts. Sinks are supplied in

one of several types: top mount (or self-
7.1.7 Exhaust Vents (when full-height rimming), undermount and “farm-home.” In
splash is required) the case of the top-mounted sinks, the weight
of the sink and its contents are transferred to
7.1.8 Electrical Outlets (roughed in) the top surface of the stone counter via the rim
of the sink. Undermount sinks can be anchored
to the underside of the stone countertop or
carried by a subtop or auxiliary frame. A
8.0 DESIGN CONSIDERATIONS subtop or auxiliary framing may be required
8.1 Joinery Layout. The layout of the for either design when stones of lesser
joinery of the countertops is extremely soundness are used, or when the sink (with
important to the overall appearance upon contents) is excessively heavy. Refer to details
completion. Being products of nature, slabs of on drawings 17-D-8 through 17-D-11 for
natural stone are limited by the yields of the examples of sink mounting.
quarry in addition to the limitations of the
equipment used in their processing. Most, but 8.4 Edge profiles. Whether shaped by a
not all materials marketed for use as router or a Computer Numeric Control
countertops will be available in lengths up to (CNC) machine, edge profiles add elegance to
±8 ft (± 2.5 m), and some materials are the finished project. Edge profiles with narrow
available in lengths of 10 ft (3 m) or slightly projections and sharp corners are more
greater. Seam location and frequency is susceptible to chipping than those with large
therefore influenced by the available stock for radii. Examples of edge profiles commonly
selected species of material. Details on used are included on drawing 17-D-16. With
drawings 17-D-1, 17-D-2, and 17-D-3 show a machinery and tooling available to modern
variety of joinery schemes. fabrication shops, many custom profiles can be
created which are not shown in this document.
8.2 Spans and Cantilevers. In designs
where part of the countertop is spanning 8.5 Corner Embellishments. Corners of
between supports, the length of the span shall stone countertops can be cut square, cut to a
be limited to 2'-0" (600 mm) for ¾" (20 mm) radius, or projected. Some hand grinding may
stone thicknesses and 3'-0" (900 mm) for 1¼" be required with projected corner designs.
(30 mm) stone thicknesses. In designs where
the countertop is cantilevered beyond the 8.6 Backsplashes. Partial backsplashes
supports (overhanging), the cantilever shall be usually range from 4" to 8"(100 to 200 mm).
limited to 6" (150 mm) for ¾" (20 mm) thick Full-height backsplashes cover the entire area
countertops and 10” (250 mm) for 1¼" (30 between the countertop and the upper
mm) countertops, but in no case may the cabinets. Backsplashes are normally made of

Page 17-4 • Countertops © 2022 Natural Stone Institute

the same thickness as the countertop material. match between the edge surface and the top
The narrow strips will aid in the layout surface may not be achievable.
efficiency and allow for better color match. It
also provides the fabricator better yield. 9.4 Cutouts for auxiliary equipment
Mixing materials of two different thicknesses can be made with hand-held or automated
requires using stone slabs sawn from two tools. Cutouts shall conform to equipment
different blocks, and color variation can be templates, with allowable tolerances. In the
pronounced. interest of safe handling, some cutouts will be
partially or completely performed in the field
after installation of the stone.
9.0 FABRICATION METHODS
9.5 Crating and Protection for
9.1 Safe Work Practices. All technicians Transport. The stone materials are to be
involved in the handling and working of stone crated or otherwise protected for transport to
materials must receive training in the safe work the project site. Local transportation laws shall
practices (Refer to NSI videos on stone shop be researched to ascertain tie-down and
and slab handling safety). clearance requirements when transporting
stones.
9.2 Layout and Sawing. The layout
should be marked on the stone slabs using a
temporary mark or by laying physical
templates on the slab. This will roughly
10.0 INSTALLATION METHODS
indicate the location and orientation from 10.1 Safe Handling. All technicians
which the finished panels will be sawn. The involved in the handling and working of stone
actual finished dimensions of the sawn slabs materials must receive training in safe work
will be controlled by the sawyer, and practices.
depending on the sophistication of the available
equipment, may be a digitally controlled 10.2 Dry Assembly. At the project site, it is
process. The slab thickness is to be sawn recommended that all stone pieces be “dry
through its full depth, in single or multiple assembled” in place to verify satisfactory fit
passes as required by the equipment used. prior to the application of adhesive.
Blade type, rim speed, saw travel rate, and
downfeed rates are to be adjusted to provide 10.3 Shims are commonly employed to level
the smoothest cut with the least amount of the stone countertops. Shim material may be
chipping possible. wood or plastic. Shims must be placed over
portions of the cabinet that are rigid enough
9.3 Finishing of Edge Profiles. Edge to support it, not over some trim filler
profiles shall be constant in section along the portion. Maximum spacing between shims is
entire length of the countertop. The shaping of 2'-0" (600 mm). Alternatively, longer spacing
the edge is normally done with hand-held between shims may be used if the stone is
routers or with CNC machinery. Some hand supported with a noncompressible filler
grinding is frequently required at inside corner material (usually epoxy or polyester resin).
conditions to create a sharp line of reprise. This practice is often referred to as “hard
Edges are to be finished to the same type and packing.”
quality of surface as the top, unless a
contrasting edge surface has been specified for 10.4 Adhesive. The stone countertops are
accent purposes. In the case of resin treated to be secured to the substrate with a
slabs, some alteration to the color of the edge nonstaining adhesive. Common construction
surface is required to be completed in the adhesives or silicone sealant are the most
fabrication shop. In some cases exact color popular materials used. Construction adhesives

© 2022 Natural Stone Institute Countertops • Page 17-5

generally provide greater bond strength, while agreements must be documented in writing.
silicone sealants offer slightly more forgiveness Unless otherwise agreed, the tolerances listed
for movements in the substrate. The adhesive in this document shall govern.
material must have a cure rate that is slow
enough to allow final positioning of the stone 11.2 Joint (seam) Widths. Joint width
countertop units. Apply adhesive to within 3" does not include the dimension of an arris on
(75 mm) of all edges and at 6" (150 mm) the stone edge. When an arris is used, the
maximum center-to-center spacing when perceived joint width may be greater that the
installing over a subtop. When installing to the actual width due to the seam filler occupying
cabinet frame without a subtop, apply adhesive the width of the arris.
to all frame members that contact the stone
slab.

10.5 Final Positioning and Joint Filling.

Final positioning of the stone is done either
manually or with the aid of commercially
available stone-alignment tools. The filling of
the seams is normally completed prior to final
positioning of the stone units, allowing the
filler material to extrude out of the joint as the
stones are pulled into alignment. The stone
surface may be masked to prevent contact by
the filler material (refer to NSI Basics of Natural
Stone Countertop Installation video).
11.3 Lippage. The term “lippage,” as used in
10.6 Sealer Application. After the the stone industry, is the planar offset of the
countertops are installed and the seams are finished surfaces of two adjacent stone units.
filled, a sealer or impregnator may be applied. Due to the relatively tight seams used in
Refer to the Maintenance section of this countertop installations, even minor amounts
chapter for further discussion of these of lippage are noticeable. Lippage may be
applications. Alternatively, some fabricators unavoidable due to permanent warp in the slab
prefer to apply the sealer or impregnator in the stock. There should be no detectable lippage at
fabrication shop prior to transporting the the front edge of the countertop. See sketch
pieces to the project site. below for clarification.

11.4 Exposed edges of adjacent stone slabs

11.0 TOLERANCES must be matched in thickness and properly
11.1 Refer to Chapter 22 for allowable installed so that neither the top nor bottom
fabrication and installation tolerances. The surface exceeds lippage tolerances.
tolerances listed in this section are achieved
using skilled tradesmen following standard
industry workmanship practices. Due to
variations in fabrication equipment and stock
availability, these tolerances may not be
achievable, or in some cases, closer tolerances
may be achievable. Therefore, for any
particular project, the supplier and customer
may agree to hold tolerances that are more or
less stringent than those listed herein. Such

Page 17-6 • Countertops © 2022 Natural Stone Institute

 12.2 Seam Filler Materials. Seams in the
stone countertop are usually filled to the level
of the top surface. The most common filler
materials are polyester resin, epoxy resin and
elastomeric sealant. Elastomeric sealants can
be of silicon, polyurethane, or acrylic bases.
The table below identifies several advantages
and disadvantages of each product.

12 pp. color brochure (2019) available from

NSI.

12.0 ADHESIVES AND JOINT

FILLERS
12.1 Types. Adhesives used for stone
installation can be either standard construction
adhesives or elastomeric sealant with strong
bonding properties to both the stone and the
substrate. Construction adhesives will
normally provide greater bond strength, while
elastomeric sealants will provide some
forgiveness for movement within the substrate
cabinet. Excessive movement of the substrate,
regardless of the type of adhesive used, will
result in cracking of the seams or stone units.
Verify that the product used does not stain the
stone material.

© 2022 Natural Stone Institute Countertops • Page 17-7

SEAM FILLER MATERIALS ADVANTAGES & DISADVANTAGES

Product Advantages Disadvantages

Polyester resin • Accepts dyes readily, allowing a • Cures to a high durometer
pleasing color match to stone. hardness which offers little or no
• Leaves joint neatly flush with forgiveness for movement.
counter-top surface. • Limited pot life.
• Can be buffed to a glossy finish that
complements the polished stone
surface.
• Relatively quick cure time.
Epoxy Resin • Leaves joint neatly flush with • Cures to a high durometer
countertop surface. hardness which offers little or no
• Can be buffed to a glossy finish that forgiveness for movement.
complements the polished stone • More difficult to achieve accurate
surface. color match than polyester resin.
• Provides stronger bond than • Long cure time.
polyester resin. • The stone fabric will fail before the
• Long pot life. seam, which is more difficult to
repair.

Grout • Simple to use. • Color may not be consistent

• Long pot life. between batches.
• Relatively easy to dye for color • Cracks easily due to movement.
matching. • Coarse texture contrasts with
polished stone.
• High porosity can be a sanitation
concern.
Elastomeric • Relatively low durometer hardness • Limited to available colors.
Sealant provides significant extension and • Some sealant products contain
(Silicone, compression capability, hence the plasticizers that can migrate into
polyurethane, or greatest accommodation for and stain the stone.
acrylic) movement of any filler material.
• Cures to a glossy surface that
compliments the polished stone
surface

Page 17-8 • Countertops © 2022 Natural Stone Institute

13.0 STONE TILE COUNTERTOP 13.9 Aprons. Where a stone apron is
INSTALLATION employed and the countertop is designed to
have a radial corner, the apron may be staved
13.1 Subtops. Stone tile countertops must to fit the radius.
have a subtop made of minimum ¾" exterior-
grade plywood or ½" cementitious backer 13.10 Flat Installation. Stone tiles must be
board. Subtop must be flat to within 1/8" in installed flat, side by side, within 1/32" (0.8
10'-0" (3 mm in 3 m). mm) maximum lippage.

13.2 Edge Treatment. Exposed edges of 13.11 Splashes must be of stone tile,
the countertop may be finished by providing an minimum of 4" high. On stones with obvious
edge profile strip of stone, wood, or metal. vein trend, the vein trend of the splash must be
Where stone is employed, it is to be used as an identical to the countertop below unless
apron to the top surface stone, which limits otherwise specified.
stress on the countertop/apron joint.
13.12 Back buttering of all stone tiles is
13.3 Stone tile tolerances for all stone required. This technique applies a portion of
types must be 1/32" (1 mm) in length, width, the installation material to the back face of the
and thickness. stone. It requires placement of one-half of the
setting material in the case of thin-set mortar,
13.4 Joint Widths. Unless otherwise epoxy, or nonwater-soluble adhesive, or a
agreed, joint widths for stone tile countertops lesser quantity of very rich mortar in the case
must conform to the following: Stone-to-wall of portland cement, to the back of the stone,
joints must be 1/8" (3 mm) in width. Stone- while the balance of the setting material is
to-stone joints must be 1/16" (1.5 mm) applied to the bed. Application should be
minimum, 3/32" (2 mm) maximum, and performed so that one pass is completed in a
uniform from stone to stone. Stone-to- north-south direction, while the second pass is
cabinetry joints must be 1/8" (3 mm) in width. performed in an east-west direction, thus
ensuring, as close as possible, 100% contact of
13.5 Vein Trend. When using stone tiles the stone to the installation bed.
with obvious trend, all tiles shall be installed
with vein trend running in the same direction 13.13 Tile Reinforcement. A common re-
unless otherwise specified. inforcement for stone tiles of limited
soundness is to adhere a fiberglass mesh to the
13.6 Shading Variation. Stone tiles are back surface of the tile. The adhesive used in
subject to manufacturing processes different this application is commonly an epoxy or
from structural stone. There is great latitude in polyester resin. When this type of
the acceptability of shaded stones. Installers are reinforcement is adhered to the tiles, the
cautioned to lay out the stone for inspection Installer must use a thin-set material that will
and obtain approval from the Owner or bond to the resin-impregnated backer. Most
Specifying Authority prior to installation. often this will require an epoxy-based, rather
than a portland-based, thin-set compound.
13.7 Tile Widths. No tile shall be employed
that is less than ½ the width of the stone tile,
except at the front of cutouts, unless previously
discussed with the client.

13.8 Cutouts should be prepared for drop-

in appliances and sinks. Avoid undermounted
sinks, stove tops, etc.

© 2022 Natural Stone Institute Countertops • Page 17-9

 Mohs Scale stone surface, so that it remains only in
In 1812, the Mohs Scale of mineral hardness depressions and some intercrystalline regions
was devised by the German mineralogist of the slab. The amount of surface area that
Friedrich Mohs (1773-1839), who selected remains as resin varies due to the natural
the ten minerals because they were common features of the material, but it is usually a
or readily available. The scale is not a linear fraction of one percent.
scale, but a relative scale.
14.1.1 The resin used in this process is
Hardness Mineral typically an epoxy, but polyester and acrylic-
1 Talc or Mica based polymers may be used.
2 Gypsum
3 Calcite 14.2 Design Considerations. While the
4 Fluorite intent of this process is to provide a
5 Apatite cosmetically more attractive surface, these are
6 Orthoclase several characteristics of which the fabricator
7 Quartz should be aware:
8 Topaz
9 Corundum 14.2.1 Color. The resin application normally
10 Diamond makes the color of the stone somewhat darker
Source: than an untreated slab. This becomes an issue
American Federation of Mineralogical Societies, Inc. when finishing the edges of the countertop, as
the color of the edge will be lighter in
appearance than the color of the face surface.
Several products are marketed in the industry
14.0 RESIN-IMPREGNATED
for the darkening of the edge, but none have
SLABS been found to be universally successful.
The application of resin to the surfaces of stone
slabs has become an ever-increasing practice. 14.2.2 Interaction with Sealers. There
The intent of this procedure is to fill pits, have been cases of incompatibility between a
cracks, and fissures of natural stones with a given resin and fabricator-applied sealer
glossy resin to enhance the appearance of the combination. This usually results in a “cloudy”
polished slab. When received, the resin or “blotchy” appearance after the sealer
treatment is usually easily detected by viewing product has been applied.
the raw edges of the slab. Evidence of excess
resin is usually visible on the edges of the slab 14.2.3 Structural Flaws. The resin process
if the stone has been treated. can hide cracks or other blemishes which are
structurally influential features of the material.
14.1 Description of Procedure. The Assessment of the structural worthiness of the
process involves screeding the resin on the material can be made more difficult as a result.
surface of the cleaned, sawn slab. This is
frequently done in an automated process, 14.2.4 UV Light Exposure. Nearly all of the
although some suppliers will do this manually. resins currently in use are vulnerable to color
Depending on the equipment used, the slab change or surface degradation when exposed to
may be placed over a large vacuum table to ultraviolet light. These materials are therefore
draw the resin deeper into the stone. The resin not suitable for exterior applications.
is allowed to cure, which may or may not be
accelerated with heat application. Once the
resin has cured, the slab is polished. The
polishing grinds most of the resin from the

Page 17-10 • Countertops © 2022 Natural Stone Institute

15.0 REINFORCEMENT surface, are required to get the maximum
TECHNIQUES benefit from this technique. A strip of
fiberglass mesh backing is often adhered over
As products of nature, stones have varying the rodded region for additional
strength and behavioral properties. Stones of reinforcement. See detail on drawing 17-D-5.
lesser soundness or stones that have had
substantial areas removed from the slab (e.g.,
sink cutouts) will benefit from reinforcement 16.0 ALLOWABLE REPAIR
by a variety of techniques.
Repair of stone countertops must be
15.1 Fiberglass Mesh. A common performed by competent, experienced artisans
reinforcement for stone slabs of limited to achieve the desired results. Repair of the
soundness is to adhere a fiberglass mesh to the stone is permitted when the repaired region is
back surface of the slab. The party doing the not in a structurally significant area of the
sawing of the slabs normally completes this countertop, and when it can be accomplished
process. The adhesive used in this application skillfully so that the repair is consistent in color
is commonly an epoxy or polyester resin. and texture with unrepaired regions of the
slab.
15.2 Liner Blocks. Although not frequently
used in stone countertop construction, a liner 16.1 Fissures occur naturally in many stone
block of stone material can be adhered to the types. A fissure is defined by the American
underside of the stone slabs (when no subtop is Geological Institute as, “An extensive crack,
used) to reinforce seams or other vulnerable break, or fracture in the rock, which may
areas. The liner block need not be of the same contain mineral-bearing material.” The term
type of stone material as the countertop. “fissure” is used commercially in the stone
industry to describe a visible separation along
15.3 Splines. Seams, particularly those intercrystalline boundaries. This separation
between narrow stone pieces, are often splined may start and stop within the field of the stone
together with a steel or stainless steel key. or extend through an edge. A fissure differs
Commonly, a large washer is used as the spline from a crack in that it is a naturally occurring
key. The metal is fully encapsulated with feature in the stone that may be found in other
polyester or epoxy resin and fitted to closely areas of the same slab or other slabs of the same
cut slots in the stone, similar to the “biscuit” material.
joint reinforcements used in woodworking.
16.2 Cracks occur in stones as a result of
15.4 Rodding. A commonly seen method of manmade mechanically induced stresses during
countertop reinforcement is the technique handling, fabrication, transport, or
referred to as “rodding.” Rodding may be installation. When cracks are detected in slab
beneficial to narrow strips of stone material, material prior to fabrication, the best method
such as those in front or behind sink or cook is to simply avoid including them in the
top cutouts. This technique requires a shallow product through culling during the layout
kerf in the underside of the stone slab (See process. In stones with lesser soundness
details on drawing 17-D-5). The kerf is then properties, this option may not be practical, or
closely fitted with a metal or fiberglass rod, possible. When working with such stones it is
which is then fully embedded in epoxy. The common practice to repair cracks by
rod, having greater tensile strength than the cementing them together with epoxy or
stone, helps prevent concave flexure of the polyester resin, either with or without dowel
stone surface. Closely matching the rod size to reinforcement. Cracks that occur as a result of
the kerf size and careful preparation of the rod, handling-induced stresses are often more
including cleaning or abrading the bonding difficult to repair, as they commonly include

© 2022 Natural Stone Institute Countertops • Page 17-11

chipping in addition to the crack. Repair is degrees of pits, depending on the amount of
frequently performed by injection of a biotite, muscovite, and phlogopite in their
penetrating resin adhesive, which may be dyed composition.
to match the stone, and then rebuffing the area
after curing of the resin. In many cases, the The pits do not make the granite less durable
entire stone must be repolished to make the or otherwise inferior, and do not in themselves
repair unnoticeable. If the repair is attempted qualify the slab for replacement. Pits are
but unsuccessful, the stone is to be replaced common in all granites and should be expected
with a new piece. when dealing with a natural, polished stone
containing several types of minerals with
16.3 Chips can occur in stones either as a different hardnesses. It is usually best to not
result of sawing operations or handling and attempt repair of pits, as most repair
restraint devices. Particularly in the igneous techniques will not cosmetically improve the
stone varieties, the exiting portion of the countertop.
diamond blade will create many small chips. A
small chamfer, called an “arris,” of
approximately 1/16" x 1/16" (1.5 x 1.5 mm) 17.0 MAINTENANCE
can be used to eliminate most of these small
chips. The use of an arris will make the seam 17.1 Application of Sealers. The
appear wider than its actual dimension when application of a topical sealer or impregnator is
filled (see section 11.2, above). Larger chips a common step in decreasing the vulnerability
may be repaired with epoxy or polyester resin of the stone to stains.
if the completed repair is consistent in color
and texture with unrepaired areas of the slab. 17.2 Topical sealers cure as a film on the
In many materials, the resin used in the repair stone surface. Since the material is actually
will appear more natural if it is not dyed. covering the stone, the appearance of the stone
surface may be altered by the application of this
16.4 Pitting of the countertop surface, type of product. This material will provide
particularly in granite material, is a commonly somewhat of a sacrificial layer over the stone
seen characteristic on natural stone. Granites and will absorb most of the wear on the
are made up of several different minerals, each countertop. Since the sealer is softer than the
mineral having a different hardness. Granites stone, normal use of the countertop will result
contain quartz, feldspars, biotite, amphibole, in abrasion of the sealer surface and dictate
ferrous titanium oxides, and other mineral reapplication to maintain the original luster of
combinations. On the Mohs Scale (see chart the surface. A properly applied topical sealer
above), diamonds are the hardest mineral, with will normally reduce, although not eliminate,
a rating of 10. Quartz and feldspar have a the vulnerability of calcareous stones to attack
hardness of 6.5 to 7 and are very durable. from mildly acidic solutions.
Biotite (small, black minerals throughout the
slab) on the other hand is very soft (2.5) and 17.3 Impregnators will penetrate the stone
flakes easily. All true granites have biotite in and cure a few millimeters below the surface,
their composition. Because biotite is relatively residing in the intercrystalline boundary areas
soft and flaky, the first few layers are often and pores of the stone. These products do not
removed during the polishing process, causing actually “seal” the stone and are more correctly
pits throughout the slab. Some granites have referred to as a repellent rather than a sealer.
more biotite throughout their composition As such, they are formulated to prevent
than others. The higher the biotite content of transmission of liquids, while allowing
the stone, the more pits it will have. Most transmission of vapor. Since they reside below
polished igneous rocks will have varying the actual surface of the stone, the change to
the appearance of the stone surface is minimal.

Page 17-12 • Countertops © 2022 Natural Stone Institute

Impregnators will be either hydrophobic, in contaminants which allow the growth of mold
that they repel water-based fluids only, or and mildew. Additionally, the loosening of
oleophobic, repelling both oil and water-based filler materials and in some cases, cracking and
fluids. The manufacturer of the impregnator separating due to thermal and/or freeze/thaw
product will recommend a reapplication cycling.
interval.
18.4 Subtops. All areas that are to receive
17.4 General Precautions. When any stone countertops should have a sub top or
surface protection product is used, care must auxiliary frame made of cement board or
be taken to read and follow the manufacturer’s mortar bed. The subtop or auxiliary framing
written instructions accurately. This will should include only materials which are rated
provide the greatest benefit from the for exterior exposure.
application and will guarantee safe handling of
the product. 18.5 Adhesives. All adhesives to be used
must be suitable for exterior installations.
17.5 Care and cleaning practices of the Since silicone is frequently used on outdoor
stone countertop are to be thoroughly kitchens, care must be taken to ensure that
discussed with the client upon completion of staining does not result from plasticizer
the installation. Refer to the NSI brochure Care migration of some silicone products. Polyester
& Cleaning for Natural Stone Surfaces for more adhesives should be avoided in an exterior
information. environment.

18.6 Seam Filler Materials. All materials

18.0 OUTDOOR KITCHENS that are to be used for seam filler must be
suitable for exterior installations and allow for
18.1 General Precautions. An some movement. Joint widths between
increasingly popular area for stone countertops adjacent stone units may be as small as nominal
is in outdoor kitchens. The installation of 1/16” (1.5 mm), but ample accommodation
natural stone countertops in these areas creates for differential movement due to thermal
additional challenges from the installation of expansion and contraction must be made at the
indoor countertops for suppliers and installers. perimeter of the stone installation.
Due to extreme temperature changes, possible
freeze/thaw cycling, UV exposure and varying 18.7 Undermount sinks can be anchored to
moisture levels, typical installation methods the underside of the stone countertop or
along with certain materials cannot be used. carried by a subtop or auxiliary frame. A
subtop or auxiliary framing may be required
18.2 Customer Communication. In and should be rated for exterior use.
addition to the prescriptions state earlier in this
chapter, customers should be made aware that
due to the use of resins in the finishing process
of natural stone, they will most likely
experience some fading in their countertops.
Nearly all resins used in the fabrication process
are subject to color change and surface
degradation when exposed to UV light See
section 14.2.4.
18.3 Materials. It is recommended that only
sound stones with minimal geological flaws or
voids be used for these areas. Stones that
contain these voids or fissures may harbor

© 2022 Natural Stone Institute Countertops • Page 17-13

NOTES:

Page 17-14 • Countertops © 2022 Natural Stone Institute

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

SLIDE-IN RANGE REFRIGERATOR

DISHWASHER BELOW (NOTE:

SEAMS OVER DISHWASHERS
ARE NOT RECOMMENDED.)

ISLAND TOP

PROVIDE REINFORCEMENT FOR JOINTS RODDING REINFORCEMENT

AT SINK - SEE DETAIL ON DRWG 17-D-4. RECOMMENDED AT THIS
LOCATION -- SEE DETAILS ON
DRAWING 17-D-5.

SEE JOINTING OPTIONS ON NOTE: TYPICAL JOINTS MUST

DRAWING 17-D-3. ALIGN WITH CABINET SEAMS
BELOW.

SERVING COUNTER

CORBEL SUPPORTS
REQUIRED BELOW

TYPICAL KITCHEN LAYOUT

(WITH JOINTS AT SINK)

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1

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DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 17-D-14
3" = 1'-0"
17-D-14 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

REV DATE
OVERHANG DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 17-D-15
3" = 1'-0"

© 2022 Natural Stone Institute 17-D-15

 t t
t
t

Notes:

1. The term "Eased Edge" more commonly refers to a slightly radiused profile than a slightly chamfered profile, although the use of the
term varies regionally and/or with specific fabricators. In either case, the edge treatment is slight, and normally does not exceed 116" (1.5 mm).
2. "Pencil Round" generally refers to a radius near that of a standard pencil, approximately 18" to 5 32" (3 to 4 mm).
3. Radius, Chamfer, or Cove edge profile can be any dimension. The actual dimension should be specified at the time of sale.
Chamfers are most commonly 45°, although not necessarily so.
4. Many of the profiles shown on this drawing can be done with laminated edge details.

REV DATE
EDGE PROFILE NOMENCLATURE
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

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NOT TO SCALE
17-D-16 © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

REV DATE
SHOP DRAWING EXPAMPLE
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 17-D-17
½" = 1'-0"

© 2022 Natural Stone Institute 17-D-17

COPING AND STOOLS - 2.5 Corrosion-Resistant Metals. All
metals that contact the stone must be
EXTERIOR CUBIC STONE corrosive-resistant.
COPING AND WALLS
2.6 Oil-based putty and sealants should
1.0 INTRODUCTION never be used in contact with stone.

1.1 Installation Method. There are 2.7 White portland cement is

several methods by which cubic coping and recommended for light-colored granite and
walls can be installed. Consideration should be marble. White portland cement with a low
given to the various features of each method in alkali content is recommended for limestone.
making a selection for a specific installation.
See information about installation methods in For additional information, refer to
this section’s Data Sheet, Part 3, and Chapter 13, Horizontal Surfaces and Chapter
illustrations of examples at the close of this 14, Vertical Surfaces.
section.
2.8 Geographic Methods. Some
installation methods and materials are not
recognized and may not be suitable in some
2.0 DESIGN CRITERIA
geographic areas because of local trade
practices, building codes, climatic conditions,
2.1 Physical Property Values. Final
or construction methods. Therefore, while
design should always be based on specific
every effort has been made to produce accurate
physical property values for the stone to be
guidelines, they should be used only with the
used. These values may be obtained from the
independent approval of technically qualified
Stone Supplier.
persons.
2.2 Backup Walls. When exterior cubic
stone is set in conjunction with masonry load-
bearing walls, the masonry backup should be DATA SHEET
solid brick or concrete. If hollow load-bearing EXTERIOR CUBIC STONE
concrete block is used to support and anchor
stone, it must be reinforced with brick,
COPING AND WALLS
concrete, or by filling the voids full of concrete
two block courses in each story height. 1.0 PRODUCT DESCRIPTION

2.3 Bonding. It is recommended for 1.1 Basic Use. Exterior masonry walls,
exterior coping that there be 100% coverage of caps, copings, and other cut stonework.
bonding material between the stone and the
substrate. 1.2 Fabrication. Exterior cubic stone
units are precut and prefinished to dimensions
2.4 Bond Stones. For cubic walls, the specified on shop drawings, and are delivered
effectiveness of bonding is improved when to the job site ready to install.
bond stones are staggered at random. The
number or percentage of bond stones depends 1.3 Finishes. Abrasive, honed, and rough
on design; from 25% to 30% is generally sawn finishes may be used for exterior cubic
sufficient. Bond stones should bear on floors stone applications.
and beams. Provide an open joint at intervals
for expansion gasket.

© 2022 Natural Stone Institute Coping and Stools • Page 18-1

Exterior Cubic Stone Coping and Walls
1.4 Colors. Most of the commercially 3.2 Methods. Stones should be set in a full
available varieties are suitable. bed of mortar with the vertical joints full of
mortar. Joints should be raked out to a depth
2.0 TECHNICAL DATA equal to the width of joint, and later pointed or
sealed with an approved, nonstaining sealant.
2.1 Each stone variety used for cubic stone
coping and walls should conform to the 3.2.1 Expansion joints should be provided as
applicable ASTM standard specification and the required and kept free of mortar. Joint width
physical requirements contained therein. The may be maintained by using nonstaining,
specification for each stone type follows: resilient cushions recessed 1" (25 mm) from
exterior face. Joints should be at least 1-1/4"
2.1.1 Granite: ASTM C615, Standard (30 mm) wide, except at control joints, where
Specification for Granite Dimension Stone greater widths may be required.

2.1.2 Limestone: ASTM C568, Standard 3.2.2 All anchors, cramps, dowels, pins,
Specification for Limestone Dimension Stone supports, and similar items that contact the
stone should be corrosion-resistant metals and
2.1.3 Marble: ASTM C503, Standard should be securely attached to the structure
Specification for Marble Dimension Stone and to the stone.

2.1.4 Quartz-based Stone: ASTM C616, 3.3 General Precaution. During

Standard Specification for Quartz-based construction, the General Contractor shall
Dimension Stone protect all stone from staining and damage.

2.1.5 Serpentine: ASTM C1526, Standard 3.3.1 Oil-based putty and sealants should
Specification for Serpentine Dimension Stone never be used in contact with stone.

2.1.6 Slate: ASTM C629, Standard

Specification for Slate Dimension Stone

2.1.7 Soapstone: No ASTM Standard exists

at this time

2.1.8 Travertine: ASTM C1527, Standard

Specification for Travertine Dimension Stone

3.0 INSTALLATION

3.1 Preparatory Work. Exterior cubic

stone may be installed against an existing
backup or concurrently with the backup wall.
It is recommended that the General Contractor
install continuous flashing for stone coping.

3.1.1 When ready for installation, stones

should be cleaned on all sides, and all dirt and
foreign material removed from all surfaces.

Page 18-2 • Coping and Stools © 2022 Natural Stone Institute

Exterior Cubic Stone Coping and Walls
COPING and STOOLS - DATA SHEET
THIN STONE STOOLS AND THIN STONE STOOLS AND
CUBIC SILLS CUBIC SILLS

1.0 INTRODUCTION 1.0 PRODUCT DESCRIPTION

1.1 Installation Methods. There are 1.1 Basic Use. Interior window stools and
several methods by which stone window stools exterior cubic sills.
can be installed. Consideration should be given
to the various features of each method in 1.2 Fabrication. Stone window stools and
making a selection for a specific installation. cubic sills are precut and prefinished to
See information about installation methods in dimensions specified on shop drawings, and are
this section’s Data Sheet, Part 3, and delivered to the job site ready to install.
illustrations of examples at the close of this
section. 1.3 Finishes. Exposed surface and edges of
thin stone stools shall be polished or honed.
2.0 DESIGN CRITERIA Cubic sills shall be abrasive, honed, or rough
finish.
2.1 Oil-based putty or sealants should
never be used in contact with stone. 1.4 Colors. Most of the commercially
available varieties are suitable.
2.2 Corrosion-resistant Metals. All
metals that contact the stone must be 1.5 Sizes. Thin stone stools shall have
corrosive-resistant. thicknesses of ¾" (20 mm) and 1¼" (30 mm),
or as specified. Cubic sills shall be as specified.
2.3 Bonding. There must be 100%
coverage of bonding material between stone 2.0 TECHNICAL DATA
window stools and substrate.
2.1 Each stone variety used for thin stone
2.4 White portland cement is re- stools and cubic sills should conform to the
commended for light-colored granite and applicable ASTM standard specification and the
marble. White portland cement with a low physical requirements contained therein. The
alkali content is recommended for limestone. specification for each stone type follows:
For additional information, refer to
2.1.1 Granite: ASTM C615, Standard
Chapter 13, Horizontal Surfaces and Chapter
Specification for Granite Dimension Stone
14, Vertical Surfaces.
2.1.2 Limestone: ASTM C568, Standard
2.5 Geographic Methods. Some
Specification for Limestone Dimension Stone
installation methods and materials are not
recognized and may not be suitable in some
2.1.3 Marble: ASTM C503, Standard
geographic areas because of local trade
Specification for Marble Dimension Stone
practices, building codes, climatic conditions,
or construction methods. Therefore, while
2.1.4 Quartz-based Stone: ASTM C616,
every effort has been made to produce accurate
Standard Specification for Quartz-based
guidelines, they should be used only with the
Dimension Stone
independent approval of technically qualified
persons.

© 2022 Natural Stone Institute Coping and Stools • Page 18-3

Thin Stone Stools and Cubic Sills
2.1.5 Serpentine: ASTM C1526, Standard
Specification for Serpentine Dimension Stone

2.1.6 Slate: ASTM C629, Standard

Specification for Slate Dimension Stone

2.1.7 Soapstone: No ASTM Standard exists

at this time

2.1.8 Travertine: ASTM C1527, Standard

Specification for Travertine Dimension Stone

3.0 INSTALLATION
3.1 Methods: Stone window stools are
installed either by the standard or thin set
method. Cubic sills are installed in a full
portland cement mortar bed with dowels.

3.2 General Precautions: During

construction, the General Contractor shall
protect all stone from staining and damage.

3.2.1 Oil-based putty and sealants should

never be used in contact with the stone.

NOTES:

Page 18-4 • Coping and Stools © 2022 Natural Stone Institute

Thin Stone Stools and Cubic Sills
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

NON-STAINING
CONTINUOUS FLASHING SEALANT
CONTINUOUS FLASHING

STONE
SEALANT

NON-STAINING STONE
SEALANT

PARAPET DETAIL PARAPET DETAIL

1 2
NOTE: MINUMUM RECOMMENDED STONE THICKNESS FOR THESE DETAILS IS 1-1/4".

SEAL AROUND PENETRATIONS

IN FLASHING WITH EXTRUDED ALUMINUM ANCHOR OR ST.
COMPATIBLE SEALANT STL. WELDED T @ EA. STONE JOINT

ST.STL. WEDGE ANCHOR

HIGH IMPACT PLASTIC
FULL BED OF NON-SHRINK SHIMS AT 1/5 POINTS
CEMENTITIOUS GROUT OF STONE
HIGH IMPACT PLASTIC
SETTING SHIMS AT
1/5 POINTS OF STONE
HOLE IN CONCRETE FILLED
WITH NON-SHRINK GROUT

COPING DETAIL COPING DETAIL

3 4
DOWEL DOWEL
DRIP

DRIP DRIP

NON-STAINING
SEALANT

MORTAR BED MORTAR BED

NON-STAINING
CONT. METAL CONT. METAL
SEALANT
FLASHING FLASHING

COPING DETAIL COPING DETAIL

5 6

REV DATE
EXTERIOR STONE VENEER
0 MAR 2022 FLASHING & COPING DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 18-D-1
3" = 1'-0"

© 2022 Natural Stone Institute 18-D-1

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

STONE STOOL

PLAN SECTION
1 (WOOD FRAME CONSTRUCTION)

STONE STOOL
MORTAR BED

SECTION
2 (WOOD FRAME CONSTRUCTION)
STONE STOOL

PLAN SECTION
3 (MASONRY CONSTRUCTION)

NOTE: USE 100% COVERAGE

OF MORTAR BED MATERIAL STONE STOOL
BETWEEN STOOL AND
SUBSTRATE.
MORTAR BED

EXTERIOR
STONE SILL

SECTION
4 (MASONRY CONSTRUCTION)

REV DATE
STONE SILL & STOOL DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 18-D-2
3" = 1'-0"
18-D-2 © 2022 Natural Stone Institute
STONE FURNITURE - 2.3.2 When using some of the more fragile
stones, including Soundness Classification
STONE FURNITURE AND Groups C and D marbles, the use of an
TOPS unsupported stone overhang of any dimension
may not be feasible.
1.0 INTRODUCTION
2.3.3 Stone thicker than ¾" (20 mm) can have
1.1 Installation Methods. There are a greater unsupported span.
several methods by which stone furniture can
be fabricated and installed. Consideration 2.3.4 Overhangs can be increased if other
should be given to the various features of each stone, such as Soundness Classification Group
method. Refer to recommendations furnished A marble, slate, or travertine, ¾" (20 mm)
by NSI Members specializing in furniture and thick exterior plywood, or other structural
top construction. See information about support is provided for the finished stone.
installation methods in this section’s Data
Sheet, Part 3, and illustrations of examples at 2.4 Exposed stone edges must be gauged
the close of this section. to the thickness specified.

2.5 Dimensions of bevel and quirk

2.0 DESIGN CRITERIA miters and radius of rounded edges should be
specified.
2.1 Sealers. Furniture or tops may be
sealed or unsealed depending upon location 2.6 Laminated Aprons. When fabricating
and conditions of usage. laminated aprons and double thicknesses, all
jointed edges and horizontal surfaces must be
2.1.1 If sealed, follow Manufacturer’s re- sanded or ground to eliminate irregularities
commendations for cleaning, stripping, and and ensure 100% contact.
resealing.
2.7 Oil-based putty and sealants
2.1.2 If tops are used for food preparation, cannot be used in contact with stone.
make certain sealer applied is nontoxic and safe
for food preparation areas. For additional information, refer to
Chapter 13 Horizontal Surfaces, Chapter 14
2.2 Base Design. Adequate support of Vertical Surfaces, and Chapter 17 Residential
stone should be designed into the base to Countertops.
prevent accidents and fracturing of the stone
after assembly or installation. 2.8 Geographic Methods. Some
installation methods and materials are not
2.3 Unsupported Spans and recognized and may not be suitable in some
Overhangs. The size of any unsupported span geographic areas because of local trade
or overhang depends upon the thickness and practices, building codes, climatic conditions,
type of stone used. or construction methods. Therefore, while
every effort has been made to produce accurate
2.3.1 It is not recommended to project any guidelines, they should be used only with the
unsupported stone past the base more than 6" independent approval of technically qualified
150 mm) for stone of ¾" (20 mm) or less persons.
thickness.

© 2022 Natural Stone Institute Stone Furniture • Page 19-1

DATA SHEET 2.2.5 Serpentine: ASTM C1526, Standard
Specification for Serpentine Dimension Stone
STONE FURNITURE & TOPS
2.2.6 Slate: ASTM C629, Standard
Specification for Slate Dimension Stone
1.0 PRODUCT DESCRIPTION
2.2.7 Soapstone: No ASTM Standard exists
1.1 Basic Use. Furniture and tops. at this time
1.2 Fabrication. Stone furniture and tops 2.2.8 Travertine: ASTM C1527, Standard
are precut and prefinished to dimensions
Specification for Travertine Dimension Stone
specified on shop drawings, and are delivered
to the job site ready to install or place in a
predetermined location.
3.0 INSTALLATION
1.3 Finishes. Polished, honed, natural
cleft, and rough. 3.1 Methods. Furniture is usually pre-
assembled in the Fabricator’s shop.
1.4 Colors. Most of the commercially
available varieties are suitable. 3.1.1 Tops are anchored to the supporting
base with dowels, pins, nonstaining adhesive,
1.5 Sizes. Custom according to design or a combination of these.
requirements and size limitations of selected
stone. 3.2 General Precautions: During
construction, the General Contractor shall
protect all stone from staining or damage.
2.0 TECHNICAL DATA 3.2.1 Oil-based putty and sealants should
never be used in contact with stone.
2.1 Each stone variety used for stone
furniture and tops should conform to the
applicable ASTM standard specification and the
physical requirements contained therein.

2.2 These specifications are as follows:

2.2.1 Granite: ASTM C615, Standard

Specification for Granite Dimension Stone

2.2.2 Limestone: ASTM C568, Standard

Specification for Limestone Dimension Stone

2.2.3 Marble: ASTM C503, Standard

Specification for Marble Dimension Stone

2.2.4 Quartz-based Stone: ASTM C616,

Standard Specification for Quartz-based
Dimension Stone

Page 19-2 • Stone Furniture © 2022 Natural Stone Institute

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

AS REQUIRED
3'-0" TO 4'-6"
8'-0" TO 20'-0" AS REQUIRED

PLAN VIEW
1 3
4" = 1'-0"

2" X 4" TUBE STEEL

2'-5" [737]
2" X 4" TUBE STEEL
BRACING
CROSS SUPPORTS

LEGS AS DESIRED

ELEVATION
2 3
4" = 1'-0"
3/4" [19] OR 11 4" [32]

TOP BONDED TO PLYWOOD WITH NON-STAINING ADHESIVE

21 4" [57]
2'-5" TO FLOOR

PLYWOOD BACKING
[19]

4" [102]
4"
3

1" [25] SECTIONS AT EDGE OF TOP

A 3" = 1'-0"
NOTE: DIMESIONS IN [ ] ARE IN MILLIMETERS
REV DATE
STONE CONFERENCE TABLE DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 19-D-1
AS NOTED

© 2022 Natural Stone Institute 19-D-1

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

BOOKMATCHED STONE TOP

WITH CONTRASTING
STONE TRIM

5'-0" [1524]
STONE BASE

PLAN VIEW
1 3
4"= 1'-0"

5'-0" [1524]
2'-5" [737]

ELEVATION
1 3
4"= 1'-0"
[13]

[19]
2"

4" [102]
4"
1

NOTE:
BOND STONE PIECES
212" [64]

11 4" [32]

TOGETHER WITH A
TWO-PART, 100% SOLIDS
EPOXY. GRIND AND
POLISH TOP AND EDGES
AFTER ASSEMBLING TO
S.S. DOWELS STONE BACKING ACHIEVE SMOOTH, UNIFORM
CONTRASTING STONE TRIM SURFACES.

SECTION AT EDGE
A 6"= 1'-0"
NOTE: DIMESIONS IN [ ] ARE IN MILLIMETERS
REV DATE
STONE CONFERENCE TABLE DETAILS
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 19-D-2
AS NOTED
19-D-2 © 2022 Natural Stone Institute
 16 "

8"

8"
±1

±1

±1
±116"

=
R=

R
±116"
Straight with Straight with Double
Pencil Round (2)
Radius Eased Edges (1) Chamfer Eased Edges (1) Pencil Round (2)

ify ify Specify

ec us ec us Specify
Sp adi Sp adi
R R

Specify
Specify
Radius (3) Double Radius (3) Chamfer (3) Double Chamfer (3)

t t
½ ½
= = t
R R =
R
t

t
Full Bullnose Half Bullnose Demi Bullnose Chiseled or "Rocked"

Ogee Ogee Roundover Dupont Normandy

ify
ify

ec
ec

Sp
Sp

Cove (3) Double Cove (3) Cove Ogee Cove Dupont

Waterfall Platner
Stair Tread Laminated (4)
(or Triple Waterfall) (or Knife Edge)
Notes:

1. The term "Eased Edge" more commonly refers to a slightly radiused profile than a slightly chamfered profile, although the use of the
term varies regionally and/or with specific fabricators. In either case, the edge treatment is slight, and normally does not exceed 116" (1.5 mm).
2. "Pencil Round" generally refers to a radius near that of a standard pencil, approximately 18" to 5 32" (3 to 4 mm).
3. Radius, Chamfer, or Cove edge profile can be any dimension. The actual dimension should be specified at the time of sale.
Chamfers are most commonly 45°, although not necessarily so.
4. Many of the profiles shown on this drawing can be done with laminated edge details.

REV DATE STONE TOILET PARTITIONS

0 MAR 2022 (FLOOR-SUPPORTED)
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
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DRWG NO: 19-D-3
NOT TO SCALE

© 2022 Natural Stone Institute 19-D-3

NOTES:

Dimension Stone Design Manual Ó 2022 Natural Stone Institute

STONE-FACED VENEER 1.5 Geographic Methods. Some
installation methods and materials are not
PRECAST CONCRETE recognized and may not be suitable in some
PANELS geographical areas because of local trade
practices, building codes, climatic conditions,
1.0 Physical Properties. When using or construction methods. Therefore, while
precast panels, careful attention should be every effort has been made to produce accurate
given to ensuring the necessary strength and guidelines, they should be used only with the
serviceability requirements, with particular independent approval of technically qualified
attention given to the physical properties of the persons.
stone, anchorage of the stone to the concrete,
safety factors, and effect of finishes on the
strength of the stone. DATA SHEET
1.1 The physical properties of the stone STONE-FACED VENEER PRECAST
facing material must be compared with the
properties of the concrete backup. These
CONCRETE PANELS
properties include:
1.0 PRODUCT DESCRIPTION
1.1.1 Tensile (axial and flexural),
compressive, and shear strength. 1.1 Basic Use. Exterior precast panels.

1.1.2 Modulus of elasticity (axial tension, 1.2 Limitations. The physical properties
flexure, and axial compression). of the stone veneer facing should be compared
with those of the concrete, including tensile
1.1.3 Coefficient of thermal expansion. (axial and flexural), compressive and shear
strength, modulus of elasticity (axial tension,
1.1.4 Volume change. flexure, and axial compression), coefficient of
thermal expansion, and volume change. Refer
1.2 Testing mockups should be built to to the Prestressed Concrete Institute
test wall, window, and joint performance Handbook for detailed information.
under the most severe wind and rain
conditions. 1.3 Finishes. Polished, honed, thermal,
bush-hammered, rough, abrasive, and natural
1.3 Coordinator. It is recommended that cleft. Polished finish is not recommended for
a qualified person be engaged to coordinate marble and limestone.
delivery, scheduling, and color uniformity of
the panels (to satisfy samples or mockup) 1.4 Colors. Most of the commercially
among the General Contractor, Stone available varieties are suitable.
Fabricator, and Precast Supplier.
1.5 Sizes. Stone veneer panels generally
1.4 Detailed recommendations can be are 1", 1¼", 1½", 2" (25 mm, 30 mm, 40
obtained from: mm, 50 mm), or thicker as specified. Refer to
Prestressed Concrete Institute PCI Handbook for detailed information.
8770 W Bryn Mawr Ave., Suite 1150
Chicago, IL 60631
Phone: (312) 786-0300
Fax: (312) 786-0353
https://www.pci.org/

© 2022 Natural Stone Institute Stone-Faced Veneer / Precast Concrete Panels • Page 20-1
2.0 TECHNICAL DATA

2.1 Each stone variety used for veneer

precast panels should conform to the applicable
ASTM standard specification and the physical
requirements contained therein. The
specification for each stone type follows:

2.1.1 Granite: ASTM C615, Standard

Specification for Granite Dimension Stone

2.1.2 Limestone: ASTM C568, Standard

Specification for Limestone Dimension Stone

2.1.3 Marble: ASTM C503, Standard

Specification for Marble Dimension Stone

2.1.4 Quartz-based Stone: ASTM C616,

Standard Specification for Quartz-based
Dimension Stone

2.1.5 Serpentine: ASTM C1526, Standard

Specification for Serpentine Dimension Stone

2.1.6 Slate: ASTM C629, Standard

Specification for Slate Dimension Stone

2.1.7 Travertine: ASTM C1527, Standard

Specification for Travertine Dimension Stone

3.0 INSTALLATION

3.1 Methods: Precast panels are generally

installed by the General Contractor. Refer to
PCI Handbook or contact Precast Producer for
detailed information.

3.2 General Precaution: Contact Precast

Producer or review the PCI Handbook for
detailed information.

Page 20-2 • Stone-Faced Veneer / Precast Concrete Panels © 2022 Natural Stone Institute
 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

"HAIRPIN" SPRING
CLIP ANCHOR

PRECAST CONCRETE

BOND BREAKER

1-1/4" STONE
FACING

TYPICAL SECTION
1

REV DATE
STONE VENEERED PRECAST
0 MAR 2022 CONCRETE DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 20-D-1
3" = 1'-0"

© 2022 Natural Stone Institute 20-D-1

 CAUTION: IF THIS SHEET IS NOT 8½" x 11", IT IS A REDUCED OR ENLARGED PRINT

STONE SILL

79
. 64
8°
1" [25]
HEAD

BOND
BREAKER

"HAIRPIN" SPRING
CLIP ANCHOR

1-1/4"
STONE
FACING

PRECAST CONCRETE

STONE SOFFIT
11 4" [32]
HEAD
TYPICAL SECTION OF UNITIZED SILL, FACIA, AND SOFFIT
1
REV DATE
STONE VENEERED PRECAST
0 MAR 2022 CONCRETE DETAILS
DIMENSION STONE DESIGN MANUAL 2022
380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 20-D-2
3" = 1'-0"
20-D-2 © 2022 Natural Stone Institute
Restoration and sections thoroughly to gain a greater
understanding of the subject matter.
Maintenance –
Stone geology
2.0 STONE FORMATION
1.0 INTRODUCTION
2.1 Thousands of stone deposits exist
1.1 One cannot effectively participate in throughout the world. Yet all stones have been
the field of stone restoration without at least a formed by one of three methods, and therefore
rudimentary understanding of the geological all stones can be classified into one of three
sciences. Stone composition is a far more groups: Sedimentary, Metamorphic, and
complex issue than is commonly thought, and Igneous.
the in-service performance and behavior of the
stone can be significantly influenced by even 2.2 The term Sedimentary comes from
minor constituents of its composition. This the Latin word sedimentum, which means
issue is further complicated by the fact that “sinking” or “settling.” It is used to describe
while geologists and petrographers identify stone deposits that are formed when sediment
hundreds of different rock types, the stone is collected over geological periods of time,
industry uses much broader definitions of stone causing individual grains, or “clasts,” to be
types than the scientific community. In doing cemented together by another agent. Common
so, the industry includes similar materials into cementing agents, in descending order of
various stone groups despite the fact that the preference, include silica, carbonate, iron
stone does not technically and scientifically oxides, and clay. Limestone and sandstone are
belong to that group. As practical examples, examples of sedimentary rocks.
popular stones such as Crema Marfil and Rojo
Alicante are commercially identified as 2.2.1 There also exist sedimentary stones
“marble,” even though they are not geologically which are not created from the settling of
marble, and would be scientifically classified as clasts, but are chemical sedimentary
“hard, compact, dense limestone.” Paradiso stones. Onyx is an example of a chemical
and Uba Tuba are commercially considered sedimentary stone.
granite, yet they are actually “gneiss” and
“charnockite,” respectively. The differences in 2.3 Metamorphic is a term used to
composition, behavior, and performance describe stones that have undergone a change
between these rocks and those rocks that in structure. The term originates from two
scientifically belong in these classifications are Greek words: meta-, meaning change, and
generally slight, and negligible in most morphic, meaning structure. Perhaps the best
commercial issues. But to the restoration known example of a metamorphic rock is
professional, such differences can be marble, which has changed its structure from a
significant. Reference is made to the Natural sedimentary limestone to a recrystallized rock
Stone Institute’s Dimension Stone Design Manual fabric known as marble due to intense heat and
Chapter 1 and Chapters 5 through 12. While a pressure.
brief introduction of stone geology is offered
here, a far more comprehensive discussion of 2.4 The term Igneous comes from the
the subject can be found in those chapters. The Latin word ignis, meaning fire. This term
reader is strongly encouraged to study those describes stones that were melted deep within
the earth by thermal energy released from the
© 2022 Natural Stone Institute Stone Geology • Page 21-1
decay of radioactive minerals within the earth’s effectively work the material, yet these same
core. These stones, eventually cooled and abrasives can create uncontrollable dishing and
solidified, have been harvested for a variety of gouging in the much softer travertine portions
uses. Commercially, the most common of of the floor. Variability in mineral hardness can
these rock types used is granite, yet many other also exist within one stone. Such variability can
igneous rock types exist in commercial trade. create the same challenges in achieving a
uniform level of grinding, and can also prevent
a uniform level of gloss from being achieved
due to the difference in the light reflectivity of
3.0 STONE MINERALOGY
the two portions of the stone.
3.1 Siliceous and Calcareous Stones.
3.2.1 Mineral hardness has long been
Geologists have identified roughly 3,500
measured by means of the Mohs Scale of
different minerals found in the earth’s
Relative Hardness. In 1822, Friedrich
composition, yet only about a dozen of these
Mohs, an Austrian mineralogist, published a
minerals are commonly found in
paper on mineral hardness based on the scratch
commercially-used stone varieties. As
resistance of each of 10 minerals when tested
previously stated, however, even minerals
against the other 9 minerals in his study. His
found in trace levels of a rock fabric can
published paper listed the 10 minerals in order
influence the behavior and performance of the
of their relative scratch resistance. As simple
stone. Minerals that make up stone are
as this study appears, almost two centuries
commonly divided into two groups: siliceous,
later, we are still using Mohs’ research and
or silicate minerals, and calcareous, or calcium
findings as the basic rank of mineral hardness.
carbonate minerals. Stones that are comprised
The ten stones included in Mohs’ scale include:
of siliceous minerals include granite, slate, and
serpentine, while stones that are comprised of
Hardness Mineral
calcium carbonate components include
1 Talc or Mica
marble, limestone, and travertine.
2 Gypsum
3 Calcite
3.2 Mineral hardness is an extremely 4 Fluorite
important consideration for the restoration 5 Apatite
professional. Mineral hardness determines 6 Orthoclase
how the stone will perform in service when 7 Quartz
subjected to abrasion, such as stones used for 8 Topaz
walking surfaces. Mineral hardness is also an 9 Corundum
important measurement in predicting how 10 Diamond
easily a stone can be resurfaced, as the grinding
operation can be significantly slowed when 3.2.2 There are two common
hard minerals make up the stone fabric. In misconceptions regarding the Mohs scale. The
addition to the absolute hardness of a mineral, first is that many do not clearly understand that
one must take into account the variability of the scale is relative, not absolute.
mineral hardness within an installation. A Relative simply means that “4” on the scale is
patterned floor, using granite bands and harder than “3,” and both of them are harder
travertine fields, can pose an extreme than “2.” The scale offers no absolute
challenge to the restoration professional information regarding how much harder, or
attempting to refinish it. The hardness of the whether the interval between 4 and 3 is greater
granite requires aggressive abrasives to
Page 21-2 • Stone Geology © 2022 Natural Stone Institute
or less than the interval between 3 and 2. A inadvertent acid exposures encountered in
mineral with a hardness of 4 IS NOT twice as both residential and commercial settings is
hard as a mineral with a hardness of 2. It is urine, which is quite acidic and has been
more than 10 times harder! Today, we have the responsible for the attack of many stone floors.
instrumentation available to measure absolute
hardness. If the Mohs scale reported absolute 3.3.1 Acidic content is measured with the
hardness, it would look like the table below: pH scale. The pH scale ranges from 0 to 14,
although there are some exceptionally acidic
Mineral Relative Absolute substances that can actually be below zero on
Diamond 10 1600 the pH scale. A value of 7 is neutral; anything
lower than 7 is acidic, while anything above 7
Corundum 9 400
is alkaline. The pH scale is not a linear scale,
Topaz 8 200
but a logarithmic scale. This means that a
Quartz 7 100 substance with a pH of 5 is 10 times more
Orthoclase 6 72 acidic than a substance with a pH of 6.
Apatite 5 48
Fluorite 4 21 3.3.2 Generally speaking, all calcareous
Calcite 3 9 stones are subject to acid attack, even
Gypsum 2 2 from the mild acids found in household
Talc 1 1 settings. The most common result of acid
exposure is etching, which is generally visible
3.2.3 The second area of confusion as a dull spot in an otherwise high gloss
regarding the Mohs scale is that it is a polished surface. Depending on the acidity of
hardness scale of minerals, not stones. the attacking agent, the dwell time that the
Since nearly all stones are polymineralic, each attacking agent was allowed on the stone
mineral within the stone’s composition has its surface, the vulnerability of the specific stone
own unique properties, including hardness. to acid reaction, and the number of repetitions
Oftentimes we see marketing literature for a allowed to occur, the result can be much more
certain stone that lists a “Mohs Hardness” for severe than a simple dull spot.
the stone. This is a technical inaccuracy, since
the stone is comprised of a variety of minerals 3.3.3 Siliceous stones are far more acid
and each mineral has a unique hardness value. resistant than their calcareous
To ask, “What is the Mohs’ hardness of this counterparts. This does not mean that they
stone?” is the equivalent of asking, “What is the are necessarily acid proof. Many siliceous
flavor of Neapolitan ice cream?” It depends on stones include minerals of minor to trace levels
which part of the stone, or which part of the ice of concentration which are acid vulnerable.
cream, we are talking about. Additionally, certain acid types will attack
silicates. One of the better known examples is
3.3 Chemical Resistance. There are a hydrofluoric acid (HF). This is a common
variety of chemicals that can attack the fabric of component found in rust-removing stain
a stone, but acidic chemicals are the cause of removers and rust-removing laundry stain
most frequent concern. Acidic chemicals are removers. Accidental exposure of stone to
commonly found in both commercial and compounds containing low concentrations of
residential settings, through food and HF is fairly common.
beverages, as well as many common cleaners
and detergents. One of the most frequent
© 2022 Natural Stone Institute Stone Geology • Page 21-3
3.3.4 Degradation due to salt attack is
included in this section, but despite the fact
that salt is a chemical, its mode of attack on
natural stone is not actually chemical, but
mechanical. Salt is readily soluble in water,
and when in solution, can penetrate the pores
of medium to highly porous stone fabrics.
When the water evaporates, the salt will
recrystallize within the confines of the pore
cavity in the stone. The expansion caused by
the recrystallization exerts significant pressure
on the walls of the pore, and is great enough to
cause fracturing, resulting in an exfoliation of
the stone face. Salt exposure is most
commonly experienced in northern climates
where salt is used as a snow melting chemical.
The exposure is not limited to exterior
surfaces, however, as the salt is carried into the
building envelope by the footwear of
pedestrians. Salt attack can be evident in both
commercial and residential properties, but it is
far more prevalent in commercial settings due
to the greater use of salts in those venues.
Limestone and travertine are the two most
commonly affected stones due to their pore
volume and pore structure.

Page 21-4 • Stone Geology © 2022 Natural Stone Institute

Restoration and 2.0 STONE FINISH
IDENTIFICATION
Maintenance –
STONE 2.1 The restoration professional must
identify the finish originally applied to a stone
IDENTIFICATION surface. There are a variety of stone finishes in
the marketplace, many of them proprietary,
but the majority of stone installations will have
1.0 FIELD IDENTIFICATION one of the standard finishes listed below.
TOOLS
2.2 Polished surfaces are smooth,
1.1 Several simple field with a highly reflective, glossy face. The
identification tools are available to level of gloss will vary from stone to stone, and
measure hardness and acid sensitivity. can vary between different regions of a stone.
Mohs Hardness picks can be purchased from Gloss level is related to both mineral hardness
any number of laboratory or geology supply and pore space, so significant variation exists.
vendors, generally for less than $100 per set. Gloss, or the level of reflectivity, can be
This set of picks consists of metal and/or measured with a gloss meter, but no industry
plastic tipped instruments which are calibrated consensus standard exists as to what level of
to correspond to the values on the Mohs scale. gloss is required to define a surface as polished.
One simply attempts to scratch the stone If such a standard were to exist, it would
surface with the pick. If the stone is scratched, actually be different for each stone on the
it is softer than that value; if it is not scratched, market. Stone polishing is strictly a
it is harder than that value. The most common mechanical, abrasive process, with the
field test for acid resistance is to use a diluted exception of some marble varieties, in which
concentration of hydrochloric acid (HCl), oxalic acid might be used. It does not produce
generally 5 or 10% concentration. The any level of pore closure, nor “mineral
hardware store variety of HCl is muriatic acid, welding.” As such, polishing does not reduce
which contains about 30% HCl. Many field absorption of the surface. However, it does
technicians purchase the economical muriatic provide greater surface tension when fluids are
acid and dilute it with water in a water to applied to it.
muriatic acid ratio of 5:1 to 2:1. Placing a drop
of the diluted acid solution on an inconspicuous 2.3 Honed surfaces are typically
area of the stone surface will tell you if the produced with the same machinery used for
stone is calcareous or siliceous. The acid will polished surfaces, with only a few of the final
bubble and fizz when placed on calcareous abrasive heads removed. A honed surface has
stones, such as marble, limestone, or the same flatness and perceived smoothness as
travertine, while it will rest on the surface of a a polished surface, but has no or very limited
siliceous stone, such as granite, quartzite, or reflectivity. Again, there is no industry
slate, without any noticeable reactive activity. consensus standard that establishes the limits in
Remember that this is an aggressive acid, even grit size or reflectivity that define the coarse
after dilution. Safe handling practices with and fine boundaries of honed finishes. It is
appropriate PPE are required at all times. commonly believed that honed surfaces have
greater frictional properties than polished
surfaces. This is true in some extremely coarse
grit honed surfaces, but in the majority of

© 2022 Natural Stone Institute Stone Identification • Page 21-5

honed stones available in today’s marketplace, cleft surface is slate, some varieties of which
the difference in measured friction between cleft into extremely flat and uniform sheets.
honed and polished surfaces is statistically
irrelevant.
3.0 DETECTION OF SURFACE
2.4 A variety of textured surfaces TREATMENTS
can be achieved in natural stones.
3.1 Many stone surfaces today are treated
2.4.1 Acid Washed, or “Acid Etched,” with some type of surface-applied product, and
surfaces are created by intentionally inducing in many cases, multiple products. Recognition
an acid attack on calcareous varieties of stone, and identification of these products is vital, as
leaving a rough textured surface. The depth of removal (or “stripping”) of them is frequently
relief achieved is dependent upon the required to prevent an incompatibility with
concentration of acid, vulnerability of the stone subsequently applied products. The best
fabric to acid reaction, and dwell time of the scenario is if the owner has retained records of
acid application. what has been used on the stone during its
service life, from which the manufacturer can
2.4.2 Flamed, or “Thermal,” surfaces be contacted and exact chemistry and removal
are created by briefly exposing the stone protocol can be determined. Four groups of
surface to a propane flame. The rapid heating surface applied products are discussed below.
of the outermost crystals of stone causes
significant expansion and results in a thermal 3.2 Sealers. True sealers are rarely used
desegregation of the stone minerals. This finish in stone applications, as they prevent the stone
is typically limited to granite and granite-like from “breathing,” and often create vapor
igneous rock varieties, but some other stones pressures, blotchiness, or other negative
are also capable of taking a flamed finish. The aspects within the stone fabric. There are a few
depth of relief and related profilometry of the true sealers marketed for use on stone, but
surface is dependent upon the stone’s most commonly when a sealer is encountered,
mineralogy, stone crystal size, and the setback, it is a product that was not specifically
speed, and angle of incidence of the flame. formulated for stone, but intended to be used
on a different surface, such as wood. Sealer
2.4.3 Sanded surfaces have been textured application can usually be detected by a
by abrasive particles striking the stone surface “plastic-like” sacrificial surface compound on
at high velocities. Again, the finish top of the stone.
profilometry is dependent upon a multitude of
factors, including the stone composition and 3.3 Impregnators are the most common
hardness, particle size and velocity, and dwell product applied post-fabrication to stone
time. surfaces. An impregnator can be solvent
carried or water carried. In either case, the
2.4.4 Cleft surfaces are produced by carrier evaporates after application, and the
splitting the stone fabric along its rift, or active ingredients, which may be a small
direction of preferred separation. Virtually all percentage of the original formula, remain to
stones can be cleft, but a much smaller variety treat the stone surface. An impregnator
of stones can be cleft to produce a surface that “impregnates,” or penetrates, the surface and
is suitable and safe for pedestrian ambulation. remains below the surface to a depth of a
The most common stone to be supplied in a couple of millimeters, depending on the
Page 21-6 • Stone Identification © 2022 Natural Stone Institute
stone’s porosity and density. Impregnators finished slab differs for each stone slab. Most
must be matched to the stone variety, as they overseas suppliers will not disclose the
are designed for optimum performance on a application of a resin treatment on their slab
specific range of stone properties. products. On rough slabs, the presence of resin
Impregnators are usually detected by the treatment can usually be confirmed by
stone’s reaction to water droplets; the greater observing the rough edges of the slab and
surface tension of an impregnated surface will noting the cured drippings of resin.
cause “beading” of water droplets.
3.5.2 Problems with resin treatment.
3.4 Dyes and some colored waxes are Although resin treatment does reduce the
occasionally used by suppliers to alter the absorption of stone surfaces, it will not have
natural color of a stone to a color that is more the same effect as impregnator treatment.
desirable and in greater demand. The presence Resin treatment has long been associated with
of a dye is rarely disclosed by the supplier. a darkening of the stone’s natural color, which
Some dyes can be detected with a simple cloth can present challenges in matching the color
saturated in a solvent. Acetone, methyl ethyl tone of an exposed polished edge to the treated
ketone, and toluene are frequently used for this surface. Some resins may also complicate the
purpose. Not all dyes are soluble with these application of impregnators due to
solvents, so while this simple test might compatibility issues between the two products.
confirm the presence of a dye, it cannot reliably No resin treatments have been proven to be
confirm the absence of a dye. 100% UV resistant. Discoloration (yellowing)
of the resin is possible, though not likely. Due
3.5 Resin impregnation prior to to the vast difference in rates of thermal
polishing is common, especially in the expansion between cured plastics and natural
countertop sector of the stone industry. The stone, dislodging of resin fillers is commonly
most common resin used worldwide is epoxy, noted when such products are used in exterior
but polyester and acrylic-based resins are also settings. Degradation of exterior surfaces is
used. likely even without freeze/thaw cycling. As
such, the use of resin-treated stone materials in
3.5.1 Process. Though resin impregnation exterior applications is not recommended.
can be done entirely manually, most major
stone slab sawyers and finishers use large,
sophisticated process lines to perform this 4.0 IDENTIFYING REPAIRS
operation. The sawn, unfinished slab is AND REINFORCEMENTS
screeded with the resin product. It is then
placed over a vacuum table, which draws the 4.1 Repairs and reinforcements are
resin deeper into the stone slab, then placed in common and necessary in many stone varieties.
an oven for accelerated heat curing. Once The restoration professional must be able to
cured, the slab is sent to the polish line, where detect and identify such repairs, because some
the majority of the resin is abraded from the modes of restorative procedures could
slab. The residual resin exists only in the compromise the integrity of the
fissures, cracks, pits, and other surface repair/reinforcement. A more comprehensive
interruptions of the slab, offering a discussion of the allowable and anticipated
cosmetically improved, uninterrupted levels of repair and reinforcement can be found
reflective surface, unattainable in an untreated in the Natural Stone Institute’s Soundness
stone slab. The percentage of resin in the Classification document.
© 2022 Natural Stone Institute Stone Identification • Page 21-7
4.2 Adhesive Repairs. Many repairs the diameter or width of the rod. The rod,
and reinforcements are adhesive, in which two either metal or fiberglass, is fully encapsulated
portions of the stone have been re-cemented in epoxy (polyester is not effective in this
using a polymer adhesive. In some cases, this application) within the groove. If metal is
is actually an intentional fabrication technique used, many choose stainless steel over mild
(not a repair), such as using an adhered liner at steel, due to the quality control aspects of
a countertop edge to create a visually thicker ensuring 100% unbreached encapsulation of
edge. the rod. This reinforcement technique is
unidirectional, meaning that it is only effective
4.2.1 Epoxy-based resins are best for in reinforcing the stone when the slab is being
adhesive repairs that carry any amount of load, loaded in a manner that would cause the face to
because these products are stronger and have be concave and the back to be convex.
higher bond strengths and greater flexibility Rodding is also ineffective if the groove is
than polyester-based resin adhesives. excessively oversized, as the adhesive cannot
effectively transfer the strain to the rod and the
4.2.2 Polyester-based resin adhesives resistance back to the stone. The third
are preferred by many fabricators and installers common error in rod installation is positioning
because they typically offer lower cost, faster the rod too deep, as the rod becomes less
cure time, and more easily-attained color effective as its position advances toward the
matches when dyed. Polyester adhesives are neutral axis of the stone.
weaker and significantly more brittle than
epoxies, making them a poor choice when high 4.3.2 Sticking, or dowelling, involves
strength is required. However, this can be used two pieces of stone being fastened together
as an advantage in some cases. If the seams of a using a stainless steel pin epoxy-adhered into
kitchen countertop have been filled with holes. This may be used to repair a cracked
epoxy, and the cabinetry moves, the stone is stone, or could be used as a higher strength
likely to crack, whereas as the same seam filled method of adhesively bonding two stone units
with polyester would have yielded prior to together. It may also be used as a secondary
fracture of the stone. safety net in case the adhesive fails, such as a
dowelled liner block on the back surface of a
4.3 Mechanical repairs. The use of facing panel.
adhesive alone is often inadequate to
accomplish the structural augmentation 4.3.3 Fiberglass mesh backers are used
desired in the stone. A mechanical device may to reinforce unstable slabs and tile to reduce
also be incorporated into the repair or the likelihood of fracture. This benefit is
reinforcement to achieve the required stability. largely limited to the handling and transport of
the slab. There is little permanent benefit after
4.3.1 Rodding is most commonly installation. Fabricators frequently use this
associated with kitchen countertop fabrication, technique in the interest of safety. If a slab is
specifically in narrow regions such as the rail in reinforced with a fiberglass mesh backer and is
front of a kitchen sink or cooktop. Rodding is fractured during transport, the fractured
not limited to these conditions, and can also be portion will be retained by the mesh, rather
used on facing panels. The technique involves than falling to the shop floor and compromising
cutting a groove, essentially a “dado,” into the safety. Like rodding, this reinforcement
back surface of the stone slab that is just slightly technique is unidirectional, meaning that it is
(not more than perhaps 0.020”) greater than only effective in reinforcing the stone when the

Page 21-8 • Stone Identification © 2022 Natural Stone Institute

slab is being loaded in a manner that would
cause the face to be concave and the back to be
convex. Two complications arise from the use
of adhered fiberglass mesh backers. First, the
back surface of the stone is truly sealed,
eliminating vapor transfer at this point.
Second, the ability of portland-based thinset to
adhere to the epoxy coated back is severely
compromised, and in most cases, effective
bond can only be achieved by using epoxy-
based thinset.

© 2022 Natural Stone Institute Stone Identification • Page 21-9

NOTES:

Page 21-10 • Stone Identification © 2022 Natural Stone Institute

Restoration and material. In this case, the entire surface must
be considered to be Emperador Dark.
Maintenance – Emperador Dark (a geological limestone) is a
highly variegated brown commercial marble
Stone behavioral with multiple colored veins and textures
groups ranging from white to tan to darker brown.

1.3 There are exceptions to any rule in

1.0 INTRODUCTION creating qualitative results on natural stone
surfaces. Most materials, however, will behave
1.1 In this section, stone varieties are in predictable ways based on a sight
classified into behavioral groups to simplify the classification.
evaluation process and create predictable
results across a broad spectrum of materials.
Many stones can be applied to a particular 2.0 TYPICAL GROUP
behavioral group by sight. The technician
begins by visually identifying the behavioral
CLASSIFICATIONS
group based on common characteristics. It is
2.1 Marble, Travertine and
important to have a general knowledge of stone
Limestone (referred to herein as MTL).
and know the differences between marble,
There are two main behavioral groups for
travertine, limestone, granite, and other stone.
calcareous stones: Consistent and Variegated.
Physical characteristics and mineralogical
MTL is a broad generalization of almost all
makeup are the primary influences of how a
calcareous stone, and covers probably 80% of
stone behaves.
what will be encountered when evaluating
Stone Behavioral Groups
restoration and refinishing jobs. Most MTL
floors can be treated with similar methods.
Consistent Variegated Quartzite/Granite Several specific trade names are used here as
examples of stone products that fit into the
Crema Marfil Botticino Serpentine described categories. These are examples only,
and do not represent a complete list of
Limestone Breccia Quartzite materials. The specific stones were chosen
because they are common and will be
Travertine Emperador Granite
frequently encountered. The behavioral
White Marble Green Marble
characteristics are the most important
information to retain.

1.2 To refinish Crema Marfil and Noce 2.1.1 Consistent MTL group. This group
Travertine to any level of gloss will require the has a consistent overall color, with light to
same actions from the technician. Each of these moderate veining. While all stones are
stones can be classified into the same behavioral polymineralic, the stones in this classification
group. When considering how a stone will will have one extremely dominant mineral in
behave during the restoration process, the their fabric. Veining in consistent material is
technician must look at the entire surface. usually of one dominant color, as opposed to
Often there are two materials set into the same variegated stones, such as Emperador, and
floor, either by design or mistake. Contrasting brecciated marble and limestone, which have
material such as Emperador Dark is frequently multicolored veining trends. Crema Marfil is
used in accent pieces between Crema Marfil or an example of the consistent MTL group. This
other class consistent tiles. If the accent pieces stone is commonly commercialized as a
require refinishing, the technician must treat marble, yet geologically is a dense limestone.
the entire floor as the more labor-intensive The surface is creamy white, with light to
© 2022 Natural Stone Institute Stone Behavioral Groups • Page 21-11
moderate veining. Most procedures and texture. These stones also wear out resin
approaches for marble refinishing are based diamonds very quickly due to the fluctuation of
from working with this stone. It can be soft/hard mineral content. They should be
refinished with a typical set of resin diamond taken as high as possible with diamonds before
marble abrasives and polished with most polishing and polished with a weighted
marble polishing compounds. Stones that are machine and a traditional wet polishing
comparable to Crema Marfil should be powder.
repaired, maintained and refinished using
similar methods. 2.1.3 Dense Limestone refers to any
limestone that has a surface similar to marble.
2.1.1.1 Effective Techniques. Crema There are no visible holes or pits, and the
Marfil is fairly soft when compared to other surface will usually have a consistent finish.
marbles. Resin diamond marble abrasives This class of limestone is very hard compared
should be used, usually starting with 220 grit to other limestone, and densities can easily be
(depending on the severity of wear), and in excess of 160 lbs/ft³. Examples of this class
ending with 1800 grit. This grit selection is would be Jerusalem (also referred to as
based on normal wear and tear for this Ramon) and Jura Limestone.
material. Lippage removal will require a more
rigid and aggressive grit selection. A standard 2.1.3.1 Effective Techniques. Dense
rotary buffer with a weighted drive plate is limestone is easier to repair, because the
ideal for normal refinishing procedures. This adhesives will blend better compared to softer
stone can be polished with a traditional wet- limestone. Dense limestone acts more like
style polishing powder (usually containing marble than its porous counterparts, but will
oxalic acid and tin oxide). It can also be still lack depth and clarity. This group will also
polished with the newer wet-to-dry method. need to be sealed more thoroughly. This
limestone is less abrasive than more porous
2.1.2 Porous Limestone refers to any limestone, but will still take its toll on
limestone that appears to have a visibly porous abrasives. Dense limestone will sometimes not
surface. Generally, these stones will have require the highest grit of diamonds when
densities of less than 150 lbs/ft³ (2,400 refinishing, but in most cases should be taken
kg/m3). When looking closely at the stone, through the full range of resin abrasives before
tiny pinholes are visible in the surface, without polishing. The full range of resin abrasives is
magnification. Two common examples are important because dense limestone is so
Crema Europa from Spain and the French delicate, its surface tends to become uneven
limestone, Beaumaniere. These are both very and bumpy (called “orange peel”) when
soft, very porous, and refinish using the same polishing due to its delicacy. Because of this, a
methods. chemically cold powder (one that has a
relatively low acid content), or a two-step
2.1.2.1 Effective Techniques. The micro- polishing procedure, should be used. By
texture and inconsistent surface make this following these recommendations, the highest
group difficult to repair. Most adhesives or clarity can be achieved without the risk of
patching material cure to a smooth, glossy “orange peel.”
texture and stand out easily against the grainy,
matte surface of these stones. This group of 2.1.4 Travertine. Despite the common
limestone typically absorbs a lot of sealer in usage of the misnomer “travertine marble,”
order to properly protect: approximately 100 travertine is a type of limestone. It is a
to 200% more than typical marble or sedimentary stone that is formed naturally by
travertine surfaces. These stones will refinish existing limestone deposits that were
nicely, but lack the depth and clarity of other dissolved, usually by hot and/or acidic springs,
materials due to the difference in surface then transported to the surface where the

Page 21-12 • Stone Behavioral Groups © 2022 Natural Stone Institute

material was allowed to settle and form a new be refinished dry. This group will overheat and
stone deposit. Most travertine varieties behave burn easily.2 Polishing should be done with a
very similarly. They all naturally contain holes traditional style wet compound, although
or cavities. In many regions, travertine is the sometimes this group responds well to the wet-
most commonly used natural stone for floors. to-dry process. These stones tend to be very
It is generally easy to refinish and repair. Its difficult to repair due to their crystal-like
hardness is typically between that of limestone transparency. Using solid color patching
and marble. Travertine has a reputation for material will stand out, even when matching
being hard to maintain in high traffic areas. the correct color. A transparent epoxy or
Holes or pits can open or develop, which will urethane should be used, taking precautions
then collect dirt, making the floor harder to not to create a stain in the material. These
clean. Despite this, travertine is very marbles stun very easily, resulting in noticeable
serviceable and restoration efforts are nearly solid white marks. Refinishing using a high grit
always successful. diamond abrasive is the best practice for this
group. Carrara can “orange peel” easily and will
2.1.4.1 Effective Techniques. Travertine typically have a very slight texture to it.
can be refinished wet or dry, and can be
polished with most marble polishing 2.1.6 General Notes Regarding
compounds on the market. Some travertine Consistent MTLs. When polishing
varieties are vulnerable to stunning, yet consistent materials, ending with a lower grit
susceptibility to stun marks is not a common abrasive, such as 400 or 800 grit, a large
characteristic of all travertine.1 Travertine is a amount of “hot” or acidic powder will be
good material to use when learning how to needed to create a clear reflective finish.
polish because it forgiving and difficult to over- However, care must be taken to avoid the
polish. “orange peel” effect. Consistent materials are
easier to clean, hone, and polish.
2.1.5 White Marble. White Carrara
(Bianco Carrara) is what most people think of 2.1.7 Repairing Limestone and
when they hear “Italian Marble.” It is a true Marble. Limestone and white marble will
geological marble. White Carrara is a white absorb the solvent from some epoxy resins
marble with gray veining. The tone of the when performing a repair. This can result in a
background and intensity of veining can vary. stain around the perimeter of the repair.
Because of the geological makeup, mostly Sometimes this stain can be removed, but most
calcium carbonate, this material is consistent in of the time it is permanent. One way to avoid
hardness throughout. Calacatta and Statuary possible staining is to thoroughly seal the area
(Bianco Statuario) marble are from the same to be repaired before applying any adhesive.
area of Italy, but are currently considered more Another way to avoid this issue is to use a
rare and exotic. Some Greek and Turkish patching material that will not create a stain. Be
marbles are also similar to these types of Italian sure to test the patching material or consult the
marble, but they exhibit a larger, more defined manufacturer prior to use.
crystal structure.
2.1.8 Cleaning Limestone. Thorough
2.1.5.1 Effective Techniques. White cleaning is required for most limestone
Carrara and its relatives vary, even though they installations. While it may seem straight
can look identical. They are somewhat softer forward, there are some necessary precautions.
than other varieties of marble and should not Limestone is very porous, and oily cleaners

1 Stun marks are the result of explosions inside 2Oxalic acid, which is used to speed the polishing
individual crystals in the stone. These marks are caused process, can burn marble. Burned marble has a dimpled
by sudden, pinpoint pressure impacting the surface of appearance and a molten, plastic shine. Rehoning is
the stone. necessary to remove the burnt surface.
© 2022 Natural Stone Institute Stone Behavioral Groups • Page 21-13
may cause some discoloration, particularly Rojo Alicante), Tennessee Pink, and the
with extended dwell times. If this occurs, it can various types of breccia. A short checklist can
usually be removed with additional cleaning, be helpful in determining the steps necessary
but prevention is a better practice than remedy for refinishing variegated stone. Technicians
in this case. Limestone can take 24 hours or should look for the following: color, veining,
more to dry out, so account for this when the and color of veins in contrasts with color of
job involves sealing after cleaning. field.

2.2 Variegated MTL Group. With 2.3 Consistent Variegated. There

MTL, if there is any question, it may be better exists a sub-classification of stones that could
to treat the stone as variegated. Variegated be termed “consistent variegated.” A prime
stones typically have a multicolored field and example of this classification would be
multicolored veining. This look is caused by Botticino. Botticino is very similar to Crema
the variety of minerals included in the stone Marfil (which is Class Consistent) and is also a
fabric, which in turn can lead to those differing compact limestone but is a little different to
minerals having a non-uniform response to the refinish. To the untrained eye Botticino can
abrasives and chemicals used in the restoration sometimes be mistaken for Crema Marfil, but
process. This class is considered more difficult it is harder.
to polish and requires special proprietary
methods. To polish these surfaces, the 2.3.1 Effective Techniques. Botticino has
restoration professional must use the highest one characteristic that makes it drastically
diamond abrasives in the sequence and finish different. It has white, cloudy minerals in it
with chemically-cold polishing powders. that do not polish easily. These areas tend to
Another method is to finish with an ultra-high burn or become very hazy as soon as they are
grit abrasive pad or powder. One example is polished. They occur in different
Emperador Dark marble. Although most concentrations across the different types of
people refer to it as marble, it is a dolomitic Botticino marble, but are almost always
limestone, yet it is actually harder than most present. Botticino should be handled the same
marbles. It is variegated, with veining that is way as Crema Marfil, with the exception that
affected differently than the other minerals in the final polishing step must be done in a way
the stone. to balance the polish and clarity so the white
areas do not burn. Sometimes, Botticino can be
2.2.1 Effective Techniques. Variegated refinished exclusively with fixed abrasives, up
stones do not take a deep, glossy shine like to approximately 8500 grit resin diamond
Crema Marfil or other similar materials, and abrasives without a polishing compound being
will typically have imperfections that can be used. The quality of the abrasives plays a
seen with natural light. Refinishing requires a critical role when using only fixed abrasives.
little more finesse than most marbles because Other times, polishing powders or liquid
of the variation in hardness. It is recommended crystallizer can be used to finish the polishing
to use a finer resin diamond abrasive, up to process.
3,500 grit, before polishing. The polishing step
should also be more aggressive than normal— 2.4 Serpentine is a variegated stone with
more pressure, friction and time is necessary. a marble-like appearance, but vastly different
Good quality diamonds are highly mineralogical makeup. True serpentine is a
recommended. Because of the hardness of silicate, is acid resistant, and will be
these stones, granite diamonds can sometimes significantly harder (Mohs = 5) than marble.
be effective. Due to the absence, or near absence, of calcium
carbonate, serpentine does not typically react
2.2.2 Other Types of Variegated with the acids in most marble polishing
marble include Rosso (with the exception of powders that aid the polishing process. For this

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reason, technicians tend to treat serpentine abundance in granite, and since quartzite is
surfaces more like granite. Many technicians nearly 100% quartz, it should be expected that
prefer to use a crystallizer or low-acid, high- a true quartzite is even harder than granite.
grit polishing powders and creams. Some This property can drastically increase the
stones, such as Rosso Levanto, are variegated amount of time necessary flatten a floor to
marble, but include large swaths of serpentine remove lippage. The best way to determine
mineral in them. Rosso Levanto is a distinctive hardness is to perform a scratch test in an
reddish-maroon marble with white veins and inconspicuous area.
hints of green and other colors, and should be
treated as a serpentine for purposes of 2.5.2 Effective Techniques. Granite and
restoration and polishing. Most, but not all, quartzite are described as dense crystalline, but
green marble-like stones are serpentine. the crystal structures of some varieties are very
porous. This is especially true on materials that
2.4.1 Effective Techniques. Serpentine are lighter in color, such as Giallo Ornamental,
contains little to no calcium carbonate, and as Santa Cecilia and Kashmir. It is very important
such, will not react to traditional marble to use a high quality impregnating repellent to
polishing powders. It can be etched and minimize the darkening of the stone caused by
scratched, but not at easily as other MTL absorption of water or other liquids. When
surfaces. When refinishing, it should be treated polishing dense crystalline surfaces, the
like granite. Using diamond abrasives and technician will often follow the same steps.
polishing compounds made for granite will be These stones must be refinished using
effective when working with serpentine. This mechanical methods with abrasives to achieve
group will not display a deep gloss or present a the highest possible shine, because they do not
lot of clarity like marble. react with conventional polishing powders and
creams. This process takes a lot more time than
2.5 Granite and Quartzite. Most dense polishing softer materials. The technician must
crystalline materials behave similarly and can take this into account when scheduling and
be classified into the same section. It is bidding the project. Scratch removal on a
important to note that many of the “granite” granite countertop can take up to five times
materials evaluated may not actually be longer than the same scratch on MTL. Even
granite. Many of the “granites” with veining are though this group can be drastically different
actually gneiss. Solid black “granites” are from one another, they are all refinished with
usually gabbro. The main concern here is to the same processes and techniques. A granite-
simplify the selection process and avoid specific diamond abrasive is used for both. The
confusing the end-user. In other words, if it major difference between the two is the final
performs like granite in use, then it should be polishing step; quartzite requires several more
called granite. While this may not always be applications of the final polish, and usually with
important to complete the project, a broader much more pressure. There are several ways to
understanding of the mineral composition of approach the final polish that will allow the
the surface will help the technician diagnose stone to be polished back to a factory finish or
and correct issues. better. Because these stones are so hard and
typically found on countertops, which are
2.5.1 Identifying Granite and closer to eye level, there is little to no room for
Quartzite. Quartzite and granite are very error when refinishing. Even the slightest pf
similar. In general, these are the hardest waves, ripples, or gloss inconsistencies are
decorative stones. Granite or granite-like stone visually noticeable. Selection of the right type
can be easier to identify because of the granular of abrasives and good quality tools is
crystal structure. A true quartzite can look paramount to a successful restoration of these
similar to marble, but is much harder. Since materials.
quartz is the hardest mineral found in

© 2022 Natural Stone Institute Stone Behavioral Groups • Page 21-15

2.6 Sandstone is an extremely porous
silica-based stone. The term “sandstone”
describes the clast size (1/16 to 2 mm), rather
than mineralogical composition. Sandstone can
therefore be of a variety of mineral types,
although the most common found in dimension
stone use is quartz-based sandstone. The
material that cements the clasts together has
more influence on its performance and
behavior than the actual sedimentary clasts.

2.6.1 Effective Techniques. The surface

of sandstone looks and responds like fine
sandpaper. It will wear out abrasives very
quickly. Sandstone is not frequently refinished
as often as it is simply cleaned. If there are
scratches that need to be addressed, honing can
be done similar to a hard limestone. The
material will not take a glossy finish. Sealing
can be time consuming and costly, because the
high absorption and porosity of the stone
requires multiple applications of generous
amounts.

Page 21-16 • Stone Behavioral Groups © 2022 Natural Stone Institute

Restoration and environments, as well as its porosity, density,
hardness, and other inherent characteristics.
Maintenance – For example, more porous limestone may
require more regular maintenance, such as
Diagnostics additional sealer applications when installed in
a wet environment. Similarly, a polished
1.0 INTRODUCTION marble floor in a commercial application can be
better protected against scratching and traffic
1.1 The word diagnosis comes from the pattern wear by the use of walk off mats.
Greek word diagignōskein, which means “to
distinguish.” It aptly describes the process that 2.2 Location. A stone’s behavior can
the restoration professional must accomplish differ depending on the environment in which
during the earliest phases of the project, even it is installed. For example, the performance of
prior to submitting a proposal to the client for the same stone may be markedly different in
performing the necessary work. Without a high traffic versus low traffic areas, or in wet
proper diagnosis, it is not possible to prepare areas versus
an accurate estimate of costs, time, or
reasonable expectations for the quality and
3.0 EXISTING INSTALLATION
performance capability of the stone after
completed restoration. A thorough and METHOD
accurate diagnosis requires distinguishing 3.1 The methods with which the stone was
between symptoms and the problems creating originally installed must be verified before
those symptoms. For example, cracks or dull restorative work may commence. Stone will
spots in a stone floor are merely symptoms, naturally age and wear throughout service.
and while those symptoms can be cosmetically Knowing the age of the installation helps
treated, they will reappear if the root problems determine if the condition of the stone
that caused them are not addressed. A represents normal aging and patina, or an
thorough onsite inspection is necessary to abnormal, premature degradation of the
provide the most accurate proposal and product as a result of conditions that need to be
treatment recommendation. In some corrected.
situations, identification and remedy of the
problems may exceed the level of expertise of 3.2 The method of attachment used in
the restoration professional, requiring the an application must be determined to ensure
consultation of additional professionals. The that the planned restorative techniques will not
items addressed below provide a general guide compromise the attachment. It also must be
for the diagnostician to accomplish this task. verified that the method of attachment is still
stable and reliable. If this is not verified, an
installation could be cosmetically restored, but
2.0 STONE TYPE then fail structurally. The simplest methods of
attachment involve adhesive bonding only.
2.1 Identifying Stone Types.
Floor and wall tiles are typically held in place
Identification of the stone by customary trade
by adhesive methods only. When the stone
name may not always be possible, nor is the
becomes thicker, starting at 20 mm and
country of origin always identifiable. The
greater, mechanical anchors may have been
geological type of stone must always be
used in combination with or in lieu of the
confirmed. This information provides insight
adhesive bonding.
into the material’s behavior in various

© 2022 Natural Stone Institute Diagnostics • Page 21-17

3.3 Resources for Tile and reduced thickness. When grinding operations
Mechanical Anchors. Most adhesively- are required, one must be careful to not only
attached floor and wall applications have been avoid grinding through the stone depth, but
installed using methods outlined in the Tile also grinding the stone to such a reduced
Council of North America’s (TCNA) Handbook thickness where it can no longer perform under
for Ceramic, Glass, and Stone Tile Installation. load. It must also be ascertained that the stone
Readers are encouraged to obtain a copy of this is solid through its depth, as opposed to stone-
publication (available for purchase through faced units consisting of a very thin layer of
NSI’s Online Bookstore) and familiarize stone laminated to ceramic, metal, or other
themselves with it prior to evaluating existing backer units. While joint fillers can be abraded
tile installations. Readers are referred to NSI’s to facilitate viewing and measurement of the
Technical Bulletin, “Dimension Stone actual stone depth, a far easier and less invasive
Anchorage; Theory, Practice, & method is to take advantage of the existing
Components,” for a comprehensive discussion mechanical and electrical penetrations. Simply
of mechanical anchorage techniques. A removing a grate over a heating duct or
mechanical anchor is any device (usually a non- removing the plate over an electrical switch or
corroding metal such as stainless steel, outlet will usually confirm the actual thickness
aluminum, copper, brass, or bronze) used to of the stone units. Stone thickness can often be
secure the stone unit to an unyielding support, ascertained at the doorway to unfinished space;
such as the building frame. Anchors are nearly for instance, where the stone work truncates at
always concealed in stonework, so the the transition between a finished space and an
restoration professional must verify their unfinished utility room.
location and ensure that the restorative
procedures will neither expose them nor
compromise their integrity. 5.0 EVALUATION OF DESIGN
AND EXECUTION
4.0 MEASURING STONE 5.1 The existing design and installation
THICKNESS must be evaluated for a series of potential
deficiencies. If deficiencies are noted, the
4.1 The thickness of the installed stone condition must be corrected as part of the
influences which restorative techniques may be restoration process, lest post-restoration
attempted, and how aggressively those failure is likely.
attempts may be implemented. Stone
thickness should be evaluated in conjunction 5.2 Five Categories of Movement
with stone strength. In flexure (bending), a Joints. A series of specialty joint designs is
stone’s strength is proportional to the square of necessary in all finished stonework to facilitate
its thickness. Therefore, a 30 mm thick section dynamic building frame movements,
of stone is over twice as strong as a 20 mm thick differential thermal expansions and
section of the same stone (30² = 2.25 x 20²)! contractions, and permanent deformation
But if the 30 mm stone is a relatively low (creep) of structural units. These necessary
strength stone with a flexural strength of 1,000 functional joints are frequently omitted from
lbs/in² (6.9 MPa), and the 20 mm stone is a stone installation designs, and their absence is
high strength stone with a flexural strength of one of the most common contributors to stone
2,500 lbs/in² (17.2 MPa), the 20 mm section installation failure. These joints can be placed
is actually stronger in service, despite its into five general categories:

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1: Expansion joints typically go through the whether or not the substrate has the required
stone installation assembly and building rigidity to adequately support the stone units.
structure, and accommodate relatively large
movements anticipated in the building frame at 5.3.1 Frame Deformation must be held
that location. to extremely low allowable deflections.
2: Isolation joints are also typically carried Various documents (building code, ACI, and
through the building structure, and are most NSI) list a maximum allowable deflection
often used to bridge between different anywhere from L/600 to L/1000. In addition
structural elements; for instance the separation to the basic deflection of the framing members,
between a footing pad at a column and the one must verify that the potential differential
surrounding concrete slab. deflection between adjacent members is not
3: Control joints are merely shallow cuts in excessive. Oftentimes, some type of load-
concrete slabs which create a slightly weaker sharing device is required to tie adjacent
zone and direct, or “control,” where shrinkage members together and reduce the inter-
cracks will occur as the concrete cures. member differences in deflection under load.
4: Perimeter joints separate the finished Since deflection and radius of curvature are not
stone surface at regions of discontinuity, for exactly the same thing, span length also
instance where horizontal finish planes becomes part of these analyses.
intersect with vertical elements, such as walls
or columns. 5.3.2 Substrate Panel Deformation.
5: Generic Movement joints are simple The substrate panel, be it a sheathing on a wall
soft joints occurring in the finish stone surface assembly or a subfloor/underlayment
only and are intended to provide an combination in a floor assembly must be
interruption in the accumulation of shear sufficiently stiff to carry the loads experienced
stresses resulting from differences in by the stone units back to the framing members
temperature or expansion rates between the without undue deformation.
stone and the rest of the assembly, or to
accommodate differences in elongation or 5.4 The setting adhesive used, if
compression as a result of floor curvature. possible, should be identified to verify its
Refer to section EJ171 of the TCNA’s suitability and the quality control of its
Handbook for Ceramic, Glass, and Stone Tile placement.
Installation for additional information on these
types of joints and requirements for their 5.4.1 Appropriate Selection. Certain
frequency in stone designs. stone types require specific types of adhesives;
for instance white colored thinsets are required
5.3 Substrate Rigidity. Stone is a quasi- for light colored marble and limestone, and
brittle material and does not bend easily. A 12” epoxy-based thinsets are required for mesh-
x 12” x 3/8” (300 mm x 300 mm x 10 mm) backed stones and many moisture sensitive
stone tile could fracture with as little as 0.010” stones.
total deformation! As thin stone tiles (less than
20 mm thickness) are considered to be 5.4.2 Adequate Coverage. The adhesive
decorative, abrasion-resistance finishes only, must have adequate contact area with the stone
they must rely on the rigidity of the substrate unit. NSI’s Dimension Stone Design Manual calls
and bedding layers to develop their resistance for 95% contact with no voids exceeding 2 in²
to applied loads. There are two primary and no voids within 2” of tile corners on 10 mm
components to consider when evaluating tile. In 20 mm thick stone, 80% contact with

© 2022 Natural Stone Institute Diagnostics • Page 21-19

no voids exceeding 4 in² and no voids within 2” 5.6 Wet Areas. Water infiltration of a
of tile corners is required. All corners and stone system is always a concern, particularly if
edges of stone tiles must be fully supported and the stone system was not designed for water
contact shall always be 95% in water- exposure. Evaluation of a proposed restoration
susceptible conditions. project should include careful study of water
control and flow, as well as evidence of water
5.4.3 Bond Strength. Adequate bond damage. In many cases, water damage repair
strength may not be achieved between some requires complete removal and replacement of
thinsets and stone materials with compromised the installation, since the damage may be
bonding surfaces, such as those that have had concealed by several layers of the installation
mesh backing applied, or those that have been system and is not accessible without
sealed or resin-treated on their bonding excavation.
surface.
5.6.1 Water Control Slopes. Water flow
5.5 Stone Jointery Alignment is governed by gravity, therefore, sloping of
influences both performance of the system and surfaces toward a drain or other path of
aesthetics of the finished installation. effective evacuation is a necessity that cannot
be compromised. In general, any slope of less
5.5.1 Joint Width Tolerances. The than 2% (¼” per foot, or 20 mm per m) is
installing contractor is allowed a tolerance of ineffective in achieving positive water flow.
the greater of either 1/16” (1.5 mm) or 25% Inadequate slope is a condition that cannot be
of the specified joint width when installing corrected in normal restorative procedures.
stone units. Many existing installations do not One must carefully guard against reducing or
comply with this tolerance. The issue can often eliminating existing water control slopes
be remedied by field cutting joints during the during restorative processes.
restoration process. A wider joint of a uniform
dimension will look better than a narrower 5.6.2 Drain Function. If the goal of the
joint of varied dimensions. sloped surfaces is to direct water to a drain,
then achieving that goal is useless unless the
5.5.2 Lippage Tolerances. Stone flooring drain is fully functional to evacuate the water
units are typically supplied with little or no once it arrives. Drains must be inspected for
chamfer at their perimeter, and are typically proper operation, and in particular, subsurface
installed with narrower joints than other hard weep holes in the drain assembly must be
surface flooring products. These factors checked for proper water flow functionality.
accentuate the perceived lippage, both from a
visual aspect as well as an occupant safety 5.6.3 Efflorescence is a collection of
aspect. Lippage tolerance between adjacent water-soluble compounds (typically salts) that
units of smooth finished stone flooring units is have been carried to the stone surface by water.
limited to 1/32” (<1 mm). The easiest way to Efflorescence deposits typically carry two or
measure this is with a digital caliper, using more of the following: potassium, sodium,
0.031” as the maximum allowable calcium, sulfates, carbonates, bicarbonates,
measurement. A common method of field and hydroxides. In some cases, the water
checking for lippage issues is to use a standard soluble compound can chemically combine
plastic credit card as a gauge, since most credit with other compounds at the surface, creating
cards measure ±0.030” in thickness. a non-water-soluble compound. The key to

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preventing efflorescence is to control water communication with the client is imperative to
migration. This may or may not be remediable establish reasonable and attainable expectations
in some restoration settings. Refer to ASTM for the project’s outcome.
C1400, Standard Guide for Reduction of
Efflorescence Potential in New Masonry Walls for 6.3 Staining does occur in natural
further guidance in this subject. stone. However, the stain potential of natural
stone has perhaps been overhyped by
marketing claims made by producers of
6.0 EVALUATION OF competing materials.
OCCUPANT AND IN-SERVICE
6.3.1 The most important step in stain
INDUCED CONDITIONS
removal is to identify the staining agent.
If this is not achievable by interviewing the
6.1 Current Maintenance Products building occupants and maintenance staff, one
and Procedures. A review of the products must speculate as to what the staining agent
used and the procedures followed will provide likely could have been based on available
insight into which professional maintenance information. Information used in this
treatments are to be prescribed for a situation. speculation includes the stain color, shape,
Some cleaners used by end-users can be size, location, frequency, and a list of potential
harmful to the stone. These products may staining agents commonly found near the site
cause blemishes that require removing (e.g., of the stain.
acidic cleaners that cause etching, abrasive
cleaners that create dullness, oil-based 6.3.1.1 Food and Beverage Stains include
surfactants that cause residue, or wax-based natural pigments (e.g., fruit, juice, or wine
cleaners that cause build up). Knowing which stains), dissolved solids (e.g., coffee stains),
cleaners have been or are being used will help and oil-based stains (e.g., cooking oils or meat
determine the best cleaning techniques fat stains). Food and beverage products may
available. One challenge in determining these also be acidic and contribute to etching of
things is that the owner may not be the original calcareous stones.
owner of the property, and therefore
unfamiliar with the entire history of 6.3.1.2 Rust Stains are generated by contact
maintenance procedures. A second challenge or close proximity to corroding metals. Rust
exists in that most owners do not perform their stains are some of the most difficult stains to
own maintenance, and are unlikely to be eradicate. The source of the rust may be
familiar with which products and/or concealed by the stone assembly, such as a
procedures were used by employees or corroded fastener in substrate layers. In rare
vendors. cases, the origin of the rust is a metallic-rich
mineral within the stone fabric. Rust stains
6.2 Previous Restoration Processes. that originate from within or below the stone
A restoration professional is often contacted are generally not removable, since the source
due to dissatisfaction with work performed by of the stain cannot be eliminated.
another company. Correction of previous,
inappropriate restoration processes will 6.3.1.3 Soiling occurs when dirt mixed with
further complicate the task of restoring the oil or grease scratches, dulls, or discolors
stone. In extreme cases, the stone may have porous stone and grout. More porous stones,
been altered beyond a state from which it can especially those pores visible to the naked eye
effectively be restored. Candid (e.g., limestone & travertine) are most
© 2022 Natural Stone Institute Diagnostics • Page 21-21
vulnerable to soiling. Aggressive grinding or repeated occurrence (i.e., excessive loading
chemical treatments may be required to that occurs on a frequent basis), or a
restore the stone’s color. In extreme cases, design/workmanship deficiency (e.g.,
soiling may be cost prohibitive to remove. inadequate substrate rigidity or insufficient
bedding coverage). In these cases, the cause of
6.3.1.4 Efflorescence (as discussed in the cracking must be identified and corrected
section 5.6.3 above) is always the result of prior to the repair of the cracks to avoid
water-soluble compounds carried to the repetition of the cracking.
surface by water migration. In most cases, the
stain is easily removed, but reoccurrence is a 6.4.1 Impact Cracks and/or Chips are
certainty unless the water migration can be caused when a heavy object falls onto the
arrested. surface or when a heavy object is moved across
the floor. In soft stones, the crack may be
6.3.1.5 Hazing is most frequently the result accompanied by a depression in the stone
of improper or incomplete cleaning after the surface. A white or light crack “stun mark” is
initial installation. The source of the haze is often visible in addition to the crack. These
frequently grout, although it can also be a types of cracks are typically due to a one-time
result of inappropriate or incorrectly applied experience.
sealers. Some grouts are so prone to hazing
that masking the stone during grouting is the 6.4.2 Cracks caused by excessive
only way to reliably prevent hazing. loading. Excessive loads may occur from
vehicles, freight delivery dollies, furniture, or
6.3.1.6 Grout Stains. All agents that can other sources. These may be individual or
cause stains in stone will also cause stains in repeat occurrences. If the latter, customer
grout. Due to the high porosity of grouts, the education is paramount to ensure that the
same type of stain may penetrate deeper into practice of excessive loading is discontinued
grout than it will in stone. after cracks are repaired.

6.3.2 Eradication. Nearly all stains can be 6.4.3 Cracks caused by building
removed from nearly all stone types. Stain movement. Dynamic building movements
identification is key; after identification, the can be caused by foundation settling, thermal
removal can generally be accomplished quickly expansions/contractions, frame deflections,
and effectively using proven methods. If the creep, and seismic or wind loads. With the
origin of the stain is unidentifiable, varying exception of foundation settling, all of these
levels of trial and error are usually required. movements should be anticipated, and the
failure of the stone installation suggests an
6.4 Cracks. A crack is a separation of the improper design.
stone fabric, typically along a grain boundary.
Cracks are easily visible. In most situations, 6.4.4 Cracks due to improper stone
they extend through the entire thickness of the installation. Voids in the setting beds,
material. The crack may be the result of a inadequate accommodation for thermal
single occurrence trauma, in which case the expansion, or failure to use appropriate
crack may be repaired without addressing the membranes where required are frequent
cause, as long as there is reasonable confidence factors in cracked stone flooring and paving.
that the trauma will not be repeated. When
multiple cracking occurs within a stone 6.5 Chips and Spalls are most often
installation, it is generally the result of a caused by impact from dropped objects or
Page 21-22 • Diagnostics © 2022 Natural Stone Institute
rolling loads with hard wheeled equipment. more aggressive measures to eliminate it, but
The client needs to understand the cause of the scratches that do not catch a fingernail are
problem to prevent further damage after usually minor and can be eliminated with
restoration. refinishing.

6.6 Etching is a dull whitish mark that 6.8.1 Scratch removal can be
results from a chemical reaction between a accomplished through abrasive grinding,
caustic or acidic liquid and calcium carbonate refinishing, and honing. The depth of the
in stones like limestone, marble, travertine or scratch determines the coarseness of the initial
engineered marble (man-made marble). The grit needed to remove it. Trial and error
depth of etching may vary, from a minor iterations may be required before one knows
surface attack representing itself as a dull spot what starting grit is required. More
on an otherwise glossy surface, to a deep attack experienced technicians may intuitively know
with a penetration of a millimeter or more which grit is needed to start the process.
where a textural difference can be felt with
one’s fingers. Simply cleaning, polishing or 6.8.2 Pressure Scratches actually damage
resealing will not remove an etch mark. To the body of the stone tile through compression
completely remove the mark, it must be and gouging. These types of scratches are
ground to the depth of the damage and usually permanent, but can be minimized.
refinished.
6.9 Topical Sealers (also referred to
6.7 Pits and Voids (holes, fissures, as film-forming sealers and coatings)
chips, cavities, veins, etc.) are common for differ from impregnating (also known as
various stone types. Materials are filled with penetrating) and enhancing sealers in that they
either resins or cementitious fillers during create a sacrificial coating on the stone’s
factory processing, or less frequently, in the surface as they cure. These products must be
field during installation. Over time, the filling stripped before maintenance or restoration
can dislodge, requiring replacement during attempts. Topical sealers contain waxes,
maintenance or restoration. Some stones, acrylics, urethanes, and other chemicals that
notably fleuri cut travertine, will have voids are high in solids – therefore, they do not
just below the surface of the stone concealed by penetrate the pores as effectively as
a thin shell of stone fabric. These voids do not impregnating repellents. Since they do not
get filled due to their concealment, and are allow for vapor transmission, moisture can be
likely to be exposed as the shell of stone trapped within the stone. Additional
covering them is broken during service. undesirable traits of topical sealers include
Rolling loads with small diameter, hard color change (yellowing), flaking, dirt
wheels, and concentrated loads such as spike attraction, vulnerability to scuffing, frequent
heeled shoes are common causes of exposing reapplication intervals, and labor intensive
these voids. removal processes.

6.8 Scratches are commonly caused by 6.10 Close grout examination is one of
grit beneath shoes or furniture, sliding objects, the more critical components of the site
or maintenance equipment with improper, inspection. Grout is softer, more porous, and
worn, or dirty cleaning heads. The severity of less resilient than stone. Grout will frequently
a scratch can be assessed by running one’s show signs of distress before similar signs of
fingernail across it. If the fingernail pauses or distress are noted in the stone components of
catches in the scratch, it will normally take the installation. Sanded grout is most
© 2022 Natural Stone Institute Diagnostics • Page 21-23
commonly used when stone tiles have been membranes, or ground water transmission.
installed with relatively wide joints [≥3/16” (5 These can result in various issues, such as
mm)]. Since the sand in these grouts is harder excessive mineral build up, mildew and moss
than some stone varieties, scratching may have accumulation, damage from the expansion and
resulted during the grouting process if the contraction of more porous materials, surface
stone was not adequately masked. Additional exfoliation, and distress in the setting beds
scratching may occur during the restoration and/or grout.
processes if the sanded grout is not removed
prior to restoration. 7.4 Saltwater Environments (regions
near oceans). Stone applications near
saltwater environments may experience
7.0 ADDITIONAL CONSIDER- additional degradation due to exposure to salts.
ATIONS FOR EXTERIOR APPLI- Salts attack the more porous varieties of stone
via a mechanical, rather than chemical mode.
CATIONS
When salt is carried in solution by water, it
penetrates the pores of the stone. As the water
7.1 Weathering. Weather exposure
evaporates, the salts recrystallize within the
causes a degradation of the stone surface over
confines of the pores, and this recrystallization
time. The degree of weathering is dependent
pressure is great enough to exfoliate the stone
on both the type of stone and the severity of the
surface. Some sealers have proven to be
environment in which it was installed.
effective in minimizing the effects of saltwater
Weathering includes both physical and
environments, or at least in retarding the rate
chemical attacks. It should be noted that some
of attack.
stones are simply not exterior-worthy
materials, and no level of restoration can
7.5 Pool/ hot-tub/ resort/
effectively compensate for an improper
commercial center environments.
selection of a stone material.
Exterior applications of natural stone in high
traffic and wet environments should be
7.2 Freeze/thaw issues. In regions
inspected for various post installation
where freeze/thaw cycling occurs, weathering
treatments that may have been applied to help
can extend beyond cosmetic issues and become
improve slip resistance. Some stones may have
structural issues. It is not uncommon for
been exposed to treatments such as acid
improperly chosen stone species in
washing, brushing with abrasive-embedded
freeze/thaw environments to degrade beyond
brushes, or coated with topical finishes
a level where restoration is achievable.
containing grit.
Horizontal applications are more severely
affected than vertical, and grout distress usually
prefaces or accompanies stone degradation.
8.0 PREVENTING DAMAGE TO
7.3 Water Damage. With or without ADJACENT SURFACES AND
freeze/thaw cycling, water ponding and water BUILDING CONTENTS
transmission through the stone can break down
either the stone fabric, the bedding layers, or 8.1 SURFACES
both. Excessive water exposure and ponding
can result from inadequate drainage, 8.1.1 Adjacent Floors. The maintenance
improperly prepared substrates, insufficient or or restoration processes used on natural stone
negative slope, ineffective moisture may damage adjacent flooring materials. It is

Page 21-24 • Diagnostics © 2022 Natural Stone Institute

best to anticipate possible damage and take valued at more than what the restoration
steps to protect these surfaces in the beginning. professional’s contract is. It is strongly
encouraged that these items be handled by
8.1.2 Adjacent Rooms and Access someone who is trained in this activity and
Routes. Adjacent rooms are best protected by specifically insured for the liability incurred.
sealing the halls/doors that lead to them,
particularly is any dry working will be 9.0 UTILITIES AND ACCESS
performed. Access routes along which
materials or equipment will be transported 9.1 Power Source. Prior to preparing an
must be fully protected from damage to any of estimate for performing the work, it must be
their surfaces. verified that adequate electrical power is
available (both required voltage and
8.1.3 Baseboards and Walls. If light amperage). If this is not the case, the cost of
honing and polishing is the only process providing generators must be considered.
needed, then it is only necessary to protect the
base during the work. More aggressive 9.2 Water Supply. If adequate quality
restoration techniques, such as lippage and quantity of water are not available onsite,
removal, require the base to be removed. considerable cost will be encountered in
Depending on the material used for the base, bringing water in from an outside source.
removal and reinstallation may require a
different trade be involved to assure quality 9.3 Water Discharge and Disposal. It
workmanship results. must be verified if water discharge and disposal
can be accomplished at the site, or if spent
8.1.4 Thresholds and Transition water supply and/or slurry needs to be
Strips. If the threshold is stone, refinishing it removed from the site.
should be part of the stone restoration process.
If it is of a different material, it may be 9.4 Building Occupants. Working in
necessary to replace it after completing the an occupied building may limit the hours
project. available to the restoration contractor, and may
also limit to number or size of areas that can be
worked on at a time to avoid inconveniencing
8.2 BUILDING CONTENTS building occupants. Early communication with
the client is essential in determining a sequence
8.2.1 Furniture and other items. of work areas and establishing an estimated
Moving furniture exposes the restoration duration for the project.
contractor to additional liability in having
his/her crews handle items for which they have 9.5 Business Schedules. Few business
not been trained. Moving a piano, for instance, can absorb the cost of suspending their business
is best handled by those who are professionals during restoration. This may mean that the site
in that line of work, and in either case, is likely is available only after hours or weekends. It also
to result in the owner having to retune the may add costs in daily cleanups and removal of
instrument after it is returned to its original equipment to allow the business to continue
position. with only minor interruptions.

8.2.2 Artwork and Antiques. Specialty 9.6 Noise and Dust Restrictions.
items, such as artwork and antiques, can be Clients and neighboring homes or businesses

© 2022 Natural Stone Institute Diagnostics • Page 21-25

may have legitimate objections to the creation 10.5.1 Stained Stone. Subsurface water,
of noise or dust. Any possible restrictions must with or without impurities, will result in
be researched in advance. surface discoloration or staining of the stone.
Removal of this discoloration is an ineffective
10.0 SERIOUS ISSUES THAT solution unless the source of the moisture can
REQUIRE RESEARCH AND MORE be eliminated.
EXPERIENCE
10.5.2 Stained Grout. Just as the stone can
10.1 The restoration contractor must be be stained, the grout will be stained as well,
aware of the limits of his/her experience and often to a greater degree.
expertise. Following is a partial list of possible
scenarios which may require the consultation 10.5.3 Efflorescence requires the presence
of another professional. of water soluble salts in subsurface levels that
are carried to the surface by moisture
10.2 Structural Problems. Any transmission, where they then recrystallize
symptom that suggests a structural problem after the moisture evaporates. Elimination of
with the building may exist: Extensive the moisture source or addition of a barrier to
cracking, chipping, grout distress, or the moisture path are the only permanent
misalignment may indicate a structural issue solutions.
with the building foundation or frame. If
structural issues are suspected, a consultant 10.5.4 Moisture Hazing. Generally, a non-
who is licensed to practice in that jurisdiction stone substance, such as a sealer or resin, is the
should be involved in the analyses. affected component when hazing at the surface
has been triggered by chronic moisture
10.3 Extensive hollow sounds or transmission.
adhesion problems. While epoxy injection
or grout replacement may be a feasible remedy 10.5.5 Spalling and other factors. This
for limited occurrences, extensive hollow may indicate water migration or higher
sounds or adhesion failures may represent a moisture levels.
systemic problem with the stone installation. In
these cases, a consultant experienced in stone
tile forensics should be contacted.

10.4 Inadequate structural support

and/or building movement issues. If
either of these is suspected, a consultant who is
licensed to practice in that jurisdiction should
be involved in the analyses.

10.5 Substrates with high moisture.

Some issues involving substrates with higher
moisture levels can be mitigated through the
use of a moisture retardant membrane. These
barriers have varying levels of effectiveness.
The following are some of the issues caused.

Page 21-26 • Diagnostics © 2022 Natural Stone Institute

Restoration and shape depending on the manufacturer, but they
typically mount on top of or around the motor
Maintenance – housing. The weight of the machine while
grinding should be approximately 200 pounds
EQUIPMENT (90 kg).

1.0 INTRODUCTION 2.1.2 Diamond Honing and Polishing.

When diamond honing and polishing (220 resin
1.1 A complete list of equipment used in grit through a powder polish), generally the
the process of restoring or maintaining stone faster the speed of the machine, the more
would be very extensive. Individual weight you will need. Most floors requiring
preferences can dictate the need for a wide refinishing are 12 to 18-inch (300 to 450 mm)
variety of items. The primary focus of this square tiles. The diamond abrasives need a
section is to identify and describe the most minimum time on each tile to cut. If the
common equipment used in restoring, machine is moving too quickly, the abrasives
refinishing and maintaining stone. will not make a thorough cut. Adding weight
to the top of a faster machine (200 RPM or
faster) will add pressure to help the abrasives
2.0 FLOOR MACHINES dig in a little more and speed up the process.
On European-style machines, the motors are
2.1 Mono-rotary machines are an usually much slower (150 RPM). This
absolute “must have” for stone eliminates the need for the extra weight,
restoration companies. Because mono- because the diamonds spend more time on each
rotary machines utilize a single, often rigid, tile. Either configuration can yield the same
drive plate; with the correct abrasive they can results.
be good for edge work on floors. Mono-rotary
machines are single disc, single speed 2.1.3 Mono-rotary machines have
machines. The most common type is a 17-inch many attachments (most commonly,
(430 mm), 180-RPM machine. They weight brushes). A light duty nylon brush can be
approximately 85 to 95 lbs (39 to 43 kg). used for scrubbing and rinsing polished stone
Speed and weight vary with the manufacturer, floors without scratching them. Brush
but “180 RPM mono‐rotary” is the general attachments increase in abrasiveness to do
description used for what has become the most heavy scrubbing, texturing and even scarifying.
commonly used piece of equipment for stone Soft nylon and natural hair pads of all different
refinishing. These machines can grind, hone, grits and densities can be fitted on a standard
diamond polish, powder polish, clean, texture, pad driver as well. These can be used to clean,
or buff, depending on the accessory used. scrub, strip, refinish, polish and hone stone
floors.
2.1.1 The speed and weight of the
machine can have a significant impact 2.2 Planetary machines can be belt
on the efficiency and quality of the or gear driven. They are much heavier than
finished product. When only diamond mono-rotary machines, making them ideal for
honing and refinishing, the optimal accessory is grinding. They are usually reserved for large
a weighted drive plate. This adds residential and commercial jobs. They have a
approximately 35 pounds (16 kg) to the pivoting head, which self‐levels as it goes over
machine and speeds up the diamond honing the floor. This allows the technician to push it
process. When grinding (also referred to as like a lawnmower and not have to use his or her
lippage removal), weight should be added to body to swing the entire weight of the machine
the machine to increase pressure and help around. The most common configuration is 17
speed up the process. Weights vary in size and

© 2022 Natural Stone Institute Equipment• Page 21-27

to 20-inch (430 to 510 mm) diameter with 3 2.3.2 Lightweight drive plates. Nylon
satellite heads. or plastic drive plates are classified as
lightweight. This style is used for light-duty
2.2.1 Active and passive planetary scrubbing and buffing and sometimes light
machines. Active planetary machines have refinishing or polishing. Lightweight drive
“driven” heads. The main head, which is the plates only weigh a few pounds and are easy to
large diameter, is driven by a belt or gear set. remove or install with one hand. The ease of
It is directly connected to the 3 planet heads changing out the drive plate results in
and drives them continuously. Passive significant time savings.
planetary machines have non-driven heads.
The main head is driven by a belt or gear set,
and the planet heads are essentially free to 3.0 HANDHELD MACHINES
rotate in the direction they are pushed.
3.1 Variable speed angle handheld
2.2.2 Floating and Rigid Heads. polishers come in multiple varieties. For
Floating heads are ideal for concrete. The heads restoration and refinishing, it is best to own a
are firmly attached to the machine, with rubber variable speed polisher. The most commonly
grommets or a cushion in between. This allows recommended variable handheld polisher is
the heads to “float” over the highs and lows of typically referred to as a 7-inch (180 mm)
the floor, or over bad lippage on stone tile polisher. This polisher is designed to accept 7-
floors. These types of heads are almost always inch (180 mm) grinding, honing, and polishing
present on belt-driven machines to help absorb abrasives. The 7-inch (180 mm) polisher is
the shock and keep the belt from slipping. larger than the machine referred to as a
Rigid heads are bolted to the machine. They are grinder. The motor is larger and more
unforgiving and offer no flexibility. These are powerful. A 7-inch (180 mm) polisher usually
usually found on gear driven machines that are features variable speed control. The ideal
built heavy duty use. Rigid heads are used with speeds start as low as 600 RPM. Most stone
the intention of planing down the stone floor refinishing jobs can be completed under 1,000
to a perfectly flat surface. Some planetary RPM. The use of a slower speed creates less
machines have the flexibility to switch between mess. Some restoration technicians prefer the
the two head configurations by simply bolting 7-inch (180 mm) polisher because of the larger
the desired set of heads on the machine. These motor so that they can apply additional
machines are preferred by many due to the pressure to the grinder by leaning on the
flexibility that they offer. machine without the motor stalling out.

2.3 Drive plates: 10”, 17”, 22”, (250, 3.2 Pad drivers: 3, 4, 5 and 7-inch (75,
430, 560 mm) and larger 100, 125, and 180 mm). Pad drivers, also
referred to as backer pads, are the connection
2.3.1 Steel drive plates usually feature a between the tool and the abrasive. They attach
hook and loop attachment configuration on the to the angle grinder or polisher and provide a
bottom that are used to attach various diamond surface or mechanism for attaching the
and other abrasive pads. This style is designed abrasive. They are available in several
to withstand adding weight to the machine to configurations.
give the abrasive more pressure and contact
with the floor. Steel drive plates also feature a 3.2.1 Rigid aluminum pad drivers are
low center of gravity to speed up production. the most rigid type available and are ideal for
The plate usually weighs approximately 35 refinishing slab counters. A rigid abrasive and
pounds (16 kg) and normally requires 2 hands pad driver will help the technician achieve a
to remove or install. flatter finished surface, which is closer to the
original factory polish.

Page 21-28 • Equipment © 2022 Natural Stone Institute

3.2.2 Rigid composite pad drivers have patching material, and sometimes taper a
the same features as aluminum pad drivers but surface to improve a transition. Each of these
have a tendency to lose their perfectly flat processes requires the use of abrasives. For
profile or warp after extended time in service. scratch removal, the abrasive is used to grind
down the surrounding material to the same
3.2.3 Flexible pad drivers are made of plane as the low point of the scratch and
hard rubber and will flex a moderate amount continue using consecutively finer grit
when under pressure. These are generally used abrasives until the original finish is matched.
for fabrication when there is a contour or shape Voids or cracks are repaired with a patching
that needs to be polished. For restoration, material. Abrasives are commonly used to
these are great for working in showers or on smooth out the patched area and blend it to the
tile countertops where rigid pad drivers might same plane and finish as the surrounding stone.
cause the abrasive to bounce from tile to tile. Transitions are needed when a stone floor is on
a higher plane than an adjacent floor or when
3.2.4 Super flexible pad drivers are tiles have been installed with excessive lippage.
made from soft rubber and can be bent with
minimal force. They are designed for extreme 4.2 Silicon carbide and diamond are
contours. Many restoration technicians use the most commonly used abrasive types
these with dry abrasives for quick touch ups on for stone refinishing and restoration.
the edge of a low tile where it meets an Both are hard enough to abrade the hardest
adjoining high tile. As with other flexible pad stone, but diamond, being the hardest natural
drivers, these can make quick work of shower substance in the world, will cut noticeably
and tile countertop restoration because of the faster when working with very hard stone
ability to allow abrasives to make contact with materials. The cost of most diamond abrasives
stone in low areas. Super flexible pad drivers is usually higher than silicon carbide. It is
can also be used in repairing and refinishing important, however, to include the costs of
complex edges on stone tops. labor and machine hours in addition to abrasive
costs when estimating total actual cost. In some
3.2.5 Free spinning pad drivers are cases, a diamond abrasive may cut too fast for
relatively new to the industry. The main drive the task. Keeping both types of abrasive in
plate is aluminum and fits onto the arbor of the inventory is the solution that works best for
machine. It is surrounded by a second plate, most companies. Either abrasive can be used
which acts as a shell, and is isolated by a bearing for the full range of refinishing or restoration
in between the two. When the outside plate tasks. These abrasives are available in many
hits glass, metal, or any other delicate surface, varieties as outlined in the following sections.
it stops spinning, but allows the inner drive
plate with the abrasive attached to keep 4.3 Bricks. 14 cm (5½”) bricks are used
spinning. These are convenient in showers and in a sweeping rotary motion instead of a
when working around metal and glass edges, straight rotary motion. Because of the
since they minimize potential damage to compound movement and features of most
adjacent materials. floor machines, 14 cm (5½”) abrasives are not
used for refinishing and restoration. The most
common abrasive bricks for stone refinishing
4.0 ABRASIVES and restoration are frankfurt segments.
Frankfurt segments are a wedge-style brick
4.1 Abrasives are used to grind, designed to fit in to a wedge-shape shoe or
hone, and polish stone for the purpose opening connected to a drive plate. Frankfurt
of restoring or refinishing. As stone bricks, often referred to as frankfurt segments,
wears, it become necessary to remove light or are available in multiple abrasive types and
deep scratches, fill in voids or cracks with a bonds.

© 2022 Natural Stone Institute Equipment• Page 21-29

4.3.1 Frankfurt does not relate to a process to the end and complete the final
specific bond, but describes the shape preparation for the polishing step.
and size of an abrasive type. The abrasives
are attached to the drive plate by wedging them 4.3.4 Hard synthetic bond frankfurt
into a holder (sometimes referred to as a shoe). segments are very hard and can be used on
It is a widely recognized abrasive used on the concrete, granite, quartz, and quartzite
more traditional style grinding machines and surfaces. This abrasive bond is typically used
slab polishers from Europe. Frankfurt abrasives after regular synthetic abrasives and continued
are typically used on flat floors or terrazzo to the end of surface preparation, or for hard
only, and are generally not used on tile floors materials only. Using a hard synthetic bond
with lippage present. Some designs allow the frankfurt segment will produce clarity that is
abrasive to grind lippage flat. The brick-style ready for polishing.
frankfurt segments are inexpensive and wear
out quickly but provide phenomenal results. 4.3.5 Polishing and cleaning brick. The
Onsite results with these segments is very close polishing (or cleaning) step is essentially an
to that of the factory process. Because of their MTL (marble/limestone/travertine) polishing
rigid design, there is absolutely no flexibility powder product compressed into a brick.
with these abrasives. This design ensures a high There are usually two products and steps
quality finished product. The floor machines involved. The final frankfurt segment is usually
designed for these frankfurt segments usually made of pure oxalic acid. Many stone
are more complicated to operate than more processing factories use oxalic acid during the
commonly found floor machines. final polishing step. When viewing MTL slabs
in direct sunlight, faint swirl scratches can
4.3.2 Magnesite bond frankfurt sometimes be detected. The swirl marks are a
segments are typically used after sintered result of the final step being performed with a
metal abrasives. They are structurally unstable fixed abrasive and not a polishing powder.
and can break easily. The instability of this
abrasive bond is two-fold. First, they are a 4.4 Plugs are often referred to as terrazzo
poured brick abrasive, so dropping them will plugs because they are commonly used during
usually result in chipping or breaking. Second, the initial grinding process for terrazzo. The
sometimes the mixture is not properly plugs are held in place using specially designed
prepared, and the abrasives can shatter with the drive plates. Terrazzo plugs are usually made as
temperature change caused by getting them a sintered metal bond diamond abrasive.
wet. Magnesite abrasive bricks, whether
frankfurt or another type, wear down very 4.5 Abrasive pads are commonly
quickly compared to other bonds. They are referred to as discs or wheels because of their
effective in removing heavy scratches from the circular shape. Square or rectangular pads are
lippage removal abrasives and leave a nice finish also available for sanding blocks and orbital
for the next step. style sanders. The most common shape is
round, and the most common sizes are 3, 4 and
4.3.3 Synthetic bond frankfurt 5-inch (75, 100, and 125 mm). Pads are
segments are similar to magnesite bond available in multiple bonds using diamond or
segments, but made from synthetic material. silicon carbide as the abrasive type. Different
This makes them similar to resin bond manufacturers attempt to gain customer
abrasives. Synthetic bond abrasives can break loyalty by using unique features like innovative
fairly easily, but not as easily as magnesite bonds, grit size, segment design, tapered edges
bond. Using more forgiving raw materials and others. A sintered metal bond abrasive
creates the increased stability over magnesite. used for more aggressive cutting is normally
When finishing MTL floors and terrazzo, the referred to as a lippage removal pad. These
synthetic tools will usually carry the finishing aggressive discs are typically mechanically

Page 21-30 • Equipment © 2022 Natural Stone Institute

attached directly to the tool or drive plate floor without leaving scratches or trailing
machines and handheld polishers. If using a marks
handheld polisher to complete the outer edges
of the floor near the walls, then a cup wheel 4.5.2.2 Cons of synthetic fiber pads.
would be used. A cup wheel is the handheld • Cannot provide a flat for when used as
equivalent to lippage discs for floor machines. a set (tend to texture the stone)
For lighter pads, the hook and loop system • Will not remove moderate to heavy
usually works well and helps to speed up the scratches
process of changing grits. Pads are the most
• Can get damaged easily on stone tiles
common abrasive variety.
with heavy lippage
4.5.1 Fiber pads are not typically used for
4.5.3 Dot pads. “Dot pad” is a generic
heavy grinding: only for honing and polishing.
name given to a certain type of fiber abrasive
They are circular in shape, but the sizes used
pad. These utilize a 17” (430 mm) synthetic
are typically much larger than the small 3, 4 or
fiber pad like described above but there are
5-inch (75, 100, and 125 mm) abrasive pads
resin dots or diamond abrasive embedded resin
mentioned earlier. Fiber pads are woven, and
sections permanently affixed to them. This
some manufacturers use this weave to hold or
variety has an advantage over the plain
suspend abrasive powders. Other
synthetic fiber pads because they contain hard
manufacturers will lightly bond the woven pad
resin dots, which allows them to work more
with abrasives. A major advantage of fiber pads
quickly and provide a superior finish.
is that they will conform to low areas of the
floor to abrade the entire floor. This is one of
4.5.3.1 Pros of dot pads.
the most common varieties for refinishing.
• Work quickly; provide a similar finish
4.5.2 Synthetic fiber pads are synthetic to traditional resin diamond pads
buffing pads that have abrasive grit • Easy to work with
incorporated into the pad. During the • Flexible and easy to navigate through
manufacturing process, these pads are sprayed lippage and other uneven areas
with an abrasive impregnated liquid • Does not need to be protected as much
compound. This process allows the mixture to as other synthetic fiber pads
penetrate deep within the fibers of the pad. The
result is abrasive content throughout the pad, 4.5.3.2 Cons of dot pads.
which extends the service life of the pad. The • Expensive when compared to
abrasive life of these pads is similar to that of a traditional diamond abrasive pads
thick resin diamond. When not in use, they
• Fiber pad can get damaged before
should be stored properly to protect them
using the entire life of the pad
from contamination from dirt or other foreign
matter.
4.6 Abrasive bonds. The bond used for
the abrasive can vary based on the abrasive
4.5.2.1 Pros of synthetic fiber pads.
type, grit, and task being performed. The bond
• Cost effective holds the abrasive in place until it is used up.
• Easy to use Depending on the task at hand and desired
• Very flexible; allows the abrasive to finish, different types of abrasives and bonds
get in and out of low areas and lippage may be used. If the task is to remove heavy
• Work quickly material stock, then a more durable bond and
• Can achieve multiple levels of honed coarser abrasive is desired. If the task is to
finishes, and in some cases, polishes, simply clean the surface, then a lighter bond
and finer abrasive is desired. There are many

© 2022 Natural Stone Institute Equipment• Page 21-31

different sizes, shapes, and prices for abrasives. pads will allow them to act as shock absorbers
With experience, each technician will develop and ride up over the uneven tiles.
a preference for different tasks.
4.6.1.3 Flexible abrasive pads are the type
4.6.1 Resin bond abrasives are by far the most commonly used in stone fabrication
most commonly used and most widely shops, in 3” to 5” (75 to 125 mm) diameter.
recognized type. They are available in several These are used on handheld machines to polish
shapes and sizes. Resin bond abrasives can start edges and tops of counters and other stone
as low as 30-grit and go as high as 8,500-grit. applications. Their flexibility allows the
This type is most commonly used for light fabricator to avoid angling off a convex edge
refinishing to remove minor scratches, etch detail. A few companies make these in 3” (75
marks and to prepare for a honed or polished mm) diameter, which can be used on a floor
finish. Resin abrasives are produced in bonds machine. Foam risers almost always
specific for different stones and hardness. The accompany this type of abrasive. The risers are
general rule is that a soft resin is used for hard very forgiving; almost spongy. They attach
stones and a hard resin is used for soft stones. directly to the drive plate, and the abrasive
If a soft-bonded granite resin abrasive is used pads attach to the riser, adding flexibility. This
on marble, it will wear at an accelerated rate. setup is used on floors with light to moderate
The same scenario applies for using marble lippage. The weight of the machine will
abrasives on granite. The resin needs to wear at compress the riser, allowing the edge of the
the correct ratio in order to allow exposure to pad to flex or curl slightly. This setup ensures
the diamond abrasive without causing the resin that the abrasive reaches the low areas of the
to form a coating over the abrasive. Soft stone uneven tiles and help to eliminate picture
attacks the soft bond in the abrasives, causing framing.1
the bond to wear faster and lose diamond or
abrasive particles. Resin bond abrasives come 4.6.2 Marble bond resin diamond
in rigid, semi‐flexible, and flexible variations. abrasive pads are designed specifically to be
used on MTL surfaces. Marble abrasive pads
4.6.1.1 Rigid, puck style abrasives are can be used on these floor types, although some
usually used for flat floors. This type is also manufacturers produce pads specifically for
used after a floor has been ground flat, like in each type. As mentioned previously in this
lippage removal. The rigid style will limit the chapter, a hard resin is more effective for soft
amount of fluctuation in the flat appearance of stones like MTLs. Although not usually
the finished product by not allowing the tools recommended, marble abrasives can also be
to flex and dig into the stone. used for concrete polishing. Many marble bond
abrasives will work quite well and provide
4.6.1.2 Semi-flexible. For stone refinishing reasonable service life when used on
and restoration, semi‐flexible abrasive pads are residential‐type concrete. Other abrasives
the most common flexible abrasives. Thick or suited for concrete will be discussed
thin, they all share a layer of foam or neoprene throughout this chapter.
between the actual pad and the Velcro surface.
This allows for some rigidity, but also some 4.6.3 Granite bond resin diamond
bend if the diamonds hit a sharp edge or uneven abrasive pads are designed to achieve the
surface. If the flexibility is not there, the resin highest possible clarity before the final
segments can break off. This type can be used polishing step. Granite is very hard compared
on anything from a perfectly flat floor to a floor to MTL stones, so time becomes a factor. The
with moderate lippage. The flexibility of these higher quality the granite resin pad, the faster

1“Picture framing” is a term used in the stone tile are not abraded when working on a floor that is not
restoration industry meaning that the low section of a completely flat.
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you will get to the polishing step. Also, the way up to 1200-grit. The bond can greatly
better quality finish the resin pads achieve, the affect the finish. A metal bond 200-grit abrasive
less work is needed on the final polishing step. is much more aggressive than a resin bond 200-
Due to the methods by which they are grit abrasive. To remove the scratch pattern of
produced, higher quality abrasives will a metal bond abrasive quickly, it is necessary to
typically result in a premium price. use a much lower grit resin bond abrasive.

4.6.4 Phenolic bond resin diamond 4.6.7 Sintered bond. Sintering is one of
abrasive pads are used to withstand heat and the most commonly used methods for
friction. These abrasives are usually used for assembling diamond abrasives in our industry.
dry honing and polishing. Because of the heat Bridge saw blades and most grinder blades use
generated from the friction during this process, a sintered metal bond. When inspected closely,
the resin was designed to withstand the small diamond segments protruding from the
temperature without burning or glazing over. metal surface can be seen, often with
Most other abrasive bonds are damaged when directional streaks trailing them. These appear
exposed to the same conditions. Phenolic almost like a comet and a tail. Sintering
resins are made mostly for concrete and are assembles abrasives in a manner that holds the
classified as a resin or a resin‐hybrid pad. diamonds within the body of the segment. As
the abrasive or segment is used, the metal
4.6.5 Hybrid bond diamond abrasive wears away, exposing new edges of the
pads are relatively new. These utilize a diamonds. This can be compared to a self-
traditional resin mixed with a soft metal like sharpening blade. However, if the metal used
copper to create a pad that is extremely for the bond and the stone are not compatible,
effective and forgiving. They are designed to the metal will glaze over the diamond. It will
remove material quickly and leave a smooth essentially cover the diamond and slow down
finish, so the next finer grit is easier the process until it can be dressed to expose the
transitioned. Hybrid pads can be used as diamond or cutting abrasive. This bond type is
transition pads when working your way out of designed for rapid removal of stone. It will
the metal grinding stages into the resin honing leave moderate to heavy scratches compared to
stage. Hybrid bond abrasives will remove the other bonds. The most common application in
heavy scratches of the metal lippage discs and the restoration industry for this bond is for
leave a finish smooth enough to be picked up lippage removal. Because of the materials used
by the next resin step. They are a very helpful to make the sintered discs, they are the usually
addition to the toolbox. the most expensive, but also have the longest
life span. Terrazzo plugs are made of sintered
4.6.6 Metal bond diamond abrasives segments.
are heavy duty and used for coarse or initial
grinding, also referred to as lippage or severe 4.6.8 Copper bond. Copper diamond
damage removal. They do the most work, take abrasive pads are also sintered, but significantly
the most abuse, and produce the quickest different. They are made with a softer lighter
results. Metal bond abrasives are mainly used copper material as opposed to the heavier
for removing heavy scratches. They can also be metal that is used for standard sintered tools.
used to remove chemical damage on terrazzo This bond is not recommended for the initial
and concrete, remove lippage from uneven step in lippage removal because it will wear
tiles, or remove a sizable amount of material. down very quickly and will not cut as fast. The
There are several different types of metal copper bond was developed as a transitional
bonds that serve different purposes. Some of bond to bridge the gap between metal and resin
these are as thin as 1 mm (0.040”) and are bonds. They offer the best of both worlds:
available up to 12 mm (½”). Metal bond heavy scratch removal while leaving a smooth
abrasives can start as low as 6-grit and go all the finish to facilitate the transition into the resin

© 2022 Natural Stone Institute Equipment• Page 21-33

steps. Copper bonds work well for cleaning up 5.0 POLISHING COMPOUNDS
traffic worn or chemically damaged surfaces to
prepare for refinishing. Copper bond discs are 5.1 Marble polishing powders have
a “must‐have” for the toolbox. revolutionized the refinishing and restoration
industry by increasing production and
4.6.9 Vacuum brazed diamond improving quality. There are so many marble
abrasives are the most aggressive metals used polishing powders on the market today it can
for floor refinishing. This type of bond abrasive be difficult to distinguish individual products.
will cut very fast and leave heavy scratch There are “hot” powders, “cold” powders, and
marks. Unlike sintered diamond bonds, many in between. For the purpose of this
vacuum brazed abrasives are attached to the discussion, “hot” or “cold” refers not to
outermost surface, exposing all the diamonds temperature, but to acid content. Acids found
on the face. This bond does not have the life in marble polishing powders vary, but a hot
span of sintered metals, but is less expensive. powder contains a higher percentage of acid.
When the goal is to remove material as fast as These tend to polish more quickly, but the
possible, vacuum brazed is the normally the technician risks over-use, which can result in a
best choice. Because of their aggressive nature, poor finish. Overuse of hot powders will result
they are not typically used on MTLs. Vacuum in an orange peel look on the stone. Cold
brazed diamonds are much thinner and lighter powders have a lower acid content and take a
than sintered discs and will most likely have a little more time to work, but they provide
convex shape to the face to allow for a smooth better protection against overuse. Most
transition over uneven tiles. polishing powders on the market work to some
extent on most marbles. However, some
4.6.10 Electroplated bonds are similar to marble will react differently and require the
vacuum brazed bond abrasives in appearance. use of a different mix of acids. Each technician
These bonds are easily mistaken for each other. will develop the sense of what mixture is
Electroplating is a coating, while vacuum needed.
brazing is a type of weld attachment.
Electroplated diamonds are the thinnest in the 5.1.1 Types of marble polishing
metal group at 1 to 2mm thick (0.040 to powders
0.080”). The diamonds appear to be on the
surface like brazed metals, but are attached 5.1.1.1 Wet polishing powders are
through a different process. Electroplated designed to be used with water. Water is added
bond abrasives are the least expensive of the and worked into an area to generate a slurry.
metal group and also have the shortest lifespan. The polishing process is completed while the
Similar to vacuum brazed abrasives, mixture is still wet, then the slurry is removed
electroplated abrasives are extremely with a wet vacuum.
aggressive, but leave a much smoother finish
when compared grit‐to‐grit. They can be used 5.1.1.2 Wet-to-dry polishing powders
for quick repairs of heavily damaged material are usually very “hot,” meaning that they
or as a transitional grit between sintered and contain a lot of acid and work very quickly.
resin abrasives. These abrasives can be used Using this type of polishing powder means that
wet or dry, and excel on MTL stones. It is also the process is started either in a wet slurry, or
possible to use them on concrete. However, with just a mist of water and worked until
electroplated bond abrasives do not hold up completely dry. The technician will get a feel
through use on harder stones, such as granite. for how much water is needed through
experience. It is better to achieve the polish in
stages than to risk over-polishing the stone and
resulting in an orange peel appearance. Using
wet-to-dry powders eliminates the need to

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vacuum after polishing each section. This down more for sensitive stones. Using too
process requires the use of more heavy-duty much powder and not enough water will
machinery, because of the significant friction damage the stone’s finish.
produced during their use.
5.1.3.2 Type of pad. The two major types of
5.1.2 Ingredients for marble polishing pads are white nylon polishing pads and hog’s
powders. MTLs are calcium-carbonate based hair polishing pads.
stones that react to most acids. Every marble
polishing powder includes an acid and an 5.1.3.2.1 White nylon polishing pads
abrasive, along with other proprietary are dense and soft to the touch, with multiple
ingredients. fibers intertwined into the same area. Due to
their density, they tend to hold more of the
5.1.2.1 Oxalic acid breaks down the surface polishing compound on the immediate surface.
of the stone to allow the abrasives to do the This allows the compound to do all the work.
work. It activates when water is added. There are pros and cons of this, depending on
what type of stone is being worked on and what
5.1.2.2 Shellac is a type of resin that naturally type of equipment is being used.
occurs on trees. It is pulverized into a powder
and added to the compound. The heat created 5.1.3.2.2 Hog’s hair polishing pads are
by the friction from the polishing process melts much coarser and less dense than white nylon
the resin and deposits it into the micro-pores of polishing pads. The fibers are a mix of natural
the stone. It hardens immediately after cooling boar and synthetic. The fibers are thicker and
and helps give the floor a more uniform look the pad is less dense. Due to the lack of density,
and increases gloss. more of the polish is absorbed by the pad,
Shellac is not often used in more recent leaving less on the contact surface. This adds a
powders to enter the market. new dimension to the polishing process.

5.1.2.3 Aluminum oxide is a 5.1.3.3 The amount of weight needed

manufactured, inert powder. It is a pure depends on the material more than the
abrasive and is used to achieve final polish. It is powder. Some materials “burn” easier than
considered a super fine grit, although it is others. It is very similar to polishing
unclear just how fine it is, and works to smooth automotive paint. The harder you push, the
out the surface of the stone while it is in a more friction is generated. Friction translates
vulnerable state from the oxalic acid. to heat and can orange peel—leaving a
Aluminum oxide is harder than granite. textured look to the finish. The experienced
technician will get a feeling for when adding
5.1.3 Characteristics of polishing weight is needed.
powders. Polishing powders vary
significantly among products. The amount of 5.1.3.4 Speed has essentially the same effect
water and pads used, speed and weight of the as weight. More speed equals more friction,
machine (including weights added), and how which in turn makes more heat. Increased
long each section is polished all have an impact speed also makes more mess, causing the slurry
on the final polish. to travel further.

5.1.3.1 The amount of water used can 5.1.3.5 Time. How long each section is
make the biggest difference when polishing. worked with a polishing powder can have a
Using less water creates a more concentrated, very big impact on the quality of the final
or potent, powder. Using more water will polish. On marble, working a section too long
dilute the powder, making it less effective. with an acidic polishing powder can cause
“Hotter” (more acidic) powders can be diluted orange peel or etching. It is better to perform

© 2022 Natural Stone Institute Equipment• Page 21-35

this task in stages until the technician is familiar is loose, as opposed to a fixed abrasive, it leaves
with the reaction between the polishing no detectable swirls or tool marks.
powder and the marble. For granite, the
overuse of polishing powders is not usually a
problem, although it can leave the stone hazy 6.0 ADDITIONAL TOOLS AND
or dull. SUPPLIES
5.2 Polishing pastes are usually 6.1 Miscellaneous honing/polishing
polishing powders in a paste form. They are pads used with compounds and
already “active,” containing their own liquid. powders. Steel wool pads are used mostly
Water can be added if the paste dries out or if when crystallizing. Champagne pads are used
a more diluted slurry is desired. Pastes are for honing and/or polishing. Black pads are
generally grittier than powders. The grit or used for stripping coatings. Tampico brushes
chunks that can be seen and felt are oxalic acid are used for polishing.
chunks. These get absorbed into the polishing
pad and act to further polish the material. 6.2 Cleaners
Although it may feel like the paste will scratch
the stone, it has no effect on the finished 6.2.1 Neutral cleaners have a pH of 7.
product. Oxalic acid is water-soluble and They are neither acidic nor alkaline. Neutral
slowly dissolves while being used. cleaners are used for light washing, rinsing,
cleaning and neutralizing after polishing or
5.3 Liquid polishes, also known as using an acid based cleaner. Homeowners are
crystallizers, are misted on the surface and advised to use these.
buffed with a mono-rotary machine with heavy
weight and a steel wool pad until dry. The 6.2.2 Alkaline cleaners are at the top of
liquid provides a chemical bond with the stone. the pH scale, with a pH typically between 12
The steel wool heats up the liquid and surface and 14, depending on the manufacturer.
and allows it to harden as it fills in the scratches Cleaners with a pH between 13 and 14 pH can
and pores of the stone. This process is used damage polished MTL floors if not correctly
mostly in commercial maintenance settings, diluted. This type of cleaner is usually used as a
although it is not designed to be a maintenance degreaser or to clean heavily soiled floors and
product. Liquid polishes work differently than grout. Alkaline cleaners are generally good at
polishing powders and pastes. Polishing breaking down soap scum and weak waxes.
powders and pastes usually contain a fine They can also be used to neutralize acidic
abrasive and a mild acid which do not coat the cleaners.
material but act more like a super fine abrasive
to enhance the reflective finish of the stone. 6.2.3 Acidic cleaners are only used on
natural stone when absolutely necessary and
5.4 Honing powders can be used either should be avoided inside the home if possible.
for minor damage removal or finishing. Most Most acidic cleaners usually have a pH between
honing powders are between 120 and 800 grit, 4 and 2, depending on the acid used. The most
depending on the manufacturer. Honing common acids used are phosphoric,
powders are made from aluminum oxide. hydrochloric and sulfuric. These cleaners are
These powders are used with water to create a usually used for removing mineral and hard
slurry and are used to put a final honed finish water deposits, cleaning excessively dirty
on almost any material. Usually the stone will grout, and removing rust stains. Only use
be refinished or the polish will be broken with acidic cleaners when other options have been
diamond abrasives, then the honing powder exhausted.
will be used as a final step. Because the powder

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6.3 Wet/dry vacuums perform a very
necessary function. It would be difficult to
refinish or restore stone without the ability to
remove the dirt and debris or slurry created
that could interfere with honing and polishing.

6.4 Antiquing Brushes. Antique

finishes have become popular in recent years.
The brushes used to achieve this finish come in
several configurations. Antique finishes are
usually presented in a matte or non-reflective
range. When a more reflective finish is desired,
each progressive grit will not reach as far into
the lower areas of the stone. This results in
only the highest points of the stone having a
shine, giving it an antiqued or worn look.

6.4.1 Diamond wire brushes are by far

the most aggressive. These brushes are made of
relatively thick, hard bristles impregnated with
diamond abrasives. Diamond wire brushes
usually start at 36-grit and go up to 600-grit.
They are usually used to remove the polish
from granite and give it the initial antiqued or
textured finish.

6.4.2 Rubber bristle brushes are

produced featuring several different
thicknesses and layers of bristles. There are
different bristles and features designed for
different grits. Lower grits will typically have
very thin, concentrated bristles, typically used
to reach the softer, lower textured areas of the
stone. Most grits feature thicker, stiffer rubber
bristles designed to reach most areas, but not
the lowest sections of the stone. Higher grits
feature larger, wider rubber bristles designed
to skim across only the top sections of the
texture. The larger, wider bristles are designed
to put a shine on the peaks of the texture.

6.4.3 Carbide bristle brushes are made

using silicon carbide abrasives. Thin, wiry
bristles are impregnated with the abrasive.
Carbide bristle brushes can be used for
antiquing, light texturing, or just for scrubbing
rough surfaces.

© 2022 Natural Stone Institute Equipment• Page 21-37

NOTES:

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Restoration and 2.0 PRODUCTS AND SUPPLIES
Maintenance – 2.1 Adhesives and Patching
Materials. Before beginning the discussion of
REPAIRS techniques, patching material selection will be
discussed. No matter how good a repair looks
1.0 INTRODUCTION cosmetically, if the wrong material was used it
will not perform and must be redone. The
1.1 Repairing stone is a normal part of most reliable product must be used to ensure
restoration. Many stones, especially very the longevity of the repair.
decorative varieties, have natural voids and
weaknesses. Filling these voids and reinforcing 2.1.1 Adhesives and patching materials are
these weaknesses is normally started early in used to adhere broken pieces back together
the processing phase at the factory level. The (also known as “sticking”), fill pits or voids
material is quarried in a block form; it is then (either natural or created by movement) and
transported to a factory for processing into reinforce weaker areas of the stone. The
useable products such as slabs or tile. After materials that are most common in the stone
cutting these blocks into slabs, many materials industry are polyester, acrylic, epoxy,
are filled, repaired, or reinforced using a urethane and cyanoacrylate (also known as
variety of methods. Once the initial repair or “CA”).
reinforcement is done, the product is ground
down to start the finishing process. After the 2.1.2 Most of these materials are available in
initial grinding step, it is sometimes necessary different viscosities for different applications.
to touch up the repair before proceeding to When trying to penetrate micro-fissures, the
finalize the desired finish for the stone. least viscous or thinnest product would be
selected for this task. Many manufacturers
1.2 Many installers will cull pieces from refer to this as a “penetrant” or “super
the lot during installation. In some cases, the penetrant.” For sticking loose pieces of stone
quantity ordered is insufficient if extensive together, a slightly thicker product would
culling is required. The bid process can be very typically be used. This product is often referred
competitive, so extra pieces are a luxury that to as “flowing.” Filling holes and voids would
cannot always be afforded in order to win the require thickest product. Most manufacturers
bid. After installation, the existing repairs may call this a “knife grade.” Many of the products
need to be retouched. Often, the processing are two-part. Part one is typically referred to
factory performs a generic repair that may as the adhesive or resin and part two is typically
work in some areas of the stone but is very referred to as the catalyst, hardener or curing
noticeable in other areas. The factory doesn’t agent. One product category requires no
always know the intended application of the curing agent because the curing process is
product when they are producing it, so activated by exposure to air. Each product
sometimes an inappropriate patching material category will be discussed in further detail
is used (for example a polyester resin when the throughout the section.
material will be used for an exterior
application). In that case, the patch needs to be 2.2 Colors and tints can be added to
removed and replaced with a more suitable adhesives and patching materials to provide a
patching material. Other times repairs need to better cosmetic blend between the repair and
be made due to everyday use, faulty installation the surrounding stone. Follow the
products or methods, structure settlement or manufacturer’s recommendation for use.
movement, and occasionally abuse or failure to Generally, if the missing sections of stone can
maintain. Post-installation repairs will be the be adhered back in to place, it will be a better
primary focus of this section.

© 2022 Natural Stone Institute Repairs • Page 21-39

repair than if patching material is substituted 3.0 CHARACTERISTICS OF
for the missing stone. ADHESIVES AND PATCHING
MATERIALS
2.3 The basics of adhesives and patching
materials are the same. One main difference is 3.1 Similar characteristics exist among the
that most fast curing two-part products are available adhesives and patching materials,
mixed with colors or tints before the curing although each variety has some distinct features
agent is added. Resin and curing agent for which are described below.
slower curing two-part products are often
mixed together before the color is added. 3.2 Polyesters.
There can be differences even within adhesive
categories because different manufacturers 3.2.1 Polyesters resins are, at this time, the
may use different ingredients to provide unique most popular patching material used in the
benefits. It is very important in any two-part stone industry. Some of the reasons for this
product to mix the products according to the popularity are assumed to be modest cost,
manufacturer’s instructions. rapid cure time, bond strength and familiarity
in working with the material.
2.3.1 CA glue. There is only one product
listed below that is not categorized as a two- 3.2.2 Polyester based adhesives are fast
part adhesive or patching material. It is curing, two-part products, so colors or tints
commonly known in the industry as CA glue or can be added to the resin before the hardener
cyanoacrylate. This product can be used with to achieve a visually better repair.
an accelerating agent. The use of accelerators
can expedite the already fast curing time. If 3.2.3 Using more catalyst can accelerate the
using an accelerator, do not use an excessive cure rate, but there is a risk of a weaker and
amount on lightly colored stones. Overuse of more brittle bond. The manufacturer’s
accelerators is a common cause of staining in instructions for mixing should be followed
these stones. Accelerators are not necessary closely for best performance.
for the adhesive to cure. It is important to be
familiar with the products before using 3.2.4 Polyester adhesives are commonly
something that may cause additional problems. used in countertop seams because movement
usually results only in a failure in the adhesive
2.3.2 Volatile Organic Compounds without damage to the stone.
(VOCs) can have a big impact on the selection
of the material to be used for a repair. VOCs 3.2.5 Polyester resin can be sanded and
are typically measured in two main ways. polished to a reasonably high shine, allowing it
VOCs as supplied is the measurement right out to better blend with polished stone.
of the container. This value is typically higher
because of the product concentration in the 3.3 Acrylics.
container. VOCs as applied is the
measurement upon activation of the product. 3.3.1 Acrylics became popular for use as
Once the product is activated the VOCs get penetrants and are considered among the least
consumed and there are fewer emitted in to the viscous among the categories. Penetrants are
air. For projects requiring VOCs below a commonly used to penetrate micro-fissures or
certain value it is important to know which very minute openings. Fissures are natural
VOC value is being referenced and how the separations in stone and are very common
measurement should be taken. Be sure to among the most decorative varieties of natural
allow for proper ventilation and use the correct stone. The next feature that helped this
Personal Protective Equipment (PPE) while category gain popularity was the availability as
using adhesives or patching materials.

Page 21-40 • Repairs © 2022 Natural Stone Institute

a “water-clear” product. Many repairs are 3.5 Urethane.
made better when the repair is “water-clear.”
3.5.1 Urethane adhesives are the newest
3.3.2 Curing agents are typically used on class of stone adhesives. The price of this
acrylics, and are usually liquid. This is done to category is relatively high. Urethane was
keep the product clearer and less viscous. developed to fill the gaps of the other product
categories. Urethane has excellent clarity and
3.3.3 Acrylics can be sanded and polished to its bond strength is close to the strength of
a reasonably high shine, allowing it to better epoxies.
blend with polished stone.
3.5.2 Urethane is a slow cure, two-part
3.4 Epoxy. adhesives. Using an accelerator can speed up
the cure rate without the risk of a weaker or
3.4.1 Epoxies became popular because of more brittle bond. Follow the manufacturer’s
their superior bond strength when compared instructions for mixing for best performance.
to other adhesives categories. Many people
hesitate to use epoxies in some situations 3.5.3 Urethane is used for many projects,
because of their lengthy cure time and including patching or filling voids in stone and
increased cost. Epoxy is most associated for bonding pieces of stone together. Urethane is
causing stains when used with white marble. also used as a caulk-like material for expansion
Epoxies are most commonly mixed with other joints and exterior joints.
categories to make hybrid adhesives.
3.5.4 The stone must be dry before using
3.4.2 Staining can be a problem when using urethane adhesives, but this product can
epoxy with white marble or other light colored withstand exposure to moisture after curing.
porous stone. Be careful to test any adhesive
for use with light colored marble, limestone 3.5.5 The mixing ratio and thorough mixing
and granite. are both critical to ensure complete
polymerization when using urethanes.
3.4.3 UV exposure can attack the look of
epoxies, but the strength of bond is relatively 3.6 Cyanoacrylate (CA) glues.
unaffected. This makes it one of the few
products that can be suitable for exterior 3.6.1 CA glues are gaining popularity in the
applications. stone industry because of the different
viscosities available and the rapid cure time.
3.4.4 The high strength and ductile CA glues are typically sold in small units
properties of epoxy make it the preferred because of their relatively short shelf life. They
adhesive for use in structurally significant are often used to fill voids and micro-fissures.
roles. Because it is a fast curing product that rapidly
cures when exposed to air, most professionals
3.4.5 The curing of an epoxy is an tint the stone prior to applying CA glue.
exothermic chemical reaction, meaning it 3.6.2 CA glue should not be used to bond
produces heat. Because of this, repairs pieces of stone together. CA glues do not bond
requiring large amounts of adhesive may have as well as other categories.
to be done in steps to prevent excessive heat
generation. 3.6.3 The use of an accelerator can cause
staining if overused on lighter, more absorbent
3.4.6 Epoxies are available in multiple stones.
viscosities: from penetrants to knife grade.

© 2022 Natural Stone Institute Repairs • Page 21-41

3.6.4 CA glues are ideal for quick and easy remain like a hard rubber, to allow for
repairs. They are suitable for UV exposure and expansion and contraction.
outdoor environments. They can also be used
for seams in countertops because movement 3.8.4 For adhesives that require very
usually results only in a failure in the adhesive accurate mixing ratios, most manufacturers
and less damage to the stone. will list the required component ratio both by
volume and by weight (mass). Accurate digital
3.7 Hybrids. scales can be readily obtained at a modest cost,
and it is recommended to measure these
3.7.1 Hybrids have been developed by many components by weight (mass) as this method is
adhesive manufacturers in an attempt to reduce more accurate than measurement by volume.
the price of some adhesives and expand the
benefits of others. A polyester/epoxy hybrid, 3.8.5 In the table at the end of this section,
referred to as a poly/epoxy, is the most each product category is compared by its
popular hybrid. typical features. These features are listed at the
top of the chart and the product categories are
3.7.2 Poly/epoxy hybrids have a stronger listed in the far left.
bond than polyester adhesives. The cure time
is shortened when compared to epoxy
adhesives. As with polyesters, the cure time of 4.0 COLORS AND TINTS
poly/epoxy hybrids can be adjusted.
4.1 Coloring powders, pastes, and liquids
3.7.3 Poly/epoxy hybrids are more flexible can be product specific, meaning there can be
than polyester adhesives. The mixing ratio is different color products made for polyester,
not as critical with poly/epoxy hybrids as it is acrylic, and hybrids than for epoxy and
with epoxy. urethanes. Some tints are more UV sensitive
than others. Check with the manufacturer to be
3.7.4 Structural movement usually causes sure the right tint for the adhesive and
failure in the adhesive, so poly/epoxy hybrids application is used.
are considered suitable for countertop seams.
They are also used for countertop laminations, 4.2 When the right color is chosen, a
mitered drop edges, and rodding or doweling. repair will be visually undetectable. It takes
practice and patience to find the right color.
3.8 General notes about adhesives For some materials, like white marbles, it is
and patching materials. better to have a semi-translucent mixture with
just a hint of the correct shade of white. For
3.8.1 Polyester, acrylic, and poly/epoxy other materials, a water-clear mixture works
require less hardener (usually in a ratio of 1% best. Attention should be paid to the specific
to 4% hardener by volume) or curing agent shade in the area of needed repair. The color
than epoxy. The typical mixing ratio for epoxy should be tested on a small area of the stone to
is either 2 to1 or 1 to1 resin to curing agent. analyze the color match. If the patching
3.8.2 Polyester, acrylic, and some hybrids material is a fast cure adhesive, the curing agent
can typically share coloring systems. Epoxies should not be added until the color is finalized.
and urethanes usually require their own Sometimes the curing agent will change the
specific coloring systems depending on the color, so it is important to anticipate that and
manufacturer. adjust for it. If the patching material is a slow
cure adhesive, then there is usually time to
3.8.3 Urethanes are unique from the rest of make adjustments. For multi-colored
the adhesive categories. Many do not cure into materials, it may be necessary to use multiple
a hard, polishable surface. Typically urethanes shades and to repair in sections.

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4.3 Translucent stones, such as onyx, will 5.8 Grinding, honing, and polishing
oftentimes be difficult or impossible to patch tools are die grinders, right angle
with perfect cosmetic results. This is due to the grinders/polishers, diamond blades/grinding
difference in light transmission within the stone wheels, diamond bits, masonry bits, 3, 4, and
fabric versus that of the patch. 5-inch pad drivers (also known as backer pads),
sandpaper (typically silicon carbide), and other
abrasives (including antiquing brushes for
5.0 TOOLS textured finishes).

5.1 Tools used for repairs may vary

slightly, depending on the personal preferences 6.0 REPAIRS
of the technician. Despite this, the uses are
universal. 6.1 Inspection. Performing a thorough
inspection during the diagnostic phase of a
5.2 Personal Protective Equipment project will allow the technician to discover
(PPE). This includes gloves, vapor masks, dust which repairs are necessary to help prevent
masks, goggles, and other equipment as further deterioration of the stone. Many times
recommended by the adhesive, abrasive, or the repairs will be natural voids or previous
tool manufacturer. repairs that just need a touch up. Occasionally,
repairs will be necessary because of structural
5.3 Cleaning tools include vacuums, movement or some other form of failure.
acetone, denatured alcohol, stone soap,
intensive cleaners, razor blades, super fine 6.2 Types of Damage. It is helpful to
steel wool, soft bristle brushes, rags, determine what caused the damage so that
compressed air, and other items as changes can be made to help minimize the
recommended by the manufacturers. chances for reoccurrence.

5.4 Dispensing tools can be a pump, 6.2.1 Upward Crack. If one or two
measuring cup, small capacity digital scale, isolated tiles are involved, then the most
putty knife, or anything similar. probable cause is that the installer left a void
under those tiles. Foot traffic, carts and other
5.5 Mixing tools can be a paint spatula, weight place on top of the damaged tiles
putty knife, mixing stick, or anything similar. exerted enough pressure on the unsupported
Thorough mixing is necessary when adding section of the tile to cause it to crack. This is
color or curing agent to resin. the classic example of an upward crack. In an
upward crack, two sections of the tile are
5.6 Spreading devices/tools. If the broken at an angle that has its high peak at the
material is in liquid form, a spout is typically crack itself.
used for the initial application process. 6.2.2 Inward or Downward Crack.
Afterwards, a putty knife or other spreading Structural movement will typically cause
tool can be used. For thicker consistencies, a damage to multiple tiles in a line that
paint spatula, putty knife, or mixing stick will sometimes crack in an inward or downward
work. Afterwards, straight edge razor blades angle. This line can be somewhat straight or it
are mainly used to smooth out the mixture. may move to one side slightly to seek out the
weakest point of the stone. This is known in the
5.7 Finishing tools typically include industry as an inward or downward crack or
razor blades, steel wool, and chemical indent fracture. These are mostly caused by the
solvents. settlement of the floor and where the crack
itself is at the lowest point of the tile.

© 2022 Natural Stone Institute Repairs • Page 21-43

6.2.3 Outward Crack. A crack in the sub barely visible, because they only appear as an
floor, or the joint of two pieces of cementitious interruption of the light reflecting on the
backerboard under the tiles, can be either cracked tile. However, if the crack can be felt
upward, or simply a slight separation of the with the fingertips and is visible, it can
tiles called an outward crack. An outward sometimes be disguised by flattening it out. To
crack is a slight gap caused by a separation of flatten an indent fracture, use fine grit
the stone. Both pieces of the stone are typically sandpaper (such as a 220 grit) and sand the
on the same plane. hairline crack flat. Be careful not to create a dip
by keeping the angle grinder flat. If the surface
6.2.4 Chips are typically missing sections of is being polished, it can be cleaned out and
stone that is usually the result of an impact filled with penetrating adhesive to repair it and
from a dropped object. Sometimes, as a result keep it clean during the process.
of a crack that splits, small sections of the stone
will become dislodged and swept or vacuumed 7.1.4 Outward Cracks involve several
up and discarded. This creates a larger gap to tiles in a row and can be repaired. It is
be filled. important to inform the client that there is
structural movement involved, so no guarantee
can be given that it will not crack again. If the
7.0 REPAIR SUGGESTIONS crack reoccurs, a better solution would be to
install an expansion joint or a crack isolation
7.1 Crack Repair. membrane. Both of these remedies require that
the stone tile be removed in order to make the
7.1.2 For upward cracks, the first step is corrections. It is very difficult to match existing
to determine is if any of the two (or more) stone unless the client kept extra pieces from
parts of the cracked tile(s) are solid, or if they the same lot.
are slightly moving. In nearly all cases, the
grout of a tile cracked upward has separated 7.2 Chips. For the best repair, some of
and become dislodged. It must be determined the stone should be glued back in to place. If
if there is enough room between the tiles the chip was discarded and there are no extra
(grout gap) to allow grout to be fully pushed pieces of stone available, then filling the void
in. If the section of grout is not deep enough to with an adhesive, as a patching material, is
hold more grout, then more of the old grout needed. It is necessary to clean the damaged
may need to be removed. Before regrouting, area thoroughly before applying the adhesive.
check to see if either section of the broken tiles Once the patch has been made and cured the
is loose. If there is no longer a bond between grinding and honing process can begin. To
the tile and the subfloor, tapping the surface verify that the patch will blend, check the patch
will produce hollow sounds. The unbonded by wetting the area after grinding the section
area (or areas) can be fixed by injecting latex flat and before finishing the honing and
adhesive or a two-part epoxy to fill the void. polishing process.
After injecting the adhesive apply weight to the
repaired areas and allow it to cure overnight or
longer as recommended by the manufacturer.
8.0 REPAIR TECHNIQUES
It is recommended to start these repairs a
couple of days before you refinish the floor. 8.1 Preparation. The crack must first be
After the tiles are secure, regrouting can be prepared, and the appropriate filler must be
done to finish the repair. determined. Vacuums and die grinders with an
assortment of bits and blades are the most
7.1.3 Downward Cracks should not be commonly used tools for crack preparation.
repaired, because this can make them more The die grinder is used to dress up or enlarge
noticeable. Most of the time such cracks are the opening as necessary to ensure proper

Page 21-44 • Repairs © 2022 Natural Stone Institute

filling. If repairing a broken corner of a tile that 1/16” (3 or 1.5 mm)] beyond the separation on
is loose but still in place, it is best to proceed each side) on the pieces needing repair.
by removing the broken piece and cleaning the
edges of the tile and the removed piece with a 8.2.4 Mix the penetrant according to the
die grinder and abrasive bit. Afterwards, the directions supplied by the manufacturer and
corner should be dry-fitted in place to ensure add color if desired.
that it is finished at the same plane as the rest of
the stone. If it is high, continue to clean the 8.2.5 Pour and spread the adhesive into the
void until it is almost flush. If it is low, fill the crack. Allow the adhesive to penetrate the
hole where the broken piece was with color- stone. The time span necessary will depend on
matching knife grade adhesive or a mixture of the curing time of the adhesive. Allow the
knife grade and flowing adhesive. Set the adhesive to cure for the time recommended by
broken piece back into place by pushing it the manufacturer.
against the broken tile and as flush as possible
with it. It is better to leave the corner very 8.2.6 After the adhesive has cured, use a
slightly raised rather than depressed. Once the razor blade to remove the tape and any excess
repair is cured, grinding it until it is flush with adhesive from the face of the stone. If this is
the rest of the stone can flatten the corner out. done before the adhesive is fully cured, leave
the excess adhesive to allow for shrinkage.
8.1.1 The consistency of the repair
adhesive necessary will depend on the type 8.2.7 Grind, hone, and polish the stone as
of crack being repaired. For general crack necessary to complete the repair.
repairs, use knife grade adhesive and push the
adhesive into the void with a spreading tool 8.3 Fixing macro-cracks and
such as a razor blade. It is best on fast cure two- separations using flowing and knife
part adhesives to mix the adhesive with the grade adhesive.
intended colors without adding curing agent
until the client approves the mix. For 8.3.1 Consult the material’s SDS to
adhesives known to shrink, it is necessary to determine if PPE is necessary before beginning
apply excess adhesive to allow for shrinkage. repair. Begin by using a razor blade to remove
Consider the finished appearance of the loose pieces or existing fill from the crack.
adhesive before using it on honed or textured Clean all sections to be filled and allow the
materials. stone to dry thoroughly.
8.3.2 Mix adhesive according to directions
8.2 Fixing micro-cracks and supplied by the manufacturer. Add color if
separations using a penetrating desired.
adhesive.
8.3.3 Apply adhesive. Use a razor blade or
8.2.1 Before beginning repairs, consult the putty knife to smooth and remove any excess
product’s SDS to determine if PPE is necessary adhesive. Most adhesives shrink or settle as
for the task. Begin by cleaning and drying the they cure; as such, it is recommended to leave
stone thoroughly. any excess in the fill areas.

8.2.2 Use a torch to warm the stone until it 8.3.4 Allow the adhesive to cure for the time
is warm, but not hot, to the touch. Do not use recommended by the manufacturer.
a flame near acetone or other solvents.
8.3.5 Grind, hone, and polish the stone as
8.2.3 To minimize the risk of a large stain, it necessary to complete the repair.
is best to mask off the stone with tape. Leave
only a narrow opening [approximately 1/8” or

© 2022 Natural Stone Institute Repairs • Page 21-45

8.4 Finishing the Repair. noticeable. There are techniques used by many
installers to adjust the material to achieve a
8.4.1 In the case of a three-step restoration better, more finished look.
procedure (flattening, honing, and polishing),
the de-lippage tools will take care of grinding 8.6.2 Seam Setter. The most common
the glue flush with the surface of the stone. technique is to use a seam-setter. A seam setter
is a device used to draw stone pieces together
8.4.2 If performing a two-step restoration and fit them at the same plane.
procedure (honing and polishing), excess filler
should be grinded using a right-angle 8.6.3 Seam Setter + Biscuit. Another,
grinder/polisher with an 80, 120 or 220 grit less common, technique is to use a biscuit
sandpaper. The area should be sanded until the joiner in combination with a seam setter. A
repair is flush with the rest of the stone. biscuit joiner is a device used to cut grooves in
the concealed edge of joined pieces to give
8.5 Tips for a Better Color Match. them a mechanical anchor to help pieces
For a better matching repair, it is sometimes remain at the same position relative to each
necessary to mix an inert material with the other. In the groove cut by the device an oval-
adhesive to give it the necessary “body.” The shaped biscuit is inserted. For the stone
most common inert materials used are marble, industry, this biscuit is usually plastic or
limestone or granite dust. Another possible stainless steel.
choice is to mix color-matching unsanded
grout with the adhesive. The grout is usually 8.6.4 Shims. Often after the weight of the
mixed approximately two parts grout to one countertops is added and the cabinets are
part adhesive. Once the compound is loaded, there is structural movement and
thoroughly mixed, check the color match, add settling that changes the original placement of
the curing agent, and proceed to fill the voids these tops. In these case it is best to adjust the
as usual. When grout is mixed with adhesive, tops to their original position by adding hard
it will become darker – as if it were wet. It will shims. Shims are spacers used to adjust the
not go back to a lighter color as it would if it surface position of stone countertops.
were mixed with water. The color of the
uncured mix is a good indicator of the cured 8.6.5 Seam Polishing. When surface
color. Before adding the curing agent, make irregularities are present and countertops
sure to lighten the mixture to the desired cannot be repositioned to an acceptable
color. The resulting compound will cure into position, then seam polishing can be
an extremely hard material that can be worked attempted. Before proceeding with any work,
in the same way that stone would. It is also the area must be inspected to determine
capable of taking a polish. whether the seam is within grinding tolerance.
1/16” (1.5 mm) lippage is a significant amount
8.6 Countertop Seam Leveling or of material to be taken down on a counter.
Scratch Repair. Because of the height and frequent use of most
countertops, it is viewed at and the close
8.6.1 The goal of a multi-piece countertop proximity to the eyes. Every dip and
installation should be scratch-free material and imperfection is magnified, especially in a well-
seams that are not easily visible. Sometimes lit area. The more material that must be taken
there can be unavoidable problems that require down, the wider the work area must be to
addressing from an experienced stone ensure a flat surface. A flat surface is free of any
technician. Occasionally, for various reasons, dips or wobbles in the reflection. While a seam
stone pieces are not perfectly flat. When these of ⅛” (3 mm) lippage can be successfully
pieces are joined together at a seam, especially removed, flattened, smoothed out and
a 90-degree seam, the irregularities are polished to show no distortion, it is extremely

Page 21-46 • Repairs © 2022 Natural Stone Institute

difficult and recommended to only be proceed after practicing and mastering the
attempted by the most skilled technician. skills described.
Lippage of 1/16” (1.5 mm) is the maximum
recommended when grinding a seam in a
granite countertop or vertical panel 9.0 RECOMMENDED TOOLS
installation.
9.1 Right-angle Polisher. The
8.6.6 A seam that has been carefully following features are recommended:
prepared and installed with no obvious lippage • 3-prong plug for safety
should take approximately one to two hours to • Variable speed dial, up to 3,000 RPM
complete. Each additional 1/32” (0.8 mm) will • Locking switch for continuous-on
add a significant amount of time to the process. operation
Any additional treatment, such as adding glue
• Lightweight (6 to 7 pounds, or ±3 kg)
to the seam, will add additional time. This
process should not be considered a cure for • Variable trigger speed
unacceptable seam tolerances. It is more of an • 5/8” – 11 TPI spindle thread
upgrade or premium service to provide the • 10 to 15 amps
best possible finished product. As mentioned • Constant speed under load
above, it can also performed to compensate for
minor lippage instead of removal and replacing 9.2 Turbo-style resin diamond abrasives
a top. (designed for use with granite) are the most
preferred abrasive.
8.6.7 High sections of the seam must be
identified. Because some granite slabs are 9.3 Rigid resin diamond abrasives are
prone to warpage, the high side may change designed for use on granite floors.
positions several times from the front to rear of
the counter. A warped slab or a high/low side
that changes from front to back is not indicative
of an inferior product, but it is a natural 10.0 RECOMMENDED PROCESS
occurrence that sometimes cannot be avoided.
10.1 All abrasives should be used with a
Identifying the high side becomes more critical
generous amount of water, especially in the
as the lippage increases. The idea is to grind the
initial grinding and honing phases of the work.
high side down to the low side: not to grind the
During the grinding and honing phase,
high and low sides at the same time. Grinding
abrasives below 1,000 grit are typically used.
only the high sections will minimize the
Granite, and stone sold as granite, is very hard
physical work needed to flatten the seam, and
and generates large quantities of heat when
it will significantly limit the chances of creating
grinding, honing and polishing. The abrasives
wobbles or dips in the reflection.
should stay lubricated and cool with the use of
water.
8.6.8 Conclusion. It is always best to
practice the techniques described within this
10.2 Water supply can be reduced slightly
section in order to develop the skill necessary
during the polishing phase to improve contact
to achieve acceptable results. For practice, the
between finer grit abrasives and the smoother
ideal material would be a scrap piece of the
stone surface. The polishing phase typically
same stone from the same lot, but that is not
begins with 1,000 grit abrasives, then
always possible. The next best piece to practice
continues to the finest grit of the series. Water
on would be a scrap piece of the same material
should not be reduced to the point that the area
from a different lot or a similar stone. Lighting
will dry completely.
on the job site, in all conditions, needs to be
considered when analyzing the results. Only

© 2022 Natural Stone Institute Repairs • Page 21-47

10.3 Machine control is critical throughout
the restoration process, but it is especially
important during the grinding and honing
stage. Any unnecessary or accidental pressure
applied in the wrong area can create more
work or even cause irreparable damage to the
surface. The abrasives can be worked in a linear
motion for part of the procedure, but the
majority of the job should be done using tight,
clockwise circles. Clockwise rotation is
important because this will keep the slurry
towards the center of the abrasive. This motion
is opposite the motion of a floor machine.

10.4 When refinishing a seam or scratch in

granite, the result is often slightly different
than the factory finish of the surrounding areas.
This is difficult to prevent, but it can be dealt
with easily. During the final steps, the work
area can be feathered out, or enlarged, while
progressing to finer grits. When progressing to
the final polishing step, fade the polish out into
the surrounding area. This technique will
make any difference in gloss or clarity almost
impossible to detect. Client satisfaction is the
ultimate goal, so leaving an obvious repair is
unacceptable. Educating the client prior to
repairing the stone will also help the client
form reasonable expectations of what the
finished job will look like.

10.5 Abrasives will often glaze over,

meaning that the resin in the abrasive will cover
the diamonds, rendering it ineffective.
Abrasives should be dressed on a regular basis
to ensure maximum efficiency.1 Refer to the
manufacturer’s instructions before dressing
abrasives.

1
Dressing is the process of removing glazed resin,
exposing the cutting abrasive.
Page 21-48 • Repairs © 2022 Natural Stone Institute
 ADHESIVE TYPE
Polyester Acrylic Epoxy Poly-Epoxy Acrylic-Epoxy Urethane (MPPH) Cyanoacrylate
Usage Most Common Most Common
Bond Strength Strong Stronger Strongest Stronger Stronger Stronger
Cure Time Fast (adjustable) Fast (adjustable) Slower Fast (adjustable) Fast (adjustable) Fast (adjustable) Fast (adjustable)
Clarity Poor Excellent Good Poor Excellent Excellent Excellent
Staining Probability (dependent on stone) Likely Likely Likely Not Likely Likely
Cost Least Costly Most Costly Moderate Middle Most Costly Most Costly Most Costly

© 2022 Natural Stone Institute

Fracture Mode In Adhesive Stone Fractures In Adhesive In Adhesive
Cosmetic Repair Difficulty More Difficult Easy Most Difficult Easy Easy
Resistance to Dampness During Cure Poor Poor Excellent Poor Poor Poor Poor
Resistance to Dampness After Cure Poor Poor Excellent Fair Poor Excellent Poor
UV Resistance Poor Good Fair Poor Good Excellent Good
Exterior/Interior Application Interior Only Ext/Int Ext/Int Interior Only Ext/Int Ext/Int Ext/Int
Countertop Laminations/Mitered Edges Not Recommended OK Best Fair OK OK Not Recommended
Doweling OK OK OK OK OK OK Not Recommended

PROPERTY
Rodding Not Recommended Not Recommended OK Not Recommended Not Recommended Not Recommended Not Recommended
Flexibility Poor Poor Somewhat Somewhat Somewhat More Flexible Poor
Shrinkage (after curing) High High Slight High Moderate Slight Moderate
Penetration (low viscosity) Slight High High Slight Slight Slight High
VOC Content High High Low High High Low High
Flammability High High Low High High Low High
Evaporative Rate (chemical components) High High Low High High Low High
Resistance to "CHALKING" Vulnerable Good Vulnerable Vulnerable Good Good Good
Resistance to "YELLOWING" Vulnerable Good Vulnerable Vulnerable Good Best Good
Component Ratio Accuracy Requirement Forgiving Forgiving Critical Forgiving Critical Forgiving N/A
Thorough Mixing Requirement Forgiving Forgiving Critical Forgiving Forgiving Critical N/A
Shelf Life 1 to 2 yrs 6 mo to 1 yr ≥ 2 yrs 1 to 2 yrs 1 to 2 yrs 1 to 2 yrs ≤ 6 month

Repairs • Page 21-49

NOTES:

Page 21-50 • Repairs © 2022 Natural Stone Institute

Restoration and 2.0 SURFACE PREPARATION
Maintenance – 2.1 Stripping and Removal of
Coatings. When a stone surface has a coating,
RESTORATIVE it must be removed before diagnosing what
PROCESSES restoration work needs to be done to the stone.
Coatings are applied to stone surfaces for
1.0 INTRODUCTION several reasons. If a stone surface has been
worn, scratched, or etched, a homeowner or
1.1 The term restoration signifies contractor may apply a coating to
“renovating, reconditioning, or returning” inexpensively achieve a shine. Coatings are also
something to an “acceptable” or “near original” used to seal stone surfaces. There are two
condition. Restoration starts with a distinct categories for coatings: water-based
comprehensive inspection of stone type, and solvent-based. Although solvent-based
condition of the stone, and possible causes of coatings have been the long-standing product
the need for restoration. of choice, there are many hazards associated
with their use, including high VOCs and the
1.2 Most often the need for restoration need for respiratory and skin PPE. The
arises from the lack of proper maintenance. technology for water-based coatings is
Other factors that make restoration necessary improving rapidly, and the industry seems to
can include improper cleaning products, wear be moving toward using more water-based
patterns, scratches, etch marks, stun marks, products.
cracks, chips, breaks, contamination from
pollutants such as smoke, leaks and floods, 2.1.1 Coating removal is called “stripping.”
contact with wet environments, cold-weather When stripping coatings, it is important to
treatments such as salt or ice melt, and work in manageable areas. Failure to do so can
degradation from years of normal exposure to cause the coating to cure in areas making it
the elements. necessary to repeat the process. A chemical
solution is used to emulsify and remove the
1.3 Processes unique to restoration coating from the stone surface. Most acrylic
include removing and replacing stained and coatings that are installed on natural stone
degraded grout, removing deeper sub-surface surfaces can be stripped using water-based
blemishes, marks, soils, scratches, etch marks, stripping methods. Lacquers, urethanes,
cracks, chips, stun marks and wear patterns on epoxies, and other clear paints are usually
stone, and filling larger holes and cracks with stripped using solvent-based methods.
color-blended resins. Restoration involves the
use of coarser diamond abrasives, such as 120, 2.1.2 Water-based Coatings. Acrylics
100, 70, and lower grits. Refinishing involves and other waxes are stripped using a stripper
the use of finer grit abrasives. Restoration also properly diluted in water as directed by the
involves utilizing acidic or alkaline chemicals manufacturer.
for more aggressive cleaning and stripping.
During any process of restoration or 2.1.2.1 Dwell Time. The stripping solution
refinishing, proper safety equipment must be is delivered with either a mop or airless pump
used. For example, eye, skin and respiratory sprayer. The solution must be allowed to sit in
protection equipment must be used around contact with the coating for a period of time in
chemicals, dust, and other hazards associated order to soften and loosen the coating and
with the process. cause it to shrink away from the surface of the
stone.

© 2022 Natural Stone Institute Restorative Processes • Page 21-51

2.1.2.2 Agitation and Extraction. After remaining residues. Another method of
the prescribed amount of dwell time, the detailing is done by immediate application and
surface is scrubbed with an abrasive pad or removal of water-based strippers.
brush. This removes the remaining coating and
converts it in to a liquid form. When the liquid 2.1.5 Poulticing is a process of stain
becomes thick and colored, it should be removal. A chemical is used to loosen the stain
removed from the immediate work area with a and an absorbent media is used to draw the
squeegee. The immediate work area should be stain out of the stone. While this can be used
examined to determine if the desired result has on any stone, it should first be determined if
been achieved. If more work needs to be done, the chemical reaction might have an adverse
use the squeegee to move the liquid back in effect of the stone. For example, when an acid
place to continue working the area. If the work is used to break down rust in any calcium
is complete, use a wet vacuum to remove the carbonate based stone, the acid will etch the
liquid. This process is repeated until the entire stone, making restoration or refinishing
area is complete. necessary. Poulticing requires the following
steps.
2.1.3 Solvent-based Coatings. Lacquers
and epoxies are stripped using a solvent-based 2.1.5.1 Identify the stone type and the type
stripper that is petroleum-based or from and source of the stain. Often this can be
another solvent source, such as soy. Soy-based determined by asking the building’s owner,
strippers tend to take longer to process, but the manager, or maintenance workers.
results are similar to petroleum strippers.
2.1.5.2 Once the source of the stain has been
2.1.3.1 Dwell Time. Solvent-based strippers identified and removed, refer to Stains &
are gels and are usually applied using a brush or Removal Procedures in the Maintenance
another type of spreading applicator. The gel is section of this document to take the
applied in such a way as to leave ¼” of the gel appropriate steps to remove the stain.
on the surface of the coating. Some technicians
prefer to cover the treated surface with plastic 2.1.5.3 After the appropriate dwell time,
to keep it wet and allow the stripper adequate remove the poultice from the stone. For large
time to react. areas, a wet vacuum can be used to speed up
the process.
2.1.3.2 Agitation and Extraction. After
the specified period of dwell time, the surface 2.1.5.4 Analyze the results and determine if
is scraped with a spatula and both the stripper another poultice application is needed. If not,
and coating are discarded. Follow follow up by cleaning the area with a pH
manufacturer’s instructions for rinsing and neutral stone cleaner before restoring or
removal of the gel. refinishing the stone.

2.1.4 Detailing is the process of 2.2 Masking and Protecting. Prior to

completing stripping a coating. It can be done stone restoration, adjacent areas should be
in several ways, based on the preference of the masked. The term mask is commonly used to
technician and the type of coating being describe the process of applying protecting
removed. One method is to reapply the same films or tapes to the surrounding area. The
stripper, allowing less contact time, then most common items that are masked include
scrubbing and extracting it. This is done using carpeting, hardwood floors, thresholds, trim
the same methods as described above in the or moldings, glass, and any and all dissimilar
acrylic removal (water-based coatings). Some materials or stone types that could be
technicians use solvents such as mineral spirits, negatively affected from contact with the
acetone, or alcohol to break and remove the cleaner, water, slurry, or polishing compound.
Page 21-52 • Restorative Processes © 2022 Natural Stone Institute
Delicate painter’s tape can be applied directly 3.1.2 For lippage removal, use a heavy
onto painted surfaces, stained finished wood, ridged planetary machine and/or a swing
metal, or other sensitive surfaces. Ensure no machine capable of being weighted. A variable
tape is covering the stone that needs to be speed machine can also be used. Access to extra
refinished. Use caution when taping baseboard weights is sometimes necessary.
and finished hardwood because even the most
delicate painter’s tape may pull paint or stain 3.1.3 An edging machine and/or variable
off of these surfaces. speed angle grinder/polisher is the proper tool
for edgework close to adjacent, dissimilar floor
2.2.1 Adjacent areas should also be covered and wall materials. Use the same grit level of
with other masking materials, such as static- abrasives and steps that are being used on the
cling painter’s plastic film. Wax paper and pre- main section of the floor.
taped rolled plastic film is acceptable as well.
Start at the baseboards and apply the masking 3.1.4 A variable speed angle grinder/
material up and along the walls, cabinets, and polisher is recommended for wall restoration.
adjacent flooring surfaces. Spot tape the
masking material to these surfaces to ensure 3.1.5 Other Recommended
that plastic film does not fall into the working Equipment.
area during the restoration process. • A squeegee with a rubber head and
extension pole
2.2.2 Make sure to cut openings in the • A wet/dry vacuum
plastic film covering vents to allow proper
• Metal bonded diamond abrasives
airflow and to apply the film in a way that does
(multiple grits) for floor and handheld
not prevent the use of appliances and doors to
machines
a pantry, closet, or entry. Make certain that
these accommodations do not allow the • Marble-specific, resin-bonded
equipment, abrasives, or water and chemicals diamond abrasives for floor and
to cause damage. Use items like caution tape handheld machines (approximately 30
and wet floor signs if working in an area where grit through 3000 grit or higher,
pedestrian traffic is likely. depending on abrasive manufacturer)
• Transitioning abrasives to be used
2.3 Cleaning. The stone should be between metal and resin-bonded
swept, vacuumed, and wet mopped using a pH abrasives
neutral stone cleaner prior to restoration. This • Marble polishing compounds
will keep grit and dirt from doing further • Hog’s hair pads
damage to the stone or causing damage to the • Diamond dressing compound or
abrasives. product to dress diamond abrasives1
• pH neutral cleaner
3.0 MTL REFINISHING AND
POLISHING 3.1.6 Surface Preparation.
3.1 Preparation. 3.1.6.1 Mask and protect the work area as
described earlier in this section.
3.1.1 Equipment. There are many
variations of machinery and abrasives. The list 3.1.6.2 Remove baseboards and other trim to
below is an example of what is typically used. make the edge work more accessible.

1
To dress a diamond means to remove metal or resin
coating over the abrasive, exposing a better cutting
surface.
© 2022 Natural Stone Institute Restorative Processes • Page 21-53
3.1.6.3 Use a vacuum to clean the entire floor, Below are two edging options for lippage
making sure there is no debris that could get removal based on job conditions.
under the machinery.
3.2.1.1 Option A. If the baseboard and other
3.1.6.4 Remove any coatings or waxes from trim can be removed, the machinery can be run
surface using the proper methods described tight to the edge of the wall on the first abrasive
earlier in this section. If no coatings are step. The second and subsequent steps will also
present, wet mop the entire area with a pH be run tight to the wall. Any scratches along the
neutral stone cleaner to remove lingering outer edges will be concealed under the
debris. moldings when they are replaced. Put a section
of the new molding (baseboard and other trim
3.1.6.5 Repair all cracks and chips. Allow pieces) in place without attaching it to verify
patching material to thoroughly cure before that the edges are properly finished. If not, the
starting the refinishing process. edges will need to be finished by using
handheld equipment.
3.1.6.6 Check for any missing grout at joints
and caulk. Fill prior to starting the refinishing 3.2.1.2 Option B. If the baseboard and other
process. This will ensure that the color will be trim cannot be removed, then this or a similar
a better match when the process is complete. grinding process should be followed. A popular
method is to use a 2 x 4-inch (50 x 100 mm)
3.1.6.7 If the floor was grouted with sanded piece of wood laid flat along the outer edge of
grout, it will need to be removed and replaced the floor. Use this as an edge to complete the
with unsanded grout. Otherwise the sand in first abrasive step. On the next abrasive step,
the grout can become dislodged and can scratch flip the wood onto the 2-inch side to use as an
the marble during the restoration process. edge. This method will help to avoid having
heavy scratches against the molding. For the
3.1.6.8 If the lippage averages more than next steps, the edge work will need to be done
3/32” (2.4 mm), it is better to float the floor using a handheld machine, such as an angle
with the same color unsanded grout to protect grinder/polisher, with the appropriate
the tile edges from chipping and/or cracking.2 diamond abrasives. Several steps will need to
be done by hand to get a 4 to 5-inch (100 to
3.2 MTL lippage removal is the 125 mm) perimeter of the floor complete. The
process of grinding the floor flat to help make edging process should match the process that
it easier to polish and maintain. will be performed for the entire floor.

3.2.1 Edging. Most floors installed in the 3.3 Steps 1 and 2: First grinding.
United States are not laid completely flat, nor Using either option A or B, above, start the
are they ground in place, meaning that the floor first grinding step. Place the lowest grit metal
has lippage. Before beginning the grinding bond diamonds on the machine. The technician
process it is necessary to consider the edges of will need to decide with which metal bonded
the floor. In some cases it may be possible to diamond abrasive grit to start the process based
stop the grinding process 3 to 6 inches from the on how much material needs to be removed. A
edges. This is a method better suited for good baseline choice would be a 70/100-grit
experienced technicians. For best results, it is metal abrasive followed by a 120/200-grit
better to grind the floor flat to the edges. metal, copper, or electro-plated abrasive. 50-
grit metal abrasives are very aggressive and are

2
To float the floor means to fill any low areas with a
recommended floating material.
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mainly used to grind the surface of concrete, optimal outcome, it may be necessary to
but are not recommended for use by a progress up to 1800-grit diamond abrasives
beginner. Abrasives should be secured to the before moving on to the final polishing process.
bottom of the machine by bolts, magnets, or For heavily soiled, worn, or damaged floors, it
cup holders. A large quantity of water is may be necessary to start with a 120-grit or
necessary for this step, so take precautions not lower abrasive. If the floor is less worn, it may
to flood lower floors or have any water escape be acceptable to begin with a 400-grit abrasive.
the work area. Build dams or pour stops if Some companies manufacture a 400-grit
needed to control water flow to adjacent or abrasive capable of removing etching and
lower areas. normal wear. The type of stone being restored
also determines the abrasive starting point. For
3.3.1 Initial Grinding should be done in travertine and other stones known to have
an out-of-the-way corner. The metal bonded many voids, overworking them with 200-grit
diamond abrasive will dig in to the stone upon abrasives or lower can open up the voids and
starting the machine. Work 50 to 100 sq. ft. make it necessary to fill them.
(4.5 to 9 m2) sections for the first step and run
the machine north to south and then east to 3.4.1 Picture Framing. If lippage is not
west. The goal is to level the floor in sections removed, diamond abrasives will not abrade
and then blend it all together. This step is noisy the low sections of the tile edge, leaving a
and time consuming, signaling that the floor is diamond hone on the high sections but the
not yet flat. Using a squeegee, check the area original finish on the low tile edge. This is
being worked. Rinse the floor and let it dry. known as picture framing. The prominence of
Inspect the area closely for inconsistencies in picture framing is affected by the thickness of
the abraded finish. It is critical to finish this step the abrasives being used. Diamond abrasives
with a uniformly abraded surface. There will are commonly produced in thicknesses of 11,
typically be some low corners that will need 9, 4, or 3 mm. The thicker the abrasive, the
more attention. If inconsistencies are found, more rigid it tends to be and the more
continue to go over those areas until it is pronounced the picture framing would be. If
uniform. This step will set the precedent for the technician is not being contracted to
the remainder of the processes. remove the lippage by grinding the floor flat, it
is better to use 4mm or thinner diamonds with
3.3.2 An equal or greater time should be a foam spacer for additional flexibility to
spent on the seconding grinding. Make sure reduce the picture framing affect.
that all of the previous grit’s scratches have
been removed. If this process is not performed 3.5 Step 3: Light grinding or
correctly, it will be noticeable in the final transitioning (step 1 if lippage removal
polish of the floor. After the 120/200-grit is is not performed). For refinishing, it is most
complete, the floor is ready for the refinishing common to begin with 220-grit diamond
phase of the process. abrasives. To begin, the technician attaches the
abrasives to a flexible riser pad. The two most
3.4 MTL Refinishing. When refinishing common diamond configurations are 3 or 4
a floor without lippage removal, the technician abrasive pads. If using 3 abrasives, the
must determine the abrasive coarse enough to technician should place the diamonds evenly on
quickly remove the deepest scratch without the drive plate (for example at 12, 4 and 8
being too aggressive and causing additional o’clock positions), forming a triangle pattern.
work. In most cases it is best to begin with 200- If using 4 abrasives, the technician should space
grit diamond abrasives, then progress to 400- them evenly on the drive plate (for example at
grit and 800-grit prior to final polishing on 12, 3, 6 and 9 o’clock positions), forming a
most marble. In some cases, to obtain the square pattern. Spacing of the abrasive from

© 2022 Natural Stone Institute Restorative Processes • Page 21-55

the outer edge of the drive plate is one method stage of the project. Some technicians move the
used by experienced technicians to ensure a machine in circular motions. This is used across
more thorough overlap is achieved with finer each section covering the same area, in the
grit abrasives. same amount of time, to ensure the stone is hit
from different angles. Once a section is
3.5.1 If using a machine with a water tank, finished, all water and slurry should be moved
engage the water flow for 3 to 5 seconds at the from the working area using a squeegee, then
beginning of the process to apply enough water extracted with a wet vacuum. Do not let the
to the working surface. Only enough water is slurry dry on the surface of the stone. A clean,
needed to create a slurry with the consistency dry surface is necessary for the technician to
of skim milk. If water is running from the inspect the work at each step to ensure that
working area onto the low areas on the floor, there are no inconsistencies in the abrasive
too much water was used. Excess water will pattern before moving to the next step. Using
not affect the abrasive’s ability to work in the a squeegee to assess each area is the quickest
initial stages, but it will cause potential work technique. This step is accomplished more
site problems such as water flowing into floor efficiently if a second technician is on hand to
vents and through ceilings of the lower level operate the squeegee and vacuum. This allows
floor. If necessary, add additional weights to the first technician to move on to the next
the machine to increase the cut rate. Be careful section of the floor while the second is
when adding weight to the machine while vacuuming the previous section.
working on filled stone like travertine. This
will make it necessary to fill the voids created 3.6 Step 4: Light grinding or initial
by overworking the stone. honing step (step 2 if lippage removal is
not performed). After the entire surface has
3.5.2 Begin grinding in the far corner of the been finished with 220-grit diamond abrasives,
room, working backwards towards a natural remove them from the drive plate and attach
stopping point, such as a front door or room 400-grit abrasives, also using foam spacers.
transition. It is helpful to visualize the floor in These abrasives should be attached in the same
10 to 20 sq. ft. (1 to 2 m2) sections and work pattern as before, but placed slightly closer to
each section moving from right to left or left to the outer edge of the drive plate. This allows
right in linear movements. When working in the technician to move the machine along walls
lower grits (200 and 400 grits), it is better to and cabinets and easily overlap each grit level.
make two passes before moving down through
the section. By making two passes, the 3.6.1 This step in the refinishing process can
technician will move the machine in a linear be thought of as the matte process of the honing
pattern from right to left or left to right, then phase. Each finer grit diamond abrasive will
reverse and move the machine over the same improve the color, shine, and clarity of the
footprint returning to the starting point. surface until a polish is produced.
Approximate coverage rate should be 10 sq. ft.
(1 m2) every 5 minutes when moving in a 3.7 Step 5: Honing step (step 3 if
straight line. The technician should ensure 50% lippage removal is not performed). After
overlap of each pass throughout the floor. finishing the entire floor with the 400-grit, the
When using one pass (or 2 passes at lower grit surface should be rinsed, vacuumed, and dried.
levels), when the area is completed the The floor should be inspected to ensure that
technician should step back only about half of there is a consistent abrasive pattern and that it
the width of the machine and reverse is ready for the next step. After 400-grit, each
directions, moving at the same pace stated subsequent grit can be thought of as a polishing
above. This will ensure there are no missed grit. The 800-grit abrasives should be attached
areas that will cause problems at the polishing

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to the drive plate as before but moved even 3.8.2 Begin in a far corner of the room,
closer to the edge of the plate. working backwards towards a natural stopping
point such as a front door or room transition.
3.7.1 When refinishing MTL floors, it is Slurry should not be tracked onto other
common to stop after finishing with 800-grit. sections of the floor, because it can create etch
Some technicians choose to progress to 1800- marks. Think of the floor in sections. On most
grit or even 3000-grit. With 800, 1800 and MTL floors it is acceptable to polish 20 to 30
above grit steps, it is acceptable to deviate from square foot sections at time. Place the polishing
the process above. The technician can perform compound of choice on the floor by pouring it
just one pass in each direction. This means that in a circle approximately 14 inches (350 mm)
if the technician is moving from right to left, in diameter. When the machine head is put in
when they reach the opposite edge of the contact with the floor, it should cover the
working area it is acceptable to take a step back applied compound. This will reduce the spray
half of the width of the machine and reverse or spread of the compound across the floor. It
direction. This makes work with the higher is common to use ¼ to 1/3 of a cup (60 to 80
grits progress much quicker. The hardness and ml) of compound in each section of the floor.
color of the stone being refinished usually has Place a white or natural hog’s hair pad to the
an impact on how fine the last grit needs to be. drive plate, ensuring that the plate is centered
With experience, the technician will know on the pad. Drop the machine head over the
how far to take this part of the process. powder and apply water. If using a machine
with a water tank, engage the water flow for 3
3.8 Step 6: Polishing step (step 4 if to 5 seconds at the beginning of this process.
lippage removal is not performed). Prior
to polishing, make sure masking is still intact. 3.8.3 Once the machine has started, work in
Polishing compounds contain acidic circular motions covering approximately a 20-
components that could damage metal or other inch diameter section, while moving in a linear
adjacent surfaces. This step is typically the pattern. As with the diamond refinishing steps,
messiest, so proper masking will reduce clean it is important to overlap the work areas to
up time upon project completion. Polishing ensure an even and uniform finish over the
compounds are covered in much more detail in entire floor. Most technicians will check the
chapter 5 of this document (Equipment). polishing progress with a squeegee. When the
desired polish has been achieved, rinse the
3.8.1 After the floor has been refinished working area and extract the slurry from the
using traditional abrasives, it is ready for floor. Total working time per section should be
polishing. If at this point there are still picture between 90 seconds and 3 minutes, depending
frames, low points on the tile that are on floor type and compound used. This step
untouched by abrasive and appear polished, should be repeated until the entire floor has
they should be minimal and will be completely been covered and the desired results have been
removed by an experienced technician during achieved.
the polishing step. There are a number of
compounds that will achieve the desired result. 3.8.4 After the floor is polished, there will
The amount of compound used and time spent be residue in grout lines and on the surface of
in each section varies slightly based on the the tile. To remove the residue, add a pH
hardness, mineral makeup, and color of the neutral stone cleaner to the water tank of the
stone and compound being used. The processes machine or apply the cleaner to the floor using
as described below are general guidelines that a pump sprayer. Then place a clean white pad
may need adjustment in the field depending on or soft brush on the machine. Starting at the far
job site and product variables. end of the floor, working backwards toward a
door or room threshold, scrub the floor to

© 2022 Natural Stone Institute Restorative Processes • Page 21-57

remove residue from the tile and grout lines. in a tumbler, causing a chipped and worn look
While the cleaner is still on the floor, use a on unused pieces of stone. Bush-hammering,
sponge to clean edges and corners to remove sandblasting and other methods can be used to
residue and debris. When the floor is dry, give larger stones a tumbled look.
remove all tape and plastic film, then
thoroughly dust mop the floor. The floor is 3.10.4 A Brushed Finish is achieved by
now ready for sealing. using abrasive brushes in place of rigid abrasives
to hone the surface of the stone. Materials that
3.9 Sealing (using an impregnating have a wide range in hardness usually produce
repellant). For sealing, refer to chapter 8 of the most diverse texture using this technique.
this document (Sealers). In general, a simple Materials that do not contain a wide range of
water test on the surface of the stone will minerals with varying degrees of hardness are
determine its porosity. If the stone darkens often textured mechanically before being
when wet, sealing the stone can be beneficial. honed with the abrasive brushes. These brushes
The general rule that applies to sealing stone is usually start at 36 grit and continue to 1200 grit
to start with a thoroughly clean and dry floor. for an even finer finish. It is always best to
Follow the manufacturer’s recommendations research and experiment with different finishes
for applying their product. A majority of to avoid damaging the installed floor.
sealer-related problems are caused by not
following directions properly.
4.0 GRANITE REFINISHING
3.10 Other Finishes. Polished is still the AND POLISHING
most popular finish for stone. Other finishes
typically seen on MTL are honed, bush- 4.1 Process. The scope of this section
hammered, tumbled, and brushed (also known includes all stones traded as granite by the
as antiqued, leathered or caressed). A floor will stone industry. Refinishing and polishing a
sometimes have a mixture of finishes in a granite floor is considered a pinnacle
pattern, making refinishing difficult. achievement for any stone refinisher. A sound
Understanding the factory process of creating plan and the right tools and equipment are
these different finishes can be beneficial during required. The technician must research
refinishing. available machinery and abrasives. Chapter 5
(Equipment) is a good place to begin this
3.10.1 Honing. A honed finish is achieved by research. The machine and abrasive needs will
stopping the process at least one step before vary.
achieving a polish. The typical honed finish is
defined as being a matte or non-gloss finish 4.1.1 Technicians must be patient when
without visual abrasive patterns. With MTL, working on granite. To achieve a factory-like
this usually begins at the light grinding and finish, some technicians may state that granite
honing steps. floors can be refinished without grinding by
using only resin diamond abrasives and granite
3.10.2 Bush-hammering is a mechanical polishes. This is possible under the right
finish produced from impact by hand or a conditions and on the right floor, but there are
pneumatic hammer that creates a textured many variables that affect the results.
surface. It is typically used on cubic material;
stone with a thickness greater than 2 inches (50 4.1.2 Granite refinishing becomes necessary
mm). for several reasons. Technicians may be called
to restore a badly worn or abraded surface or a
3.10.3 A Tumbled Finish is usually new floor installation with excessive lippage.
achieved by placing smaller pieces of stone tiles Another reason would be to change the

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existing finish (changing from a polished to 4.3.2 If possible, remove baseboards and
honed or honed to polished floor) for any other trim to make edge work easier and more
number of reasons. It is also possible to be accessible.
called in to brush or texture a granite floor.
Textured finishes are becoming more popular 4.3.3 Use a vacuum to clean the entire floor,
each year, so it is important to understand the making sure there is no debris that could get
process. under the machinery.

4.2 Equipment. There are many 4.3.4 Remove any coatings or waxes from
variations of machinery and abrasives. The list the surface using the methods described in
below is an example of what is typically used. section 2.1.
• A heavy ridged planetary machine
and/or swing machine capable of 4.3.5 If the floor was grouted with sanded
being weighted. A variable speed grout, it must be replaced with unsanded
machine is preferred. Access to extra grout.
weights can be necessary.
• An edging machine and/or variable 4.3.6 If lippage averages more than 3/32”
speed angle grinder/polisher (2.4 mm), it is better to float the floor with the
same color unsanded grout to protect the tiles
• A squeegee with a rubber head and
from chipping and/or cracking.
extension pole
• A wet/dry vacuum 4.4 Granite Lippage Removal. Before
• Metal bonded diamond abrasives refinishing, all lippage must be eliminated so
(multiple grits) for flor and handheld that the floor is flat. This is a once in a lifetime
machines process for a granite floor that increases its
• Granite-specific, resin bonded value exponentially.
diamond abrasives for floor and
handheld machines - approximately 30 4.4.1 Edging. Edges must be considered
grit through 3000 grit or higher before beginning the grinding process. In some
(depending on manufacturer) cases it may be possible to stop the grinding
• Copper-bonded diamond abrasives or process 3 to 6 inches from the edges. This is a
hybrids used for transitioning between method better suited for experienced
metal and resin-bonded abrasives technicians. For best results, grind the floor
• Other transition abrasives for use after flat to the edges. Below are two edging options
grinding to remove any excess for lippage removal.
scratches and prepare surface for
honing 4.4.1.1 Option A. If baseboards and other
trim can be removed, machinery can be run
• Granite final polishing compounds
tight to the edge of the wall on the first abrasive
• Hog’s hair pads for polishing step. The second and subsequent steps will also
• Diamond dressing compounds or be run tight to the wall. Any scratches along the
product to dress diamond abrasives outer edges will be concealed under the
• pH neutral cleaner replaced moldings (baseboards and other trim
pieces). Put a section of the new molding in
4.3 Surface Preparation. place without attaching it to verify that the
edges are properly finished. If not, the edges
4.3.1 Mask and protect the work area as will need to be finished by using handheld
described in section 2.2. equipment.

© 2022 Natural Stone Institute Restorative Processes • Page 21-59

4.4.1.2 Option B. If baseboards and other 4.5.2 Using a squeegee, check the area being
trim cannot be removed, then this or a similar worked. Rinse the floor and let it dry. Inspect
grinding process should be followed. Use a 2 x the area closely for inconsistencies in the
4-inch piece of wood laid flat along the outer abraded finish. This step must finish with a
edge of the floor. Use this as an edge to uniformly abraded surface. If inconsistencies
complete the first abrasive step. On the next are found, continue to go over those areas until
abrasive step, flip the wood onto the 2-inch they are uniform. Areas with negative lippage
side to use as an edge. This method will help should be worked using handheld machinery to
avoid having heavy scratches against the avoid the risk of overgrinding, but be careful
molding. For the next steps, the edge work when using handheld machinery not to create a
will need to be done using a handheld machine, dip in those areas. It may be a better to add
such as an angle grinder, with the appropriate weight to the machine and make the
diamond abrasives. Several steps will need to corrections on the second step.
be done by hand to get a 4 to 5-inch (100 to
125 mm) perimeter of the floor complete. The 4.6 Step 2: Second grinding step.
edging process should match the process that When the first step is complete and consistent,
will be performed for the entire floor. begin the second grinding step. Attach the next
set of grinding abrasives to the machine. The
4.5 Step1: First grinding step. Using machine can be run in any direction that
option A or B (above), start the first grinding ensures adequate surface coverage. Work the
step. Place the lowest grit metal bond entire floor and remove all scratches from the
diamonds on the machine. The metal bonded previous grit. Run the machine as close to the
diamond abrasive grit used to start the process edge as possible. After completing this step,
should be determined based on how much rinse, dry, and examine the floor. This step
material needs to be removed. Although many must be finished with a uniformly abraded
variations can be used, a good baseline choice surface. Once the abraded surface is consistent,
would be a 46/50 grit followed by a 100 grit move to step 3. If using option B (described in
abrasive (depending on the abrasive section 4.4.1.2), complete the edging work
manufacturer). using a handheld machine before moving to
step 3.
4.5.1 Abrasives must be secured to the
bottom of the machine by bolts, magnets or 4.7 Step 3: Transition step. This step
cup holders to ensure the first step goes transitions from metal-bond to resin-bond
smoothly. This step requires a great deal of diamond abrasives. Use copper, ceramic,
water; build dams or pour stops if needed to phenolic, or granite-specific resin-bond
control water flow to adjacent or lower areas. diamond abrasives to remove scratches from
Start the machine at approximately 300 to 500 the last grinding process. It is usually best to
rpm, then find a speed that works best with the drop to a lower grit than the last metal-bond
abrasives and the granite. Work 50 to 100 sq. grit used. For example, if the last metal bond
ft. (4.5 to 9 m2) sections for the first step and grinding grit was a 100, step 3 should start with
run the machine north to south, then east to a 50 grit transition abrasive. Remove all
west. Level the floor in sections and then blend scratches from previous grits and finish with a
together. It will take approximately 30 to 60 uniform abrasive pattern. If using option A,
minutes for 50 to 100 square feet. This step is continue working each grit to the edge of the
noisy, indicating that the floor is not yet flat. floor. If using option B, work the grit over the
When the machine quiets down and becomes last metal cut to start blending each cut into the
smooth, the floor is getting flat. This step sets edge previously created. Clean, dry, and
the precedent for the remainder of the process. inspect the entire floor for uniformity before
moving to the next step.

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4.8 Steps 4 through 10: Honing and to abrasive contact. However, too little water
polishing steps. When floor is thoroughly will cause the abrasive to heat up and glaze
clean and dry, inspect before proceeding. over.

4.8.1 Step 4. Attach 50 grit (or comparable 4.9 Step 11: Final polishing step. The
grit) resin-bond diamond abrasives to the final polishing will only be as good as the
machine. The machine can be run in any honing of the surface. Simply put, if the floor is
direction that ensures adequate coverage of the honed well, the polishing results will reflect
surface. Work the entire floor and remove all that work.
scratches from the previous step’s grit. After
completing this step, rinse, allow the floor to 4.9.1 There are many polishing compounds
dry, and inspect. If the abrasive pattern is on the market, and each has its own strengths
uniform, move to step 5. and weaknesses. For highly competitive jobs,
an inexpensive but effective compound is often
4.8.2 Step 5. Attach 100 grit (or used. Stone that is polished with a chemical
comparable grit) resin-bond diamond abrasives compound should receive a final cleaning with
to the machine. Continue with the same a pH neutral cleaner. The easiest compounds
process as Step 4. to use will be compounds that can be worked
wet. Some companies prefer granite
4.8.3 Step 6. Repeat step 4 using 200 grit crystallizers that are applied using #1 grade
resin-bond diamond abrasives. steel wool.

4.8.4 Step 7. Repeat step 4 using 400 grit 4.10 Sealing (using an impregnating
resin-bond diamond abrasives. repellant). For sealing, refer to chapter 8 of
this document (Sealers). In general, a simple
4.8.5 Step 8. Repeat step 4 using 800 grit water test on the surface of the stone will
resin-bond diamond abrasives. determine its porosity. If the stone darkens
when wet, sealing the stone can be beneficial.
4.8.9 Step 9. Repeat step 4 using 1500 grit The general rule that applies to sealing stone is
resin-bond diamond abrasives. to start with a thoroughly clean and dry floor.
Follow the manufacturer’s recommendations
4.8.10 Step 10. Repeat step 4 using 3000 grit for applying their product. A majority of
resin-bond diamond abrasives. sealer-related problems are caused by not
following directions properly.
4.8.11 Considerations. Inspection after
Step 7 is typically more critical as you move 4.11 Other Finishes. Different finishes
into the honing and polishing phases. This can are increasingly becoming more popular for
give you a glimpse of the consistency of the natural stone. Finishes typically seen are
final polish. If the surface is uneven, it is honed, flamed, bush-hammered, and brushed
imperative to go back over the floor until it is (also known as antiqued, leathered or
consistent. The speed of the machine can be caressed). Most granite can be flamed and this
increased when using the finer grit abrasives. is a popular choice for improving slip
For example, on Step 9 (1500 grit) the speed resistance. On occasion, a floor will have a
can be set to 1,100 RPMs. During the use of mixture of finishes in some form of pattern,
finer grit abrasives there is less material being making refinishing difficult. Understanding the
removed and the water required to keep the factory process of creating these different
stone and the abrasives cool is reduced. A finishes can be beneficial when refinishing it.
heavy water flow during this phase increases
the changes of hydroplaning or reduced stone

© 2022 Natural Stone Institute Restorative Processes • Page 21-61

4.11.1 A Honed Finish is achieved by countertop. Because they are naturally scratch
stopping the process at least one step before resistant, granite countertops rarely, if ever,
achieving a polish. The typical honed finish is require refinishing using diamond abrasives.
defined as being a matte or non-gloss finish When they do, abrasives up to 3,500-grit
without visual abrasive patterns. With granite, followed by a buff abrasive pad should be used.
this usually begins at Step 7 and continues to Buff pads typically come in black or white
Step 9. varieties and contain extremely high grit
abrasives (8,000 or 11,000-grit). The use of
4.11.2 A Flamed Finish is achieved by using the buff abrasive pad will result in a high quality
and oxygenated torch to heat the surface of the mechanical finish. When polishing granite, the
granite to approximately 1,600 degrees better quality mechanical finish the technician
Fahrenheit. This process is not recommended can achieve, the easier it is to achieve an
for installed stone without thorough research acceptable polish using chemical and abrasive
and trials. granite polishing compounds.

4.11.3 A bush-hammered finish is 5.2 Equipment. The following

typically used on cubic material. It is a equipment is recommended for granite
mechanical finish produced from impact by countertop polishing:
hand or a pneumatic hammer that creates a • Variable speed right-angle
textured surface. grinder/polisher
• 3, 4, 5, or 7-inch backer pad
4.11.4 A Brushed Finish is achieved by
• 3, 4, 5, or 7-inch diamond abrasives
using abrasive brushes in place of rigid abrasives
to hone the surface of the stone. Materials that • Water supply (spray bottle or water
have a wide range in hardness usually produce supply for a center water feed
the most diverse texture using this technique. polisher)
Materials that do not contain a wide range of • Squeegee
minerals with varying degrees of hardness are • Granite polishing compound
often textured mechanically before being • Hog’s hair burnishing pad
honed with the abrasive brushes. These brushes • pH neutral cleaner
usually start at 36 grit and continue to 1200 grit
for an even finer finish. It is always best to 5.3 Surface Preparation. Before
research and experiment with different finishes beginning the refinishing process, adjacent
to avoid damaging the installed floor. areas (including floors, cabinets, walls,
mirrors, ranges/cooktops, and refrigerators)
should be masked. Delicate painters tape can
5.0 GRANITE COUNTERTOP be applied directly onto painted surfaces,
POLISHING finished wood, metal, and other sensitive
surfaces. 2” painter’s tape can also be applied
5.1 Granite is naturally resistant to to the edge of the counter, leaving
scratches, chemicals (it is not acid sensitive), approximately 1 to 1½-inches of tape above
and moisture. Because of this, most granites the surface of the countertop. This will reduce
maintain a high quality finish. It is not unusual splatter and necessary cleanup. Use caution
for granite countertops to be serviced in 5-7 when taping painted cabinets and finished
year windows or longer. In most cases only hardwood because even the most delicate
spot refinishing is required to remove a scratch painter’s tape may pull paint or stain off of
or other imperfections from a portion of the these surfaces.
countertop. These smaller areas can be
polished to blend in with the entire

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5.3.1 Other masking materials should also working pattern (also known as the scratch
be used. The most common masking material profile) is even and does not show arrant
is static-cling painter’s plastic film. Wax paper scratches. Stop to clean slurry off the working
and pre-taped rolled plastic film are also area, using a rag or small squeegee to check
acceptable. Starting at the top of the cabinets progress. When finished with each step, clean
just below the countertop, unravel masking the working area and dry it for inspection.
material down and along cabinet faces. Then Inspect the area closely to ensure that there is a
use a small piece of plastic to cover the range consistent abrasive pattern. Once the
or cooktop. Plastic film or canvas tarps should imperfection has been successfully removed
be laid on the floor in the working area. and the abrasive pattern is consistent, move to
Review the surroundings and cover furniture the next step.
or other items that are close enough to be hit
by splatter with plastic film or canvas tarps. 5.4.3 Repeat the process above with the
Masking for countertop refinishing is designed next finer-grit abrasive. Overlap the previous
to catch splatter. The splatter caused by scratch profile by about 25% of the abrasive
countertop refinishing and polishing footprint to prevent a halo. Continue by
compounds will generally not stain or damage moving the machine in a consistent pattern
floors, cabinets, or nearby furniture, but across the designated work area with each
protecting these surfaces with plastic film abrasive. The abrasive part of the work is
provides a professional look and greatly completed when technician has progressed to
reduces clean up upon completion of the the use of the buff pad and achieved a near
project. factory shine mechanically. By overlapping and
thoroughly inspecting the work, the reflective
5.4 Refinishing. Begin by identifying the finish will be the same from the center to the
area that requires refinishing. If it is a small outside of the scratch profile.
scratch or small area, use a china marker or
lumber crayon to circle the scratch. 5.4.4 When using higher grits (1000-grit
and finer) some technicians prefer to use the
5.4.1 Use a variable speed right-angle tool wet-to-dry. To do this, use a sprayer to
grinder with a 3, 4, 5, or 7-inch backer pad. It apply a mist of water on to the work area. Start
is common to refinish small areas using 3 or 4- the machine on the lowest speed, applying
inch diamond abrasives. Spray the working area more pressure than usual to the machine.
with water. Allow for consistent and even Work the area back and forth until the area
water distribution; do not flood the surface. begins to dry out. As the area dries out, the
Choose a coarse grit abrasive (typically 50, abrasive will start to grip the surface and jerk
100, or 200-grit) and attach it to the backer the machine. Apply more pressure to the
pad. Use the highest or finest grit abrasive tooling head, creating more friction and heat.
capable of effectively removing the The work area will completely dry out. As this
imperfection. This will decrease the steps happens, continue applying pressure while
necessary to achieve the desired result. increasing machine speed no higher than the
middle speed setting of approximately 3,500
5.4.2 After selecting the abrasive, place the RPMs.
machine flat on the surface and run the machine
in an even, consistent pattern across the 5.4.5 At this point, the work area should
working area. The first step is not completed start to show a polish but the color will appear
until the imperfection is removed. It may be muted or greyed in comparison to the rest of
necessary to pause and spray more water onto the countertop. The depth and clarity of the
the surface if a constant water supply is not reflection in the working area will be slightly
being used. Ensure that the edge of your diminished when compared to unworked

© 2022 Natural Stone Institute Restorative Processes • Page 21-63

areas. The surface is now ready for the use of for sealing when the desired level of polish and
polishing compound. depth of color are achieved.

5.4.6 There are several different types of 5.5 Cleaning and Polishing. Because
granite polishing compounds. Some are strictly granite holds up so well and rarely requires
abrasive products that contain aluminum or tin refinishing, technicians are often asked to clean
oxide. Others are creams that combine and polish granite countertops. In these cases,
chemical and abrasive technology. Regardless it is common to polish the entire countertop
of the type of compound used, most surface with a granite polishing cream using a
technicians use a hog’s hair burnishing pad that hog’s hair burnishing pad or a spray
is cut to fit the backer pad (pad driver) to finish polish/crystallizer with a steel wool pad. The
polishing the work area. hog’s hair pad or steel wool pad is cut to fit the
machine’s backer pad. Both processes remove
5.4.7 If a traditional powder is used, add grimy buildup that dulls a countertop. This
enough powder to cover the area. Spray with process enhances the color and shine of the
enough water to wet the powder slightly, then stone and restores the surface to the level of
place the machine on the wet powder. With finish the customer desires.
the dial set to the lowest speed, start the
machine. The process should produce a thick 5.6 Sealing (using an impregnating
slurry of polishing compound. As the slurry repellant). For sealing, refer to chapter 8 of
dries onto the surface, spray a small amount of this document (Sealers). In general, a simple
water to keep the surface and polishing water test on the surface of the stone will
compound wet. As the compound dries, add a determine its porosity. If the stone darkens
little more, apply pressure, and increase the when wet, sealing the stone can be beneficial.
speed of the machine. The added pressure will The general rule that applies to sealing stone is
cause friction and heat that creates a better to start with a thoroughly clean and dry floor.
polish. Follow the manufacturer’s recommendations
for applying their product. A majority of
5.4.8 If using a granite polishing cream or sealer-related problems are caused by not
paste, place a quarter-sized amount on the following directions properly.
surface of the work area for a section
approximately 8-inches in diameter. Attach a 5
or 7-inch (125 or 175 mm)foam backer pad to
6.0 CRYSTALLIZATION
the machine and use a hog’s hair burnishing pad
cut to fit the backer pad. Start the machine at 6.1 The term crystallization (also
the lowest speed to spread the product around known as vitrification and re-
on the surface in small sections. Use moderate crystallization) describes the act of polishing
pressure to work the product into the surface MTL and other surfaces containing calcium
in a linear or figure-8 pattern. As the heat carbonate. Crystallizers usually contain
generated by the machine dries the cream, magnesium hexafluorosilicate or a like
increase the speed of the machine and maintain compound. The compound is designed to react
a light pressure. After a few passes it may be with the surface of MTL and chemically etch a
necessary to increase the speed to the middle shine into the surface. Although the majority of
setting of approximately 3,500 RPMs and crystallizers are liquids, magnesium
burnish the surface to achieve the high-gloss hexafluorosilicate is naturally a solid white salt
deep color of a factory finish. It may take and is present in many commercial marble
multiple applications to achieve the desired polishing powders and pastes.
finish and depth of color. The surface is ready

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6.2 The polishing medium used during dust mop to remove all steel wool residue. If
crystallization is a hog’s hair pad, a white pad, the cleanup is not performed in a diligent
or a steel wool pad. Steel wool is the most manner, adding water from mopping and
popular polishing medium used to crystallize a maintenance will react with the steel wool
MTL surface. However, many newer products fragments and cause the floor to yellow and
have been introduced that can be successfully rust. This is usually seen on the edges of the
used with hog’s hair or white pads. When using tiles, in the grout, and sometimes on the
steel wool, the fragments left behind can rust surface of the stone.
causing staining to the stone and grout.
Vacuuming or using a magnetic broom should
always follow the use of steel wool to ensure
that all fragments are removed.
6.3 Popularity. Crystallization is
popular is because the average well-trained
maintenance professional can crystallize 300
(or more) square feet per hour. A steel wool
pad typically lasts 300 to 500 sq. ft. (~30 to 50
m2) when both sides are used. Crystallization
is performed with a janitorial swing machine
(also known as a janitorial buffer or floor
buffer). A drive plate with sufficient “grab” to
turn the steel wool is all that is needed. The
operator usually pours the crystallizer,
undiluted, into a chemical squirt bottle and sets
the nozzle to a medium mist.
6.4 Process. Start from the upper left of
a room or area (based on the revolutionary turn
of the machine) and work toward the door or
exit. Add a small amount of liquid to the
surface and move the machine with the
polishing media across it. Buff the surface until
the streaks and liquid disappear. The
movements should be overlapping to make
sure all spatter marks are removed. Most
technicians will work a 5 sq. ft. (0.5 m2) area
and work backwards, but some technicians
work larger areas. After a short period of time,
the steel wool pad will become loaded with
residue from the buffing process and removal
of excess crystallizer. When this happens, turn
the pad over and buff the area just completed
to remove final residue. The entire service area
will be treated in the same way.

6.5 Dust will settle on the floor after

polishing is complete. This is usually from the
steel wool used in the process. Clean the area
with a vacuum, magnetic broom, or microfiber
© 2022 Natural Stone Institute Restorative Processes • Page 21-65
NOTES:

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Restoration and solvent (“Carriers”) into the interior of the
stone. When cured, these compounds provide
Maintenance – resistance to stain sources or contaminants that
are water or oil-borne. Impregnating
SEALERS repellents minimally affect the stone’s color,
texture, or finish, and require a minimum level
1.0 INTRODUCTION of maintenance. They are composed mostly of
silicone-based chemicals and fluoropolymers,
1.1 Sealing is the process of applying and are ineffective against highly acidic or
chemical solutions—known as sealers—to alkaline chemical etching. They require the use
stone that, when cured, alter the inherent of pH-neutral cleaners. Most importantly, they
absorption qualities, increase the resistance to allow moisture vapor transmission (MVT),
staining, and/or alter the stone’s appearance which is the natural process of moisture
for aesthetic enhancement. transfer through the stone.

1.2 Sealing natural stone is a science 2.2 Color-enhancing Impregnators

involving knowledge from disciplines such as are a sub-category of impregnators that contain
geology, construction, chemistry, and a higher concentration of actives or solids that
maintenance. The larger question is, “Does darken and enrich certain natural stone colors.
stone have to be sealed?” The short answer is, They are more viscous in consistency, moisture
“No.” Before dimension stone was cut and sensitive, require greater care during
polished and set in a home or office, it was just application, and should be applied when the
a rock in the ground. There are millions of stone is as dry as possible. Be sure to consult
unsealed stone installations with which humans the manufacturer’s directions for specifics.
have interacted for hundreds, if not thousands, Color-enhancing impregnators also allow
of years. Why is stone sealing now common? vapor transmission (MVT). They accentuate
Modern consumers want to protect stone’s color and contrast, texture, and finish
appearance, reduce maintenance costs, and variations in the stone and grout and may
preserve the investment that stone surfaces create a light sheen.
represent.
2.3 Film-forming sealers (also known
1.3 Because of different performance as “coatings” or “topical coatings”) contain
goals, desires, and perceived acceptability for higher concentrations of actives compared to
stone use, there are different product offerings impregnating repellents or color-enhancing
in the market. The sealer product selection impregnators. The actives are deposited by a
needs to be made based on sealer type and carrier onto the stone’s surface, where they
other criteria as described within this cure and ultimately create a hardened film.
document. There are three basic categories of The film-forming sealer creates a sacrificial
sealers commonly used in the stone industry. physical barrier between the stone’s surface,
potential contaminants, and the environment.
They can consist of acrylic, urethane, and
2.0 TYPES AND epoxy chemical compounds.
CHARACTERISTICS OF SEALERS
2.3.1 Important Characteristics of
2.1 Impregnating Repellents (also Film-forming Sealers. Film-forming sealers
known as impregnators and penetrating protect the stone’s factory finish and diminish
sealers) are chemical compounds known as the effects of pedestrian and vehicle traffic.
“Solids” or “Actives” (a contraction for “active They can effect slip-resistance when wet,
ingredients”) that are carried by water or a unless combined with grit additives, and can

© 2022 Natural Stone Institute Sealers • Page 21-67

create various types of finishes, from matte to protection. Consult the manufacturer’s
high-gloss. Film-forming sealers can enhance documentation for information. Water-based
color, texture, and finish variations in the stone sealers are sensitive to lower temperatures, but
and grout. They are subject to abrasion, which less sensitive to higher moisture content in the
can breach the integrity of the protection the stone. Consult sealer manufacturer for specific
film-forming sealer affords and reflect the wear recommendations. Generally, water-based
patterns of foot traffic. In the presence of sealers are better for lower density stones with
Moisture Vapor Transmission (MVT) they higher porosity.
could turn milky white. Film-forming sealers
2.4.2 Actives. Also known as “solids,”
require additional cleaning steps and require
actives are the chemicals that penetrate the
the surface of the stone be maintained by high-
stone and cure a few millimeters below the
speed burnishing and/or recoating at regular
surface. They reside in the intercrystalline
intervals.
boundary areas and pores of the stone.
2.4 Sealer Components. Sealers are 2.4.2.1 Silicone-based chemicals are used
comprised of two main components: carriers primarily for repelling water or water-borne
and actives (also known as “solids”). The contaminants. This quality is commonly
primary carriers are water and solvent, and referred to as hydrophobic. The actives for this
new carriers are being tested regularly. category include silane, siloxane and silicone.
2.4.2.2 Fluoropolymers are used primarily
2.4.1 Carriers. The carrier component of a
for repelling oil or oil-borne contaminants.
sealer facilitates the delivery of the active
This is trait is commonly referred to as
ingredients to the interior of the stone.
oleophobic.
2.4.1.1 Solvent-based Carriers usually
2.5 General Characteristics of
contains higher amounts of Volatile Organic
Sealers.
Compounds (VOCs). Most solvent-based
sealers have strong, distinctive odors and 2.5.1 Sealing can alter the inherent
require the use of Personal Protective absorption qualities of stone, increase
Equipment (PPEs) and adequate ventilation resistance to staining, and/or alter the stone’s
during application and curing. Solvent-based appearance for aesthetic enhancement. In
sealers are sensitive to ambient air and surface certain situations, sealers can be employed to
temperatures. The stone should be dry. improve slip resistance.
Excessive moisture inhibits a sealers’ curing
and may also prevent adequate protection. 2.5.2 There are some conditions in which
What constitutes “a dry stone” needs to be sealing stone could be ineffective or dangerous.
defined by reading the instructions or Moisture, vapor, UV light, landscape, and
contacting the sealer’s manufacturer. chemical exposure are all variants that may
Generally, solvent-based sealers are better for render sealing inappropriate. For instance,
higher density stones with lower porosity.1 freeze-thaw conditions and standing water can
create slip hazards, and have the potential to
2.4.1.2 Water-based Carriers usually have damage material over time. Careful
less VOC components, less odor, and less consideration of the activities and the
environmental regulations concerning their manufacturer’s recommendations will aid in
use. They rarely require PPE, though the the selection and application of a sealer for a
method of application may require breathing particular installation.
1
Density is the weight of material expressed as its mass
divided by volume; porosity is the ratio of a stone’s
pores to its total volume.
Page 21-68 • Sealers © 2022 Natural Stone Institute
2.5.3 Sealers are maintenance products and chemicals and procedures, adequate drying
require periodic reapplication. Even though time, and proper application techniques are
some manufacturers warrant their sealers for critical to ensure a successful application.
certain time periods, because these sealers
dissipate and lose their protective quality as
time goes on, resealing is required. 3.0 DETERMINING THE
APPROPRIATE SEALER
2.5.4 Sealers do not alter a stone’s molecular
structure. In stone restoration work, a class of 3.1 After the decision has been made to
products known as consolidators and densifiers use a sealer, it is important to narrow the
do reintroduce mineralogical components lost offerings. When determining which sealer is
from the weathering process in order to slow best suited for a material, stone care
the natural deterioration of the stone. These professionals must take several factors into
products are not considered sealers. account. It is best to begin with the
identification of the stone’s geological
2.5.5 Depending on the type, sealers do classification and identify the protection
make stone surfaces more resistant to water, needed.
oil, contaminant and weather. Some sealers
repel both types of contaminants. However, 3.2 Geological Classification. Proper
they are not weatherproofing and stone identification is important when applying
waterproofing agents. They act as a barrier, but sealers. Each stone classification has
will break down through prolonged exposure performance parameters. These parameters
to contaminants. help establish the suitability of a particular
stone for the considered or existing
2.5.6 Sealer performance is not dependent installation.
on whether a product is solvent-based or
water-based. There are varying degrees of 3.2.1 Hardness is a measure of the
quality amongst the water-based and solvent- mineral’s resistance to scratching.
based sealer categories. The sealer’s quality is
based on purity of the carrier, quality of the 3.2.2 Permeability is the capability of a
actives used, and concentration of actives in the porous rock or sediment to permit the flow of
product. fluids through its pore spaces.

2.5.7 Sealer performance is dependent on 3.2.3 Chemical Sensitivity is a reaction

the type of stone, the demands on it, and the to acid or alkaline. Natural stone is categorized
location of the installation. Interior or exterior into three basic geological classifications by
location, traffic levels, and climate extremes of their respective formation processes:
the installation are contributing factors to sedimentary, metamorphic and igneous.
product performance and will help determine Additionally, stones in each category can be
the sealer selected. Tests should be conducted either calcareous or siliceous, based on their
to ensure the right sealer is matched mineral components. These mineral
appropriately to a particular stone and components determine the reactiveness of the
application. stone to acid or alkaline solutions.

2.5.8 Sealer performance is only as good as 3.2.3.1 Calcareous Stone is composed

the technician applying it. Following the mainly of calcium carbonate, a chemical
manufacturer’s directions is the best way to compound commonly found in natural stone,
ensure a successful result. Thorough cleaning shells, and pearls. Calcium carbonate is
and preparation of a stone with approved

© 2022 Natural Stone Institute Sealers • Page 21-69

sensitive to acidic solutions, so mild, non- Understanding the various types of
acidic cleaners are recommended. contaminants and the environmental impact on
stone applications will provide the information
3.2.3.2 Siliceous Stone is composed
to decide the appropriate sealer. The product
primarily of silicates such as quartz, feldspar,
performance expectations must be realistic. It
and mica. As such, siliceous stone is generally
is important to note that neither impregnating
resistant to most acids found in kitchen
repellents nor film-forming sealers can prevent
settings. Acidic cleaners are still not
normal weathering and deterioration from
recommended, because these stones may
normal traffic and use.
contain trace levels of minerals that are
vulnerable to acid attack, or the cleaners may
3.4.1 Residential and Commercial
contain levels of one of the few acid types that
Interiors. Always identify the possible
attack silicates such as hydrofluoric acid (e.g.,
sources for stains, evaluate the materials,
toilet bowl cleaners, rust removers, chrome
stones, and sealers relative to the activities and
wheel cleaners, plant food and wood
stain sources present, and determine suitability
treatments containing ammonium bifluoride).
of masking adjacent surfaces prior to sealing.
Geological Classification Chart
Sedimentary Metamorphic Igneous 3.4.1.1 Considerations for Residential
Limestone Interiors. The type of stone and susceptibility
Marble
Calcareous Travertine
Serpentine to reaction, abrasions, and other breakdown
Onyx should always be considered, especially when
Slate working with polished marble and granite or
Siliceous Sandstone Quartzite Granite
Soapstone
honed travertine and limestone. The use area
should also be considered, especially in high-
traffic areas such as kitchens, family rooms, and
3.3 Appropriate Material for the
bathrooms/showers. Other factors to consider
Intended Use. An analysis of whether the
in residential applications include: family size,
stone is suitable for the proposed use or
pets, and associated use; foods and liquids
existing installation is important. First, the
(lemon, vinegar, wine, juices, and oils);
environment needs to be identified. This is
cleaning chemicals (toilet bowl cleaners and
often done by consulting plan specifications
citrus cleaners); and personal toiletries (lotion,
and post-construction manuals and talking to
shampoo, conditioner, hand soap).
sources such as the homeowner or tenant,
building or maintenance manager. Once the
3.4.1.2 Considerations for Commercial
nature of the use or environment is
and Industrial Interiors. Factors to
determined, stone professionals can help
consider in commercial and industrial interiors
specify materials best suited for that use or
include: issues caused by luggage, bell carts,
environment. Possible sources to determine
dollies, and other equipment; water features
suitability can be the stone supplier, a stone
and fountains; interior landscaping; proximity
maintenance and restoration contractor, an
to food courts, restaurants, and common areas;
installation contractor, a stone geology
maintenance practices and needs; slip
resource, or NSI.
resistance and safety; increased volume and
traffic patterns; and sealer odors multiplying
3.4 Determining the Potential
through HVAC systems.
Source of Staining or Problems.
Residential homes require some different care
3.4.2 Exteriors
and considerations than commercial or
industrial buildings. Because of the different 3.4.2.1 Considerations for Exterior
elements of exposure, interior stone behaves Applications. Vapor transmission must be
differently from exterior stone.
Page 21-70 • Sealers © 2022 Natural Stone Institute
achieved in exterior applications. A lack of 3.5.1 Performance Expectations. There
vapor transmission can lead to spalling and can be a trade-off between appearance and
other issues. Several other things must be taken functionality. For instance, a film-forming
into consideration for exterior applications, sealer provides protection against chemical
including: biological growth (moss, algae, exposure to the stone, but usually gives the
lichen, and mold), environmental conditions surface a plastic-like look. Each installation is
(freeze-thaw, salt water, high water tables, unique and the sealer selection will require
acid rain, pollution, UV exposure, and cold consideration of a number of variables, as listed
weather treatments such as grit or salt), vehicle in the next section.
stain sources (oils, antifreeze, and rubber
marks), pitch of surface (should be 2%), 3.5.2 Factors to Consider. Impregnating
landscape, fertilizer run-off, irrigation, and repellents are best for maintaining a stone’s
water run-off systems. natural appearance. Color-enhancing
impregnators best enrich a stone’s color and
3.4.2.2 Further Considerations for character. Film-forming sealers are best for
Exterior Applications. Exterior creating low-gloss, semi-glass, and high-gloss
installations are unique, because they will finishes.
interact with climate and environmental forces
as well as human activities. It is important to 3.6 Determining the Desired Level
consult with manufacturers to determine their of Maintenance. Maintenance costs are
sealer’s suitability with the stone and often overlooked in the process of selecting a
installation. A sealer’s resistance to ultraviolet stone and sealers. Maintenance is the most
light degradation impacts its effective lifespan. important factor in preserving the appearance
In order to prevent freeze/thaw issues, a sealer and protection of a sealed stone. The client’s
used in an exterior installation should have an expectations need to be clarified in order to
acceptable percentage of Moisture Vapor best assess the material and sealer for the desire
transmission (MVT). outcome. Use and traffic, compounded with
sealer choice and material used, can all affect
3.5 Determining the Desired maintenance needs.
Finished Appearance. The choice of the
final appearance of the stone is driven by 3.6.1 Residential Clients typically expect
aesthetic considerations, which will be a high level of presentation, but may fail to
determined by an architect, interior designer, consider preservation requirements. It is
and/or the owner of the property. Aesthetics important to set achievable expectations. Many
is a major determinant in sealer selection. As residential clients want a material that usually
mentioned above, different sealer types requires a high level of maintenance to be
provide unique options for appearance. maintenance free. Residential environments
Impregnating repellents provide resistance to are typically maintained on a sporadic basis,
staining while retaining the natural appearance depending on the commitment of the owner to
and beauty of stone. Color-enhancing the cleaning process.
impregnators can darken or bring back the
color of polished stone to stone that has been 3.6.2 Commercial Clients, Such as
textured or honed. Film-forming sealers Hotel Facilities Managers, are often
provide a mechanical or physical barrier concerned about cost, durability, and safety.
between the stone and potential stain sources. There are times when these clients have similar
Film-forming sealers will also alter the natural desires to the residential client, but there is
appearance of a stone, changing sheen of the usually very little emotion tied to their
surface from a matte finish to a reflective finish objectives. Commercial environments are
or from a reflective finish to a matte finish. typically maintained on a daily basis by either

© 2022 Natural Stone Institute Sealers • Page 21-71

in-house personnel or contracted cleaning 4.0 BUDGETARY CONCERNS
firms.
4.1 Points to Consider. End users need
3.6.3 Guidance in Sealer Selection. to be informed about the projected
Type of sealer used and installation location maintenance costs. Facility managers need
will dictate the level of maintenance needed. information regarding regular scheduled visits
Maintenance refers to regular periodic cleaning and the associated costs. Commercial and
with the appropriate products and procedures. industrial applications need regular
The installation type determines the cycle of professional maintenance; and require daily or
cleaning. nightly cleaning as an ongoing service.
Maintenance charts, lists of acceptable
3.6.4 Maintenance Needs. Maintenance products and equipment, training material and
charts, lists of acceptable products and training sessions with cleaning companies.
equipment, training material, and training Follow up visits by a stone care professional to
sessions with cleaning personnel are important ensure that the proper maintenance program
in developing a realistic plan to sustain the has by followed.
service life of the sealed surface. Sometimes
the cleaners recommended for use on stone
with an impregnating repellent will contain 5.0 FIELD TESTS FOR
small amounts of the sealer. This will help DETERMINING SEALING NEEDS
increase or eliminate the interval for
reapplication. Check the specific product 5.1 Performing field tests is a common
manufacturer’s guidelines as to the industry practice for stone professionals. Most
maintenance of their products. A thorough consider water absorption as being an
understanding of an end user’s expectations important test, especially if the surface is
involves balancing form and function when exposed to water and water-borne
applying sealers and because each installation is contaminants. Water beading on the surface is
unique, sealer selection involves the not indicative of a sealed stone. The beading of
consideration of multiple variables. water demonstrates the properties of surface
Impregnating repellents provide longer-term tension. For example, water will react
protection and are less costly, due to their less- similarly when applied to factory resin-coated
frequent maintenance needs. Also, there needs or enhanced stones and denser stones with
to be periodic reevaluation of methods based tighter mineralogical matrices. It is important
on product and technique advancements. to note that some natural stones may not
require sealing, and can even be negatively
3.6.5 Determining the Tolerance for impacted if sealed. This negative impact is the
Volatile Organic Compounds (VOCs). result of the product not being absorbed in to
Most solvent-based sealers have strong, the stone and drying on the surface. This is a
distinctive odors and require the use of correctable error, but it requires reactivating
Personal Protective Equipment (PPE) and the product with a solvent and removing the
adequate ventilation during application and residue while the product is in the reactivated
curing. If adequate ventilation is impossible state.
during the application and curing process, then
VOCs must be considered when deciding the 5.2 Selecting the Test Specimen. It is
appropriate sealer. Even when there is better to test a sample of the exact material
adequate ventilation, the use of personal (same stone and lot) than to risk damage to the
protective equipment is still recommended. installed material. The main negative issue
with sample testing is the lack of the exact same
history of the installed material after use.
Sometimes inconspicuous areas, such as
Page 21-72 • Sealers © 2022 Natural Stone Institute
closets, also lack chemical treatments that may amount of time left on the surface. Add any
have been applied to the conspicuous areas. If other important information such as moisture
the issue can be duplicated on a sample or an levels and temperature.
inconspicuous area, then proceed by testing the
sample or the inconspicuous area. To be sure 5.7.2 Label Test Area. Use a permanent
that each sealer is given a fair chance it is marker on the label. Make sure that the marker
recommended to determine that each sample or any label adhesive does not stain the stone.
or area has similar mineral and porosity Include things that identify the whole area and
characteristics. To keep chemical wicking quadrants (measurement marks can also be
from affecting your tests, be sure to physically used with axis labels).
separate or allow enough distance between test
areas. 5.7.3 Exposure. Determine the length of
exposure to each contaminant. If it is likely that
5.3 Recommended contaminates for the area may not be cleaned for a week, then
basic field testing include: oils (corn, olive, the exposure time needs to be a week or more.
coconut, or others that may come in contact On countertops, where they are likely cleaned
with the stone), water (or water-based multiple times throughout their use, an
contaminants such as tea or coffee), acids exposure of 8 to 24 hours should be sufficient.
(vinegar, citrus, fruit juice, etc.), red wine, or
any other contaminant that may come in 5.7.4 Execute the Field Test in the
contact with the stone. Following Manner. Ensure surface is clean
and dry. Apply an adequate, measured amount
5.4 Preparation of the Stone. Clean of the contaminant to the surface (for example:
the stone with a neutral pH stone cleaner and 1/2 teaspoon of water, oil, or vinegar). Allow
allow to dry for 24 hours or until thoroughly the contaminant to dwell on the horizontal
dry. Be sure to follow the preparation surface for five minutes or longer (as
procedures recommended by the manufacturer mentioned above). Ideally the contaminant
of the sealer. (with the exception of acid) will be repelled for
no less than ten minutes when placed on a
5.5 Application of Sealers. Sealers properly cured sealer. Remove the
should be applied according to manufacturer’s contaminant by blotting the area. Do not wipe
instructions. To get proper protection more to dry. Carefully exam the test area directly
than one application may be necessary. afterwards and again later.

5.6 Cure Time. Allow appropriate cure 5.7.5 Results. After the predetermined
time per the manufacturer’s exposure time has been reached, clean
recommendations. specimens with a neutral pH stone cleaner.
Allow the area to dry once contaminant is
5.7 Test Procedures. Stone care removed (approximately 20 minutes for initial
professionals must understand how to properly review and sometimes after a day or more
perform informal field tests. Testing is the best depending on the results). Visually evaluate
way to learn how the specific product or and log results. A successful stone/ sealer test
products will perform in a real life setting. would show no absorption, no staining, and no
etching. If the stone turns darker, it will stain
5.7.1 Record Keeping. Prepare a written if not sealed. If the stone turns dull and whitish
and photographic log to document the test in color, then the stone is likely to etch.
methods and results. Note date, time intervals, Another possibility is that an acidic solution can
test area, and quadrant. Identify each disturb the impregnating repellent that has
contaminant tested, the quantity, and the been applied to a very dense stone so it appears

© 2022 Natural Stone Institute Sealers • Page 21-73

whitish. In this last scenario, the difference is provides counsel and evidence regarding which
that it still has polished reflection. sealers would best preserve a stone’s condition
and presentation, and meets the end user’s
5.7.6 Etch Test. When working with an needs.
unidentifiable stone, the etch test will confirm
if the stone is calcium carbonate based. To 6.2 Important Points to Remember.
perform the etch test the stone care Sealers are water, oil, dirt, contaminant, stain,
professional should use an acid that is and weather resistant agents only. Sealers
commonly used around the stone on different minimize the effects of harmful contaminants,
areas of the stone. Serpentines will typically making end-user care and professional
only react to mild acids in the calcium maintenance easier and less costly. Sealers are
carbonate-based veins. It is recommended to most effective when paired with the
test a sample of the same material and lot if appropriate stone and substrate. Sealers
possible. If the stone reacts to the acid, it will applied to stone used in exterior and wet
need to be restored to the original finish. environments can alter the dynamic coefficient
of friction. Appropriate tests should be
5.7.7 Other Things to Consider. Only performed to determine suitability prior to
perform these tests in an inconspicuous area or application. Sealers can minimize and slow the
on an uninstalled sample tile. It is important to effects of biological, chemical, and physical
note that impregnating repellents will not interior and exterior weathering and their
repel acidic liquids like vinegar, lemon juice, byproducts, such as exfoliation, fracturing,
red wines, tile cleaners, and so on. In fact, frost or salt-wedging, movement, oxidation,
acids will damage the surface. Be prepared to slaking, sugaring, etc., but cannot prevent
repolish the surface after testing with acidic them from occurring. No natural stone
liquids. Topical sealers are much more installation is maintenance-free.
effective at repelling acidic liquids.

6.0 FINAL THOUGHTS ABOUT

SEALERS
6.1 The stone care professional plays a
critical role in determining the selection of
sealers. The desired appearance, functionality
and maintenance required are all important
considerations in the selection process.
Whether involved with new construction or
maintaining an existing structure, it is
important to consult with others involved in
the natural stone industry, understand the role
of the specifying authority, and the various
aspects of stone behavior in relation to
environmental suitability to ensure the
information provided is thorough, accurate and
beneficial. The consummate professional is
educated and experienced and has a thorough
working knowledge of natural stone, sealers
products, and the effects of various
environments. The stone care professional
Page 21-74 • Sealers © 2022 Natural Stone Institute
Restoration and 3.1 Polished-finish Stone has a glossy
surface that provides clear reflections and
Maintenance – accentuates the color, contrast, and character
of the material. Due to abrasion from foot
MAINTENANCE traffic, soft stones with a polished finish will
generally wear to a dull surface. Due to varying
1.0 INTRODUCTION hardness of the minerals that comprise the
stone’s fabric, uniform gloss and/or
1.1 This section will provide end users reflectivity may not always be achieved in all
with basic information pertaining to natural stones.
stone maintenance. Since general specifications
and finishes of natural stone affect cleaning 3.2 Honed-finish Stone has a smooth,
procedures, this section will include an overall matte surface with limited reflection. This
description of the most common stone finish is generally preferred for softer stone
specifications and finishes. It is important to varieties used for floors, treads, thresholds,
also acquire background data on the individual and other pedestrian locations where heavy
stone(s), such as type and source of stone, type traffic would dull a polished finish. Its lack of
of sealer used (if any), and recommendations of gloss makes it a more forgiving surface in that
sealer manufacturers as to care of sealed stone, unevenness or waviness will not be as easily
etc. detected. Due to varying hardness of the
minerals that comprise the stone’s fabric,
2.0 SLIP RESISTANCE OF uniform gloss and/or reflectivity may not
STONE FLOOR SURFACES always be achieved in all stones.

2.1 In commercial environments it is 3.3 Maintenance. Regular cleaning

important to maintain a log detailing daily and should be scheduled, using specific procedures,
periodic maintenance. This log should products, and equipment. Inspections should
document the procedures followed on days of be performed at prescribed intervals.
inclement weather, such as rain or snow.
3.4 Restoration involves the refinishing
2.2 The Americans with Disabilities
of existing stonework to return its appearance
Act (ADA). This federal legislation, passed in
to that of a newly supplied, unworn product.
1990, is the most comprehensive civil rights
This process may include minor repairs such as
legislation adopted to prohibit discrimination
filling of chips or pits in the stone surface,
against people with disabilities. Public and
replacement of cracked or missing grout,
private businesses, state and local government
removal of stains and/or etching, and honing
agencies, and private entities offering public
or polishing.
accommodations and services, transportation,
and utilities are required to comply with the
3.5 Purpose and Benefits of
law. At one time, ADA documents prescribed
Maintenance.
a recommended minimum coefficient of
friction for walkway surfaces in accessible
3.5.1 Appearance. Efficient regular
routes of commercial and public buildings, but
cleaning removes fine particulates, which can
the section of the ADA documents that
abrade and dull the surface of the stone over
contained this recommendation have since
time.
been withdrawn.

3.0 DEFINITIONS, PURPOSE, 3.5.2 Sustainability. Proper maintenance

will lengthen the stone’s service life,
AND BENEFITS OF STONE
effectively delaying the need for more
MAINTENANCE
© 2022 Natural Stone Institute Maintenance • Page 21-75
aggressive restoration methods or water used and the dwell time water is allowed
replacement. on the stone surface.

3.5.3 Safety. A properly maintained stone 4.2.2 Adhesives. Some adhesives may be
surface that is free of contaminants will provide adversely affected by some cleaning agents.
a safer walking surface with better, and more
uniform traction available for occupant 4.2.3 Grout. Various products are used for
ambulation. grouting joints (e.g.: cement, cement with
additives, and epoxy), all of which have unique
4.0 CONDITIONS INFLUENC- maintenance and sealing requirements.
ING MAINTENANCE
4.2.4 Joint Sealant. Different elastomeric
4.1 Stone type will determine necessary materials are used to caulk joints in finished
methods and frequency of maintenance. stonework (e.g.: silicone, urethane, acrylic),
Knowledge of the stone’s properties will aid in each of which have unique performance traits
designing a maintenance program. For and maintenance requirements.
example, granite is a very hard stone with little
absorption capacity, while limestone has a 4.3 Characteristics of Certain
softer composition and a greater absorption Stones. Many stones have unique features,
capacity. The stone properties will also such as fillers, voids, or repairs, which
influence the selection of appropriate sealing influence maintenance practices.
products. For maintenance purposes, specific
groups of stones should be considered in order 4.4 Condition of Stone Installation.
to properly maintain them. Residual issues from the initial installation or
previous restoration attempts, such as lippage,
4.1.1 Group 1. Stones that typically do not scratches, etch marks, acid burn marks, and
contain calcium carbonate and typically do not cracks will influence maintenance needs or
react to most common acids: create a requirement for subsequent
• Igneous rocks: granite, basalt restoration activity.
• Metamorphic: slate, gneiss, schist
4.5 Location of Installation.
• Volcanic: Adoquin, Canterra
4.5.1 Interior. Whether residential or
4.1.2 Group 2. Stones that contain calcium commercial, interior surfaces require careful
carbonate and typically react to common, mild consideration of the surrounding materials.
acids: Maintenance can impact adjacent surfaces such
• Calcite: marble, travertine, as floor molding, furniture, other stone
limestone, onyx, terrazzo surfaces, wall coverings, and painted walls.
Care must be taken to protect these surfaces or
4.2 Installation Methods and use materials that will not impact their
Related Components. appearance or function.

4.2.1 Substrate. The rigidity and quality of 4.5.2 Exterior installations require the
the substrate may affect not only the same attention to adjacent surfaces as interior
performance of the stone, but also the settings. Additional attention must be paid to
necessary maintenance. Some substrates are landscape, vegetation (plants, bushes and
very vulnerable to water infiltration, so trees), and water runoff. Check federal, state,
maintenance methods must limit the amount of and local codes for building, safety, and
environmental requirements.

Page 21-76 • Maintenance © 2022 Natural Stone Institute

4.5.3 High Rise Claddings. Cladding debris, dirt and fine particulate matter.
restoration is a specialty area due to the Vacuuming is the preferred method because it
difficulty of access and potential influence to lifts abrasive materials up and away from the
building seals and curtainwall performance. floor. Dust mops should be dry and untreated.
Adjacent materials, such as joint sealers and
aluminum and glass curtainwall wall 5.3 Weekly maintenance involves
components must be protected from damage washing with clean, potable water and pH
by chemical or abrasive cleaning methods used neutral cleaners. Soapless cleaners are
on the stone panels. preferred because they minimize streaks and
film. Mild, phosphate-free, biodegradable
5.0 MAINTENACE METHODS liquid dishwashing soaps or powders or stone
soaps are acceptable if rinsing is thorough.
FOR RESIDENTIAL CLEANING
5.1 Products and Equipment. 5.3.1 Process. Wet the stone surfaces with
clean water. Using the cleaner (following
5.1.1 Products. Use only stone cleaners or manufacturer’s directions), wash in small,
pH neutral cleaners. Some stone cleaners also overlapping sweeps. When using the brush
contain small amounts of sealer. These apply light pressure so that only the ends of the
products help to maintain the level of bristles are doing the scrubbing. Work from
protection. the bottom up if it is a vertical surface. Rinse
thoroughly with clean, potable water to
5.1.2 Equipment. New equipment is being remove all traces of soap or cleaner solution.
developed continually to clean stone surfaces. Change the water in the rinse pail frequently.
Common equipment used includes: Dry with a soft cloth and allow to thoroughly
• A small canister vacuum with non- air dry. Alternatively, employ the use of a wet
metallic wheels and a flat floor head vacuum to extract contaminants. In
with soft bristles made of nylon or commercial applications with high traffic
horsehair, or a smooth felt liner along levels, the use of an automatic scrubber fitted
the bottom edges. Metal attachments with a disc-type brush system and continuous
should never be used. extraction is generally the most effective
method. Brush aggressiveness must be matched
• Clean cotton string or sponge mop.
to the stone type and hardness to prevent
Dirty mop heads are a major source of
damage.
residual soil on the floor.
• Plastic buckets. Never slide the bucket 5.4 Safety Precautions. Any flooring
on the floor. If the bucket has wheels, surface, regardless of its finish, can be slippery
they should be non-metallic and non- when wet. Promptly remove liquids or foreign
marring. materials that might result in safety hazards
• In-home steamers. Steamer head rags before permitting pedestrian traffic. Use
should be changed frequently. warning cones or other means of alerting
• Small scrub brush and/or a deck occupants to a temporary reduction in traction.
brush. Bristles should be soft nylon to
reduce scratching. 5.5 Precautions. For counter or table
tops, use coasters under all glasses, particularly
5.2 Daily Maintenance. The removal those containing alcohol or citrus juices. Many
of dirt, debris, and dust is essential to common foods, drinks, and cosmetics contain
maintaining the appearance of the floor. All acids that will etch or dull stone surfaces. Use
stone flooring should be dust mopped or trivets or mats under hot dishes and placemats
vacuumed daily or as necessary to remove under china, ceramics, silver, or other objects

© 2022 Natural Stone Institute Maintenance • Page 21-77

that can scratch the surface. Blot spills with a 6.1.2 Metamorphic Rocks (slate,
paper towel or cloth as they occur or as soon as gneiss, and schist).
possible thereafter. Clean regularly with a • Clean daily, using methods outlined in
neutral cleaner that does not contain solvents. section 5.0.
• Yearly (for floors and stairs): Scrub
5.5.1 In food preparation areas, stone floors with a standard 175 RPM
surfaces may require an impregnator or topical
buffer, using a soft nylon brush and a
sealer. If an impregnator or topical sealer is
applied, it must be nontoxic and safe for use on neutral cleaner. An automatic
food preparation surfaces. scrubber machine can be used for
larger floors. For stairs, use a slow
5.5.2 Never use acidic or ammoniated speed hand polisher.
cleaner or chemicals on calcium carbonate- • The stone and/or grout may need
based stone surfaces. Use a cleaner specifically resealed at intervals of 2 to 5 years. See
formulated for stone cleaning. section 9.0 for more information on
sealing.
5.6 Heavy Duty Cleaning. High traffic
areas such as kitchens may require a yearly deep
cleaning and resealing. This requires the use of 6.1.3 Volcanic Rocks (adoquin and
floor machines, brushes, and specialized pads. canterra).
• Clean daily, using methods outlined in
6.0 MAINTENANCE METHODS section 5.0.
FOR COMMERCIAL CLEANING • Yearly (for floors and stairs): Scrub
AND SEALING floors with a standard 175 RPM
buffer, using a soft nylon brush and a
6.1 Group 1 includes stones that typically neutral cleaner. An automatic
do not contain calcium carbonate and typically scrubber machine can be used for
do not react to most common acids.
larger floors. For stairs, use a slow
speed hand polisher.
6.1.1 Igneous Rocks (granite and
basalt). • The stone and/or grout may need
• Clean daily, using methods outlined in resealed at intervals of 2 to 5 years. See
section 5.0. section 9.0 for more information on
• Yearly (for floors and stairs): Scrub sealing.
floors with a standard 175 RPM 6.2 Group 2 includes stones that typically
buffer, using a soft nylon brush and a contain calcium carbonate and react to acids.
neutral cleaner. An automatic These calcite stones include marble,
scrubber machine can be used for travertine, limestone, onyx, and terrazzo.
larger floors. For stairs, use a slow
• Clean daily, using methods outlined in
speed hand polisher.
section 5.0.
• Stone and/or grout may need to be
• Twice yearly: Scrub floors with a
resealed at intervals of 3 to 5 years. See
standard 175 RPM buffer, using a soft
section 9.0 for more information on
nylon brush and a neutral cleaner. An
sealing.
automatic scrubber machine can be
• Extremely worn or damaged surfaces used for larger floors. For stairs, use a
will require restoration rather than slow speed hand polisher.
standard cleaning.
• Stone and/or grout may need to be
resealed at intervals of 2 to 3 years See
Page 21-78 • Maintenance © 2022 Natural Stone Institute
 section 9.0 for more information on maintenance should include periodic
sealing. inspection of stone surfaces for structural
• Extremely worn or damaged surfaces defects, movement, deterioration, or staining.
will require restoration rather than Distress in joint fillers is a common sign of
standard cleaning. stone unit or substrate movements.

6.2.1 Maintaining Finishes on Calcite 7.2.1 The large expanses of stone generally
Stones. found on exterior applications may make it
impractical to perform frequent normal
6.2.1.1 Polished Surfaces. Buff the stone maintenance. Large installations, however,
with a slurry of water and a non-acid polishing should be given periodic overall cleaning to
compound. Specialized diamond impregnated remove accumulated pollutants. If the exterior
pads can also be used, using a standard 175 stone surface has calcium deposits, an acid
RPM buffer or a high-speed burnisher. cleaner can be used on igneous rocks only.
Combining the compound with a diamond Easily accessible stone surfaces such as steps,
impregnated pad may produce a higher-gloss walkways, and fountains should be kept free of
finish. A slow speed hand polisher can be used debris and soiling by periodically sweeping and
for stairs, walls, and tops. This should be done washing with water.
four times a year, or as needed.
7.3 Local Regulations. Many local
6.2.1.2 Honed Surfaces. Buff the stone with municipalities have regulations related to water
a slurry of water and a non-acid honing use and chemical disposal. Always check these
compound. Specialized diamond impregnated regulations and authorizations before bidding
pads can also be used, using a standard 175 on such cleaning projects; in some cases, there
RPM buffer or a high-speed burnisher. are additional costs associated with these
Combining the compound with the diamond regulations.
impregnated pad may produce a better honed
finish. A slow speed hand polisher can be used 8.0 EXTERIOR BUILDING
for stairs, walls, and tops. This should be done STONE CLEANING
four times a year, or as needed.
8.1 Exterior building stone is
7.0 MAINTENANCE METHODS considered in this section to be all stone used
on the exterior of a structure, either as a
FOR EXTERIOR STONE
structural component or as a facing material,
7.1 Exterior stone is a general term with the exception of polished, finished
denoting stone installed where temperature, marble. Although a polished finish is not
moisture, and airborne contaminants are recommended for exterior use with most
caused primarily or solely by forces of nature. marble varieties, it is occasionally used on
It can be used in a honed, textured, or polished storefronts, column facings, and similar
finish in any mode in an exterior environment. treatments.
Uses include building cladding, walkways,
steps or stairs, retaining walls, paving, 8.2 Regular Cleaning. The ideal in
fountains, benches, planters, and decorative maintaining exterior building stone is to clean
items such as sculptures. it at periodic intervals (at least annually,
depending on atmospheric conditions) by
7.2 Normal Maintenance. In accessible simply hosing down with clean water. This will
areas, routinely follow maintenance prevent accumulation of dirt and impurities. In
procedures as specified in Sections 5.0 and 6.0 accessible areas, routinely follow maintenance
of this chapter, as applicable. Normal procedures as specified in Sections 5.0 and 6.0

© 2022 Natural Stone Institute Maintenance • Page 21-79

of this chapter, as applicable. Brushes may be also oleophobic (oil-repelling). They penetrate
necessary for the removal of certain surface below the surface and become repellents. They
impurities. Soft fiber brushes are keep contaminants out, but do not stop interior
recommended. moisture from escaping. Impregnators are
considered breathable, meaning they have
8.3 Sporadic Cleaning. If the stone is vapor transmissibility.
not cleaned regularly, a water system
(hydraulic, hydro-air, or plain water) will be 9.3 Treatment Type. The type of stone
the most effective method at the lowest cost. and environment of the application determine
the type of sealer treatment (impregnator or
8.4 Dirt on Older Buildings. When topical) to be used. All treatments must be
dirt has accumulated on older structures over a applied in accordance with the manufacturer’s
long period of time, a combination of methods specifications.
may be necessary to properly clean the stone.
A plain water jet will remove most 9.4 When to Seal. A treatment may be
accumulation. No chemicals should be used used when a defined benefit can be
that could be harmful to the stone. determined. For example:
• When the risk of staining is present
8.5 Test Panels. By cleaning and • As an aid in daily maintenance
inspecting test panels, the Specifying Authority procedures
can determine if the method is satisfactory.
• Where a coating may help to preserve
This procedure eliminates the possibility of
the stone finish in excessively high
improper cleaning; since the Owner and
wear conditions
Specifying Authority can see what results will
be obtained prior to commencement of the • Where weathering has affected or may
total contract. It also gives the Cleaning affect the integrity of the stone surface
Contractor a standard to work toward, making • To prolong the aesthetic beauty of the
definition of the cleaning more specific for all original installation
parties. • Where the risk of graffiti or other
vandalism is high.
8.6 Local Regulations. Many local
municipalities have regulations related to water 10.0 STAINS AND REMOVAL
use and chemical disposal. Always check these PROCEDURES
regulations and authorizations before bidding
on such cleaning projects; in some cases, there 10.1 Oil-based Stains (grease, tar,
are additional costs associated with these cooking oil, cosmetics). An oil-based stain
regulations. will darken the stone and normally must be
chemically dissolved so the source of the stain
9.0 TOPICAL SEALERS AND can be flushed or rinsed away. First, remove
IMPREGNATORS excess staining agent by wiping or chipping (if
tar). Clean gently with a liquid cleanser,
9.1 Topical sealers are coatings household detergent, ammonia, mineral
designed to protect the surface of stone against spirits, or acetone. Do not pour cleaner
water, oil, and other contaminants. They are directly on the staining agent, as this can thin
formulated from natural wax, acrylic, and the contaminant and further its penetration and
other plastic compounds. spread. Partially saturate a paper or cloth towel
with the cleaner and attempt to draw the stain
9.2 Impregnators (penetrating into the towel. Commercially available
sealers). Impregnators are generally
hydrophobic (water-repelling), but some are
Page 21-80 • Maintenance © 2022 Natural Stone Institute
specialty cleaners, such as alkaline degreasers 10.6 Paint Stains. Small amounts of paint
and/or poultices may also be used. can be removed with lacquer thinner or
scraped off carefully, using a razor blade.
10.2 Organic Stains (coffee, tea, fruit, Heavy paint coverage should be removed with
tobacco, paper, food, urine, leaves, a commercial liquid paint stripper. Other
bark, animal droppings). Organic stains methods to remove paint would include baking
may cause a pinkish-brown stain and may soda blasting or glass bead blasting. These
disappear after the source of the stain has been methods should be undertaken by experienced
removed. Outdoors, with the sources professionals. Begin by testing a small area to
removed, normal sun and rain action will determine the efficacy of the method. Do not
generally bleach out the stains. Indoors, clean use acids or flame tools to strip paint from
with 12% hydrogen peroxide and a few drops stone. Use of solvents can potentially drive the
of ammonia. Commercially marketed cleaners stain further into the stone.
and poultices are also available.
10.7 Water Spots and Rings (surface
10.3 Inorganic Metal Stains (iron, accumulation of hard water). Buff with
rust, copper, bronze). Iron or rust stains dry steel wool.
are orange or brown and leave the shape of the
staining object, such as nails, bolts, screws, 10.8 Fire and Smoke Damage. Older
cans, flowerpots, or metal furniture. Copper stone surfaces and fireplaces stained by smoke
and bronze stains are green or muddy brown or fire may require a thorough cleaning to
and result from the action of moisture on restore their original appearance.
nearby or embedded bronze, copper, or brass Commercially available smoke removal
items. Metal stains must be removed with a products may save time and effort. Calcareous
poultice (see Section 11.0 of this chapter). stones may also require refinishing due to
Deep-seated rust stains are extremely difficult etching from carbonic acid.
to remove, and the stone may be permanently
stained. 10.9 Etch Marks are caused by acids left
on the surface of the stone. Some will etch the
10.4 Biological Stains (algae, mildew, finish but not leave a stain; others will both etch
lichens, moss, and fungi): Clean with and stain. Once the stain has been removed,
diluted [1⁄2 cup per gallon of water (32 wet the surface with clean water and sprinkle
ml/liter)] ammonia, bleach, or hydrogen with polishing powder. Rub the powder into
peroxide. Do not mix bleach and ammonia; the stone with a damp cloth or by using a
this combination creates a toxic gas. There are buffing pad with a low-speed power drill or
a number of commercial products available polisher. Continue buffing until the etch mark
that are as effective as ammonia, bleach, or disappears and the surface shines. Honing may
hydrogen peroxide without the potentially be required for deep etching. This process may
hazardous downside. require the services of a professional refinisher.

10.5 Ink Stains. Clean light-colored 10.10 Efflorescence is caused by water

stones with bleach or hydrogen peroxide. Use carrying soluble salts from below the surface of
lacquer thinner or acetone for dark-colored the stone. The salts are deposited and
stones. Do not pour cleaner directly on the recrystallize upon evaporation of the water,
staining agent. This can thin the contaminant leaving a powdery salt residue. If the
and further its penetration and spread. Partially installation is new, dust mop or vacuum the
saturate a paper or cloth towel with the cleaner powder. Repeat as necessary as the stone dries
and attempt to draw the stain into the towel. out. Do not use water to remove the powder.
If the problem persists, contact the contractor

© 2022 Natural Stone Institute Maintenance • Page 21-81

to identify and remove the cause of the 11.6 Allow the poultice to dry thoroughly;
moisture. this usually takes 24 to 48 hours. The drying
process draws the stain out of the stone and
11.0 POULTICE MIXTURES FOR into the poultice material. After approximately
VARIOUS STAINS 24 hours, remove the plastic and allow the
poultice to dry.
11.1 Overview. A poultice is a chemical or
mixture of chemicals combined with an 11.7 Remove the poultice from the stain.
absorbent material to form a thick paste, which Rinse with distilled water and buff dry with a
is applied to stone to remove stains. soft cloth. Repeat the poultice application if the
stain is not removed. It may take five or more
11.2 Poultice materials include kaolin, applications for difficult stains.
fuller’s earth, whiting, diatomaceous earth,
powdered chalk, white molding plaster, and 11.8 If the chemical etches the surface,
talc. Approximately one pound (0..45 kg) of apply polishing powder and buff with a
prepared poultice material will cover one polishing pad recommended by the polishing
square foot. Do not use whiting or iron-type powder’s manufacturer.
clays such as fuller’s earth with acid chemicals
as the chemical reaction will cancel the effect 11.9 Poultice Mixtures for Various
of the poultice. A poultice can also be prepared Stains.
using white cotton balls, white paper towels or
terry cloth rags, or gauze pads, which may be 11.9.1 Oil-based Stains. Poultice with
more effective when using highly volatile baking soda and water or one of the powdered
solvents such as acetone or mineral spirits. poultice materials and mineral spirits or a
Premixed poultices are available in ready to use commercial degreaser.
form or require adding only water. These are
available from stone maintenance supply 11.9.2 Organic Stains. Poultice with one of
companies. the powdered poultice materials and acetone
or 12% hydrogen peroxide solution.
11.3 Prepare the Poultice. If using a
powdered poultice material, mix with the 11.9.3 Iron Stains. Poultice with
cleaning agent or chemical to a paste with a diatomaceous earth and a commercially
thick, creamy consistency (approximately the available rust remover. Rust stains are
consistency of peanut butter). If using paper, particularly difficult to remove; professional
soak it in the chemical and let drain. Do not let assistance may be required. Many rust
the liquid drip. Prepare stain area. Wet the removers contain acids that will etch marble,
stained area with distilled water. limestone, and certain granites.

11.4 Apply the poultice to the stained area 11.9.4 Copper Stains. Poultice with a
about 1⁄4" to 1⁄2" thick (6 to 12 mm), and powdered poultice material and ammonia.
extend the poultice beyond the stained area by These stains are difficult to remove;
about 1". Use a wood or plastic scraper to professional assistance may be required.
spread the poultice evenly.
11.9.5 Paint Stains (water-based).
11.5 Cover the poultice with plastic and Poultice with a powdered poultice material and
tape the edges to seal it. Punch several small a commercial paint remover.
holes in the plastic to allow vapor to escape.
11.9.6 Paint Stains (oil-based). Poultice
with a powdered poultice material and mineral

Page 21-82 • Maintenance © 2022 Natural Stone Institute

spirits. Deep stains may require methylene • Location, size, and description of
chloride. When using highly volatile solvents in materials requiring protection
poulticing, use a paper towel, pouring the • Building and property boundaries
solvent on the paper towel and then placing the
towel on the stained area. 12.3 Repointing, Sealing, and
Replacement. Specify if repointing or re-
11.9.7 Ink Stains. Poultice with a powdered sealing of joints and replacement of stone are
poultice material and mineral spirits or included in the cleaning scope of work.
methylene chloride. When using highly volatile
solvents in poulticing, use a paper towel, 12.4 Related sections are to be
pouring the solvent on the paper towel and determined by design requirements.
then placing the towel on the stained area.
12.5 Requirements.
11.9.8 Biological Stains. Poultice with a
poultice material and diluted ammonia, bleach, 12.5.1 General requirements include the
or hydrogen peroxide. Do not mix ammonia plans, general conditions, supplementary
and bleach; this combination creates a toxic general conditions, and the executed
gas. agreement.
11.10 Flammable Materials. The 12.5.2 Certified statements must be
preceding text does not address possible safety furnished as required, attesting that all
concerns associated with the use of flammable materials to be used meet the requirements
solvents. Refer to the manufacturer’s labeling specified and approved.
and MSDS for further direction in the safe
handling and use of these products. 12.5.3 Scheduling. Provide Specifying
Commercially available cleaners exist for Authority with schedule of cleaning operations
remedy of many common stains. These indicating time of day work will be performed.
cleaners may have fewer health and safety Wet cleaning methods should not be
concerns. Always use appropriate Personal performed when temperatures reach 35°F
Protective Equipment (PPE) when handling
(2ºC) or lower.
solvents or other chemicals.
12.5.4 Test Areas. For approval by
12.0 SPECIFICATIONS FOR Specifying Authority, clean at least a 4’x4’ (1.5
BUILDING CLEANING m2) test area for each type of soiling, stone
variety, and finish requiring cleaning. Test
12.1 Introduction. This section pertains
panels should include intersection of horizontal
to the furnishing of all labor, materials,
and vertical joints. The approved panel(s)
equipment, and services necessary for the
should be the standard for cleaning methods
complete cleaning of exterior building stone as
and finish of all areas to be cleaned.
indicated on the plans and described in the
specifications.
12.5.5 Protection. For approval by
Specifying Authority, provide material types
12.2 Information to be shown on drawings:
and methods to protect adjacent materials and
• Location, size, and area or items to be surfaces from damage, moisture, and staining.
cleaned If other refurbishing operations are being
• Location, size, and number of test conducted, protect cleaned stone areas with an
panels approved non-staining covering.
• Areas not included in cleaning

© 2022 Natural Stone Institute Maintenance • Page 21-83

12.5.6 Cleaning. After the surface has been washing methods to dislodge soiled particles.
cleaned, rinse with potable water applied to Chemicals can be dangerous to the stone, the
the temperature and pressure of the municipal technician, and the surrounding landscape.
water supply. Therefore, all chemicals used must be tested
and monitored.
12.6 Materials. Water should be potable,
non-staining, and free of materials detrimental 12.7.5 Acids. Chemicals with a pH below 7
to the surface being cleaned. should not be used on calcareous or dolomitic
stones.
12.7 Methods to be determined by
approved test areas. 12.7.6 Alkalis. Chemicals with a pH above 7
are safe for use on most stones. These are
12.7.1 Hydraulic. Water at varying usually followed with a mild acid wash to
pressures between 300 and 600 psi (2 - 4 MPa) neutralize the alkaline salts.
and at municipal supply temperatures shall be
12.7.7 Neutral Cleaners. Chemicals
jetted against the surface to be cleaned. Care
containing surfactants with a pH equal to 7 are
must be exercised in selecting nozzle tip
safe for most stones.
degree; zero nozzle tips should never be used.
12.7.8 Solvents. Waterless chemicals, such
12.7.2 Water Misting. Clean the surface
as mineral spirits and acetone, are rarely used
with water. Misting heads are set up on
for building cleaning due to their high
scaffolding and water is misted onto the surface
flammability.
of the building. The misting heads may be set
on a timer so that they go on and off 12.7.9 Bacteria. Special bacteria can be
intermittently. The intermittent cycle allows applied to “eat” dirt and salts.
the building to dry and prevents oversaturation
of the stone. This method is the safest for 12.7.10 The J.O.S. (or TORC or
cleaning and is widely used on historical DOFF) system for removal of dirt and graffiti
buildings. uses a low-pressure washer and milled glass or
dolomite powder. Pre-rinsing is required.
12.7.3 Pressure washing employs the use
of high-pressure water jets of up to 2,500 psi 12.7.11 Dry cleaning uses organic
(17 MPa) or more. Pressure washing works by powder or mineral powder (aluminum silicate)
blasting the dirt off the surface of the stone, and crystals sized between 10 and 90 micros.
can cause irreversible damage to the stone
12.7.12 Sandblasting is an extremely
surface. Pressure washing can be an effective
aggressive method of cleaning and should only
and efficient means of removing dirt and other
be considered when believed to be the only
contaminants. Modern pressure washers can
effective solution. Soda blasting (using baking
produce pressure in excess of 2,500 lbs/in²,
soda in lieu of sand) is generally not as
which can permanently damage many stone
destructive and has some limited usage in the
types. Maximum allowable pressure should be
cleaning of natural stones.
determined by slowly increasing pressure
while testing in an inconspicuous area. In no 12.8 Safety Requirements. All the
case is pressure in excess of 1,000 lbs/in² (7 methods listed above require specialized
MPa) recommended, and usually much less equipment. Adherence to OSHA safety
pressure is appropriate. Always use a fan-tip requirements by highly skilled technicians is
spray nozzle. Only highly trained technicians mandatory.
should employ this method.
12.9 Testing. All methods must be tested
12.7.4 Chemical cleaning is used in for potential damage to the stone.
combination with one or several of the water
Page 21-84 • Maintenance © 2022 Natural Stone Institute
COMMERCIAL AND traffic,” making “efficiencies of scale” more
important for these projects.
HISTORIC
restoration 2.3 Levels of Pedestrian Traffic.
Pedestrian traffic rates in most commercial
settings will generally be much greater than
1.0 INTRODUCTION those encountered in residential settings. The
1.1 When compared to residential amount of abrasive particles (dirt and grit)
restoration, commercial and historic stone introduced to the stone surface via footwear is
restoration poses several unique requirements also substantially greater. These abrasive
and challenges. While many underlying particles can do significant damage to most
techniques in residential restoration are stone finishes, particularly in the softer stone
applicable to commercial projects, changes varieties.
must be made to adapt to a more complex
nature. Commercial and historic stone 2.4 Challenges Encountered With
restoration both require a strong Site Access and/or Restrictions
understanding of laws and regulations to
protect the integrity of the structure as well as 2.4.1 Work Platforms. Vertical surfaces
to avoid fines and/or citations. Further in commercial applications can extend to great
challenges arise due to the scale, intensity, heights, often necessitating the use of work
location, traffic patterns and management of platforms beyond ladders. Scaffolding, scissors
these projects. This section will cover most of lifts, and even mast climbers or suspended
the common requirements and challenges scaffolding may be required to gain access to
associated with commercial and historic commercial facades. The use of these and other
restoration. For the purposes of this document, equipment requires knowledge of OSHA
the term “restoration” will include cleaning, regulations, local ordinances (right-of-way
refinishing, repair, sealing, and maintaining. permits), and common sense safety
knowledge. All workers using elevated work
2.0 DIFFERENCES platforms must be trained in the safe use of the
equipment and the health and safety regulations
2.1 Rules and Regulations. On any that govern its use.
commercial or historic project, it is absolutely
necessary to familiarize oneself with and follow 2.4.2 Existing lighting in commercial
all federal, state, and local regulations and spaces may be insufficient for restoration
requirements. Regulations are in place for work, or may be on automated switches that
worker protection and public safety. cannot be overridden by onsite restoration
Noncompliance with these mandates is not mechanics. The restoration contractor is
only dangerous and unprofessional, but can usually best served by providing his/her own
result in substantial fines. The most common lighting equipment to adequately illuminate
sources for these regulations in the U.S. are the the work area.
Occupational Safety and Health Administration
(OSHA) and the U.S. Department of the 2.4.3 Electrical Power. It must be verified
Interior, through the National Park Service that adequate electrical power is available (both
(NPS). required voltage and amperage). If this is not
the case, the cost of providing generators must
2.2 Size of Project. The size of lobbies be taken into consideration.
or commercial spaces are typically larger than
residential spaces, with significantly more “foot 2.4.4 Water Supply. If an adequate quality
and quantity of water is not available onsite,

© 2022 Natural Stone Institute Commercial and Historic Restoration • Page 21-85
considerable cost will be encountered in mandated accessibility guidelines, staircases are
bringing water from on outside source. rarely the only access point to a floor, so
alternate means of access can usually be
2.4.5 Water Discharge and Disposal. It arranged while the staircase is being restored.
must be verified if water discharge and disposal
can be accomplished onsite, or if spent water 2.5.3 Vertical Surfaces (interior and
supply and/or slurry must be removed from exterior). It is far more common to
the site. This is just as important as verifying encounter expansive vertical surfaces in
water supply. commercial projects than in residential
projects. In addition to general soiling, these
2.4.6 Hours of Site Access. Many surfaces can be abused by other construction
commercial restoration projects require that trades, delivery equipment, improper cleaning
the work is performed when the building is methods, snow removal equipment, or signage
unoccupied or at a reduced level of occupancy. and decoration mounting. It is important to
This may require working at night or on the eliminate the source of abuse to the surface
weekend. Ensure that onsite workers have prior to restoration, otherwise the damage will
access to the restoration company’s simply reoccur after the stone is restored.
management personnel, safety managers, and
building managers while working during these 2.5.4 Special Features (stone trim such
non-traditional hours. as base, plinth blocks, jambs, casings,
etc.) are not subject to normal foot traffic, but
2.4.7 Maintaining Occupants’ Access can still take abuse from getting hit with carts,
during Working Hours. Work areas may vacuums, floor scrubbers and other items.
be limited in certain projects so that access can Restoring specialty features can be very time
be maintained. For example, if the restoration consuming and the required hours can be
includes the elevator cab floors in a hotel, it difficult to estimate in the bidding phase.
may be necessary to do one elevator at a time Additionally, these features are by design a
so that the other elevators remain functional, “focal feature,” so the customer’s demands of
even in off-peak hours. the quality of the restoration efforts may be
elevated.
2.5 Unique Features Found in
Commercial Buildings 2.5.5 Multi-component Surfaces.
Surfaces that include different materials such as
2.5.1 Revolving Doors. In most cases a metal dividers, carpet, wood, or even stones of
revolving door is not the only entrance to a differing hardness present an additional
building, so the revolving door area can be challenge to the restoration professional.
worked on while occupants are given an Protection of the various components becomes
alternate, temporary entrance to the building. the responsibility of the restoration
The doors can be collapsed or removed to professional. Refer to the Restorative
increase access to the workspace during Processes section (page 21-51) for more
restoration. Pending weather and location of information on how to handle multiple
the project, varying levels of temporary surfaces.
building enclosure may be required over the
area until the revolving doors can be replaced. 3.0 MAINTENANCE HISTORY
AND PRODUCTS USED
2.5.2 Staircases are common in
commercial and historic restoration projects. 3.1 Janitorial staffs of commercial
Smaller equipment is normally utilized, and the buildings may be employees of the building
production rate is greatly reduced. Due to owner, a building tenant, or a subcontractor.

Page 21-86 • Commercial and Historic Restoration © 2022 Natural Stone Institute
Varying levels of stone care knowledge and competent restoration contractors may use
experience exist amongst janitorial staffs and these products to cover up processes that were
supervisors. Those with higher knowledge and not performed properly. Due to the topical
experience levels, particularly when willing to coverage and prohibition of both fluid and
research the unique maintenance needs of the vapor transmission, these products can actually
stone product, are undoubtedly more damage the stone. However, since these
successful in keeping building owners and products form a sacrificial layer above the
occupants satisfied with the appearance and stone’s surface, there are unique exposure
performance of the stone products. Refer to conditions where they may be recommended.
page 21-75 (Maintenance) for more
information on this topic. 4.0 LABOR RESTRICTIONS
3.1.1 The restoration professional is often 4.1 Unions. Commercial restoration
responsible for instructing the janitorial staff on projects frequently mandate that the work be
required techniques and products to use after performed by union personnel. Check all
the stone has been restored. In these cases, it is union regulations, including pay scales,
often easier to instruct a staff with little or no benefits, and staffing requirements prior to
stone care experience, which eliminates the bidding to ensure that adequate funding exists
need to change the bad habits previously used to comply with the unions’ requirements. It is
by the staff. possible, depending on the nature of the work,
that more than one union will have jurisdiction
3.1.2 The restoration professional is usually over parts of your scope of work.
best serving the client by encouraging them to
contract with experienced, competent stone 4.2 Federal Projects. Most federal jobs
maintenance providers for their daily or require certified payroll reports. This report
weekly maintenance needs. This usually proves show which days were worked, labor
to be a wise investment for facility managers classifications of the workforce, and rates of
and owners that want to protect their stone pay.
investment.
4.2.1 Labor Classifications and
3.2 Maintenance Products Education. All labor classifications and
corresponding pay scales must be met.
3.2.1 Topical sealers and/or coatings. Maintain records to verify compliance in case
Long-term waxes, sealers, epoxy coatings, and the project is audited.
other topcoats are more common in older
lobbies, when topcoats were the preferred 4.2.2 Confusion Regarding
option. These coatings must be removed prior Classifications and Pay Scales. In some
to restoration of the stone surface. cases, it may be difficult to find an exact match
Identification of the product is usually of job descriptions in federal documents to
necessary to ensure that the removal and accurately determine the correct pay rates. If
disposal of it is done in a safe, environmentally doubt exists, contact the agency involved for
friendly, and legal manner. Refer to page 21- their input. Maintain records and document all
75 (Maintenance) for more information on this conversations in case a dispute develops at a
topic. later date.

3.2.2 Short-term Coatings or Waxes. 4.2.3 Report Filing. Frequency of filing

Stone maintenance and restoration may vary from weekly to monthly. Determine
professionals do not advocate the use of these the frequency required and comply with the
products, except in extremely rare cases. Less reporting requirements.

© 2022 Natural Stone Institute Commercial and Historic Restoration • Page 21-87
4.2.4 Other Restrictions. Federal be high, since they are usually all property
Department of Interior Standards must be owners in the complex.
followed. This requires a thorough knowledge
of various restoration disciplines and an 5.3.2 Historical Review Committees
aptitude for report writing. Information on this will be encountered any time work is done to
can be found beginning on page 21-121 of this a project that is deemed to have some level of
chapter (Additional Learning Resources). historical significance.

5.0 GETTING APPROVAL FOR 6.0 MANAGING

WORK PERFORMED PERFORMANCE
5.1 Customer satisfaction is the 6.1 Large commercial restoration projects
ultimate goal. In order to achieve this goal, it is may have extremely long durations. Progress
necessary to communicate the proposed and expenses must be tracked throughout the
improvements accurately. Test patches, project to ensure that the anticipated
mockups, and samples will help with this profitability can be achieved. Discuss the labor
communication. Ideally, test areas or mockups and material requirements with the job
should remain in place until the balance of the foreman or superintendent at the beginning of
work is completed to serve as a benchmark of the project and revisit these requirements
acceptance. frequently.

5.2 Single Person Responsibility. It is 7.0 FUNDING, BILLING, AND

typically easier to communicate with and COLLECTING
satisfy one person, such as a maintenance
supervisor or facilities manager, who may have 7.1 The process of payment on a
the sole authority to accept or reject the work commercial or historic project can be different
of your crews. Additionally, if a problem or than on a residential project. Sometimes
question arises, this person can usually be payment will only be considered if the request
included in the problem solving and decision is submitted on the responsibly party's form.
making processes. Payment can also depend on the tax and
restoration parameters allowed by the
5.3 Boards and Committees. When Historical Review Board, various funding
the contracting and acceptance of the work is procedures and taxes. Every state usually has a
decided by a board or committee, it may be historical society, committee, or department
difficult to achieve consensus within the group, in charge of maintaining and preserving
since the individuals comprising the group may historical landmarks. Depending on the
have differing standards, perceptions, and historical structure or place, there may be
experiences. It is a good practice to meet with available tax credits to help offset the costs of
the group prior to submitting your proposal. restoration or repair. The National Register of
This will allow you to learn of their exact Historical Places, which is administered by the
expectations and provide an opportunity to National Park Service, gives status and possible
discuss of how these how these expectations tax credits and funding for significantly
may impact the cost of the project. historical structures.

5.3.1 Commercial Committees. One of 8.0 ADDITIONAL RESOURCES

the most common committees encountered in
commercial work is the “condominium board,” 8.1 See the last section of this chapter for
when doing work in a condominium complex. Additional Learning Resources (page 121).
The emotional investment of its members may

Page 21-88 • Commercial and Historic Restoration © 2022 Natural Stone Institute
 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Consult with structural engineer for remedial
Photo 53,
Cracking, alignment, Structural settling or suggestions. Replace tile or clean, prep and
All All Natural stones Photo 75,
and grout distress instability repair tile and refinish as necessary to smooth
Photo 127
out repair.
Clean, prep and use a penetrating or flowing
epoxy to bond though the stone. Next use a knife
Fractures caused by material
grade epoxy with the correct color tint if needed.
handling, substrate
All Cracks in Slabs All Natural stones For outdoor repairs, use a UV stable, two part Photo 121
deformation, or vibration
epoxy with the correct color tint. For white
from field cutting.
marble and porous limestone, preseal to keep
the resin from bleeding into the stones.

Exfoliation occurring either

to poorly cemented minerals Clean, prep, and fill with a clear or a custom Photo 37,
Exfoliation of Minerals or minerals that have been colored epoxy. The stone may need to be Photo 38,
All All Natural stones
at face of stone loosened by expansions, resurfaced. If stone is resurfaced, apply Photo 47,
mechanical stress, or appropriate impregnating sealer. Photo 72
freeze/thaw cycling.
Photo 68,
Spall (chips or splinters
Lack of vapor transmission at Remove coatings that block stone’s ability to Photo 80,
All separated from the All Natural stones
stone's surface. breathe. Photo 84,
main mass of a stone)
Photo 128
Clean, prep and use a penetrating or flowing
epoxy to bond though the stone, then a knife
Natural seams in the stone
grade epoxy with the correct color tint if needed.
that have fully opened to be
All Fissures All Natural stones For outdoor repairs, use a UV stable, two part Photo 43
considered a crack or
epoxy with the correct color tint. For white
fracture.
marble and porous limestone, preseal to keep
the resin from bleeding into the stones.
Gray colored stain Stone was installed using
Light colored Remove and replace - only white thinsets may be
All bleeding through light gray colored portland based
calcareous stones used with light colored calcareous stones.
stone thinset

© 2022 Natural Stone Institute Restoration and Maintenance • Page 105

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Occasional small holes
(taroli , in Italian) and voids
Clean, prep and fill holes with color matched
All Pin Holes Marble are to be expected, and are Photo 15
epoxy.
characteristics of Soundness
Classification B marbles.
On light colored stones, clean with bleach or
hydrogen peroxide. On dark colored stones,
All Ink Stains All Natural stones Ink pen or marker stains. clean with lacquer thinner or acetone. Do a test
in an inconspicuous area to make sure this is the
correct method.
Numerous, possibly
hundreds of small pits in the Clean and prep as best as possible and fill with
All Pits Limestone Photo 59
stone visible with certain CA glue, or color matched polyester acrylic.
lighting.
If possible, identify the stain origin, then poultice
with appropriate poultice recipe. If stain origin
Random stains caused by
cannot be identified, several trial and error Photo 7,
All Random Stains All Natural stones known or unknown staining MIA’s book on Poultice
attempts may be necessary. Multiple Photo 101
agents.
applications of poultice may be required to fully
eradicate the stain.
Review manufacturer's application instructions
Dark spots remain after Sealer did not fully penetrate to ensure proper application methods are being
All water wiped from All Natural stones stone due to improper used. Allow full cure time between applications. Photo 64
stone. application. Use multiple applications until desired
performance is achieved.
This is usually the result of
too much detergent or Clean with a heavier cleaner for stone and hot
Sticky or Clouded
All All Natural stones cleanser being used during water. For hair spray on marble, use a safe HD Photo 44
Surface
normal cleaning cleaner with a white pad.
maintenance.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 106

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference

Identify the sealer that was used, then try to re-

emulsify with the same sealer with a white or
hog's hair pad by breaking the surface tension
Streaks or haze in cured
Streaking or Haziness and then wipe it up and buff it out. Or use Photo 74,
All All Natural stones sealer cannot be cleaned
from Sealer Mineral Spirits and again break the surface Photo 78
with regular cleaners.
tension. Or use a safe alkaline stripper and break
the surface tension, wipe off and buff out. If
unsuccessful, then stone must be refinished.

Swirl marks in the stone

surface are generally caused
Start refinishing from the least abrasive diamond
by equipment malfunctions
grit until you can successfully remove the swirl
All Swirl Marks All Natural stones or operator errors in the Photo 40
marks, then proceed to finer grit sizes until the
original fabrication of the
desired gloss level is achieved.
stone or in a previous
restoration attempt.

Dark banding visible in the

stone surface is frequently
residual adhesive from tape
that had been applied and
removed. Some tapes have
Use acetone with a white nylon pad and rub
mildly acidic adhesives,
vigorously. Multiple applications may be
which are more prone to Photo 42,
All Tape marks All Natural stones required. If unsuccessful, diamond grind the
surface damage of Photo 51
areas and then refinish to desired level of gloss.
calcareous stones. Extended
Some "feathering" and blending will be required.
dwell time on the stone
surface, and exposure to sun
or other heat source also
increase the likelihood of
tape marks.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 107

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Countertop settling
Clean with acetone and a white pad vigorously. It
- edge not polished
the stain does not go away, diamond grind until
to factory polish -
the residue is gone, then bring back to the
correct: break the Dark lines, usually dull, and Photo 71,
All Tape Residue factory shine. (Note: tape adhesive may have
seam, relevel the often showing dirt collection. Photo 51
penetrated significant depth of the stone, which
tops with proper
can make the lines reappear if color enhancer is
support and polish
used).
the edges

Small amounts can be removed with lacquer

thinner or scraped off carefully with a razor
blade. Paint strippers can be effective but may
etch some stones. Follow the manufacturers'
directions for use of these products, and flush
the area thoroughly with clean water. Use
Usually this can be identified appropriate PPE when using these chemicals.
All Topical, colorful stains All Natural stones
as paint. Use only wood or plastic scrapers for removing
the sludge and curdled paint. Normally, latex and
acrylic paints will not cause staining. Oil-based
paints, linseed oil, putty, caulks and sealants may
cause oily stains. Refer to the section on oil-
based stains. (In short, a good quality colloidal
cleaner is probably the best and safest solution.)

Yellow-to-orange staining Rust poultice will be required Most rust

can either be from ferrous poultices are acid based and will etch calcium-
content indigenous to the carbonate based stones, so refinishing will be
stone fabric, or from an necessary after the rust treatment. Quick rust
Light colored Photo 95,
All Yellowing outside source, like a metal treatments can be less damaging to the stone
Natural Stones Photo 96
container or object in but the purple stain left from improper use of
contact with the stone, or a some products can be fixed with 20-30%
fastener corroding beneath hydrogen peroxide. Testing in an inconspicuous
the stone. area should be done before the final application.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 108

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Clean, prep, and fill chips with a polyester epoxy
with a custom tint or CA Glue. For outside chips
you will need a UV stable two part epoxy with a
Chips occurring from impact
custom color tint. For white marble and porous
Countertop Chipping due to impact All Natural stones by pots, pans, and other hard Photo 79
limestone, preseal to prevent any bleeding from
objects.
the resin in the two part epoxy. In some cases
you may need to drill small holes into the chip to
get better tooth or bite.

Use a poultice (a blend of clays) with hydrogen

Food, and specifically fruit
peroxide (20%). Use nitrile gloves and safety
and fruit juices, like grape
goggles when using this product. Sometimes a
juice, wine, coffee,
Countertop Colored Stains All Natural stones mild bleach solution will take stains out.
vegetables, tea, and even
Neutralize the beach after use with water mixed
grass and mud create
with a neutral cleaner. Calcareous stones may
different colored stains.
etch and the surface may need to be refinished.

Wiping with a towel saturated in mineral spirits

Dark areas around
will usually be effective, although many
Countertop fixtures and/or soap All Natural stones This is obviously a soap stain. Photo 101
applications are usually required. Denatured
dispensers
alcohol is also sometimes effective.
Resin, color enhancer, or
Countertop Change or faded color All Natural stones sealer not 100% UV Refinish; use UV resistant resin/ color enhancer. Photo 4
resistant.
Use a poultice with the correct additive in the Photo 8,
blend of powder or a good, ready-to-use Photo 41,
Dark colored stains are
Countertop Dark Stains (Oil) All Natural stones poultice liquid. Follow manufactures' directions. Photo 100,
frequently oil based.
This may have to be done over weeks or months Photo 101,
until the stain is gone. Photo 102
Regrind with coarse grits and then bring the Photo 12,
Granite, Marble, Substandard edge polishing
Countertop Dull Edges surface back to a factory shine using Photo 13,
Limestone on original material.
progressively finer grits. Photo 14
The edges are fuzzy and not Diamond grind surface and repolish back to the
Countertop Dull or Clouded edges All Stone Types Photo 63
even. desired gloss level.
Areas are dull and have
Diamond grind surface and repolish back to the Photo 45,
Countertop Dull Spots or Rings Marble reduced gloss due to mild
desired gloss level. Photo 110
etching.
© 2022 Natural Stone Institute Restoration and Maintenance • Page 109
 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Dull areas around grout due
All Calcareous Diamond grind surface and repolish back to the
Countertop Etched areas to inappropriate (acidic) Photo 104
Stone Types desired gloss level.
grout cleaner.
Clean the copper stain with a very mild acid.
Neutralize and you have to resurface the stone
Green-to-blue Colored Green-to-blue colored stains Photo 18,
Countertop All Natural stones back to its original state. If the stain remains, a
Stains are usually cuprous in origin. Photo 28
poultice may be need with the correct additive
for the stain.
Hard water deposits are
usually caused by a
combination of high mineral Carefully use single edge razor with mild soap to
Hard water deposits
Countertop All Natural stones content water supply and remove buildup from counter top, or remove the Photo 22
near faucet fixtures
occupants allowing the fixtures and refinish.
water to puddle, unwiped,
on the countertop surface.

This is typically indicative of

a slab that has been
"rodded," meaning that a
reinforcement rod had been
If you can open the stone carefully, pull out the
embedded into the
metal rusted rod, using a two part UV stable
underside of the slab at this
epoxy with the correct color tint and glue it back Photo 29,
location. If a mild steel rod
Linear Crack at front of together and top polish the next day. If the crack Photo 30,
Countertop All Natural stones has been used, and if the
sink location is too small to get any penetrating glue in, you Photo 76,
fabricator did not
might want to wait till it opens further. If Photo 99
successfully fully encapsulate
unrepairable, the only remedy is replacement of
the rod in epoxy, corrosion
the countertop.
can occur. The swelling of
the rod due to corrosion can
create enough pressure to
crack the stone slab.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 110

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Break the seam if possible. Use a seam setter to
level the two slabs and apply a flowing epoxy DSDM, COUNTERTOPS:
Lippage on One stone slab is higher than
Countertop All Natural stones followed by a knife grade epoxy with the correct TOLERANCES -Lippage Photo 17
Countertops adjacent slab.
color. Or diamond grind the high slab to match Section
the other slab, and then refinish to original gloss.

All true granites contain a

micaceous mineral called
"biotite," which is a black
colored mineral of "flakey"
or layered construction. Fill pits with CA adhesive and when cured, scrape
Countertop Mineral Pitting Granite During the polishing process, with a razor in multiple directions until the filler Photo 35
biotite can be "plucked" matches the plane of the stone surface.
from the stone fabric by the
abrasive heads of the
polishing machine, leaving a
shallow pit in the surface.

Whitish rings or spots

occurring on black granite
(which technically are not
granite) have often been
blamed on dyes used in the
stone. While this is possible,
it is not as common as
believed. These materials
may have complex Either refinish starting with very fine grit, or buff
Countertop Rings or Spots Granite Photo 3
mineralogy including with a pad.
minerals that are not
traditionally included in true
granites. Calcium-carbonate
based minerals and clays can
be present in these
materials, both of which can
change color due to wet/dry
cycling.
© 2022 Natural Stone Institute Restoration and Maintenance • Page 111
 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Verify that it is a stain and not an etch. True
Commonly caused by the granite can be cleaned with acidic cleaners.
Rings or Spots on
Countertop All Natural stones stone's reaction to ponded Calcareous stones must be resurfaced. These Photo 106
Outdoor counters
water on the surface. marks will usually reoccur if the exposure is
unchanged.
Deep clean all smoke stains (if needed) with an
Staining, discolored sealer, alkaline cleaner or mild acid, (5-6 on the pH
Surface staining from soot, or other stains from scale). Diamond grind and polish back to desired
Countertop All Natural stones Photo 16
heat source heat source such as fireplace gloss. Grinding may be required to significant
or cooktop. depth if stone has been etched due to carbonic
acid.
Stone had originally been Photo 85,
Countertop White Rings Granite Attempt to re-dye to stabilize color.
dyed (normally black stones). Photo 86
Sealer did not fully penetrate Remove sealer with an acidic marble polishing
Countertop White Rings Granite Photo 3
stone. compound.
Moisture reacting with ANSI A118.10
Stop source of moisture & resurface stone,
Flooring Blistered Surface Granite minerals in stone (this can be TCNA F122 Stone Photo 36
refilling as necessary.
confused with spalling). or F121 Stone
Usually caused by
Blotchy, Uneven nonuniform application as a
Strip the enhancer off and then start over. In
Flooring appearance in Color All Natural stones result of the floor being wet Photo 61
some cases, refinishing will be required.
Enhanced Floor when the color enhancer
was applied.
Clean, prep and use preferably a slow curing
Corners are broken, usually
epoxy with a custom color to rebuild the corners.
as a result of heavy rolling
Following cure of the epoxy diamond grind and
Flooring Broken Corners All Natural stones loads over corners that have Photo 19
refinish to desired gloss. A polyester resin (fast
no support due to voids in
curing) can also be used, but does not have the
the setting bed.
performance of the epoxy.
Flooring Cracking Granite Improper substrate Replace tile. Photo 31
Flooring Cracking Granite Deflection issue Check joist size, spacing & span. Photo 31
Lack of crack
Replace tile and utilize crack isolation
Flooring Cracking Granite isolation/suppression
membrane.
membrane.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 112

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Seams in cement board not
Flooring Cracking Marble Tear out and replace. ANSI 108.5
filled.
Flooring Cracking Marble Improper adhesive coverage. Tear out and replace. ANSI 108.5 Photo 27
Insufficient joint width at
Flooring Cracking Marble change of plane or other Saw out and open joint with cosmetic repair. TCNA EJ171
region of discontinuity.
Replace tile and implement correct installation Photo 1,
Flooring Cracking Marble or Granite Improper substrate. TCNA F250 Stone
method. Photo 10
Flooring Cracking Marble or Granite Excessive deflection. Check joist size, spacing and span. TCNA F250 (Optional)
Lack of crack
Replace tile and utilize crack isolation TCNA F125 Stone
Flooring Cracking Marble or Granite isolation/suppression Photo 27
membrane. (Concrete)
membrane.
Use appropriate adhesive, reset with a minimum Photo 9,
Lack of bonding adhesive
Flooring Cracking Slate 95% of coverage with the mortar. Many times ANSI 108.5 Photo 107,
under the tile.
the stone can be reused. Photo 108
Flooring Cracking Slate Lack of expansion joints. Tear out and replace. TCNA EJ171, F250 Stone
Lack of bonding adhesive
Flooring Cracking Travertine Replace broken tile. ANSI 108.5 Photo 23
under the tile.
Flooring Cracking Travertine Lack of expansion joints. Tear out and replace. TCNA EJ171, F250 Stone
Lack of alkaline resistant
Flooring Cracking Travertine Tear out and replace. ANSI 108.5, TCNA EJ171
mesh tape.
Difference between Usually this is due to color
Carefully strip off the wax, neutralize with water Photo 56
Flooring covered areas and All Natural stones change as a result of UV
and refinish. Photo 55
exposed exposure of a wax.
Polishing compound used
Photo 125
Flooring Dimpled appearance Travertine, Marble too hot resulting in 'orange Grind and refinish to original surface quality
Photo 124
peel'

© 2022 Natural Stone Institute Restoration and Maintenance • Page 113

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference

Identify the sealer that was used, then try to re-

Foot prints can be seen in
emulsify with the same sealer with a white or
certain lighting conditions in
hog's hair pad by breaking the surface tension
the sealed floor, but cannot
Foot Prints in Sealed and then wipe it up and buff it out. Or use Photo 118
Flooring All Natural stones be cleaned with regular
Stone Mineral Spirits and again break the surface Photo 119
cleaners due to floor having
tension. Or use a safe alkaline stripper and break
been walked on prior to full
the surface tension, wipe off and buff out. If
cure of the sealer.
unsuccessful, then stone must be refinished.

Insufficient accommodation Cut grout joints and replace with appropriate Photo 26,
Gaps in stone or
Flooring All Natural stones for thermal expansion and movement and/or expansion joint detail per TCNA EJ171 Photo 70,
corners
contraction industry standards. Photo 105
Excessive and non-uniform
depth of thinset over a
Remove and replace, using proper floor leveling Photo 10,
Flooring Indent Fractures All Natural stones membrane, creating uneven TCNA F141
techniques and controlled thinset depth Photo 11
shrinkage and suction upon
cure
MIA Design Manual,
Either remove the tile and set a new one in place HORIZONTAL SURFACES
One stone unit is higher that
with correct alignment, or diamond grind the – LIPPAGE
adjacent unit (Note: 1/32",
Flooring Lippage on Floors All Natural stones high tile to match the elevation of the Photo 73
or 0.8 mm is acceptable
surrounding tiles and refinish to achieve desired TCNA Handbook,
tolerance).
level of gloss. Lippage in Natural Stone
Installations
Lack of drainage mat and/ or Tear out required to totally correct the problem.
Flooring Loose Tiles Slate TCNA F122 Stone
waterproofing. Many times the stone can be reused.
Use appropriate adhesive to rebond and
minimum 95% of coverage with the mortar.
Flooring Loose Tiles Slate Oil content present in slate. ANSI A118.4 Photo 6
Apply a burn coat or scratch coat on the back of
the tile.
TCNA Handbook, ANSI
Insufficient contact between Achieve minimum of 95% of coverage on the 108.5 3.3,
Flooring Loose Tiles Granite Photo 39
adhesive and stone. bonding mortar (Dry & Wet Areas). TCNA F102 Stone,
ANSI 108.5.3.3

© 2022 Natural Stone Institute Restoration and Maintenance • Page 114

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
TCNA EJ171
Flooring Loose Tiles Slate Lack of expansion joints. Implement expansion joints.
ANSI 108.1
Presence of bond breaker on
Flooring Loose Tiles Slate Remove bond breaker prior to repair. TCNA F122 Stone
concrete slab or substrate.
Grout has eroded due to
Missing grout or normal service exposure, but Thoroughly remove all cracked grout and either
Flooring All Natural stones Photo 24
caulking no other signs of distress re-grout or caulk with appropriate joint sealant.
exist.
Excessive moisture in
Open the grout and allow to dry or use a
Picture Framing after bedding layers wicks into
Flooring All Natural stones commercial dehumidifier to remove the ANSI A108.5 Photo 34
installation edges of stone, creating a
moisture.
darkened perimeter.
Plastic Look; Orange
Flooring Marble Over crystallization. Grind and refinish to original surface quality. Photo 125
Peel
Carefully remove the excess grout with the
Stones were not properly
proper cleaner for grout or a razor blade with
Flooring Smeared Grout All Natural stones masked or cleaned during ANSI A108.10 Photo 126
soapy water to cut down any possible scratching
original grouting.
the surfaces.
Stone has lost its color
(outdoor application) due to Use enhancer or a colored tint with the enhancer
Flooring Stone Discoloration Granite
fading of dyes that were per manufacture's directions.
applied to original material.

Inadequate movement
and/or expansion joints, Remove and replace affected stone, adding
Flooring Tenting All Natural stones causing compression in floor movement and/or expansion joints per industry TCNA EJ171 Photo 98
surface to raise, or "tent" recommendations.
two or more courses of tile.

This is referred to as "Indent

fracturing," and is caused by
All stone,
White, random non-uniform shrinkage of Replacement is the only remedy, with attention
specifically soft Photo 87,
Flooring direction lines in face thinset that has either been paid to proper slab leveling prior to installing
marble and Photo 88
of material used too thick, or too replacement tiles.
limestone.
uneven, and typically over a
membrane.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 115

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Carefully strip off the wax, neutralize with water
and diamond grind, then refinish the floor to
Yellow-to-brown Photo 54,
All calcareous Residual wax on stone achieve desired level of gloss. Do a small test
Flooring blotchy surface on Photo 55,
stone types. surface. area in an inconspicuous area prior to starting
floors. Photo 56
balance of work. NOTE: Black or brown stripping
pads can hone and open the softer stones.
Carefully strip off the wax, neutralize with water
and diamond grind, then refinish to achieve
Yellow-to-brown
All siliceous stone Residual wax on stone desired level of gloss. Do a test in an
Flooring blotchy surface on
types. surface. inconspicuous area before starting balance of
floors.
work. NOTE: Black or brown stripping pads
should not hurt the stones.
Lime from mortar has
Clean all surfaces with acidic cleaner and refinish
Calcium deposits on leached through to the
Paving All Natural stones if necessary. Eventual failure is likely unless a TCNA F103B Photo 2
stone surface. surface as a result of the
method of bed drainage can be accomplished.
repeatedly saturated bed.
Repeated saturation and/or Temporary correction can be achieved by surface
Erosion or excessive freeze/thaw cycles of grout cleaning the resultant staining and regrouting,
Paving All Natural stones TCNA F103B Photo 2
cracking of grout. due to ponding as a result of but eventual failure of the system is nearly a
insufficient surface slope. certainty if not replaced.
Clean up the loose pieces and then sand down
Internal expansions within
the edge if it is a tripping hazard. Blend and
the stone fabric either due to
feather with a brown and a black hypo pad (wet Photo 50,
Paving Flaking Slate, sandstone freeze/thaw cycling or
is better). Then dry and check for correct Photo 103
minerals with expansive
appearance. If too much breaks off, replace the
behavior in a saturated state.
tile or slab.
Lifted tiles and Remove the stone, clean the substrate and the
Moisture trapped below
Paving extensive grout All Natural stones back of the tile and then re-bond them using a Photo 116
surface layer.
cracking. hard scratch coat on the back of the tiles.
Temporary correction can be achieved by surface
Photo 113,
cleaning the resultant staining, but eventual
Paving Ponding Water All Natural stones Insufficient surface slope. TCNA F103B Photo 114
failure of the system is nearly a certainty if not
Photo 120
replaced.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 116

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Surface cleaning of the stone will provide
Usually caused by
Water staining on temporary cosmetic improvement, but
Paving All Natural stones inadequate, or reverse pitch, Photo 103
exterior stairs. permanent remedy can only be accomplished by
of treads.
removing and re-setting stones.

This is usually caused by a Remove stone and re-set with proper slope.
Corner area of shower Photo 5,
Showers All Natural stones flat, or reverse sloped area Check that membrane has proper slope and that
floor is dark. Photo 48
that does not drain properly. dry-pack has adequate lateral transfer capability.
Dull areas due to use of
All calcareous Diamond grind surface and repolish back to the
Showers Etching in showers. inappropriate (acidic) Photo 52
stone types. desired gloss level.
cleaner.
Extremely warped or Some limestone, Selected stone was not
Showers exfoliated stone in wet travertine, and appropriate for wet area Remove and replace. Photo 84
area. onyx. exposure.
Test section with rust removing poultice.
Current TCNA Handbook,
Faint rust colored Repolish surface as necessary. Seal stone with
Light colored Ferrous content indigenous Natural Stone Tile Photo 46,
Showers stains in shower or appropriate impregnating sealer. NOTE:
calcareous stones. to stone has oxidized. Selection and Installation Photo 83
curb. Removal of stain is not always successful or
Guide, "Iron Staining"
permanent!
Carefully cut out the cracked grout and apply a
Gaps around tubs or
The grout is not adhering to flexible, non-shrinking sealant. (100% RTV
Showers other dissimilar All Natural stones TCNA EJ171 Photo 77
the dissimilar material. Silicone) In wet areas make sure the substrate is
materials.
fully dry before applying sealant.

Growth occurring on BOG (Bio-Organic-Growth) is

Showers All Natural stones Upgrade to frameless shower door. Photo 67
shower curb. present on shower curb.
No permanent solution exists. Temporary
Saturated subsurface
correction may be achieved by diamond grinding
allowing hard water to wick
the hard water deposits and removing the grout Photo 33,
Showers Hard Water Deposits All Natural stones to stone surface, depositing TCNA F103
and allow to air dry. Regrout when dry. An Photo 112
hard water deposits on stone
alternate solution is to apply urethane caulk in
surface.
place of grout.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 117

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
There are multiple possible Try the weep holes first. If you cannot get it from
causes for this: The weep the inside of the drain then remove the tiles and
holes could be clogged; the mud 4-6 inch around the drain and clean the Photo 20,
Heavy Water Deposits dry pack may be too tight weep holes from the outside and then set your Photo 21,
Showers on Grout Lines in All Natural stones and not allowing the water dry pack again and tile and grout. If the pack is Photo 58,
Shower Floor to drain down into the weep too tight, then the entire shower pan tile and Photo 65,
holes; or the water proofing mud must be removed and redone. If it is the Photo 66
membrane is not correctly water proofing membrane, well then you must
sloped. remove the shower and start over.
Clean with a safe mildew cleaner that will not
Inadequate sealing of high
etch stone, remove the affected grout lines, use
porosity stone, inappropriate
Mildew Growth in a dehumidifier to dry out the substrate, when
High Porosity stone selection, or high
Showers shower walls and grout dry, re-grout, apply the sealer correctly and Photo 122
Stones humidity is maintained in
joints inform the client to keep the shower door open
area when shower is not in
after use. Check the inside grout lines of the
use.
shower curb also.
Clean with the proper mildew remover for
Orange, Yellow, or This is frequently the growth natural stone. Bleach only puts the mold in Photo 117,
Showers Black Stains in a Wet All Natural stones of mildew as the result of dormancy; it does not kill it forever. Refinishing Photo 122,
Area inadequate ventilation the stone may be necessary in some cases (see Photo 123
diamond grinding).
Test section with rust removing poultice.
Ferrous content indigenous
Repolish surface as necessary. Seal stone with
Rust bleeding through Light colored to stone has oxidized, and is
Showers appropriate impregnating sealer. NOTE: Photo 81
veins in stone calcareous stones traveling through veins as
Removal of stain is not always successful or
the path of least resistance.
permanent!
Corrosion protection on
shower drain has been Test section with rust removing poultice. Seal
Rusting at Shower
Showers All Natural stones breached, allowing rust to stone with appropriate impregnating sealer. Photo 83
Drain
bleed into surrounding Replace drain.
stone.
Test section with rust removing poultice.
Current TCNA Handbook,
Repolish surface as necessary. Seal stone with Photo 89,
Rusting on Walls, Light colored Ferrous content indigenous Natural Stone Tile
Showers appropriate impregnating sealer. NOTE: Photo 91,
benches, or floors calcareous stones to stone has oxidized. Selection and Installation
Removal of stain is not always successful or Photo 92
Guide, "Iron Staining"
permanent!
© 2022 Natural Stone Institute Restoration and Maintenance • Page 118
 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
Clean out the inside of the drain and then clear
the weep holes of white bar soap residue, hair,
This is frequently caused by hair conditioner, hard water buildup, and body
Shower floor and walls
Showers All Natural stones clogged weep holes in the oils. This is for cast Iron drains. Check to verify Photo 62
are darkening
drain. that the weep holes are not plugged. Cut around
the tar or membrane if necessary so the weep
holes are clear.
Surface spalling, usually due
to expansion of some Grind and fill as necessary. Encapsulate Photo 82,
Showers Spalling of Stone Limestone
mineral content during limestone with penetrating epoxy. Photo 97
saturated state.
Moisture Resistant Gypsum Board, a.k.a.
Tiles becoming
Improper substrate typically "Greenboard" is not an appropriate substrate for Current TCNA and MIA
Showers dislodged from wall All Natural stones Photo 32
"greenboard" gypsum board. direct application of tiles in wet areas. Remove documents
surface
and replace.
Take out the shower door and cut the grout line
on the shower curb on both sides and now into
Most commonly, this is the pan. Replace with epoxy grout or a
Water penetrating leaking at the shower curb polyurethane sealant. Another option is to tear it Photo 5,
Showers All Natural stones
sheetrock backing due to inadequate out and start over but slope the shower curb Photo 25
membrane overlap. membrane back to the shower at a rate of ¼ inch
per ft. Dry the substrate toughly before re-
grouting.
Removal and replacement per MIA guidelines is
White area or surface Certain green Many green marbles and best permanent solution. Use proper setting
Showers degradation in green marble and serpentine do not perform materials recommended for serpentine and Photo 49
marble serpentine. well in wet environments. green marble. Use of an impregnating sealer is
also helpful.
This is caused by water
White Spots on Mosaic Check weep holes, density of dry-pack, and slope
Showers All Natural stones evaporation when the Photo 109
Tiles of membrane.
shower is holding water.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 119

 TROUBLESHOOTING
Prevention or Photo
Application Symptom Stone Type Possible Causes Potential Solutions
Cross Reference Reference
DSDM, VERTICAL
SURFACES – RELATED
One stone unit face is proud Either remove the stone and re-set in place with
COMPONENTS Section
of adjacent units (Note: correct alignment, or diamond grind the proud Photo 90,
2.6 Lippage
Walls Lippage on Walls All Natural stones 1/32", or 0.8 mm is stone to match the elevation of the surrounding Photo 93,
maximum acceptable stones and refinish to achieve desired level of Photo 94
Current TCNA Handbook,
tolerance). gloss.
Natural Stone
Installations, "Lippage"

Mechanically remove as much residue as

possible with a dry brush. Then clean the area
Moisture migrating from sub
with a mild acid for slate, sandstone, and granite. TCNA F122 Stone
White Residue layers carrying salts, which Photo 57,
Walls All Stone Types For marble, a slightly alkaline chemical can be (Concrete) or F101
(Efflorescence) are then deposited on stone Photo 69
used. (8-9 on the pH scale). Note: Don’t let it run Stone
surface.
down a vertical area as it may etch. Some
neutral cleaners may also work.

© 2022 Natural Stone Institute Restoration and Maintenance • Page 120

Photo # 1 Photo # 2

Spot bonding - improper coverage Bonded to flashing - not suitable bonding substrate

Photo # 3 Photo # 4
Etch ring (resin enhancer disturbed) - correct: use final Resin enhanced slab faded by UV exposure - correct:
granite buff pad or powder refinish; use a UV resistant enhancer/colorant

Photo # 5 Photo # 6
Shower curb floor corner waterproof membrane improperly sloped to drain -
Improper bonding coverage & improper bonding
cracked grout on shower curb (mineral deposits) - correct: remove grout, dry
substrate with dehumidifier and regrout with epoxy substrate (flashing)

Photo # 7 Photo # 8
Sandstone improperly sealed (oil stain) - correct: remove stain and Improperly sealed granite (oil stain) - correct: remove
seal with multiple applications of appropriate sealer stain with poultice and use multiple applications of sealer

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 1 of 16
© 2022 Natural Stone Institute
Photo # 9 Photo # 10
Improper bonding, hollow slate tiles - correct: apply scratch to backs of Indent fractures - substrate (rubber soundproof material)
slate & use a proper notched trowel method (per TCNA guidelines) - stone cannot take deflection

Photo # 11 Photo # 12
Indent fractures, different cause - builder did not wait 28 Improper edging technique - correct: redo the edge
days for thinset to cure correctly

Photo # 13 Photo # 14

Another view of Photo 12 Edge not polished to match factory finish

Photo # 15 Photo # 16
Pits/holes in stone - correct: clean, prep and fill with the Damage from heat - correct: clean soot and smoke with
correct patching material degreaser. Will need refinishing if etched.

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 2 of 16
© 2022 Natural Stone Institute
Photo # 17 Photo # 18
Countertop edge not polished to factory finish - correct: break the Copper stain (caused by copper gutters) - Correct: use mild acid, then
seam, relevel the tops with proper support and polish the edges neutralize the acid or use a copper poultice & refinish area

Photo # 19 Photo # 20
Chipped outcorner - correct: replace with matching material or clean, Shower pan holding water and corner improperly sloped to drain - correct:
prep and fill with a slow-curing epoxy (not polyester) remove grout & drain and clean the weep holes. Dry thoroughly, regrout and seal

Photo # 21 Photo # 22
Calcium deposit on granite - correct: remove deposit with a straight-edge razor
Improper slope to drain, lacking two-stage drain function
balde and soapy water (acid can damage plumbing fixture)

Photo # 23 Photo # 24
Structural crack (foundation crack) - correct: replace Different expansion and contraction rates between floor and wall -
broken tile correct: use the correct flexible material for this application

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 3 of 16
© 2022 Natural Stone Institute
Photo # 25 Photo # 26
Waterproofing membrane on the shower curb is not properly sloped to Cracked grout between tile and concrete - correct: install
the drain - correct: redo per TCNA guidelines proper expansion joint material (no latex caulk)

Photo # 27 Photo # 28
Crack (at tape) due to improperbond or excessive Copper stain on natural stone - Correct: use mild acid, then neutralize
deflection. Also etched. Correct: check floor rigidity, the acid or use a copper poultice & refinish the area

Photo # 29 Photo # 30
Blown rod from using metal in wet area and not Blown rod from using metal in wet area and not
encapsulated properly (fiberglass preferred) encapsulated properly (fiberglass preferred)

Photo # 31 Photo # 32
Structural crack (foundation crack) - floor joists too far apart and cannot
properly support the weight (live-load and dead-load specification - see TCNA Water intrusion - improper substrate
guidelines)

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 4 of 16
© 2022 Natural Stone Institute
Photo # 33 Photo # 34
Moisture in granite floor - partially hollow - caused by stripping wax & voids in
Water intrusion into the substrate and permanently
substrate - correct: replace with proper TCNA methods or remove the grout,
staining the tile on the way out thoroughly dry and regrout (inject with adhesives to fill voids before grouting)

Photo # 35 Photo # 36
Pitting in granite from high mica content in the stone -
Pitting similar to that shown in Photo 35
correct: clean, prep and fill with epoxy or CA glue

Photo # 37 Photo # 38
Poor quality stone (close up) - correct: replace the Poor quality stone (different view) - correct: replace the
countertop countertop

Photo # 39 Photo # 40
Poor quality installation methods and lack of bonding material - correct: clean Swirl marks - correct: Start refinishing from the least abrasive diamond grit until
the back of tile and substrate and reinstall using proper TCNA installation the swirl marks are removed. Proceed to finer grits until the desired gloss level is
methods achieved.

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 5 of 16
© 2022 Natural Stone Institute
Photo # 41 Photo # 42
Oil staining in granite countertop - correct: use oil poultice and Tape residue - correct: use acetone and a white pad - if the
seal thoroughly with multiple applications stone is stained below, then refinishing may be needed

Photo # 43 Photo # 44
Natural seams in the stone that have fully opened to be Soap residue or surfactants from using the wrong cleaners - correct: remove
repaired like a crack or fracture with warm water and a good rinseless cleaner and a white pad

Photo # 45 Photo # 46
Etch marks on polished travertine - correct: refinish the Iron stain in white marble (white stones have iron content which oxidizes with
stone back to the factory polish moisture over time) - correct: use a rust poultice and refinish the stone

Photo # 47 Photo # 48
Natural voids in some limestone - correct: clean, prep and Shower pan holding water - correct: remove grout in critical
fill with epoxy areas, clean weep holes, thoroughly dry, grout and seal

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 6 of 16
© 2022 Natural Stone Institute
Photo # 49 Photo # 50
Pressure on edges causing cleavage in stone to break off - partially hollow tile at
Lack of slope, moisture evaporation causing spalling -
the edge - correct: wet or dry sand the slate until smoother and fill void in with
correct: remove and replace using TCNA guidelines adhesive, then regrout

Photo # 51 Photo # 52
Tape stain - oils from adhesive staining the stone - correct: vigorously clean with Badly etched stone shower - correct: grinding, refinishing
acetone and a white pad, grinding and refinishing may be necessary and seal

Photo # 53 Photo # 54
Substructural crack on wall - correct: replace tile or clean, prep and Multiple coats of topical sealer on a textured granite floor - correct: carefully
repair tile and refinish as necessary to smooth out repair strip the floor, allow to thoroughly dry and use an impregnator

Photo # 55 Photo # 56
Another view of too many coats of topical sealer on a Another view of too many coats of topical sealer on a
textured granite floor textured granite floor

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 7 of 16
© 2022 Natural Stone Institute
Photo # 57 Photo # 58
Hollow installation, efflorescence from joint resulting Shower pan holding water and wicked off the walls past
from moisture trying to escape the membrane

Photo # 59 Photo # 60
Blown rod from using metal in wet area and not
Holes in travertine - correct: clean, prep and fill with epoxy
encapsulated properly

Photo # 61 Photo # 62
Inadequate waterproofing membrane installation leading to potentially clogged
Using an enhancer on a moist floor - correct: strip the old enhancer, allow the
weepholes - correct: redo the the process according to TCNA guidelines and
floor to thoroughly dry and reapply enhancer correctly
plumbing code

Photo # 63 Photo # 64
Granite countertop edge not properly polished to match factory finish - Improper specification of material - very porous material in a wet area - correct:
correct: repolish the edge correctly multiple sealing applications on multiple days

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 8 of 16
© 2022 Natural Stone Institute
Photo # 65 Photo # 66
Shower pan with clogged weepholes - correct: carefully remove grout, clear out
the weepholes and allow substrate to thoroughly dry, then regrout and seal
Inside of drain in MIA Photo 65

Photo # 67 Photo # 68

Lack of slope on shower curb Spalling - correct: replace or clean, prep and repair

Photo # 69 Photo # 70
Efflorescence - face of a waterfall in a pool - correct: use Grout cracked - correct: cut out the grout and install an
a mild acidic cleaner and neutralize expansion joint material (driveway)

Photo # 71 Photo # 72
Possible spacer used when resining stone slab leaving a stain within the
resin - correct: completely refinish or replace
Holes in a travertine - correct: clean, prep and refill

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 9 of 16
© 2022 Natural Stone Institute
Photo # 73 Photo # 74
Lippage - Maximum accepted lippage for the stone industry - correct: Sealer streaking - correct: break down the sealer and follow
replace or grind and refinish back to specs manufacturer's recommendations

Photo # 75 Photo # 76
Hollow edge - correct: replace tile or repair using the proper amount Blown rod from using metal in wet area and not
setting material to support the hollow areas, then clean, prep and fill encapsulated properly (fiberglass preferred)

Photo # 77 Photo # 78
Different expansion and contraction rates between rigid and flexible
materials - correct: use the correct flexible material for this application
Excess sealer

Photo # 79 Photo # 80

Chip - correct: clean, prep and fill with epoxy or CA glue Spalling - correct: replace

Restoration & Maintenance SITE PHOTOGRAPHS

Troubleshooting Page 10 of 16
© 2022 Natural Stone Institute
Photo # 81 Photo # 82

Iron oxidation - use a rust poultice, then seal thoroughly spalling on limestone shower floor - correct: replace floor

Photo # 83 Photo # 84

Rust stain on limestone shower floor - rusted drain Spalling - correct: replace stone

Photo # 85 Photo # 86

Dyed stone Dyed stone - another view

Photo # 87 Photo # 88
Indent fracture - lack of bonding adhesive in the corner - Shrinkage cracks - too much thinset adhesive used -
correct: replace tile correct: replace

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 11 of 16
© 2022 Natural Stone Institute
Photo # 89 Photo # 90
Same as MIA 91 & 92 - defective material for a wet
Excessive lippage - correct: replace the material
application - correct: replace the material

Photo # 91 Photo # 92
Same as MIA Photo 89 & 92 - defective material for a wet Same as MIA Photo 89 & 91 - defective material for a wet
application - correct: replace the material application - correct: replace the material

Photo # 93 Photo # 94
Misaligned, hollow and incorrectly spaced - correct:
Hollow tiles and spalling
remove and replace

Photo # 95 Photo # 96

Stone not properly sealed Stone not properly sealed

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 12 of 16
© 2022 Natural Stone Institute
Photo # 97 Photo # 98
Spalling - moisture intrusion behind the wall - correct: Tenting - remove and replace affected tiles. Add
replace it movement and/or expansion joints per industry

Photo # 99 Photo # 100

Blown rod from using metal in wet area and not Oil staining in granite countertop - correct: use oil
encapsulated properly (fiberglass preferred) poultice and seal thoroughly with multiple applications

Photo # 101 Photo # 102

Soap staining granite countertop - correct: use towel Oil staining in granite countertop - correct: use oil
saturated with mineral spirits. Repeat as necessary. poultice and seal thoroughly with multiple applications

Photo # 103 Photo # 104

Green (environmental) citrus cleaner on a marble floor
Efflorescence in slate
used to clean the grout - correct: refinish the floor

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 13 of 16
© 2022 Natural Stone Institute
Photo # 105 Photo # 106
Tile separation due to lack of expansion joint - correct: cut grout Stain from planter - correct: mild acid wash, neutralize,
and replace with appropriate expansion joint detail. refinish (blend and feather out)

Photo # 107 Photo # 108

Project in Photo 108 after installation of expansion joints Lack of bonding adhesive under the tile - correct: use
and proper bonding correct type and amount of bonding.

Photo # 109 Photo # 110

Ceramic tile - pan is holding water - correct: remove tiles, clear the
weepholes and replace per TCNA guidelines
Etch mark on 'marble' - correct: refinish

Photo # 111 Photo # 112

Spalling - wrong thinset on a large format tile - latex, modified thinset Hard water deposits on black marble - correct: temporary fix: diamond
instead of a medium bed mortar - correct: replace grind, remove & replace grout when dry, or replace stone

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 14 of 16
© 2022 Natural Stone Institute
Photo # 113 Photo # 114

Another view of Photo 114 Demonstrating surface slope. Ball bearings roll downhill.

Photo # 115 Photo # 116

Moisture in substrate permanently staining slate pavers -
Close-up of Photo 115
tile sloped but the membrane is not

Photo # 117 Photo # 118

Fungus - the start of mold in the grout line - correct: use a mildew
cleaner that will not damage marble
Sealing in hot dry environment - dries too quickly

Photo # 119 Photo # 120

Sealer walk on before dry - correct: re-emulsify sealer and buff. Deck insufficiently sloped away from building - correct:
May have to refinish. remove and reinstall properly

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 15 of 16
© 2022 Natural Stone Institute
Photo # 121 Photo # 122
Cracks caused by material handling, substrate deformation, or Same as MIA Photo 123 - lack of proper maintenance, lack of proper sealing and
vibration from field cutting keeping shower door closed after use (not allowing moisture to escape)

Photo # 123 Photo # 124

Same as MIA Photo 122 - lack of proper maintenance, lack of proper sealing and Polishing compound too hot (orange peel) - correct:
keeping shower door closed after use (not allowing moisture to escape) refinish with 'cold' powder.

Photo # 125 Photo # 126

Close up of 124: Polishing compound too hot (orange Excessive grout haze - correct: carefully clean excessive grout off of calcium
peel) - correct: refinish with 'cold' powder. based stone (if an acid is used, neutralize the acid and refinish the stone)

Photo # 127 Photo # 128

Settling and chipped edges (caused by butt joint installation -
Spalling on outside of shower
minimum 1/16" gap)

Restoration & Maintenance SAMPLE PHOTOGRAPHS

Troubleshooting Page 16 of 16
© 2022 Natural Stone Institute
Restoration and Maintenance –
Additional Learning Resources
Stone Behavior Groups, pp. 21-10–16

• For more information about Crema Marfil and the company and quarries that produce it,
see, http://www.levantina.com/us/.
• Online Resource: http://www.natural-stone-database.com, type “Crema Europa” in the
search box.
• Online Resource: http://www.bempe.com/en/crema-europa-limestone
• Stone Care Guide, Ted McFadden. 2008.

Restorative Processes, pp. 21-51–66

• Stone Care Guide, Ted McFadden. 2008.

• Online Resource, http://www.stonerefinishing.com

Maintenance, pp. 21-75–84

• ASTM C1515, Standard Guide for Cleaning of Exterior Dimension Stone, Vertical and
Horizontal Surfaces, New or Existing.
• Cleaning Masonry – Review of the Literature by Grimm, Clayford T., P.E. Construction
Research Center, and University of Texas at Arlington, 1988.
• Cleaning Stone and Masonry, Clifton, James R., Editor. ASTM Special Technical Publication
935, American Society for Testing and Materials, 1983.
• Keeping It Clean by Grimmer, Anne E. U.S. Department of the Interior, National Park
Service, Washington, DC: U.S. Government Printing Office, 1988
• “Cleaning of Masonry Interiors of Public Buildings,” Cleaning Stone and Masonry by Roth,
J.W., ASTM STP 935, 1986.
• “Chemical Cleaning of Historical Structures – A Practical Approach,” Cleaning Stone And
Masonry by Rudder, T.H., ASTM STP 935, 1986.
• “A Case Study of the Cleaning of Marble at the Schenectady, New York, City Hall,” Cleaning
Stone and Masonry, by Waite, J.C. and R.J. Chen, ASTM STP 935, 1986.
• “A Macrosteriogrammetric Technique for Measuring Surface Erosion Losses on Stone,”
Cleaning Stone and Masonry by Winkler, E.M., ASTM STP 935, 1986.

Commercial and Historic Restoration, pp. 21-85–88

• Occupational Safety and Health Administration (OSHA): https://www.osha.gov/law-

regs.html

© 2022 Natural Stone Institute Additional Learning Resources • Page 21-121

• Occupational Safety and Health Administration (O.S.H.A.) – Guide to Controlling Silica
Exposure: https://www.osha.gov/Publications/3362silica-exposures.pdf
• Union Requirements – National Labor Relations Board: http://www.nlrb.gov/rights-we-
protect/employerunion-rights-and-obligations
• Federal Labor Requirements – United States Department of Labor:
http://www.dol.gov/whd/programs/dbra/wh347.htm
• National Park Service – Historic Rehabilitation Guidelines:
http://www.nps.gov/tps/standards/rehabilitation/rehabilitation-guidelines.pdf
• National Park Service – The Secretary of the Interior’s Standards for Rehabilitation:
http://www.nps.gov/tps/standards/rehabilitation/rehab/stand.htm
• National Park Service – Tax Incentives: http://www.nps.gov/tps/tax-incentives.htm
• National Park Service – Register of Historic Places Database:
http://www.nps.gov/history/nr/research/
• Milan Restoration Triumph – InfoTile.com
http://www.infotile.com/pdfFile/Product/ProductFile/1604201343759.pdf
• Historic Preservation – Technical Procedures:
http://www.gsa.gov/portal/content/111858
• National Trust for Historic Preservation: http://www.preservationnation.org

DSDM VIII (2016)

• ASTM International, ASTM C119, Standard Terminology Relating to Dimension Stone.

West Conshohocken, PA: ASTM International.
• National Tile Contractors Association, NTCA Reference Manual. 2022. Jackson: NTCA.
• Tile Council of America, Tile Council of North America Installation Handbook. Princeton:
TCA, 2022.
• International Code Council, 2012 International Plumbing Code. ICC, 2020.

Page 21-122 • Additional Learning Resources © 2022 Natural Stone Institute

TOLERANCES IN THE 2.0 Tolerances should not be confused
with the difference between nominal and actual
DIMENSION STONE dimensions. Perhaps the best known example
INDUSTRY of nominal dimensions exists in the dimension
lumber industry, where the common 2 by 4
does not measure 2 inches by 4 inches, but
1.0 Nothing in manufacturing, instead has an actual cross-section of 1½ inches
construction, or commerce is exact. Whether by 3½ inches. A similar situation exists in
it’s the weight of a product purchased at the stone supply, where a nominal paver size of 12
market, the concentration of a chemical inches by 24 inches might have an actual size of
solution, or the length of a stone panel, none 11¾ inches by 23¾ inches, allowing for ¼ inch
of them will measure exactly what they are joints while still maintaining a 12 inch by 24
specified to measure. More sophisticated inch installed grid. The fabrication tolerances
methods, machines and controls will produce in these cases, would be applied to the actual
results with lesser amounts of error, yet no dimensions, and not the nominal.
techniques will produce exact results. For
these reasons, all things must have a tolerance,
which is an allowable deviation from a 3.0 There are several different types of
specified, or designed value. In some cases, tolerance expressions:
like the machining of critical machine parts,
that allowable deviation may be so small that it 3.1. Bilateral Tolerance. This is the
is measured in micro-inches or microns. While most frequently encountered type of tolerance
the stone industry does not have tolerances in the stone industry. A bilateral tolerance is
requiring this level of precision, there exist one that expresses an allowable deviation that
critical dimensions that directly affect visual can be either greater or lesser than the desired
appearance and structural integrity of stone value. These are often referred to as “plus or
installations. minus” tolerances.
1.1. Tolerances are established to protect 3.1.1. Bilateral tolerances are usually
both the buyer and seller of a product or symmetrical. A symmetrical bilateral
service. The buyer is protected by knowing tolerance is one that allows the same amount of
that the workmanship must result in products deviation for both greater and lesser than the
that fall within the range of the prescribed target value. For instance, considering a 1¼”
tolerances. The seller is protected by having an (30 mm) thick slab, a tolerance of plus or
accepted variation from the specified values or minus ⅛” (3 mm) is considered to be a
measurements, so as not to be held to symmetrical bilateral tolerance. Most often
unattainable expectations. these types of tolerances are expressed using
the “±” symbol, and would be written as ±⅛”,
1.2. Units of measure in this document are
or ±3 mm.
expressed on both United States Customary
Units and SI units. The values stated in each
3.1.2. Some bilateral tolerances are
system are not exact equivalents of each other,
asymmetrical. An asymmetrical bilateral
as the conversions have been “rationalized” to
tolerance is one that describes a condition
provide rounded, convenient numbers in both
where the actual value is allowed to deviate
systems. Each system of measurement shall be
both greater and lesser than the specified, but
used exclusively and independently of the
not to the same extent. For instance, the depth
other, as combining values from both systems
of a continuous kerf is allowed to be either
may result in incompatibilities.
deeper or shallower than specified, but it is
only allowed to be 1/16” (1.5 mm) shallower,

© 2022 Natural Stone Institute Tolerances • Page 22-1

while it is allowed to be ⅛” (3 mm) deeper. 1
/32” (0.8 mm), but on a ½” (12 mm) joint, the
This would be an asymmetrical bilateral error would need to be much greater to be
tolerance, and is expressed as -1/16”, +⅛” (- visually detectable. Stating that the allowable
1.5, +3 mm). tolerance is ±25% is a simple way of having a
self-adjusting tolerance which gets larger as the
3.2. Unilateral Tolerance. This term is specified dimension gets larger.
used where deviation is allowed only in one
direction. For example, the depth of a back 3.5. Percentage tolerances are frequently
anchor is allowed to be 1/16” (1.5 mm) deeper coupled with an absolute dimensional limit,
than specified, but never shallower. This either a maximum or a minimum. Such limits
tolerance is expressed as -0, +1/16” (-0, +1.5 are typically referred to as “Not Less Than”
mm). (NLT) or “Not to Exceed” (NTE). These limits
are used when the percentage tolerance
3.3. Limit tolerances are those that represents a very small or very large tolerance
simply prescribe the minimum and maximum at either end of the target value range. Joint
dimensions allowable, without defining an width variation, for example, is allowed to be
actual target dimension. This method is ±25%. But that would mean that a stone setter
sometimes referred to as a “Go – No Go” working with 1/16” joints has an acceptable
expression. A limit tolerance would typically variation of only 1/64”, which would be
be written as “1⅛” min, 1⅜” max”. Limit unattainable in most scenarios. To address
tolerances are infrequently used in the stone or this, the tolerance is expressed as
construction industries. ±25%, NLT 1/32”. This means that the setter
is allowed to have joint widths that are 25%
3.4. Percentage tolerances are larger or smaller than the specified, but in no
sometimes used when the allowable deviation case shall he/she be held to a tolerance of less
varies with the value of the target dimension. than ±1/32”.
Percentage tolerances can be either bilateral or
unilateral, and simply state the percentage of 3.6. The same tolerance can be
variation that is acceptable. These types of communicated by writing it as a bilateral,
tolerances are most often used for things that unilateral, or limit tolerance. The only
affect visual characteristics only. For example, difference is the format of the expression. For
one’s eye may be able to detect an error in the example, the five examples below describe
width of a ⅛” (3 mm) joint when it approaches exactly the same allowable range of dimension:

Examples of Tolerance Formatting Differences

Tolerance Type Unit of Measure SI Equivalent

Bilateral (symmetrical) 1¼” ±⅛” 30 ±3 mm
Bilateral (asymmetrical) 13/16” -1/16”, +3/16” 29 -2,+4 mm
Unilateral 1⅛” -0, +¼” 27 -0, +6 mm
Limit 1⅛” min, 1⅜” max 27 mm min, 33 mm max
Percentage 1¼” ±10% 30 mm ±10%

Tolerances • Page 22-2 © 2022 Natural Stone Institute

5.0 Measurement of stone units to 6.5. The natural stone industry works with
determine compliance with published a nearly limitless variety of products in a nearly
tolerances shall be done with instruments that limitless variety of installation methods.
are appropriate for the level of precision Extreme circumstances may exist for which the
required. A common tape measure is adequate tolerances listed herein are either not
for most dimension checks, but when a feature appropriate or not attainable. Tolerances for
must be measured to fine degrees of accuracy, such conditions shall be established on a project
a caliper or feeler gauge may be necessary. All specific basis.
instruments used for measuring should be
calibrated, or checked for accuracy, prior to
use. Normal usage of a tape measure, for 7.0 A chart of stone fabrication,
example, will frequently result in the loosening installation, and substrate condition tolerances
or bending of the end hook, which will produce is provided following these pages.
significant errors in linear measurements.

8.0 Some of the tolerance expressions

6.0 Applicability of this Document. included in the chart require a graphic to
ensure correct and uniform interpretation.
6.1. There are a variety of sources from These graphics are provided immediately
which stone fabrication and installation following the chart in drawing D-22-1.
tolerances can be obtained. This document
was cross-referenced with tolerances published
by a variety of organizations. While most of
the published tolerances are in agreement or
exhibit only slight differences, some conflicts
may exist between this document and those
published by other organizations.

6.2. This document is considered to be a

voluntary standard. It has been drafted and
reviewed by industry stakeholders and
represents a consensus opinion of industry
participants. When specified as the
enforceable standard, it becomes part of a
binding agreement.

6.3. When no document has been specified

to govern the tolerances of a stone project or a
stone purchase, this document, by default, may
be cited as the appropriate industry standard
for those products.

6.4. More or less stringent tolerances may

be specified or adopted for any particular
product or purchase. When alternate
tolerances have been agreed upon between the
buyer and seller, those tolerances supersede
the tolerances listed herein.

© 2022 Natural Stone Institute Tolerances • Page 22-3

Notes:

Tolerances • Page 22-4 © 2022 Natural Stone Institute

 STONE INDUSTRY TOLERANCES
SECTOR ISSUE ITEM TOLERANCE
1 5
Thickness ranging from /4" to /8" (6 mm to 15 mm) with Smooth Finishes sold
±1/32" ±0.8 mm
as "Calibrated"
1 5
Thickness ranging from /4" to /8" (6 mm to 15 mm) with Flame or Textured
Depth of Finish Relief, NTE 1/8" ±1.5 mm
Finishes sold as "Calibrated"

Thickness ranging from >5/8" to 1¼" (>15 to 30 mm) with Smooth Finishes ±1/8" ±3 mm
Thickness

5
Thickness ranging from > /8" to 1¼" (>15 to 30 mm) with Flamed or Sanded 3
Depth of Finish Relief, NTE /16" Depth of Finish Relief, NTE 5 mm
Finishes
5
Thickness ranging from > /8" to 1¼" (>15 to 30 mm) Finished 2 Faces with
±1/16" ±1.5 mm
Smooth Finishes
Slab thickness of >1¼" to 2" (>30 to 50 mm) ±1/8" ±3 mm
1
Slab thicknesses over 2" (>50 mm) ± /4" ±6 mm
1
Face Dimension of Calibrated Tiles (see graphic) ± /32" ±0.8 mm
Face Size

Face Dimension of Pieces with Lengths up to 6'-0" (2 m) (see graphic) ±1/16" ±1.5 mm
Face Dimension of Pieces with Lengths > 6'-0" (2 m) and Areas ≤ 50 ft² (5 m²)
±3/32"
FABRICATION

±2.5 mm
(see graphic)
Face Dimension of Pieces with Areas > 50 ft² (5 m²) (see graphic) ±1/8" ±3 mm

Maximum Deviation from Square - Calibrated Tiles (see graphic) Governed by Face Dimension Tolerance - See Graphic
Squareness

Maximum Deviation from Square - Cut-to-Size Dimension Stone (see graphic) Governed by Face Dimension Tolerance - See Graphic

Perpendicularity Error of Edge to Face, Exposed Edge with Smooth Finish ±1.0° (about 1/64" per in) ±1.0° (about 0.18 mm in 10 mm)

Perpendicularity Error of Edge to Face, Concealed Edge with Smooth Finish ±2.0° (about 1/32" per in) ±2.0° (about .35 mm in 10 mm)
1
Maximum Deviation from Flat Plane - Calibrated Tile with Smooth Finish ± /32" in 2'-0" 0.8 mm in 600 mm
1
Maximum Deviation from Flat Plane - Back Surface of Calibrated Tile ± /32" in 2'-0" 0.8 mm in 600 mm
Maximum Deviation from Flat Plane - Cut-to-Size Dimension Stone with 1
± /16" in 4'-0" ±1.5 mm in 1.2 m
Smooth Finish
Flatness

Maximum Deviation from Flat Plane - Cut-to-Size Dimension Stone with 4-Cut, 1
± /8" in 4'-0" ±3 mm in 1.2 m
6-Cut, 8-Cut Finish
Maximum Deviation from Flat Plane - Cut-to-Size Dimension Stone with Flamed
±3/16" in 4'-0" ±5 mm in 1.2 m
or Coarse Stipple Finish
Maximum Deviation from Flat Plane - Cut-to-Size Dimension Stone with
±1" in 4'-0" ±25 mm in 1.2 m
Pointed or Rough Cut Finish
Maximum Deviation from Flat Plane - Cut-to-Size Dimension Stone with
Per Stock Per Stock
Splitface Finish

© 2022 Natural Stone Institute Dimension Stone Tolerances Page 22-5

 STONE INDUSTRY TOLERANCES
SECTOR ISSUE ITEM TOLERANCE
1
Exposed Heads/Calibrated edges (see graphic) ± /16" ±1.5 mm

Quirk miters (when width of nose ≤ ¼"; ≤6 mm) (see graphic) -0, +25% of dim -0, +25% of dim
Edge Conditions Quirk miters (when width of nose > ¼"; >6 mm) (see graphic) -0; + /16"
1
-0; +1.5 mm

Chamfers (when dimension ≤ ¼"; ≤6 mm) (see graphic) -0, +25% of dim -0, +25% of dim
1
Chamfers (when dimension > ¼"; >6 mm) (see graphic) -0; + /16" -0; +1.5 mm
Bullnose, Semi-Bullnose, & Rounds for thickness up to 1¼" (30 mm) (see
±1/32" from Theoretical Surface ±0.8 mm from Theoretical Surface
graphic)
Bullnose, Semi-Bullnose, & Rounds for thickness greater than 1¼" (30 mm) (see 1
± /16" from Theoretical Surface ±1.5 mm from Theoretical Surface
graphic)
Plunge Cut Anchor Slots: From face to C/L of slot ±1/16" ±1.5 mm
1
Plunge Cut Anchor Slots: Lateral placement ± /4" ±6 mm

Plunge Cut Anchor Slots: Width of Slot -0; +1/16" -0; +1.5 mm
FABRICATION (Continued)

1
Plunge Cut Anchor Slots: Depth of Slot at maximum ± /8" ±3 mm
1
Back Anchors: Location ± /8" ±3 mm

Back Anchors: Depth -0; +1/16" -0; +1.5 mm

1
Anchor Holes: From face to C/L of slot ± /16" ±1.5 mm
1
Anchor Holes: Lateral placement ± /8" ±3 mm
Anchor Preps

Anchor Holes: Diameter ±1/16" ±1.5 mm

1
Anchor Holes: Depth ± /8" ±3 mm
1
Anchor Holes: Depth of Anchor Sinkages: -0, + /8" -0, +3 mm
1
Continuous Kerfs: From face to C/L of kerf ± /16" ±1.5 mm

Continuous Kerfs: Maximum bow in 4'-0" ±1/16" ±1.5 mm

1
Continuous Kerfs: Width of Kerf -0; + /16" -0; +1.5 mm
1 1
Continuous Kerfs: Depth of Kerf - /16", + /8" -1.5, +3 mm
1
Rebated Kerfs: Elevation of Bearing Surface ± /16" ±1.5 mm
1
Bearing Checks: Elevation of Bearing Surface ± /16" ±1.5 mm
1
Bearing/Clearance Checks: Lateral Location ± /2" ±13 mm

Bearing/Clearance Checks: Setback from Face ±1/16" ±1.5 mm

© 2022 Natural Stone Institute Dimension Stone Tolerances Page 22-6

 STONE INDUSTRY TOLERANCES
SECTOR ISSUE ITEM TOLERANCE
1
Lippage, Maximum on Calibrated Tile (Smooth Surfaces) /32" 0.8 mm
3
Lippage, Maximum on Calibrated Tile (Flamed or Textured Surfaces) Depth of Finish Relief, NTE /16" Depth of Finish Relief, NTE 5 mm
1
Lippage, Maximum on Stone Pavement Walking Surfaces (smooth surfaces) /32" 0.8 mm
Lippage, Maximum on Stone Pavement Walking Surfaces (Flamed or Textured 3
Depth of Finish Relief, NTE /16" Depth of Finish Relief, NTE 5 mm
surfaces)
1
Lippage, Maximum on Interior Vertical Panels ≤20 ft² (≤2 m²) (smooth surfaces) /32" 0.8 mm
Lippage

Lippage, Maximum on Interior Vertical Panels ≤20 ft² (≤2 m²) (Flamed or
Depth of Finish Relief, NTE 3/16" Depth of Finish Relief, NTE 5 mm
Textured surfaces)
1
Lippage, Maximum on Interior Vertical Panels >20 ft² (>2 m²) (smooth surfaces) /16" 1.5 mm
Lippage, Maximum on Interior Vertical Panels >20 ft² (>2 m²) (Flamed or
Depth of Finish Relief, NTE 3/16" Depth of Finish Relief, NTE 5 mm
Textured surfaces)
Lippage, Maximum on Countertop @ Front 0 0
1
Lippage, Maximum on Countertop @ Back /32" 0.8 mm
INSTALLATION

1
Lippage, Maximum on Island Top @ Center /32" 0.8 mm

Joint Width, Variation from Specified ±25% of Specified Dimension, NLT ±1/32" ±25% of Specified Dimension, NLT ±0.8 mm"
1
Seam (Joint) Width, Countertop (Stone to Stone) ±25%, NLT ± /64" ±25%, NLT ±0.4 mm
1
Seam (Joint) Width, Countertop (Stone to Other) ± /16" ±1.5 mm
Width
Joint

Seam (Joint) Width, Countertop (Full-Height Backsplash to Upper Cabinet) ±1/8" ±3 mm

1
/8" in 10'-0" 3 mm in 3 m
1
Joints, Variation from Straight Line /4" in 20'-0" 6 mm in 6 m
3
/8" Maximum 10 mm Maximum
1
/8" in 10'-0" 3 mm in 3 m
1
Maximum Variation from Flat & Level, Interior Flooring /4" in 20'-0" 6 mm in 6 m
3
/8" Maximum 10 mm Maximum
Alignment

1
Maximum Variation from Flat & Level, Flooring underneath a Revolving Door ± /16" ±1.5 mm
1
/8" in 8'-0" 3 mm in 2.5 m
Maximum Variation from Plumb, Walls & Vertical Lines , Interior Cladding 1
/4" Maximum 6 mm Maximum
1
/8" in 10'-0" 3 mm in 3 m
1
Maximum Variation from Level (Sills, Lintels, Etc.), Interior Cladding /4" in 20'-0" 6 mm in 6 m
3
/8" Maximum 10 mm Maximum

© 2022 Natural Stone Institute Dimension Stone Tolerances Page 22-7

 STONE INDUSTRY TOLERANCES
SECTOR ISSUE ITEM TOLERANCE
1
/8" in 10'-0" 3 mm in 3 m
1
Maximum Variation from Building Line Position, Interior Cladding /4" in 20'-0" 6 mm in 6 m
3
/8" Maximum 10 mm Maximum
1
Maximum Variation from Flat & Level, Countertop /8" in 10'-0" 3 mm in 3 m
3
/8" Max Difference Between 10 mm Max Difference Between
INSTALLATION (Continued)

Largest & Smallest Risers; Largest & Smallest Risers;

Maximum Variation of Riser Height in Stairs
ALIGNMENT (Continued)

NTE 3/16" Difference Between NTE 5 mm Difference Between

Consecutive Risers Consecutive Risers
1
/4" in 10'-0" 6 mm in 3 m
3
Maximum Variation from Plumb, Walls & Vertical Lines , Exterior Cladding /8" in 20'-0" 10 mm in 6 m
1
/2" Maximum 12 mm Maximum
1
/8" in 10'-0" 3 mm in 3 m
1
Maximum Variation from Plumb, Exterior Corners or Conspicuous Lines /4" in 20'-0" 6 mm in 6 m
3
/8" Maximum 10 mm Maximum
1
/8" in 10'-0" 3 mm in 3 m
1
Maximum Variation from Level (Sills, Lintels, Etc.), Exterior Cladding /4" in 20'-0" 6 mm in 6 m
3
/8" Maximum 10 mm Maximum
1
/4" in 20'-0" 6 mm in 6 m
Maximum Variation from Building Line Position, Exterior Cladding 1
/2" Maximum 12 mm Maximum
1
Maximum Variation from Flat & Level; Substrate for Thinset Interior Flooring /8" in 10'-0" 3 mm in 3 m
SUBSTRATES

Surface Plane

1
Maximum Variation from Flat & Plumb, Adhered Interior Wall /8" in 10'-0" 3 mm in 3 m
1
Maximum Variation from Flat & Plumb, Adhered Exterior Cladding /4" in 10'-0" 6 mm in 3 m
1
Maximum Variation from Flat & Level, Countertop /8" in 10'-0" 3 mm in 3 m

© 2022 Natural Stone Institute Dimension Stone Tolerances Page 22-8

 REV DATE
GRAPHIC INTERPRETATION OF TOLERANCES
0 MAR 2022

DIMENSION STONE DESIGN MANUAL 2022

380 East Lorain Street, Oberlin, OH 44074 USA
www.naturalstoneinstitute.org SCALE:
DRWG NO: 22-D-9
NOT TO SCALE

© 2022 Natural Stone Institute 22-D-9

NOTES:

Dimension Stone Design Manual Ó 2022 Natural Stone Institute

GLOSSARY OF
STONE INDUSTRY TERMS
Additional references are listed at the end of this glossary.

A repellents, coloring agents or to adjust

the curing rate of the concrete or mortar.
Abate
In stone carving, to cut away material, Adoquin
leaving parts in relief. A volcanic, quartz based stone containing a
variety of colored aggregates and pumice
Abrasive Finish in a quartz matrix. Quarried in Mexico.
A non-reflective surface finish. An abrasive
finish may be defined by the grit size of Agate
the abrasive. A variegated, translucent, cryptocrystal-
line variety of quartz showing colored
Abrasive Hardness (Ha) bands or other markings (clouded, moss-
A measure of the wearing performance like, etc.).
of stone for floors, stair treads, and other
areas subjected to abrasion by foot traffic. Agglomerated Stone
Refer to ASTM C241 and C1353. A manmade product composed of crushed
stone combined with resin. See also en-
Absorption gineered stone and cultured stone.
The amount of water absorbed by a stone,
expressed as a percentage by weight. Refer Aggregate
to ASTM C97. A small mass of rock, having occurred
naturally (as in sand or gravel) or by means
Abutment of manufacture (as in a crushed aggregate
A solid stone “springer” at the lowest product), used either in a loose, noncohesive
point of an arch or vault. state, or as an ingredient in mortar or
concrete products.
Accelerator
In masonry, any ingredient added to mortar Alabaster
or concrete to speed the curing process. A fine grained and translucent variety
of gypsum, generally white in color. Com-
Acid Wash monly used in decorative applications as it
A treatment applied to the face of a stone is can be cut and carved easily with a knife
to achieve a texture or finish that is dis- or saw. Term is often incorrectly applied
tressed. Most acidic chemical treatments to fine grained marble.
are effective only when applied to calcar-
eous stone varieties. Alkaline
Pertains to a highly basic, as opposed to
Adhered acidic, substance; for example, hydrogen
Used in reference to stone veneer, or carbonate of sodium or potassium.
secured and supported by adhesion of
an approved bonding material over an Allowable Capacity
approved backing. The safe load that can be resisted by a
stone anchor, determined by dividing the
Admixture ultimate capacity by the factor of safety.
A material other than water, aggregates,
lime or cement, added to concrete or Ambient Temperature
mortar at the time of mixing. Admixtures Temperature of the surrounding environ-
are typically added to function as water ment.

© 2022 Natural Stone Institute Glossary of Terms • Page 23-1

 Anchor Argillite
A corrosion resistant metal fastener used A weakly metamorphosed compact rock
for securing dimension stone to a struc- composed mainly of clay and shale. Used
ture or adjacent stone units. Anchor types locally as building stone, although rarely
for stonework include those made of flat produced commercially.
stock (straps, dovetails)and round stock Arkose
(rod cramp, rod anchor, eyebolt and dowel).
A feldspar-rich sandstone containing 10%
Angle of Repose Anchorage or more clastic grains of feldspar. Also
The means by which slabs are secured to a called “arkosic sandstone” and “feldspathic
self supporting structure. sandstone.”
Angle of Repose Arris
The angle a normal pile of loose material A slight, although measurable, chamfer
makes to the horizontal. Used as an indi- where two surfaces meet
cator of flowability; the steeper the slope,
the more sluggish the flow. Artificial Stone
A manmade product attempting to
Anisotropic replicate the look of natural stone. This
Having properties, either visual or me- term is actually a misnomer, as it includes
chanical, that differ based on the direction an obvious contradiction of terms. Stone
Apron in which they are measured. All stones are is naturally occurring earth material. See
anisotropic to some degree, but the sedi- engineered stone and cultured
mentary stones typically have the greatest marble.
degree of anisotropy.
Anorthosite Ashlar
A dark-colored igneous rock consisting A stone façade of generally square or
mostly or entirely of calcic plagioclase. rectangular units having sawed or dressed
beds. There are three generally recog-
ANSI nized distinctions:
American National Standards Institute
1. random ashlar: ashlar set with
Antique Finish stones of varying length and height so
Arch A finish that replicates rustic or distressed that neither vertical nor horizontal
textures. Produced through mechanical joints are continuous.
or chemical means to simulate the naturally
2. coursed ashlar: Ashlar set to form
occurring effects of the aging process.
continuous horizontal joints.
Apex Stone 3. stacked ashlar: Ashlar set to form
Uppermost stone in a gable, pediment, continuous vertical joints.
vault or dome.
Apron ASI
(Allied Stone Industries)
A trim piece under a projecting stone top, The Allied Stone Industries is made up of
stool, etc. stone quarriers, fabricators, and the sup-
Architrave
Arch pliers of natural building materials and
The curved or pointed construction over related machinery and tools.
a doorway or opening. Arch shapes range
from flat to semicircular or semielliptical ASTM International
to acutely pointed. A consensus standards authoring organi-
zation originally founded 1896 as Ameri-
Architrave can Society for Testing Materials.
The beam or lowest division of the en-
tablature in the classical orders, spanning Axed Work (British)
from column to column. The decorated Hand-dressed stone surface showing fine-
surrounds of a window or door at the to-course, generally linear toolmarks made
Arris head and jamb. by axe, pick or bush hammer.

Page 23-2 • Glossary of Terms © 2022 Natural Stone Institute

B Basalt
A dark colored, igneous rock commer-
Back Anchor cially known as granite when fabricated
Any of a variety of anchors that extends as dimension stone. The fine-grained and
from the back surface of a stone panel, extrusive equivalent of gabbro.
as opposed to anchors that penetrate the Base
edges of a stone panel. In masonry, the bottom course of a stone
wall, or the vertical first member above
Backer Rod grade or a finished floor.
A flexible and compressible type of closed Coursed Ashlar
cell foam polyethylene, butyl rubber, or
Basic
In geology, one of four subdivisions used
open-cell or closed-cell polyurethane, to classify igneous rocks based on silica
rounded at surface to contact sealant. content: acidic, intermediate, basic and
The backer rod is positioned within the ultra-basic. Said of igneous rock contain-
joint so as to maintain appropriate depth ing relatively low silica content (approx.
and crosssectional shape of the bead. 45 to 50%).
Back-parging Batted Work (British)
The process of slathering the back of an Hand-dressed stone surface scored top
to bottom in narrow parallel strikes, using
adhered stone unit with an adhesive ma- a batting tool. Strokes may be vertical Random Ashlar
terial to reduce or eliminate voids in ad- (in which case the surface may be called
hesive contact. Also used in travertine or tooled) or oblique, and may range from
with the application of damp proofing. 8 to 10 per inch. Batting is also called
Also referred to as “back-buttering.” “broad tooling,” “droving,” or “angle dunting.”
Backsplash Bearing Check
A vertical covering of the wall where a A slot, generally not continuous, cut into
countertop surface meets the wall sur- the back or bed of dimension stone to
face, designed to protect the wall from allow entry of a supporting angle or clip.
moisture. Backsplashes range from a few Bed Joint
inches in height to “full height backsplashes” A horizontal joint between stones, usually
that extend from the countertop surface filled with mortar or sealant.
Backer Rod
to the underside of the upper cabinets. Bed
1. The top or bottom of a joint, natural
Back-up Structure bed; surface of stone parallel to its
A structural support wall erected behind stratification.
stone or brick facing. 2. In granites and marbles, a layer or sheet
Baluster of the rock mass that is frequently
horizontal, commonly curved and
A short post or vertical member in a
lenticular, as developed by fractures.
series that supports a railing or coping Sometimes also applied to the surface
forming a balustrade. Balusters are tradi- of parting between rock sheets.
tionally decorative forms that are turned 3. In stratified rocks, the unit layer formed Bearing Check
on a lathe. by sedimentation; of variable thickness,
Balustrade and commonly tilted or distorted by
A railing system with top rail, balusters subsequent deformation.It generally
and bottom rail. develops a rock cleavage, parting, or
jointing along the planes of stratification.
Band Course
See string course.
Bedding Plane
Plane of sedimentary stone in the position
Banker of its original formation. This plane may
Bench of timber or stone (may be a single be horizontal, coincident with mountain
block) on which stone is worked. slopes, or random. Bedding Plane

© 2022 Natural Stone Institute Glossary of Terms • Page 23-3

 Bedrock Block
General term referring to the rock un- See quarry block.
derlying other unconsolidated material,
such as soil. Bluestone
A fine- to medium-grain, quartz based
Belt Course stone of the U.S. Appalachian Plateau.
A continuous horizontal course, marking The stone is well known for relatively
a division in the wall plane. easy cleavage along generally flat planes,
Bench making it a common choice for naturally
Steps formed in a quarry by removal of cleft products such as flagstone. The term
stone. Also, a long seat of cubic stone. “bluestone” may be used in other parts of
bevel. A term describing the intersection the world to describe very dissimilar re-
of two surfaces meeting at an angle other gional products.
than 90 degrees.
Black Granite Bollard
A free standing stone post or guard.
Rock species known to petrologists as di-
abase, diorite, gabbro and other varieties Bond
quarried as dimension stone. As dimen- 1. Pattern of joints in successive courses.
sion blocks or slabs, they are valued spe- 2. To stick or adhere.
cifically for their dark grey to black color
when polished. Scientifically, they are far Book Match Pattern
removed in composition from true gran- A vein matching technique where oppo-
ites though they may be satisfactorily used site faces of adjacent slabs are exposed,
for some of the purposes to which com- producing a repeating mirror image of
mercial granites are adapted. They possess the veining trend of the material. Book-
an interlocking crystalline texture, but matched material is most commonly
unlike granites, they contain little or no polished to allow the greatest visibility of
quartz or alkalic feldspar, and are charac- the veining character of the stone.
Book Match Pattern terized by an abundance of one or more Border Stone
of the common black rock-forming Usually a flat stone used as an edging
minerals (chiefly pyroxenes, hornblende, material. A border stone is generally used
and biotite). to retain or define the pattern around the
Blade Dressing field of paving.
A maintenance process required periodi-
cally to restore optimum performance Boss
of diamond abrasive cutting tools. The In masonry, a roughly shaped stone set to
process consists of cutting or grinding project for carving in place. A carved
into a softer material which will abrade ornamentation to conceal the jointing at
at the matrix and expose new diamond the junction of ribs in a Gothic vault.
surfaces. Dressing is frequently done with Boulder
manufactured dressing sticks, soft brick, Naturally rounded rock fragment larger
and some abrasive sandstones. than 256 mm diameter. Used for crude
Bleed walls and foundation, generally in mortar.
Staining caused by corrosive metals,
oil based putties, mastics, caulking, or Bowing
sealing compounds. A warping or curving of a stone unit.
Blending Breccia
The random positioning of adjacent Rock characterized by course, angular
veneer panels, floor slabs, or tiles, to fragments, either the result of crushing
prevent large regions of uniform color, and recementing essentially in place, or
contrasted by adjacent large regions of deposition of angular pieces that become
dissimilar uniform color. consolidated. Numerous marbles owe

Page 23-4 • Glossary of Terms © 2022 Natural Stone Institute

their distinctive appearance to the Bugged Finish
brecciation caused by metamorphism. A smooth finish produced in limestone by
Italian for, “broken stones, rubble.” grinding with power sanders.
Brecciated Marble Building Stone
Any marble composed of angular Rock material in its natural state of com-
fragments. position and aggregation as it exists in the
Bridge Crane quarry and is usable in construction
A hoisting system that consists of a hoist, as dimension building stone. Also used
normally using cables, which moves on interchangeably with the term dimension
a beam or “bridge” spanning an open- stone.
ing between two rails. The hoist moves Building Stone Institute (BSI)
laterally along the bridge and the bridge Founded in 1919, BSI was a trade asso-
moves longitudinally along the rails, ciation of quarriers, fabricators, dealers,
allowing the hoist to be over any position and others working with natural stone.
within the rectangle contained within the In 2018, BSI merged with the Marble
lengths of the two rails. Institute of America to form the Natural
Bridge Polisher Stone Institute.
A single spindle polishing machine that Bullnose
travels along a beam, or “bridge”, which Convex rounding of a stone edge, such as
travels atop two rails. Also known as a a stair tread or countertop.
“gantry” polisher.
Bush Hammering Bullnose
Bridge Saw A process which produces textured
A saw that travels along a beam, or surfaces with small evenly spaced pits
“bridge”, which travels atop two rails. produced by hand or pneumatic hammer.
These saws are typically powerful and The spacing between the pits is often
fitted with large diameter blades. A
defined as “6-cut,” “4-cut,” etc.
rotating table is positioned below the
saw, allowing for skew cuts, and the saw Butt Joint
arbor typically rotates, allowing for An external corner formed by two stone
angled cuts. panels with one finished edge in a lap joint
Broach configuration.
1. To drill or cut out material left Buttering
Placing mortar on stone units with a Butt Joint
between closely spaced drill holes.
2. A mason’s sharp-pointed chisel for trowel before setting them into position.
dressing stone. C
3. An inclined piece of masonry filling
Calcarenite
the triangular space between the base
Limestone composed predominantly of
of an octagonal spire and the top of a
cemented sand-size grains of the mineral
square tower. calcite (more rarely aragonite), usually
4. A type of chisel used for working as fragments of shells or other skeletal
narrow surfaces. structures. Some calcarenites contain
Brownstone oolites (small, spherical grains of calcium
A trade term applied to ferruginous dark carbonate that resemble fish eggs) and may
brown and reddish-brown arkosic quartz be termed oolitic limestone. Calcareous
based stone extensively used for construc- sandstones, in which the calcium carbon-
tion in the U.S. during the 19th century. ate is present chiefly as bonding material,
Brushed Finish are not included in this category.
A subtly textured surface finish achieved Calcareous
by wet brushing a stone with a coarse Refers to substances containing or com-
rotary-type abrasive brush. posed of calcium carbonate.

© 2022 Natural Stone Institute Glossary of Terms • Page 23-5

 Calcite Carve
A common rock forming mineral. The To shape a solid material such as stone by
chief constituent of limestone and precisely cutting it with a tool.
most marble.
Caulk
Calcite Limestone To seal a joint with an elastomeric, adhe-
Limestone containing not more than five sive compound.
percent of magnesium carbonate.
Cavity Vent
Calcite Marble An opening in joints of stone veneer to al-
Cantilever A crystalline variety of limestone containing low the passage of air and moisture from
not more than 5% of magnesium carbonate. inside the wall cavity to the exterior. The
Calcite Streaks vents may be weep holes, plastic tubing,
White or milky streaks occurring in or wicks.
stone. It is a joint plane usually wider than Cavity Wall
a glass seam which has been recemented A multi-wythe masonry wall built with a
by deposition of calcite in the crack. It is
continuous cavity between the outer ma-
structurally sound.
sonry, typically brick or stone, and the
Calibration inner wall, typically concrete block or
Overhang
Within the stone industry, the process in frame construction. The cavity is vented
which stone slabs or units are abraded to reduce the amount of condensate that
to achieve a more precise thickness will collect in the space, and is wept to
tolerance (±1mm) than what would provide an evacuation path for any mois-
normally be produced by standard sawing ture that collects within the space.
techniques. The term is most frequently
used in the production of stone tile, which Cement Putty or Butter
must have limited thickness variation to See neat cement.
allow installation using thinset adhesive. Chamfer
The term gauge is essentially synony- A flat treatment, produced by either
mous, although is more commonly used grinding or cutting, to eliminate the sharp
Cap or Capital
to describe less precise techniques. edge where two surfaces meet.
Canopy Chat Sawn Finish
A sheltering roof, as over a niche or a
A rough, gang-sawn finish produced by
doorway.
sawing with coarse abrasives.
Cantera Chert
A volcanic, quartz based stone with quali-
ties similar to adoquin, but not as dense. Hard, dense sedimentary rock composed
Quarried in Mexico. of interlocking quartz crystals and pos-
sibly amorphous silica (opal). Synony-
Cantilever mous with “flint”.
A structural member supported at only one
Caulk end. The term is loosely used, although Chiseled Edge
not technically correct, to describe an The rustic, aged appearance produced by
overhang. mechanically chipping the stone edge.
Cap or Capital Cladding
The culminating stone at the top of a col- Exterior veneer stone covering. Non-load
umn or pilaster, often richly carved. bearing stone veneer used as the facing
material in exterior wall construction.
Carbonic Acid
A weak acid with the formula H2CO3. It is Clast
also a name sometimes given to solutions An individual grain or constituent of a
Chamfer of carbon dioxide in water. sedimentary rock.

Page 23-6 • Glossary of Terms © 2022 Natural Stone Institute

Cleavage Column
The ability of a rock mass to break along A vertical support, usually consisting of a
natural surfaces; a surface of natural base, shaft, and capital.
parting. Compressive Strength
Cleavage Plane (ASTM C170)
Plane or planes along which a stone may A measure of the resistance of the stone
likely break or delaminate. to crushing loads, generally tested per
ASTM C170.
Cleft Finish
Rough-surfaced stones such as slates or Conglomerate
sandstones that are cleaved or separated A coarse-grained sedimentary rock, with
along a natural seam are referred to as clast grains larger than 2 mm.
natural cleft. Construction (cold) Joint
Closer (British) The joint between two separate place-
1. In equidimensional stone masonry, a ments of concrete.
stone trimmed to non-uniform length Contractor, stone
to close a course next to a quoin or Company or person that erects and
other end unit. installs fabricated dimension stone.
2. A stone course running from one Column
Control Joint
window sill to another (a variety A partial depth joint that is either
of string course). formed or sawed in concrete to control
CNC Machine the location and frequency of shrinkage
cracking.
A computer numeric controlled, multi-
axis, vertical spindle machine designed to Conveyor
use rotating milling and profiling tools to A general term, often used interchange-
produce shapes, cut outs, holes, finishes, ably with belt conveyor, but applicable
and various other operations in stone that to all conveyor types including pans, Control Joint
are otherwise accomplished by more screws, buckets, pneumatics, radial
labor intensive techniques. stackers and others.
Cobblestone Coping
A dimension stone large enough for use A stone used as a cap on freestanding
in paving. A term commonly used to de- walls.
scribe paving blocks, usually granite, and Coquina
generally cut or cleft to approximately Limestone composed predominantly of
rectangular prisms. shells or fragments of shells loosely
Colonnade cemented by calcite. Coquina is coarse
A range of columns supporting an entab- textured and has a high porosity. The
term is applied principally to a very Coping
lature or one side of a roof.
porous rock quarried in Florida.
Color Enhancer/Sealer
A product that is designed to enrich, Corbel
brighten and enhance the color and/or A projection or bracket extending from
character of the stone. Stone enhancers the face of a wall to support an element
are more frequently used on honed or above it.
textured surfaces where the stone color Core
and/or character are muted by the finish. The cylindrical mass of stone that results
Enhancers are also used to match the from drilling a hole in stone with a
color of an exposed slab edge to that of a hollow core bit, often times is used as a
resin treated slab face. sampling technique in quarries.

© 2022 Natural Stone Institute Glossary of Terms • Page 23-7

 Core bit Cross-bedding
A hollow cylindrical drilling tool that The arrangement of laminations of strata
bores a hole by abrading only the perimeter transverse or oblique to the main planes
of the core, utilizing less abrasive than a of stratification.
bit that would abrade the entire diameter Cross-cut
of the hole. The process of cutting the initial block
Cornice Core sampling of stone parallel to the natural bedding
A drilling process by which a section of plane. The effect is a mottled or cloudlike
rock is taken for the purposes of testing appearance. Synonymous with fleuri cut,
and evaluation. although the term cross cut is most often
Cornerstone used when describing travertine materials.
A ceremonial stone at an exterior corner Crowfoot
of a building, generally engraved with See stylolite.
pertinent information about the build- Cubic Stone
ing’s construction, including the date. Dimension units more than 2 inches thick
Also used to describe a masonry stone e.g., cubic limestone, cubic marble.
Coursed Veneer
unit erected at an exterior corner from
which lines can be strung to control the Cultured Marble
linear position of subsequent stone units. An artificial, manmade product some-
Cornice what resembling marble.
Any projecting ornamental molding that Cup Wheel
crowns or finishes the top of a building Shop tool used to remove large amounts
or wall. of material from the edge of a stone.
Course These can be used to aid in the creation of
A horizontal range of stone units the edge profiles and larger radii.
length of a wall. Curbing
Coursed Veneer Stone, generally in cubic forms, border-
Cove Base A veneer achieved by using stones of the ing streets, walks, etc. Sometimes spelled
same or approximately the same height “kerbing.”
with stones that achieve that height in Cure Time
multiple courses. Some horizontal joints The time required for a chemical reac-
run the entire length of the veneered area. tion (polymerization or hydration) to be
Vertical joints are constantly broken, so that completed in a sealant, concrete, mortar,
no two joints will be over one another. or other construction element until the
Cove Base finished visual and performance attributes
A concave stone molding. See base. are developed.
Cove Molding Curtain Wall
A concave molding, typically found at A non-bearing exterior stone cladding
Cove Molding the sloped or arched junction of a wall supported by an anchoring system. Used
and ceiling. to protect a building from the elements.
Crack Cushion
A man-made break, split, fracture, sepa- A resilient pad placed between adjoining
ration, cleavage, or elongated narrow stone units and other materials to absorb
opening, visible without magnification to or distribute loads.
the human eye and extending from the Cut Stone
surface into the stone, which must extend Currently, stone that has been fabricated
through the grain or matrix of the stone. to a finished size and configuration and
Cramp ready to be installed. Historically, the
A U-shaped metal anchor used to hold term “cut stone” was used to describe
Cramp two adjacent units of stone together. limestone products.

Page 23-8 • Glossary of Terms © 2022 Natural Stone Institute

Cycle Time Digital Layout Application
Time for a machine to complete one Software designed to allow CAD drawing
cycle, i.e., load, haul, dump, return. files to be used with scaled digital pho-
D tographs to allow a fabricator to preplan
the layout of his slab or tile project prior
Damp Proofing to cutting.
One or more coatings of a compound that
is impervious to water. Usually applied to Digital Templating
the back or face of the stone or the back A process for virtual, digital measurement
of the wall at or near grade. of site conditions which eliminates the
need to make physical templates. Digital
Dead Load templating information can be interfaced
Permanent gravity induced loads, such as
with various CAD and CNC systems to
those developed by the structure, finishes,
allow rapid transfer and utilization of the
and permanently affixed elements. See
information.
also live load.
Dentil Dimension Stone Curtain Wall
Block projections on an entablature. A natural stone product that has been cut,
machined, and/or finished to specific size
Dentil Course or shape.
Mold course immediately below the
cornice, comprising of small, uniformly Dolomite
spaced blocks referred to as “dentils.” 1. The mineral form of calcium-
Derrick magnesium carbonate. Constituent Diamond Match
A hoisting device, usually made up of a of some building limestones.
guyed mast and hinged boom with pulleys 2. A crystalline variety of limestone
and cables. containing in excess of 40 percent
Diamond magnesium carbonate as the
A carbon based mineral, usually man- dolomite molecule.
made, used as an abrasive in stone cut- Also called “dolostone”.
ting equipment. Dolomitic Limestone
Diamond Match Limestone that contains more than 10 Die
A vein matching technique in which percent but less than 80 percent of the
contiguous faces of adjacent slabs are mineral dolomite.
“unfolded” about two perpendicular axes,
producing a vein pattern which has Dolostone
approximate symmetry about a point. See entry 2 under dolomite.
Diamond Wire Saw Dovetail Slot Dovetail Slot
A machine using cable of various diameters A continuous groove with a trapezoid
and lengths, impregnated with diamond section resembling a dove’s tail.
dust or more commonly fitted with Dowel
cylindrical diamond coated segments. Di-
A short piece of cylindrical nonferous
amond wire saws are used in quarrying,
metal used as a stone anchor.
slabbing, and contour sawing operations. Dowel
Die Drafted Margin (British)
A covering layer of interior stone from Tooled border around the face of a stone.
wainscot to ceiling. Also called “margin draft”.
Digital Inventory Management Dressing
A software and camera system allowing The shaping and squaring of natural stone
fabricators and distributors to have a pho- blocks for storage and shipment. Some-
tographic inventory of their materials. times called “scabbing”. Drafted Margin

© 2022 Natural Stone Institute Glossary of Terms • Page 23-9

 Drill Rigs Edge Chiseling Tool
Machines used in quarry operations to Tool with carbide jaws used to create a
bore holes in a linear path to facilitate “pitched”, “quarry”, or “chiseled” edge
separation of the stone loaf from its without using a hammer and chisel.
insitu position. Edge Profile
Drip The specific contour to which an exposed
A groove or slot cut beneath and slightly edge has been shaped, normally for deco-
behind the forward edge of a projecting rative purposes.
stone member, such as a sill, lintel or cop- Efflorescence
ing to cause water to drop at that location
A salt deposit, in the form of a white
and prevent water from running down
powder residue that forms on the surface
the face of the wall
of stone, brick, or mortar. It is caused by
Drip Stone alkalis leached from the masonry or soil
A projecting molding over the heads of and carried to the surface by moisture
doorways, windows and archways to throw Elevation
off the rain. Also known as a “hoodmold”
A drawing of the vertical faces and
and, when rectangular, as a “label”.
elements of a structure, either interior or
Dry Seam exterior.
Drip and Drip Stone A naturally occurring unhealed fracture Encrinal Marble
in stone which may be a plane of weakness. Marble deriving decoration from fossils
Dry Stack (encrinites) or shells.
In rubble masonry construction, a self- Engineered Stone
supporting wall erected without mortar. A manmade product composed of a blend
Dual Finish of natural minerals (generally quartz) and
Multiple contrasting finishes, such as manmade agents (such as polyester, glass,
thermal and polished, on one piece of stone. epoxy, and other such ingredients).
Entablature Durability Entablature
The measure of the ability of natural A composite beam member carried by
building stone to endure and to maintain columns and made up of an architrave
its essential and distinctive characteristics (bottom), frieze (middle), and cornice
of strength, resistance to decay, and (top).
appearance, while exposed to the ele-
ments encountered in its application Entasis
environment. The slight convexity designed in a col-
umn shaft for aesthetic purposes. This is
Dutchman done intentionally to offset the per-
1. A small piece of stone inserted as ceived illusion of concavity of a perfectly
a patch in a larger piece of dimension straight shafted column.
stone. Epoxy Resin
2. A small piece of stone inserted in A flexible, usually exothermic curing
an ashlar wall.
resin made by the polymerization of an
E epoxide; used as an adhesive.
Eased Edge Erection
A slightly arrised, chamfered, or radiused The process of setting vertical dimension
edge to eliminate the sharpness of the stone into place.
fabricated stone edge. Etched
Eaves A decorative surface pattern created by
The underside of a sloping roof that over- a variety of methods, produced either by
Entasis hangs a wall. chemical or mechanical methods.

Page 23-10 • Glossary of Terms © 2022 Natural Stone Institute

Exfoliation Fieldstone
Peeling or scaling of stone surfaces caused A naturally occurring, irregularly shaped
by chemical or physical weathering. stone, as found in a field, used for various
Expansion Anchor or Bolt building applications without further
A socket that grips a drilled hole in con- fabrication. Field stone are commonly
crete by expanding as a tapered bolt is used in freestanding walls, veneers, walk-
drawn into it. ways, and garden bed linings.
Expansion/Contraction Joint Filler Strip Expansion Anchor or Bolt
A flexible joint between stone units designed See backer rod.
to expand or contract to accommodate Filling
movements due to temperature change
A trade expression used to indicate the
or dynamic structural movement.
filling of natural voids in stone units with
Exposed Face cements or synthetic resins and similar
The visible side of any stone element. materials.
F Fines
Fabricated The powder, dust, and silt- or sand-sized
Used in reference to dimension stone, material resulting from processing, usu-
Expansion/Contraction Joint
it means having undergone cutting, ally crushing, stone.
machining, or other processes in order Finish
to refine the product for its intended Process applied to the exposed surfaces
application manufactured and ready for of dimension stone during fabrication
installation. to achieve the desired aesthetic and/or
Face performance characteristics of the stone.
The exposed surface of stone on a structure. The finish may be applied early or late in
the fabrication sequence.
Fascia
Any flat horizontal member, generally Fissure
between moldings, most frequently used An industry term describing any naturally
when referring to elements of a classical occurring separation along crystalline
architecture cornice. boundaries visible in exposed surface of
Feed Rate the stone. Note that the industry use of
The rate of speed with which routing, this term is different than the scientific,
cutting, or sawing blades and bits travel as geological use of this term.
they are cutting the material. Flagstone
Feldspar Thin slabs of stone with irregular shapes
A group of crystalline minerals, all silicates and split edges used for paving surfaces
of aluminum with potassium, sodium, such as walks, driveways, and patios. The
calcium, or barium. An essential constituent term is used to describe any stone used in
of nearly all crystalline rocks. this pattern, although is most often used
to describe sedimentary stones that have
Ferruginous been cleft into their final thickness.
Said of limestone or sandstone containing
a high proportion of iron oxide. Flamed Finish
See Thermal Finish.
Fiberglass Backing
A fine grid mesh reinforcement that is Fleuri
adhered to the back surface of stone slabs The mottled random effect obtained
which have limited stability. The primary when slabs of certain stone varieties are
intent of this reinforcement is to reduce sawn parallel to their natural bedding
safety risks in the handling of fragile slabs. planes. See also Cross Cut. Fleuri

© 2022 Natural Stone Institute Glossary of Terms • Page 23-11

 Fleuri Cut Gallet (British)
To cut slabs of quarried stone parallel to A stone chip or spall.
the natural bedding plane. Gang Saw
Flexural Strength A mechanical device employing a series
A bending strength test, normally per- of parallel reciprocating saw blades to cut
formed per the ASTM C880 test method, stone blocks into slabs of predetermined
in which a sample of stone of the project thickness. The most common variety of
thickness is supported by two support gang saw used in the stone industry uses a
rods creating a span of at least 10 times slurry containing steel shot as the abrasive
the thickness, and loaded to failure by two medium; but diamond segments mount-
rods positioned at quarter points of the ed to steel blades are commonly used in
gang sawing softer stone such as marble
span.The results are reported as the stress
experienced by the stone sample at the or limestone.
time of specimen failure, and expressed as Gauge
a force per unit area (lbs/in² or pascals). Any process, although most frequently
See also modulus of rupture. grinding, done to reduce the effects of the
tolerances of stone slab thickness. Gaug-
Flooring ing may be done to a precise thickness
Stone used as an interior pedestrian with a specific tolerance, or may simply
walking surface. be done to two or more stones until the
Flute thickness of the lot is uniform.
One of series of shallow, concave, parallel See also calibrate.
grooves running vertically on the shaft of Glass Seam
a column, pilaster, or other surface. A trade term in the limestone industry
Fracture for a former fracture or parting that has
Any break or separation of fabric within been naturally recemented and annealed
the stone as a result of mechanical stress. by deposition of transparent calcite. Simi-
Flute Freestone lar to calcite streak, but transparent.
A stone that may be cut freely in any Compare with dry seam.
direction without fracture or splitting. Gloss Meter
Also called “universal stone.” See isotropic. An instrument designed to measure the
Frieze reflectivity of a surface.
1. A decorated band along the upper Gneiss
part of an interior wall. Coarse-grained, metamorphic rock with
2. The middle member of the entablature, discontinuous foliation caused by planar
located above the architrave and alignment of plate and lath-shaped minerals.
below the cornice. When used for building stone, generally
Front-end Loader classed as trade granite. Most gneiss is
A heavy equipment earth moving ma- dark and composed mainly of quartz,
Frieze chine with a hydraulically powered bucket feldspar, mica and ferromagnesian min-
on two booms (or arms) extending in eral (iron-magnesium silicates).
front of the tractor portion of the ma- Grain
chine. The bucket may be replaced with 1. A quarry term for a plane of parting
other devices to accomplish specific tasks in a metamorphic rock, e.g. slate; the
in stone quarrying operations. direction along which a stone is more
G easily broken, split, or cut. The main
Gabbro direction of the mineral composition
A group of dark-colored basic intrusive and arrangement in stone.
igneous rocks composed chiefly of labra- 2. A very small (less than a few mil-
dorite or bytownite and augite. It is the limeters diameter) particle of rock,
approximate intrusive equivalent of basalt. such as a sand grain.

Page 23-12 • Glossary of Terms © 2022 Natural Stone Institute

 3. A general or descriptive term used Greenstone
to describe the relative size of crystal- A metamorphic rock, typically with poorly
line rock components, as in defined granularity, ranging in color
“fine-grained” and “course-grained.” from medium-green or yellowish-green
Granite (commercial definition) to black. Refer to greenstone group in
A term that includes granite (as defined ASTM C119.
below) plus gneiss, gneissic granite, gran- Grind
ite gneiss, and the rock species known to To remove portions of stone material by
petrologists as syenite, monzonite, and any abrasive method. Grinding may be
granodiorite, species intermediate be- part of producing a finish, shaping a pro-
tween them, the gneissic varieties and file, achieving a specific dimension, creat-
gneisses of corresponding mineralogic ing flatness between adjacently installed
compositions and the corresponding va- pieces, or part of a restorative effort.
rieties of porphyritic textures. The term Grout
commercial granite shall also include other 1. A mixture of cementitious material
feldspathic crystalline rocks of similar and water, with or without aggregate,
textures, containing minor amounts of
proportioned to produce a plastic
accessory minerals, used for special
decorative purposes, and known to consistency without segregation of the
petrologists as anorthosite and larvikite. constituents; also a mixture of other
composition but of similar consistency.
Granite (scientific definition) 2. To place and tool grout in the joints
A visibly granular, crystalline rock of pre- of stonework.
dominantly interlocking texture com- 3. In quarrying: a term describing the
posed essentially of alkalic feldspars and
product of the quarry which is
quartz. Feldspar is generally present in
excess of quartz, and accessory miner- unusable for dimension stone,
als (chiefly micas, hornblende, or more often piled near the extraction site.
rarely pyroxene) are commonly present. Guillotine
The alkalic feldspars may be present (1) A device used for cutting stone slabs to
as individual mineral species, (2) as iso- sizes by means of wedges driven by
morphous or mechanical intergrowths hydraulic pressure. The resultant fracture
with each other, or (3) as chemical inter- is of low precision, with a ragged, chipped
growths with the lime feldspar molecule, appearance.
but 80 + 3% of the feldspar must be
composed of the potash or soda feldspar H
molecules. Halite
Granite Rock salt; the mineral form of sodium
A very hard, crystalline, igneous rock, chloride (NaCl); a sedimentary rock.
gray to pink in color, composed of feldspar, Hardness
quartz, and lesser amounts of dark ferro- In stones, hardness most frequently refers
magnesium materials. Gneiss and black to stone’s resistance to abrasion, particu-
“granites” are similar to true granites in larly abrasion due to foot traffic, as tested
structure and texture, but are composed by either ASTM C241 or C1353. In min-
of different minerals. Commercial and erals, hardness generally refers to the
scientific definitions of the granite group mineral’s rank within the Moh’s Scale of
are explained in detail in ASTM C119. Mineral Hardness.
Granular Head
Stones having a texture characterized by The exposed surface of the jointed end
particles that are apparent to the unaided of any given piece of stone with a gauged
eye. For sedimentary rocks, particles less dimension not more than the minimum
than 4 inches in diameter and approxi- thickness of the material specified. Also
mately equal in size. known as “return head.”

© 2022 Natural Stone Institute Glossary of Terms • Page 23-13

 Hearth Incise
1. The floor of a fireplace together with To cut inwardly or engrave, especially in
an adjacent area of fire-resistant a “V” shaped profile, as in an inscription.
material that extends into the room. Inscription
2. An area permanently floored with Lettering cut in stone.
fire-resistant material beneath and
surrounding a stove.
Isolation joint
A joint separating a concrete slab from
Hearth Stone another element, such as a column or wall.
Originally the single large stone or stones
used for the hearth, now most commonly
J
Hearth
used to describe the stone in front of the Joint
fire chamber and many times extending A space between installed stone units or
on either or both sides of the front of the between a dimension stone and the
fire chamber. adjoining material.
Honed Jointing Scheme
A satin-smooth surface finish with little or
The intentional pattern created by the
no gloss. direction and position of stone joints as
Hysteresis, thermal determined by the design professional for
A residual or permanent volume change aesthetic reasons.
in stones after the temperature has been K
normalized, generally causing the stone Kaolinite
panel to bow. Most commonly associated A hydrous aluminum silicate mineral.
Kerf with fine grained true marbles used in
thin panel applications. Kerf
1. A slot, either local or continuous, cut
I into the edge of a stone with a saw
Igneous blade for insertion of anchors.
Any of the various volcanic rocks, 2. The width of a cut when sawing
solidified after the molten state, such as through stone blocks or jointing slabs.
granite. Igneous is one of the three main
rock classifications. Compare with meta- Keystone
morphic and sedimentary. The central stone of an arch, sometimes
sculpted or otherwise embellished.
ILIA
(Indiana Limestone Institute of America) L
A trade organization established for the Lamination
dissemination of information on lime- Two or more thicknesses of stone slab
Keystone stone standards, recommended practices, adhered together at an exposed edge,
grades, colors, finishes, and all technical usually in decorative work such as coun-
data required for specifying, detailing, tertops, creating an aesthetic effect that
fabricating, and erecting Indiana Lime- suggests that the stone is thicker than
stone. Publishers of the Indiana Lime- it actually is. Laminated edges may be
stone Handbook and other technical dressed or profiled to a variety of shapes
publications, founded in 1928. for additional decorative value.
Impregnators Laser
Any applied repellent that penetrates the An acronym for Light Amplification by
stone and resides below the plane of the Stimulated Emission of Radiation, which
finished surface. Impregnators may be produces an intense narrow beam of co-
hydrophobic (water-repellent), oliophobic herent, monochromatic light. Lasers are
(oil repellent), or both, and are used in used in the stone industry for a variety
some stone varieties to increase stain of cutting machine alignment aids, layout
Lamination resistance. aids, and leveling instruments.

Page 23-14 • Glossary of Terms © 2022 Natural Stone Institute

Lathe Lintel
Any machine that spins a block or mul- A horizontal stone spanning over the
tiple blocks of material about a horizontal opening of a door, window, or other
axis for the purposes of creating shapes opening that acts as a beam to carry the
that have symmetry about the axis of weight of the wall above it.
rotation, such as columns, balusters,
and urns.
Lippage
The planar offset of the finished surfaces Lewis
Lead Buttons of two adjacent stone units.
Although not often used in modern
masonry construction, these were small Live Load
shims made of lead or similar malleable The portion of a load on a structural
metal alloys used in horizontal joints to member that is variable, such as occu-
support the stones until the mortar has set. pants, furniture, traffic, and wind.
See also Dead Load.
Lewis Lewis Pin
A lifting device consisting of multiple sec- Load Cell
tions of metal forming a tapered shape An electronic device (transducer) that
which is inserted into a dovetail shaped emits an electric signal based on the force
preparation cut into the stone. Although applied to the device.
uncommon in current industry use, lewis Lug Sill
lifters were frequently used for hoisting In stone masonry, a sill that projects into
quarry blocks or for heavy, cubic sections the jambs of a window or door opening
of finished stone work. Also known as (compare slip sill).
“box lewis.”
M
Lewis Pin Liner
A pin, usually with an eye at the upper Machine Finish
end, used in pairs and fitted to holes In limestone, the generally recognized
drilled at opposing angles in cubic stones standard machine finish produced by the
for hoisting purposes. planers. Also known as “machine smooth”
Limestone or “planar” finish.
A sedimentary rock composed primarily Maintenance
of calcite or dolomite. The varieties of Cleaning and/or other remedial activity
limestone used as dimension stone are performed on a scheduled basis: daily,
usually well consolidated and exhibit a weekly, etc. in order to remove dirt, dust Lintel
minimum of graining or bedding direction. and other contaminants that degrade the
See definition of limestone group in stone’s appearance and/or performance.
ASTM C119. Marble
Line (edge) Polisher A metamorphic crystalline rock com-
A large production machine which utilizes posed predominantly of crystalline grains
one or more spindles to achieve a finished of calcite, dolomite, or serpentine, and
edge profile on a piece of stone as it is fed capable of taking a polish. Commercial
through a conveying line. and scientific definitions of the marble Lippage
Liners group are explained in detail in ASTM
C119.
An additional block or strip of stone ad-
hered and doweled to the back face of a Marble (commercial definition)
stone panel for the purpose of providing a A crystalline rock, capable of taking
horizontal surface which can be supported a polish, and composed of one or more
by a shelf angle. The liner material may of the minerals calcite, dolomite, and
or may not be of the same stone species serpentine. Commercial and scientific
as the panel. Also known as “liner block” definitions of the marble group are
or “cleat.” explained in detail in ASTM C119. Lug Sill

© 2022 Natural Stone Institute Glossary of Terms • Page 23-15

 Masonry Modulus of Elasticity
1. Built up construction, usually individ- Tested per ASTM C1352, the ratio of
ual units set in mortar. stress to corresponding linear strain of
2. That branch of construction dealing a material, expressed as a force per unit
with plaster, concrete construction, area (lbs/in² or pascals), and used as a
and the laying up of stone, brick, tile measure of a material’s stiffness. Also
and other such units with mortar. known as “Young’s Modulus.”
Metamorphic Rock Modulus of Rupture
Rock altered in appearance, density, A bending strength test, normally
crystalline structure, and in some cases, performed per the ASTM C99 test
mineral composition, by high tempera- method, in which a small sample of stone
ture and intense pressure. Includes slate (8” x 4” x 2¼”) is supported by two sup-
derived from shale, quartz based stone port rods, and loaded to failure by a third
from quartzitic sand, and true marble rod positioned at the center of the span.
from limestone. The results are reported as the stress ex-
Metamorphism perienced by the stone sample at the time
The change or alteration in a rock caused of specimen failure, and expressed as a
by exterior agencies, such as deep-seated force per unit area (lbs/in² or pascals).
heat and pressure, or intrusion of rock See also flexural strength.
materials.
Moh’s Scale
Microcrystalline A relative scale of mineral hardness devel-
Said of a stone that consists largely or oped by German Mineralogist Friedrich
wholly of crystals that are so small as to Mohs in 1822 ranking ten common min-
be recognizable only under magnification. erals by their scratch resistance.
Milling Moldings
In the stone industries, comprehensive
term for processing quarry blocks Decorative stone deviating from a plane
through sawing, planning, turning and surface by projections, curved profiles,
cutting techniques to finished stone. recesses or any combination thereof.
Miter Monolithic
Any condition of stone veneer, coping, Shaped from a single block of stone,
paving strips, etc, where a corner condi- in contrast to a unit that was created by
tion is accomplished by two stones with using multiple units of stone.
angular cuts, with the angles of the cuts Mortar
being equal to the bisection of the total
A mixture of cement paste and fine aggre-
angle. See also quirk miter.
gate used in setting stone units or filling
Mockup joints between stone units. Mortar may
A sample section of stonework that is contain masonry cement, or may contain
installed, often including other related hydraulic cement with lime (and possibly
construction components, for the pur- other admixtures) to afford greater plas-
pose of obtaining designer and owner ticity and workability than are attainable
approval prior to commencement of with standard portland cement mortar.
quarrying, fabricating, or installation of Mosaic
stonework. The mockup may be indepen- A decorative installation, usually a graphic
dent of the project or may be part of the or artwork display, made up of an assem-
project and remain in place as part of the blage of small units of different colored
completed work. stones or glass to create the total image
Modular or pattern.
Refers to standard patterns used throughout Movement Joint
the stone industry that are usually based In tile installations, a joint where only
Miter on multiples of a given height or size. the finish material is separated by an

Page 23-16 • Glossary of Terms © 2022 Natural Stone Institute

elastomeric filler, and the substrate is posed of granite producers in the United
uninterrupted. Also known as a “generic States. Collectively, these companies
movement joint.” provide a major portion of the domes-
MSDS tically quarried architectural granite
The abbreviation for Material Safety Data produced in the U.S.
Sheet.The information required by OSHA’s Neat Cement
Hazard Communication Standard (HCS) A fluid mixture of portland cement and
to convey hazardous information to water, with or without other ingredients;
downstream customers. also the hardened equivalent of such mix-
Mullion ture. Commonly used in a thick, creamy
A structural unit that separates two consistency to parge the stone surfaces
window units and strengthen the bond between a stone
and a setting bed. Also called “cement but-
N ter,” “cement paste” and “cement cream.”
Natural Bed See also back parging and parge.
The horizontal stratification of stone as it Niche
was formed in the deposit. A recess in an interior or exterior wall
Natural Cleft usually for a statue or an urn, often semi-
Stone that is split (cleaved) parallel to its circular in design.
stratification, yielding a surface that is ir-
regular to a degree that corresponds with
NIOSH
the flatness of the material’s layering. The National Institute for Occupational
Safety and Health
Natural Stone
A product of nature. A stone such as granite, Nonstaining Mortar
marble, limestone, slate, travertine, or Mortar composed of materials which in-
sandstone that is formed by nature, and is dividually or collectively do not contain
not artificial or manmade. material that will stain the adjacent mate-
rials to which it comes in contact.
Natural Stone Institute
The Natural Stone Institute was formed Notch
in 2018 as a merger of the Marble Insti- A V-shaped cut made on the edge or head
tute of America and the Building Stone of a stone.
Institute. The Natural Stone Institute is NTCA
a trade association representing every (National Tile Contractors Association)
aspect of the natural stone industry. The A trade association whose active mem-
association serves as the authoritative bership consists of ceramic and stone
source for safety and technical standards tile installation contractors in the United
and information regarding the use of States, with an associate membership of
natural stone. It operates an industry ac- those who supply products and services
creditation program and two prestigious to the industry. Founded in 1947.
awards programs, as well as a continuing
education program for architects and O
designers. The association offers a wide Obsidian
array of technical and training resources, A glassy phase of lava.
professional development opportunities,
regulatory advocacy, and networking Off Fall
events. Also “fall off.” See Remnant.
NBGQA Ogee
The abbreviation for the National Build- A stone molding roughly resembling an
ing Granite Quarries Association, a trade “S” shape, with a reverse curved edge:
association whose membership is com- concave above, convex below. Ogee

© 2022 Natural Stone Institute Glossary of Terms • Page 23-17

 Onyx P
A frequently translucent and generally
layered, cryptocrystalline calcite with Palletize
colors in pastel shades, particularly off To stack and secure stone units to a pallet
white, yellow, tan, and green. Commer- for ease, safety, and efficiency in handling
cial definitions of onyx are given in ASTM and transport.
C119 as part of the marble group. Panel
Oolitic Limestone A term used to describe either a single
A calcite-cemented calcareous stone unit of fabricated stone veneer, or a preas-
formed of shells and shell fragments, sembled panel including multiple stone
practically noncrystalline in character. units affixed to a structural panel frame-
It is found in massive deposits located work.
almost entirely in Lawrence, Monroe, Parapet
and Owen Counties, Indiana; and in Ala- A low wall along the edge of a terrace,
bama, Kansas, and Texas. This limestone roof, or balcony, which is usually simply
is characteristically a freestone, without the extension of the exterior wall below it.
cleavage planes, possessing a remarkable Parge
uniformity of composition, texture, and To apply a thin coat of mortar, thin-set, neat
structure. cement, or other bonding agent to the
Overhang Open-faced Quarry back of stone units, or to the face of the
A quarry with relatively large lateral ex- backup material, normally for the pur-
panse when compared to its depth, in pose of reducing the voids, increasing
contrast to traditional derrick quarries bond strength, or waterproofing. See also
which had relatively short lateral dimen- back parging and neat cement.
sions and great depths. Patina
OSHA The change in color or texture of the
The acronym for Occupational Safety and surface of natural stone due to age or ex-
Health Administration. posure to various elements
Out-crop Paver
That part of a geologic formation or A single unit of fabricated stone for use as
structure that protrudes above or at an exterior paving material.
ground level. Paving
Outriggers Stone used as an exterior wearing surface,
A temporary support extending from as in patios, walkways, driveways, etc.
Pedestal machinery, such as cranes, to provide Pedestal
greater stance width and improve stability In classical architecture, the support for
when handling loads with extended boom a column or statue, consisting of a base,
lengths. dado, and cap.
Overburden Pediment
Waste stone, earth or other material cov- The gable end of a roof in classical architec-
ering the deposit of stone which must be ture. Located above a horizontal cornice
removed to gain access to the desired stone. member, it comprises the raking cornices
Overhang and the tympanum. It is typically triangular,
The portion of a stone that protrudes past but can also be curved when applied as a
the surface on which it is set. decorative element over windows.
Pediment Oxalic Acid PEL
A relatively strong acid that is used, typi- Permissible Exposure Limit: PELs are
cally as an additive to other polishing established and enforced by OSHA to
compounds, in the polishing of many protect workers against the health effects
marbles and limestones. of overexposure to hazardous substances.

Page 23-18 • Glossary of Terms © 2022 Natural Stone Institute

Percussion Drilling Plutonic
Any method of drilling that includes a Applies to igneous rocks formed beneath
combination of hammering blows along the surface of the earth, typically with
the longitudinal axis of the bit with ro- large crystals owing to the slowness of
tation of the bit. Also called “hammer” cooling.
drilling. Pointing
Perforated Wall The final filling and finishing of mortar
One which contains a considerable joints that have been raked.
number of relatively small openings, Polished Finish
often called pierced wall or screen wall. A glossy, highly reflective surface finish
that brings out the full color and character
Pergola of the stone.
Garden structure formed by two rows
of posts or pillars with joists and open Polishing
framing above, often covered by climbing A process utilizing abrasives in combina-
plants and shading a walkway. tion with specific polishing powders and/
or chemicals to produce a glossy, highly
Phenocryst reflective surface finish on the stone.
One of the relatively large and ordinarily Polishing Compounds Pergola
conspicuous crystals of the earliest gen- Any of the powders or chemicals used in
eration in a porphyritic igneous rock. addition to the abrasive machine heads
Pilaster that are used to achieve a polished finish.
A shallow, engaged pier or column Polishing Cream
projecting from a wall, only decorative in A polishing compound that is supplied in
function. a cream or paste consistency.
Pillowed Polishing Pads
A tile finish that features softly rounded Small diameter flexible disks with embed-
edges, thus giving the tile a pillowed look. ded abrasives used with handheld tools or
small portable machines for polishing of
Pit Quarry stone. These pads may be used in combi-
Below ground-level quarry. nation with compounds, and may be used
either wet or dry. Pilaster
Pitch Faced
A rustic finish for veneer stone created
Porphyry
An igneous rock characterized by dis-
with a split or chiseled face, and dressed
tinct and contrasting sizes of coarse and
along the stone’s perimeter to produce
fine-grained crystals. Used as a decorative
convex projection. See also rock faced.
building and/or paving stone.
Pitched Stone Portico
See pitch faced. A porch formed by a roof supported with
columns, similar to a temple front.
Plinth
1. The base block at the junction of the Poultice
stone base and trim around a door or Any absorbent material (powder, cloth,
other opening. etc) used in a saturated condition with Plinth
water or solvent based fluids and applied
2. The bottom stone block of a column
to a stone surface for the purpose of re-
or pedestal. moving embedded stains.
Plucked Finish PPE
A stone surface produced by setting a The abbreviation for Personal Protective
planer blade so deep that it removes stone Equipment, such as protective clothing,
by spalling rather than by shaving. safety toe shoes, helmets, goggles, etc.,

© 2022 Natural Stone Institute Glossary of Terms • Page 23-19

 designed to protect the wearer’s body Q
from injury from exposures in the work
environment. Quarried Stone
Stone which has been extracted from
Preassembled Units the earth by means of man power and
A composite unit consisting of a struc- machines.
tural backing, usually steel or concrete,
multiple panels of stone, and necessary Quarrier
anchorage and connection hardware that Company or person that extracts natural
is built off-site and transported to the stone from a quarry.
construction site for erection.
Quarry
Precast
1. The physical site, open or under-
In stone facades, refers to a bi-material
ground, where stone is extracted
panel consisting of multiple stone face
units and a concrete backer panel. The from the earth.
panel is cast off-site, then transported to 2. The process of extracting stone from
the construction site for erection. open pit or underground mine.
Pressure Relieving Joint Quarry Block
See expansion joint. Generally, a piece of rough stone as it
comes from a quarry, generally dressed or
Primer wire sawed to the shape of a rectangular
1. A unit or package of ignition devises
prism (having three pairs of roughly
used to initiate other explosives or parallel faces) for shipment.
blasting agents in the quarry.
2. A liquid coat applied to increase Quarry Run
bond strength of a joint sealant. A term used by some producers to mean
the lot of material has not been culled or
Privacy Partition otherwise limited for range of color and/
A thin stone panel between urinals. or features, and includes the entire spec-
See urinal screen. trum of material that is yielded by that
Producer particular deposit.
Company or person that quarries and
Quarry Sap
supplies dimension stone to the commer-
A term used by the limestone industry to
cial market.
describe the natural moisture in freshly
Profile Wheel quarried stone.
Any grinding wheel that has convex or
concave shapes and can be adapted to a Quartz
router, hand held grinder, or CNC A silicon dioxide mineral that occurs in
machine for the purpose of producing a colorless and transparent or colored hex-
desired shape to a stone edge. agonal crystals or in crystalline masses.
One of the hardest minerals of abundance
Projections in stones such as sandstone, granite, and
Any stone that is installed in a position quartzite.
outward of the balance of the wall for
aesthetic or water control purposes. Quartz Based Stone
A dimension stone group that includes
Prospecting both sedimentary (as in sandstone) or
The practice of locating mineral deposits metamorphic (as in quartzite) stones and
of commercial value. are characteristically high in free silica
Pumice content. Definitions of the classes of stone
Exceptionally cellular, glassy lava resem- which form the quartz based stone group
bling a solid froth. are explained in ASTM C119.

Page 23-20 • Glossary of Terms © 2022 Natural Stone Institute

Quartzite position of the anchor so that it doesn’t
A dense, hard metamorphic quartz based occupy any of the joint region, allowing
stone typically formed from sandstone. full movement capability of the joint
In some deposits, intrusion of minerals dimension.
during the formation process creates un- Recess
usual coloration. See ASTM C119. Any feature cut into a stone that is set
Quartzitic Sandstone back or indented from the balance of the Quirk Miter
A variety of sandstone including higher stone surface, either to accommodate an-
content of free silica and siliceous cements other element, such as anchorage, or for
than typical quartz-based sandstones. aesthetic appeal.
Quirk Miter Recrystallized Limestone
An external corner formed by two stone A limestone in which a new pattern of
panels with beveled (usually 45°) edges crystallinity has pervasively replaced the
and blunted, finished noses to reduce the crystal orientation in the original clastic
chipping vulnerability of the sharp edges Rabbet
particles, fossils, or fossil fragments, and
that occur with a common miter. interstitial cement.
Quoin Refinishing
One of the decorative dressed stones or The process of insitu finishing of existing
bricks used at the corner of a building. stonework to return it to its near original
Quoins are usually laid so their faces are appearance.
alternately large and small.
Reglet
R A narrow groove cut in stone to receive
Raked Joint
Rabbet flashing.
A groove cut into the surface along an Reinforcement
edge so as to receive another piece. Any element, metal, fiberglass, stone,
Rain Screen etc. that is embedded in or applied to the
A curtain wall system in which the outer stone panel for the purpose of increasing
façade shields, or “screens,” rain from strength.
infiltrating the wall cavity, but is not Relief
actually sealed. The cavity is pressure
equalized with the outside air, avoiding Carving or embossing raised above a
pressure differences that would other- background plane, as in a bas-relief. Rebated Kerf
wise draw water into the cavity. Minor Relieving Arch
amounts of water that penetrate the rain One built over a lintel, flat arch or small-
screen are evacuated via weep systems de- er arch to divert loads, thus relieving the
signed into the system. lower member from excessive loading.
Raked Joint Remnant
A mortar joint in which the mortar, while A leftover portion of a slab that cannot be
still soft, has been scraped back to a specified utilized in the primary project, but is
dimension with a square-edged tool. It is salvaged for possible use in another project. Reglet
generally used to accentuate the joint due to
Reprise
the pronounced shadow line produced.
The line formed by the intersection of
Random Slab two like profiles upon meeting at an inte-
A stone slab of length and width that are rior corner.
not prespecified, but rather determined Resin
by the size of the block from which it Any of a number of clear or translucent
was cut. substances, either from plant origin or
Rebated Kerf synthetics, used in producing lacquers,
A kerf that includes a second cut at 90° adhesives, plastics, polyesters, epoxies,
to the kerf axis which accommodates silicones, etc. Relieving Arch

© 2022 Natural Stone Institute Glossary of Terms • Page 23-21

 Resin Patching Sticks Rock Faced
A stone patching material supplied as a A rustic finish for veneer stone created
solid substance and installed in a heated with a split or chiseled face, and dressed
condition to facilitate flowing into surface along the stone’s perimeter to produce
imperfections to be filled. convex projection. See also pitch faced.
Resin Polishing Rock
A reference to abrasive pads used for hand 1. Geologically, any natural mass of earth
Return tool polishing, in which abrasives are em- material that has appreciable extent.
bedded in a resin matrix. 2. In engineering, solid natural material
Resined Slab that requires mechanical or explosive
Slabs that have been treated with a cos- techniques for removal.
metic improvement process prior to pol- 3. In the quarry industries, the term
ishing, in which a resinous adhesive, usu- stone is more common and means
ally epoxy, is applied to the face of the firm, coherent, relatively hard
slab, filling various voids in the stone sur- earth material.
face. The resin is cured at elevated tem-
perature, after which it is polished, allow- Rodding
ing the resin to remain in the voids. This A reinforcement technique used princi-
produces a more cosmetically attractive pally in countertop fabrication wherein
surface without the interruptions of the metal or fiberglass rods are embedded
Reveal natural defects. into shallow kerfs in the underside of the
Restoration stone slab at narrow regions of the coun-
Remedial action taken to return an exist- tertop, such as the portion in from of a
ing installation of stone to its original or sink. See reinforcement.
acceptable “near original” condition. Roman Arch
Return A semicircular arch. If built of stone, all
The right-angle turn of a stone surface, units are wedge shaped.
either a molding or flat, as in a window Rough Back
jamb condition. The outermost slab produced when
Return Head slabs are sawn from a block, having one
See head. side sawed and the other rough from the
Reveal original quarry block face. Also known as
“skin.”
The exposed portion of a stone between
its outer face and a window or door set Rough Sawn
Rodding into an opening. A surface finish resulting from the gang or
Ribbon wire sawing process.
Narrow bands of rock within the quarry Rubbed Finish
deposit of contrasting color and/or tex- A stone finish between smooth machine
ture due to varying mineralogical compo- finish and honed, obtained by mechanical
sition rubbing to a very smooth surface.
Rift Rubble
Direction in which stone splits most read- A term applied to dimension stone used
ily.Term is most commonly used for gran- chiefly for walls and foundations, consist-
ite or other stone without visible stratifi- ing of stone units that may be highly irreg-
cation or foliation. ular or partly trimmed or squared, gen-
Riprap erally with one or more split faces, and
Large, irregular shaped stones randomly selected and specified with a size range.
placed on an embankment to prevent or Rubble stone may be installed randomly
Roman Arch minimize soil erosion or coursed.

Page 23-22 • Glossary of Terms © 2022 Natural Stone Institute

Rustication ized by thin foliae that are composed
Any embellishment done to the joints in predominately of minerals of thin platy
stonework, either chamfers or grooves, or prismatic habits and whose long di-
for the purpose of visually accentuating mensions are oriented in approximately
the joint by increasing the shadowline. parallel positions along the planes of fo-
liation. Because of this foliated structure,
S schists split readily along these planes
Saddles and so have a pronounced rock cleavage.
See thresholds. The more common schists are composed
of mica-like minerals (such as chlorite)
Sample and generally contain subordinate quartz
An actual piece of dimension stone in a and/or feldspar of a comparatively fine-
small size used to demonstrate the gen- grained texture; all gradations exist be-
eral color, markings, and finish of a given tween schist and gneiss (coarsely foliated
variety of stone.
feldspathic rocks).
Sandblasted Scotia
A matte-textured surface finish produced
A deep concave molding
by small particles (“sand”) striking the
stone surface at high velocities. Screed
Sandstone A flat board or other straight piece used
Sandstones are sedimentary rocks usu- to level freshly placed concrete, mortar,
ally composed of quartz cemented with or sand by sliding it over prepositioned
silica, iron oxide or calcium carbonate. guides that determine the height of the
Sandstones range from very soft and fri- concrete or mortar.
able to very hard and durable, depending Sculpture
on the depth at which it was buried and A three-dimensional art form cut or chis-
the nature of the cement. Generally, the eled from a monolithic block of stone.
most durable sandstones are cemented with
silica.Sandstone has a wide range of colors Sealant
or textures. See quartz based stone. An elastic adhesive compound used to
seal stone veneer joints while still allow-
Sawed Edge ing differential movement between the
A clean-cut edge generally achieved by stone units.
cutting with a diamond blade.
Sealer
Sawed Face A protective coating or treatment which
A finish obtained from the process used in prevents or retards foreign liquid or mat-
the cutting of the blocks, slabs, or other ter from penetrating the stone by closing
units of building stone without further the pores in the surface.
embellishment. It varies in texture from
smooth to rough, and is typically named Sealing
for the type of material used in sawing, The process of applying a sealer.
e.g. diamond sawn, sand sawn, chat sawn, Seam Setter
and shot sawn.
A tool designed to pull two pieces of stone
Sawyer together and make the surfaces flat with
One who operates a saw. each other. The tools are made with suc-
tion cups and attached with a set of steel
Scabbing glides. The tool will allow the installer to
See dressing.
apply adhesive, pull the stone together,
Schist shim if necessary to make flat, while the
A loose term applying to foliated meta- tool is holding the pieces together until
morphic (recrystallized) rock character- the adhesive dries.

© 2022 Natural Stone Institute Glossary of Terms • Page 23-23

 Sedimentary Shop Ticket
Rocks formed by deposition of particles, A document used by a stone fabricator
or “sediments” laid down in successive describing the fabrication details of an in-
strata and cemented together by another dividual piece of dimension stone, most
agent. The materials of which they are commonly employing graphics in addition
formed are derived from preexisting rocks to text, and possibly including production
or the skeletal remains of sea creatures. and/or quality control monitoring. Also
referred to as a “cutting” or “cut” ticket.
Serpentine
Setting Space A common hydrous magnesium silicate Shot Sawed
rock-forming mineral; generally dark Description of a finish resulting from us-
green in color with markings of white, ing steel shot abrasive in the gang sawing
light green, or black. Rocks composed process without further embellishment.
predominantly of such minerals are This surface will normally have random
correctly called “serpentinites”, and are linear markings for a rough surface texture.
commercially sold as a marble because Silica
they can be polished. The definition of An oxide of silicon with the chemical for-
serpentine is given in ASTM C119 under mula SiO2, found abundantly in nature as
the marble group. sand quarts, or other rock components,
Setter The dry cutting or grinding of silica will
A field mechanic who specializes in the produce silica dust, which when airborne
Shim installation of dimension stone. in particles of respirable size, are a well
Setting Space known health hazard to those exposed to
The distance from the finished face of it without adequate PPE.
a stone unit to the face of the backup Siliceous
material. (Note: in some regions, the A rock bearing abundant silica.
term is used to describe the distance be-
tween the back of the stone and the face Sill
of the backup material. See also “cavity”) The bottom horizontal part of a window
or opening in a structure.
Setting
The installation of dimension stone units. Siltstone
A fine-grained, non-carbonate clastic rock
Shale composed of detrital grains of quartz and
Sill A fine grained sedimentary stone formed silicate minerals of silt size. Siltstones are
by the compaction of clay, silt, or mud. rarely marketed as such but commonly are
Shear considered as fine-grained quartz-based
A force that causes, or attempts to cause, stones (sandstones). Siltstone is textur-
internal adjacent planes of material to ally transitional between quartz-based
slide along one another. stones and shales (mudstones). Many
Shim bluestones and siliceous flagstones fall
A piece of plastic or other non-corrosive, within this category. The term is included
in these definitions chiefly to explain the
non-staining material used to temporarily
relationship of some siliceous flagstones
or permanently adjust the position of a to the quartz-based stone category.
stone unit.
Shop Drawing Simulated Stone
A detailed fabrication and installation An artificial manmade product that at-
tempts to resemble natural stone.
drawing showing layout, joinery, dimen-
sions, materials, finishes, methods of an- Slab
chorage, and/or any other information A flat “sheet-like” section of natural stone
pertinent to the fabrication or installation sawn to a prescribed thickness, with
of the stone material. length and width determined by the size

Page 23-24 • Glossary of Terms © 2022 Natural Stone Institute

of the quarry block from which it was sawed. Soundness
Slabs will generally receive a face finish A property of stone used to describe rela-
and further fabrication processes to be- tive freedom from cracks, faults, voids,
come usable dimension stone products. and similar imperfections found in un-
treated stone. One of the characteristics
Slate encountered in fabrication.
A very fine grained metamorphic rock
derived from sedimentary shale rock, Spall
with excellent parallel cleavage, and A chip or splinter separated from the main Slip Joint
entirely independent of original bedding, mass of a stone. Also known as sprawl.
slate may be split easily into relatively Spandrel
thin slabs. See definition of slate in ASTM
1. The often-decorated triangular area
C119. between an arch and a wall, or
Sling between two arches.
A type of strap, typically in the form of 2. In modern high-rise construction, the
a “loop”, made of high-density cloth and panel area between the head of one
rated for the intended load, which is window and the sill of the one above
wrapped around an object that is being it. Can be clad in stone, metal, Slip Sill
lifted. or glass.
Slip Joint Splay
A connection which permits vertical or A surface that makes an oblique angle
horizontal movement of a stone unit rela- with another surface, such as the non-ver-
tive to the adjacent unit. tical riser face frequently seen on steps.

Slip Sill Split

Division of a rock by cleavage.
A stone sill set between jambs. (compare
lug sill). Split-faced Stone
Stone on which the face has been broken
Slurry to an approximate plane.
A suspension of insoluble particles in a
liquid. Split-stone Finish
In building stone, a rough face formed
Smooth Finish by splitting slabs in a split-face machine.
A finish of minimum textural quality, pre- Generally the slabs are sawed parallel to
senting the least interruption of surface. bedding in stratified stone, so that the
Smooth finish may be applied to any sur- split face exposes the bedding in natu-
face, flat or molded. It is produced by a ral orientation or overturned, but some
variety of machines. stone is sawed perpendicular to bedding
and then split with the bedding vertical,
Snapped Edge either exposed as a cleft surface or vertical.
See Guillotine.
Spot or Spotting
Soapstone Spandrel
The mortar applied to the back of dimen-
A talc-rich stone with a “soapy” feel, used sion stone veneer to bridge the space
for hearths, tabletops, chemical-resistant between a stone panel and the backup
laboratory tops, stove facings, and clad- wall. Often used to describe the plaster
ding; known for its heat, chemical, and or mortar spot used with wire tie anchorage.
stain resistant properties.
Spreader Bar
Soffit A beam with two lifting slings or cables,
The underside of any architectural ele- one on each end, intended to spread the
ment, such as an arch, beam, lintel, or lifting points while the bar is hoisted from
balcony. its center. Splay

© 2022 Natural Stone Institute Glossary of Terms • Page 23-25

 Stacked Bond Support
Stone that is cut to one dimension and An angle, plate or other stones which carry
installed with unbroken vertical and hori- a gravity load.
zontal joints running the entire length
and height of the veneered area. T
Sticking TCNA
The butt edge repair of a broken piece of (Tile Council of North America)
stone, now generally done with dowels, An organization of manufacturers serving
cements, or epoxies. The pieces are the ceramic tile industry, with overlap-
“stuck” together; thus “sticking.” ping interest in the stone tile industry,
Stone particularly in installation. The TCNA
Sometimes synonymous with rock, but publishes the Handbook for Ceramic Tile
more properly applied to individual Installation and serves as the Secretariat
blocks, masses or fragments taken from for the ANSI accredited A108 and A118
their original formation or considered for committees. Established in 1945 as the
commercial use. In commercial use, the Tile Council of America (TCA), it be-
term stone is more frequently used, while came the Tile Council of North America
scientifically, geologists and petrogra- (TCNA) in 2003 to reflect its member-
phers more frequently use the term rock. ship expansion to all of North America -
Stool Canada, Mexico and the United States.
The interior sill of a window. Template
Stratification A pattern for a repetitive marking or fab-
The layered structure in sedimentary ricating operation.
stone deposits as a result of the deposi- Terrazzo
tion of sediments in beds or layers (also A flooring surface of marble or granite
Stool “strata” or “lamina”). chips in a cementitious or resinous
String Course matrix, which is ground and finished
A horizontal band of masonry, generally after setting.
narrower that other courses, extending
across the façade of a structure and in Texture
some structures encircling such deco- Surface quality of stone independent
rative features as pillars or engaged col- of color.
umns. May be flush or projected, and flat Textured Finish
surfaced or decorated. Also called belt Any of the rough surface finishes used in
course or band course. dimension stone, selected for aesthetic
String Course Stripping reasons or as friction performance for
To remove coatings that block a stone’s walking surfaces.
ability to breathe which may cause spall- Thermal Finish
ing (when the stones crack, pop, or shale). A textured surface treatment applied by
Some examples of common coatings are brief exposure to intense heat.
topical acrylic sealers, janitorial waxes,
and polyurethanes. Thin Stone
Stylolite Dimension stone units that are 2” (50
mm) or less in thickness.
In limestone and marble, generally a bedding
plane, along with differential solution Threshold
of the material on each side has caused A flat or profiled strip of stone project-
interpenetration of points, cones, or ing above the floor between the jambs of a
columns, forming a contact surface that door, often marks the transition between
is rough when separated. Also known as two different flooring materials. Also
Threshold crowfoot. known as a “saddle.”

Page 23-26 • Glossary of Terms © 2022 Natural Stone Institute

Tile U
A thin modular stone unit, less than
¾” (20 mm) thick, and not exceeding
Ultimate Capacity
The load resisted by a stone anchor at
24” (600 mm) in its greatest dimension.
failure. This load must be divided by the
Tilt Shop Cart factor of safety to determine a safe load,
A device used in stone fabrication areas or allowable capacity.
to move slabs and/or cut-to-size pieces Undercut
within the shop. The cart has a bed that Cut so as to present an overhanging part. Tread
tilts, allowing it be loaded with a slab in a
vertical orientation but unload the same Unit
slab in a horizontal orientation. A piece of fabricated cubic or thin di-
mension stone.
Tin Oxide Urinal Screen
A powder used in the polishing of granite
A thin stone panel used as a privacy parti-
with a talc-like appearance and applied tion between urinals.
with a felt pad and slow speed buffer.
V
Tolerance
The permissible limit of variation from Vacuum Cups
the specified dimension. A device used in the handling of smooth
surfaced stone which secures itself to the
Tooled Finish stone surface using vacuum contained
A finish that customarily has four, six, within an enclosed chamber that is sealed
or eight parallel, concave grooves to against the stone via gasketing.
the inch. See also bush hammered. Vacuum Lifter
Translucence Any stone handling device using vacuum
Vein Cut
A characteristic of light colored onyxes cups as a means of securing itself to
and some light colored marbles allowing the stone.
light to diffuse as it passes through. Vein Cut
A cut in quarried stone that is perpen-
Travertine dicular to the natural bedding plane,
A variety of limestone formed by chemi- exposing the veining of the material.
cal precipitate from hot springs. Some va-
rieties of travertine take a polish and are Vein
known commercially as marble. ASTM A layer, seam, or narrow irregular
C119 classifies travertine in both the body of mineral material contrasting
limestone and the marble groupings. the surrounding material in either color,
texture, or both.
Tread
A flat stone used as the top (horizontal)
Veneer
A non-structural facing of stone, interior
walking surface on steps.
or exterior, serving as ornamentation and
Trim a weather barrier.
The framing or edging of openings and Venting
other features on the interior or exterior See Cavity Vent.
of a building, including baseboards, pic-
ture rails, cornices, and casings. Vug
A pocket-like natural cavity in stone,
Tumbled Finish generally the result of solution or recrys-
A weathered, aging finish created when tallization. Size not limited, but most are
the stone is tumbled with sand, pebbles, between a small fraction of 1 inch and a
or steel bearings. few inches in average diameter. May be Veneer

© 2022 Natural Stone Institute Glossary of Terms • Page 23-27

 lined with crystals or botryoidal layers of Water-jet Finish
mineral materials. Most common in dolo- A surface treatment performed by using
mite, limestone and marble. Adj.: vuggy
water under extreme high pressure.
W
Waterproofing
Wainscot See Damp Proofing.
An interior veneer of stone covering the
lower portion of an interior wall. Waxing
Wall Tie The practice of filling minor surface im-
In masonry, a type of anchor, generally perfections such as voids or sand holes
a metal strip, used to secure facing to with melted shellac, cabinetmaker’s wax,
backup wall or to connect the wythes of a
or certain polyester compounds. In the
cavity wall. Ties are mortared into joints
during setting, and thus do not require dimension stone industry, it does not
that slots or anchor holes be cut. refer to the application of paste wax to
Walls, bearing make surfaces shinier.
A wall supporting a vertical load in addi- Wear
tion to its own weight
The removal of material or impairment
Walls, cavity of surface finishing through friction or
Wainscot A wall in which the inner and outer impact use.
wythes are separated by an air space but
tied together with metal ties. Weathering
Wash Natural alteration by either chemical or
The slope on the top of a stone unit mechanical processes due to the action of
intended to shed water. constituents of the atmosphere, soil, sur-
Water Jet face waters, and other ground waters, or
A machine which uses extremely high by temperature changes.
pressure water and an abrasive to cut
stone material in complex and exacting Wedging
Wash shapes from slabs or tile. Splitting of stone by driving wedges into
Water Recycling System planes of weakness or holes in the stone.
Any system that recovers water used in Weep Holes
shop fabrication machinery and restores
it to a reusable condition by filtering and/ Openings for drainage in veneer joints or
or chemical neutralization, after which it in the structural components supporting
is returned to service. the veneer.
Water Repellent Wire Sawing
Any of several types of liquid-applied for-
A method of cutting stone by a wire or
mulations used to render masonry walls
cable. Traditionally, the term applied
less absorptive. These treatments are said
to the use of a twisted wire carrying an
to maintain a material’s ability to breathe
away moisture, as distinct from “sealers”abrasive slurry as the cutting agent. Cur-
which form impervious, non-breathing rently, the term is more frequently used
coatings. to describe the use of a cable that is fitted
Water Table with diamond abrasive segments at regu-
A course that projects from the face of lar intervals, cooled with water.
a wall, generally near grade and having
a beveled top and a drip cut in the pro- Wythe
jecting underside, to deflect water. The inner or outer part of a cavity wall.

Page 23-28 • Glossary of Terms © 2022 Natural Stone Institute

References
American Concrete Institute (ACI), Farmington Hills, MI.
ASTM International. ASTM C119: Standard Terminology Relating to Dimension Stone.
West Conshohocken, PA: ASTM International.
Amrhein, James E., and Michael W. Merrigan. Marble and Stone SlabVeneer.
Los Angeles: Masonry Institute of America, 1986.
Bates, Robert L. and Jackson, Julia A., ed. Dictionary of Geological Terms. 3rd edition.
The American Geological Institute.
Carnella, Enrico. The Architect’s Handbook of Marble, Granite and Stone,Volume I,Technical
Guide; New York: Van Nostrand Reinhold, 1990.
Chacon, Mark. Architectural Stone: Fabrication, Installation, and Selection. New York:
John Wiley & Sons, Inc., 1999.
Donaldson, Barry, ed. New Stone Technology, Design and Construction for Exterior Wall
Systems. ASTM Special Technical Publication 996. West Conshohocken:
ASTM International, 1988.
Indiana Limestone Institute of America, Inc. Indiana Limestone Handbook. 22nd Edition.
Bedford: ILIA, 2007.
McGraw-Hill Construction. Sweet’s Catalog.Chicago: McGraw-Hill Construction, 2010.
National Building Granite Quarries Association, Inc. Specifications for Architectural
Granite. Washington, DC: NBGQA, 2011.
National Tile Contractors Association. NTCA Reference Manual. 2011.
Jackson: NTCA.
Patton, John B. Glossary of Building Stone and Masonry Terms. Geological Survey
Occasional Paper 6; Bloomington: Indiana Dept. of Natural Resources, 1974.
Pit & Quarry. Glossary of Terms. By: P&Q Staff, 2007.
Prestressed Concrete Institute. StoneVeneer-Faced Precast Concrete Panels.
Chicago: PSI, 1988.
R.E.D. Granti S.p.A. Stone Industry Technical Glossary. Massa: promorama, 2003.
Tile Council of America. Tile Council of North America Installation Handbook.
Princeton: TCA, 2011.
Winkler, Erhard M. Stone in Architecture. 3rd ed. Notre Dame: University of Notre
Dame, 1994.

© 2022 Natural Stone Institute Glossary of Terms • Page 23-29

 Conversion tables
Inches to Millimeters Centimeters to Inches

Inches Millimeters Centimeters Inches

1/32 in 0.794 mm 0.2 cm 1/16 in
1/16 in 1.588 mm 0.3 cm 1/8 in
3/32 in 2.381 mm 0.5 cm 3/16 in
1/8 in 3.175 mm 1.0 cm 3/8 in
5/32 in 3.969 mm 1.4 cm 9/16 in
3/16 in 4.763 mm 1.5 cm 5/8 in
7/32 in 5.556 mm 2.0 cm 3/4 in
1/4 in 6.350 mm 2.5 cm 1 in
9/32 in 7.144 mm 3.0 cm 1-3/16 in
5/16 in 7.938 mm 3.5 cm 1-3/8 in
11/32 in 8.731 mm 4.0 cm 1-9/16 in
3/8 in 9.525 mm 4.5 cm 1-3/4 in
13/32 in 10.319 mm 5.0 cm 2 in
7/16 in 11.113 mm NOTE: Centimeters (cm) have been rounded
15/32 in 11.906 mm off to the nearest tenth of a cm.
1/2 in 12.700 mm
17/32 in 13.494 mm
9/16 in 14.288 mm Square Feet to Square Meters
19/32 in 15.081 mm
5/8 in 15.875 mm Square Feet Square Meters
21/32 in 16.669 mm 1 sq ft 0.093 sq m
11/16 in 17.463 mm 2 sq ft 0.186 sq m
23/32 in 18.256 mm 3 sq ft 0.279 sq m
3/4 in 19.050 mm 4 sq ft 0.372 sq m
25/32 in 19.844 mm 5 sq ft 0.465 sq m
13/16 in 20.638 mm 6 sq ft 0.558 sq m
27/32 in 21.431 mm 7 sq ft 0.651 sq m
7/8 in 22.225 mm 8 sq ft 0.744 sq m
29/32 in 23.019 mm 9 sq ft 0.837 sq m
15/16 in 23.813 mm 10 sq ft 0.930 sq m
31/32 in 24.606 mm
1 in 25.400 mm
Square Meter to Square Feet
Feet Millimeters
1 ft 304.8 mm Square Meters Square Feet
2 ft 609.6 mm 1 sq m 10.764 sq ft
3 ft 914.4 mm 2 sq m 21.528 sq ft
3 sq m 32.292 sq ft
Note: Some of the SI International System of 4 sq m 43.056 sq ft
Units (metric) conversions listed in these tables 5 sq m 53.820 sq ft
are rounded numbers at the third decimal 6 sq m 64.583 sq ft
place. 7 sq m 75.348 sq ft
8 sq m 86.111 sq ft
9 sq m 96.875 sq ft
10 sq m 107.639 sq ft

© 2022 Natural Stone Institute Appendix • Page 24-1

 Conversion tables
Conversion Ratios Mohs Scale
Length and Area In 1812, the Mohs Scale of mineral hardness
Convert Multiply was devised by the German mineralogist
To
from by Friedrich Mohs (1773-1839), who selected the
millimeter inch 0.04 ten minerals because they were common or
centimeter inch 0.3937 readily available. The scale is not a linear scale,
centimeter foot 0.03281 but somewhat arbitrary.
meter inch 39.37
meter foot 3.281
square meter square foot 10.763 Hardness Mineral
inch millimeter 25.4 1 Talc or mica
inch centimeter 2.54 2 Gypsum
inch meter 0.0254 3 Calcite
foot meter 0.3048 4 Fluorite
yard meter 0.9144 5 Apatite
square inch square meter 0.000645 6 Orthoclase
square foot square meter 0.092990 7 Quartz
square yard square meter 0.836127 8 Topaz
9 Corundum
Weight 10 Diamond
Convert Multiply
To Source:
from by
American Federation of Mineralogical
pound kilogram 0.4536
Societies, Inc.
ounce gram 28.3495
long ton pounds 2240
short ton pounds 2000
gram ounces 0.0353
kilogram pounds 2.2046
Slab Production Table
Volume
Convert Multiply
To Slab
from by
Blocks Slabs/Foot Thickness
cubic cm cubic inch 0.061
1 cu ft 10 3/4"
cubic meter cubic feet 35.3198
1 cu ft 8 1-1/4"
cubic inch cubic cm 16.387
1 cu ft 7 1-1/2"
cubic feet cubic meters 0.028
1 cu ft 5 2"
liter gallons 0.2642 1 cu ft 4 2-1/2"
lb/ft³ kg/m³ 16.02 1 cu ft 3½ 3"
MPa lbf/in² (psi) 145 1 cu ft 3 3-1/2"
lbf/in² (psi) pascals (Pa) 6895 1 cu ft 2½ 4"
lbf/in² (psi) kg/sq m 4.882
kg/m² pascals (Pa) 9.807

Page 24-2 • Appendix © 2022 Natural Stone Institute

 Additional NSI resources

MIA Technical Bulletin Series: MIA Technical Modules:

Tolerances in the Dimension Stone Industry Illustrated Glossary of Stone Industry Terms*
(Sept 2014)*
Installation of Modular Stone Floor Tile:
Dimension Stone Test Methods Guides and Thin-Set Method *
Standards (June 2014)
Interior Stone Wall Cladding *
Calcareous Onyx (December 2011)
Q&A: Expert Answers to Technical Questions
Cement Types and Usage with Natural Stone about Working with Natural Stone
(October 2010)
Residential Stone Countertop Installations *
Joint Sealants (May 2010)
Safety in the Stone Business (also available in
Dimension Stone Anchorage Theory Practice Spanish)
Components (January 2010)
Silicosis: An Industry Guide to Awareness and
The Truth about Granite Radon Radiation Prevention
(March 2007)
Stone Selection & Stone Testing *
Countertop Sanitation Study Compares
Natural with Engineered Stone (February Wet Areas*
2006)

OSHA Bulletin Hazards Associated With *Information contained in these technical

Transporting Granite and Marble Slabs publications was taken directly from the Dimension
(September 2005) Stone Design Manual. Additional illustrations and
pictures have been added in these stand-alone
Marble Soundness Classification (January publications.
2005)

R-Value for Natural Stone (August 2004)

© 2022 Natural Stone Institute Appendix • Page 24-3

ASTM Classification Index

C97 C97 C99 C120 C121 C170 C241 C880

Modulus of Flexural Water Compressive Abrasive Flexural
Density lb/ft³ Absorption Rupture Strength (Slate) Absorption (Slate) Strength Resistance Strength
ASTM Dimension Stones (minimum) (max %) psi (min) psi (min) (max %) psi (min) (minimum) psi (min)
C503 Marble Calcite 162 0.20 1,000 na na 7,500 10 1,000
C503 Marble Dolomite 175 0.20 1,000 na na 7,500 10 1,000
0.20 exterior
C1526 Serpentine 160 0.60 interior
1,000 na na 10,000 10 1,000
C1527 Travertine (exterior)³ 144 2.50 700 na na 7,500 10 500
C1527 Travertine (interior)³ 144 2.50 700 na na 5,000 10 500
C568 Limestone (low density)¹,² 110 12.00 400 na na 1,800 10 none est.
C568 Limestone (med density)¹,² 135 7.50 500 na na 4,000 10 none est.
C568 Limestone (high density)¹ 160 3.00 1,000 na na 8,000 10 none est.
C615 Granite 160 0.40 1,500 na na 19,000 25 1,200
5,500 along grain
C629 Slate (interior) 170-190⁴ na na 7,200 across grain
0.45 none est. 8 none est.
7,200 along grain
C629 Slate (exterior) 170-190⁴ na na 9,000 across grain
0.25 none est. 8 none est.
Quartz-based Stones
C616 Sandstone 125 8.00 350 na na 4,000 2 none est.
C616 Quartzitic Sandstone 150 3.00 1,000 na na 10,000 8 none est.
C616 Quartzite 160 1.00 2,000 na na 20,000 8 none est.

Notes:
1. Limestone shall be sound, durable, and free of visible defects or concentrations of materials that will cause objectionable staining
or weakening in normal environments of use.
2. Limestone that is of low or medium density may not be suitable for use in all interior and exterior applications.
3. Travertine that is fleuri-cut (cross cut) can be vulnerable to certain problems because some areas of the exposed
surface will consist of only a thin layer of stone covering a void in the stone.
4. Historical data not established by ASTM.

© 2022 Natural Stone Institute Page 24-4

 rigid resin diamond abrasives, green marble, 13-18
Index 21-47 hybrids, 21-42
Note: Page numbers in italics refer silicon carbide, 21-29 identification, 21-19
to figures. Page numbers that refer sintered bond, 21-33 maintenance, 21-76
footnotes include the number of turbo-style resin diamond marble and onyx, 7-3
footnote (for example, 10-7 n2). abrasives, 21-47 outdoor kitchens, 17-13
A uses for, 21-29 penetrating adhesives, 21-45
abate, defined, 23-1 vacuum brazed diamond poly-epoxy, properties, 21-49
abrasion index, 4-8 abrasives, 21-34 polyester, 21-40
abrasion resistance water supply, 21-48 properties, 21-49
flooring, 4-8 water use, 21-48 selection, 21-19
foot traffic, 13-4 absorption of stone serpentine, 9-4, 9-8, 13-18
granite, 5-11 defined, 23-1 urethane, 21-41
horizontal applications, 13-4 exterior application, 3-4 properties, 21-49
limestone, 6-12, 6-13 granite, 5-11 adhesive repairs, 21-8
marble and onyx, 7-17 to 7-18 limestone, 6-12 admixture, defined, 23-1
quartz-based stone, 8-12 marble and onyx, 7-17 adoquin, defined, 23-1
serpentine, 9-13 quartz-based stone, 8-11 aesthetics, 3-1 to 3-2
serpentine, 9-14 serpentine, 9-13 agate, 8-7, 8-9
slate, 10-11 slate, 10-11 defined, 23-1
thin-stone pavers, 4-3 travertine, 12-12 agglomerated stone, defined, 23-1
travertine, 12-12 absorption rate, 4-1 aggregate, defined, 23-1
travertine, 12-13 abutment, defined, 23-1 alabaster
abrasion resistance index, 4-8 accelerators, defined, 23-1 composition of, 1-6
abrasive finish accelerators, staining and, 21-40 defined, 23-1
defined, 23-1 access routes, damage prevention, albite, 9-11
exterior cubic stone coping and 21-25 alignment, tolerances, 22-7 to 22-8
walls, 18-1 accessories, 14-D.23 to 14-D.25 alkaline, defined, 23-1
limestone, 6-10 acid etched finish, defined, 21-6 alkalinity sensitivity, 13-18
marble and onyx, 7-3, 7-14 acid wash, defined, 23-1 alkalis, cleaning with, 21-84
marble and onyx acid washed finish, 3-2 allowable capacity, defined, 23-1
abrasive hardness defined, 21-6 allowable repair of countertops, 17-
defined, 23-1 acids, 21-3 to 21-4 11 to 17-12
foot traffic, 14-1 cleaning with, 21-84 aluminum oxide, polishing
pavers, 14-1 acrylic-epoxy, properties, 21-49 powders, 21-35
stair treads, 14-13 acrylic resin, 17-7, 17-10 ambient temperature, defined, 23-1
abrasives acrylics, properties, 21-49 American Institute of Architects
abrasive bonds, 21-31 to 21-32 ADA requirements, 21-75 (AIA), vi
abrasive pads adhered fiberglass netting American National Standards
defined, 21-31 reinforcement, 16-10 Institute (ANSI), 2-3
fiber pads, 21-31 adhered, defined, 23-1 American Society of Testing and
synthetic fiber pads, 21-31 adhesive Materials (ASTM), sustainability,
dot pads, 21-31 acrylic-epoxy, properties, 21-49 vii to viii
bricks, 21-29 to 21-30 acrylics, 21-40 to 21-41 amphibole, 11-5
copper bond, 21-33 to 21-34 properties, 21-49 anchorage
diamond, 21-29 bond strength, 21-20 defined, 23-2
diamond abrasive pads, 21-33 consistency, 21-45 granite, 5-7
electroplated bonds, 21-34 countertops, 17-6, 17-7, 17-13 interior cladding, 14-14 to 14-
frankfurt coverage, 21-19 to 21-20 15
defined, 21-30 cyanoacrylate (CA) glues, 21- limestone, 6-6 to 6-7
magnesite bond, 21-30 41 to 21-42 marble and onyx, 7-7
synthetic bond, 21-30 properties, 21-49 quartz-based stone, 8-5 to 8-6
hard synthetic bond, 21-30 epoxy, 21-41 serpentine, 9-7
polishing and cleaning properties, 21-49 slate, 10-6
brick, 21-30 for repairs, 21-39 thermal isolator, 14-10
glazing over, 21-48 consistency, 21-45 travertine, 12-6
plugs, 21-30 general notes, 21-42 anchors, 14-D.23 to 14-D.25
resin bond abrasives, 21-32 granite, 5-3 aluminum, 5-3

© 2022 Natural Stone Institute Index • Page 25-1

 back, 14-5 angle of repose, defined, 23-2 serpentine, 9-1
defined, 23-3 angular grain (sand), 1-5 slate, 10-1
with clips, 14-D.5 anisotropic, defined, 23-2 soapstone, 11-1
bent plate, 14-4 anorthosite, 5-9 test standards, 2-4 to 2-5
column, free-standing, 14-D.12 defined, 23-2 travertine, 12-1
cramp anchor, defined, 23-8 ANSI (American National ASTM tests, 3-6, 4-1, 4-2
defined, 23-2 Standards Institute), 2-3, 2-6, 23- augite, 11-5
dowel, 14-4 2 axed finish, marble and onyx, 7-14
expansion, 14-D.1, 14-D.4 antiqued finish, 6-10 axed work (British), defined, 23-2
exterior stone veneer, 14-D.1 to countertops, 17-2
14-D.7 defined, 23-2
goose neck, 14-D.25 antiquing brushes, 21-37 B
granite, 5-3 apatite, hardness, 21-2 back anchor
hairpin precast, 14-D.25 apex stone, defined, 23-2 defined, 23-3
hairpin spring appearance, 3-1 to 3-2 soffits, 14-D.18
slate panels, 10-5 aprons, for stone tile countertops, T-31, 14-D.24
quartz-based stone panels, 17-9 undercut, 14-D.24
8-5 defined, 23-2 back buttering
interior stone veneer, 14-D.8 aragonite, 6-9 interior cladding, 14-15
lace, 14-D.25 arch, defined, 23-2 stone tile countertops, 17-9
limestone, 6-4 architrave, 23-7, 23-8, 23-10, 23-12 back-checking granite, 5-4
masonry bed, 14-5 defined, 23-2 limestone, 6-5
mechanical anchors, 21-18 area, conversion ratios, 24-2 marble and onyx, 7-4
mechanical systems, 14-14 to argillite, defined, 23-2 quartz-based stone, 8-4
14-15 arkose, defined, 23-2 serpentine, 9-4
nonferrous, 6-4 arris, 17-6, 17-12 slate, 10-4
pin, 14-4 defined, 23-2 travertine, 12-4
plug, 14-D.24 stone edges, 13-6 backer rod, defined, 23-3
serpentine, 9-4 artificial stone, defined, 23-2 backing materials, portland cement
shelf, 14-4 artwork and antiques, 21-25 mortar, 14-6
showers, residential, 16-8 asbestos, 9-3, 9-9 to 9-10 backing rods, 13-D.1, 13-10 to 13-
split-tail anchor, exterior stone ashlar 11, 14-D.9
veneer, 14-D.2, 14-D.3 coursed ashlar, 23-2 back-parging, defined, 23-3
stainless steel, 5-3, 6-4, 12-3 defined, 23-2 backsplashes, 17-5, 17-D.12
strap, 14-4 random ashlar, 23-2 defined, 23-3
slate, 10-5 stacked ashlar, 23-2 back-up structure, defined, 23-3
stair treads, 13-D.7 to 13- ASI (Allied Stone Industries), backup walls, 18-1
D.8 defined, 23-2 bacteria, 21-84
T-31 back, 14-D.24 ASTM (American Society of granite, 5-14
thin stone, 14-5 Testing and Materials), baluster, defined, 23-3
tolerances, 22-6 sustainability, vii to viii balustrade, defined, 23-3
travertine, 12-3 ASTM Classification Index, 24-4 band course (string course),
vertical surfaces, 14-4 to 14-6, ASTM Committee on Stone (C- defined, 23-26
14-D.23 to 14-D.25 18), 4-2 banker, defined, 23-3
wet areas, 16-1 ASTM International, 2-2 to 2-3, 4- basalt, defined, 23-3
wire loop anchor, 14-D.21 2 basaltic lava, 1-3, 5-9
anchors, wire, 14-5, 14-D.25 defined, 23-2 base
copper, 7-3 to 7-4, 9-4 ASTM standards, 4-2 cove base, defined, 23-8
interior cladding, 14-D.10 development of, 2-2 to 2-3 defined, 23-3
non-ferrous, 8-3, 10-3, 10-5 granite, 5-1 to 5-2 base design, furniture and tops, 19-
quartz-based stone, 8-3 horizontal applications, 4-3 1
serpentine, 9-4 limestone, 6-1 base molding, 23-7, 23-9, 23-18,
slate, 10-3, 10-5 marble, 7-1 23-19
installation, 10-5 material specifications, 2-4 baseboards, damage prevention,
stainless steel, 7-3 to 7-4, 9-4 onyx, 7-1 21-25
stair treads, 13-D.8 other application standards, 2-5 basic, defined, 23-3
tie back, 14-D.17 to 2-6 batted work (British), defined, 23-3
Andesite, 1-3 quartz-based stone, 8-1 battered splay, free-standing

Page 25-2 • Index © 2022 Natural Stone Institute

 column, 14-D.14 D.15 cabinet components, 17-4
bearing check, defined, 23-3 breccia, defined, 23-4 to 23-5 cabinet measurements, 17-3
bed, defined, 23-3 brecciated marble, 23-5 calcarenite, defined, 23-5
bed joint, defined, 23-3 bricks, as abrasives, 21-29 to 21-30 calcareous, defined, 23-5
bed width bridge crane, defined, 23-5 calcareous stones
granite, 5-4, 5-8 bridge polisher, defined, 23-5 acid attack, 21-3
marble and onyx, 7-4 bridge saw, defined, 23-5 behavioral groups, consistent,
quartz-based stone, 8-3 broach, defined, 23-5 21-11
serpentine, 9-4 brownstone behavioral groups, variegated,
slate, 10-3 composition of, 1-6 21-14
travertine, 12-4 defined, 23-5 defined, 21-2
bedding plane, defined, 23-3 brucite, 9-9, 9-11 sealers, 21-69 to 21-70
bedrock, defined, 23-4 brushed finish calcite, 1-6, 9-10
beds countertops, 17-2 abrasion resistance, 24-4
granite, 5-4 defined, 23-5 absorption of stone, 24-4
limestone, 6-4 granite, 21-62 acid reaction, 7-11
marble and onyx, 7-4 MTL, 21-58 anisotropy, 7-11 to 7-12
quartz-based stone, 8-3 brushes as cementing material, 1-6
serpentine, 9-4 antiquing brushes, 21-37 chemical properties, 7-10 to 7-
slate, 10-3 carbide bristle brushes, 21-37 11
travertine, 12-4 diamond wire brushes, 21-37 cleaning and maintenance, 21-
belt course, defined, 23-4 rubber bristle brushes, 21-37 79
bench, defined, 23-4 BSI (Building Stone Institute), cleavage, 7-11
bending strength, 4-6, 5-12 defined, 23-5 color, 7-11
bent rod, 14-D.24 budgetary concerns, 21-72 composition of, 7-11
beveled block joint, 14-D.16 bugged finish, defined, 23-5 compressive strength, 24-4
bevels, furniture and tops, 19-1 building cleaning, 21-83 to 21-84 crystals, 7-10 to 7-11
biotite, 5-8, 5-9, 17-12 building movement defined, 23-6
biscuits, countertop repair, 21-46 consultants, 21-26 density, 24-4
black granite, 5-9 cracks, 21-22 dolomite vs., 6-9
defined, 23-4 buildings flexural strength, 24-4
blade dressing, defined, 23-4 occupants, 21-25 hardness, 6-9, 21-2
bleed, defined, 23-4 structural problems, 21-26 Iceland Spar, 7-11
blend pattern, 7-D.2 building stone, defined, 23-5 in limestone, 6-9
blending, defined, 23-4 Building Stone Institute (BSI), in marble, 7-9
blind connections, exterior stone defined, 23-5 maintenance, 21-76
veneer, 14-D.5 bullnose edge, 17-D.16, 19-D.3 modulus of rupture, 24-4
bluestone, defined, 23-4 corner joinery, 17-D.3 optical character, 7-11
bollard, defined, 23-4 tolerances, 22-D-App B physical properties, 7-10 to 7-
bond, defined, 23-4 bullnose, defined, 23-5 11, 24-4
bonding bush hammering, defined, 23-5 thermal hysteresis, 7-12 to 7-13
cubic sills, 18-3 bush-hammered finish, 3-2 water absorption, 24-4
exterior cubic stone coping and granite, 5-7, 21-62 calcite limestone, defined, 23-6
walls, 18-1 limestone, 6-10 calcite marble, defined, 23-6
window stools, 18-3 marble and onyx, 7-14 calcite streaks, defined, 23-6
bond stones, 18-1 MTL, 21-58 calcium carbonate, weather
bond strength, 21-20 slate, 10-9 resistance of, 10-13
book match pattern, 7-D.3, 19-D.2 weakening of stone, 6-10, 8-10 calibration, defined, 23-6
defined, 23-4 business schedules, 21-26 canopy, defined, 23-6
border stone, defined, 23-4 butt joint, 14-D.9, 14-D.16 cantera, defined, 23-6
boss, defined, 23-4 defined, 23-5 cantilevers, 17-4
boulder conglomerate, 1-5 buttering, defined, 23-5 defined, 23-6
boulder, defined, 23-4 cap (or capital) , 23-7, 23-8, 23-9,
boulders, clast size, 1-5 23-10, 23-12, 23-18, 23-19
bowing C defined, 23-6
See also hysteresis C-18 (ASTM Committee on carbide bristle brushes, 21-37
defined, 23-4 Stone), 4-2 carbonates, as cementing material,
bracket detail, interior cladding, 14- CA glue (cyanoacrylate), 21-40 1-6

© 2022 Natural Stone Institute Index • Page 25-3

carbonatites, 6-8 n2 chemical precipitates, 1-1 to 1-2 rod, 5-6
carbonic acid, defined, 23-6 chemical reactivity of soapstone, limestone, 6-7
carve, defined, 23-6 11-5 quartz-based stone, 8-6
carving, 13-2 chemical resistance, 21-3 to 21-4 serpentine, 9-7
granite, 5-4 chemical sedimentary stone, 1-1 to slate, 10-6
limestone, 6-5 1-2, 1-6 closer (British), defined, 23-7
marble and onyx, 7-5 chemical sensitivity, sealers, 21-69 CNC machine, defined, 23-7
models chert, 1-6, 8-7, 8-9 coatings, 21-67 to 21-68
granite, 5-4 defined, 23-6 detailing, 21-52
limestone, 6-5 chips, 21-23 poulticing, 21-52
marble and onyx, 7-5 countertops, 17-12 removal of, 21-51
serpentine, 9-5 repairs, 21-44 solvent-based coatings, 21-52
travertine, 12-5 chiseled edge, 17-D.16, 19-D.3 water-based coatings, 21-51 to
serpentine, 9-5 defined, 23-6 21-52
travertine, 12-5 chlorite, 7-9, 9-11 cobble conglomerate, 1-5
cast-iron sinks, 17-3 chrysotile (asbestos), 9-10 cobbles, clast size, 1-5
caulk, defined, 23-6 cladding, defined, 23-6 cobblestone, defined, 23-7
caulking, slate, 10-6 clast, defined, 23-6 Code of Federal Regulations, Title
caulking clast sizes, 1-4 to 1-5 21, 2-4
granite, 5-6 clastic sedimentary stone, 1-4 to 1- coefficient of friction (COF), 4-9
limestone, 6-7 5 pavers, 13-5
marble and onyx, 7-7 clay coefficient of thermal expansion
quartz-based stone, 8-6 clast size, 1-5 granite, 5-11
serpentine, 9-8 coloring in limestone, 6-9 limestone, 6-12
soapstone, 11-3 to 11-4 defined, 10-7 n2 marble and onyx, 7-17
travertine, 12-7 clay balls, travertine, 12-9 precast concrete panels, 20-1
cautions, vertical surfaces, 14-16 to clay minerals as cementing serpentine, 9-15
14-17 material, 1-6 slate, 10-11
cavities, 14-3 to 14-4 cleaners, 21-36 to 21-37 stone veneer panels, 20-1
cavity vent, defined, 23-6 acidic cleaners , 21-37 cold applied membrane, defined,
cavity wall, defined, 23-6 alkaline cleaners, 21-36 16-2
ceiling channel for toilet partitions, neutral cleaners, 21-36 cold weather and installation of
16-3 cleaning limestone, 6-6
ceiling-hung, toilet partitions, 16- building cleaning colonnade, defined, 23-7
D.1 specifications, 21-83 to 21-84 color, 13-3
ceilings in steam rooms and commercial cleaning and precast concrete panels, 20-1
showers, 16-8, 16-12 sealing, 21-78 to 21-79, 21-87 resin-impregnated slabs, 17-10
cement backer board, interior stone countertops, 17-13 stone veneer panels, 20-1
veneer, 14-D.8 granite, 5-7 color and veining
cement butter (neat cement), granite countertops, 21-64 crystalline quartz, 8-8
defined, 23-17 limestone, 6-7 granite, 5-9
cement putty (neat cement), marble and onyx, 7-7 limestone, 6-10
defined, 23-17 quartz-based stone, 8-6 marble and onyx, 7-13
cementing minerals, 1-5 to 1-6 residential cleaning, 21-77 to quartz-based stone, 8-9
cementitious backer units, 13-11, 21-78 serpentine, 9-11 to 9-12
16-D.8, 16-D.10 serpentine, 9-8 slate, 10-8
horizontal applications, 13-11 slate, 10-6 translucence, 7-21
mold and mildew, 16-2 soapstone, 11-4 travertine, 12-10
thin-bed mortar, 13-16 travertine, 12-7 color enhancer/sealer, defined, 23-7
CEN standards, 2-6 cleaning tools, 21-43 color matching, 21-46
centimeters to inches, 24-1 cleavage, 10-8 colored waxes, 21-7
chamfer, defined, 23-6 crystalline quartz, 8-7 colors and tints, in adhesives and
chamfer edge, 13-6, 17-D.16, 19- defined, 23-7 patching materials, 21-39 to 21-
D.3 cleavage membranes, 13-7, 14-3 40, 21-42 to 21-43
tolerances, 22-D-App B cleavage plane, defined, 23-7 column, defined, 23-7
chat sawn finish, defined, 23-6 cleft finish, defined, 21-6, 23-7 commercial center environments,
chemical analysis, 4-1 Clinton, Bill, vi diagnostic considerations, 21-24
chemical cleaning, 21-84 closed-cell ethafoam rope backer commercial restoration

Page 25-4 • Index © 2022 Natural Stone Institute

 additional resources, 21-121 to projected stone, 18-D.1 elastomeric sealant, 17-7, 17-9
21-122 sloped stone, 18-D.1 epoxy resin, 17-7, 17-9
labor restrictions, 21-87 copper wire anchors exposed edges, 17-6
levels of pedestrian traffic, 21- marble, 7-3 to 7-4 fabrication, 17-5
85 onyx, 7-3 to 7-4 fiberglass mesh backing,
multi-component surfaces, 21- serpentine, 9-4 adhesive, 17-11
86 coquina, defined, 23-7 field measurements, 17-3 to 17-
payment, 21-88 corbel, defined, 23-7 4
performance expectations, 21- core bit, defined, 23-8 final positioning, 17-3, 17-6
88 core, defined, 23-7 finishes, 17-2
revolving doors, 21-86 core (Earth), 1-2 fissures, 17-11
rules and regulations, 21-85 core sampling, defined, 23-8 flush subtops, 17-D.6
size of project, 21-85 corner block joint, 14-D.16 granite, 3-5 to 3-6, 17-1
staircases, 21-86 corner cove joint, 14-D.16 grout, 17-9
stone trim, 21-86 corner embellishments of impregnators (penetrating
vertical surfaces, 21-86 countertops, 17-4 sealers), 17-12 to 17-13
work approval, 21-88 corners, standard, for exterior stone installation, 17-5 to 17-6
common joint for countertops, 17- veneer, 14-D.9 stone tile, 17-9
D.3 cornerstone, defined, 23-8 joinery layout, 17-4
compressive loads, 4-5 cornice, 23-7, 23-10, 23-12 joint filling, 17-6
compressive strength defined, 23-8 joint width, 17-6
defined (ASTM C170), 23-7 corrosion-resistant metals joints at sink, 17-D.1, 17-D.4
granite, 5-11 to 5-12 cubic sills, 18-3 joints away from sink, 17-D.2
limestone, 6-12 window stools, 18-3 kitchen layouts, 17-D.1 to 17-
marble and onyx, 7-17 corundum, hardness, 21-2 D.2
measurement, 4-5 to 4-6 cost of stone, 3-7 to 3-8 layout, 17-5
precast concrete panels, 20-1 maintenance, 3-8 limestone, 17-2
quartz-based stone, 8-11 countertops, 3-5 liner blocks, 17-11
serpentine, 9-13 adhesive, 17-6, 17-7, 17-13 lippage, 17-6, 17-7
slate, 10-10 allowable repairs, 17-11 to 17- maintenance, 17-12 to 17-13
stone veneer panels, 20-1 12 marble
travertine, 12-12 arris, 17-6 miter joint, 17-D.3
concrete flooring, cast in place, 13- backsplashes, 17-5 no joints at sink, 17-D.5
5 bullnose edge, 17-D.3 no subtops, 17-D.6
concrete subsurface, 13-D.3, 13- cabinet requirements, 17-3 onyx, 17-1
D.4, 14-8 to 14-9 cantilevers, 17-4 outdoor kitchens
mortar bed bonded to, 13-11 to cleaning, 17-13 overhangs, 17-D.7 to 17-
13-12 common joint, 17-D.3 D.8, 17-D.15
concrete walls, exterior stone contracts, 17-3 pitting, 17-12
veneer, 14-D.1, 14-D.5 corbel supports, 17-D.1 to 17- polishing, 21-62
concrete/CMU backup, 14-14 D.2, 17-D.14, 17-D.15 polyester resin, 17-9
conference table, 19-D.1, 19-D.2 corner embellishments, 17-4 protective transport, 17-5
conglomerate, defined, 23-7 corner joinery, 17-D.3 radius edges, 17-D.8
construction (cold) joint, defined, cracks, 17-11 to 17-12 recessed hardware for doors,
23-7 crating, 17-5 17-D.7
continental stone, 1-2 to 1-3 customer communication, 17-2 reinforcement techniques, 17-
contraction joint, defined, 23-11 to 17-3, 17-13 11
contractor, stone, defined, 23-7 cutouts, 17-5 repairing damaged stone, 17-11
contracts details, 17-D.4 to 17-D.10, 17- to 17-12
for countertops, 17-3 D.14 to 17-D.15 resin-impregnated slabs, 17-11
suggested, xii to xiii documentation of resin-treated, 3-6
control joints, defined, 21-19, 23-7 communication, 17-2 to 17-3 rodding, 17-11, 17-D.1 to 17-
conversion ratios, 24-2 doors, 17-D.7 D.2, 17-D.5
conversion tables, 24-1 to 24-2 drop-in sink styles, 17-D.10 safe work practices, 17-5
conveyor, defined, 23-7 dry assembly, 17-5 sawing, 17-5
coping edge profiles, 17-4, 17-D.13, scratch repair, 21-46
defined, 23-7 17-D.16 sealers, 3-5 to 3-6, 17-6, 17-12
flush face stone, 18-D.1 finishing, 17-5

© 2022 Natural Stone Institute Index • Page 25-5

 seam filler material, 17-7, 17-9, 21-23 for anchors
7-13 macro-cracks, 21-45 to 21-46 granite, 5-4
seam leveling, 21-46 micro-cracks, 21-45 limestone, 6-4 to 6-5
seam polishing, 21-47 cramps marble and onyx, 7-4
seam width, 17-6 defined, 23-8 quartz-based stone, 8-4
serpentine, 17-1 granite, 5-3 serpentine, 9-5
setback subtops, 17-D.6 marble, 7-3 to 7-4 slate, 10-4
shelves, 17-D.14 non-ferrous, 10-3 travertine, 12-4
shims, 17-5 onyx, 7-3 to 7-4 for other trades
shop drawings, 17-3, 17-D.17 quartz-based stone, 8-3 granite, 5-4
sidesplashes, 17-D.13 serpentine, 9-4 limestone, 6-5
sink flange, 17-D.8 slate, 10-3 marble and onyx, 7-4
sink mounts, 17-4 creep. See hysteresis quartz-based stone, 8-4
slate, 17-2 cross cut stones serpentine, 9-5
soapstone, 17-2 filling, 3-2 slate, 10-4
spans, 17-4 serpentine, 9-13 soapstone, 11-3
spline joint reinforcement, 17- travertine, 12-11 travertine, 12-4 to 12-5
D.4 cross-bedding, defined, 23-8 cyanoacrylate (CA) glue, 21-40
splines, 17-11 cross-cut, defined, 23-8 adhesives and patching
stone slab layout, 17-3 crowfoot (stylolite), defined, 23-26 materials, 21-41 to 21-42
stone tile, 17-2, 17-9 crushing loads, 4-5 properties, 21-49
subcontractor responsibilities, crypt, 14-D.15 cycle time, defined, 23-9
17-3 crystal structure, translucence, 7-21
subtops, 17-3, 17-13, 17-D.8, crystalline quartz, physical
17-D.14, 17-D.15 properties, 8-7 to 8-8 D
surface protection, 17-12 to 17- crystallization damage prevention
13 defined, 21-64 adjacent surfaces, 21-25
thicker slabs, 17-D.6 polishing pads, 21-64 to 21-65 building content, 21-25
thickness, 17-3 popularity, 21-65 damage types, for repairs, 21-43
transport, 17-5 process, 21-65 damaged stone, repairing
travertine, 17-2 cubic sills granite, 5-3
undermount sink support, 17- bonding, 18-3 limestone, 6-2
D.8 color, 18-3 marble, 7-2
UV light exposure, 17-10, 17- corrosion-resistant metals, 18-3 onyx, 7-2
13 fabrication, 18-3 quartz-based stone, 8-2
course, defined, 23-8 finishes, 18-3 serpentine, 9-2 to 9-3
coursed ashlar, 23-3 full mortar method, 18-4 slate, 10-2
coursed veneer, defined, 23-8 installation, 18-4 soapstone, 11-2
cove base oil-based putty, 18-3, 18-4 sticking, 9-2
See also base sealants, 18-3, 18-4 travertine, 12-2
defined, 23-8 sizes, 18-3 damp proofing
cove edge, 17-D.16, 19-D.3 thickness, 18-3 defined, 23-9
cove molding, defined, 23-8 cubic stone, defined, 23-8 limestone, 6-11
cove ogee edge, 17-D.16, 19-D.3 cultured marble, defined, 23-8 travertine, 12-14
cove-Dupont edge, 17-D.16, 19- cup wheel, defined, 23-8 dead load
D.3 curbing, defined, 23-8 See also live load
crack, defined, 23-8 cure time, defined, 23-8 defined, 23-9
crack isolation membranes, 13-7, curtain walls, defined, 23-8, 23-9 deflection, 13-5
14-3 cushion, defined, 23-8 backup stair treads, 14-13
cracks customer communication about cementitious backer units
building movement, 21-22 countertops, 17-2 to 17-3, 17-13 flooring, 14-9 to 14-10
chips, 21-22 cut stone, defined, 23-8 flooring, 14-9
in countertops, 17-11 to 17-12 cut-to-size stones, defined, 13-1, stair treads, 14-13
defined, 21-22 14-1 steam rooms and showers, 16-8
excessive loading, 21-22 cutouts wood substrate flooring, 14-9
granite, 21-48 countertops, 17-5 deicing chemicals
impact cracks, 21-22 stone tile countertops, 17-9 defective work, granite, 5-3
improper installation, 21-22 to cutting limestone, 6-13

Page 25-6 • Index © 2022 Natural Stone Institute

 quartz-based stone, 8-2 abrasion resistance, 24-4 for anchors
serpentine, 9-2 absorption of stone, 24-4 granite, 5-4
travertine, 12-13 calcite vs., 6-9 limestone, 6-4 to 6-5
demi bullnose edge, 17-D.16, 19- compressive strength, 24-4 marble and onyx, 7-4
D.3 defined, 23-9 quartz-based stone, 8-4
dense limestone density, 24-4 serpentine, 9-5
defined, 21-12 flexural strength, 24-4 slate, 10-4
effective techniques, 21-12 hardness, 6-9 travertine, 12-4
density, 4-1 modulus of rupture, 24-4 for other trades
defined, 21-68 physical properties, 24-4 granite, 5-4
granite, 5-11 solubility, 6-9 limestone, 6-5
limestone, 6-12 water absorption, 24-4 marble and onyx, 7-4
marble and onyx, 7-17 dolomitic limestone, defined, 23-9 quartz-based stone, 8-4
quartz-based stone, 8-11 dolostone (dolomite), defined, 23-9 serpentine, 9-5
serpentine, 9-13 double chamfer edge, 17-D.16, 19- slate, 10-4
slate, 10-10 D.3 soapstone, 11-3
travertine, 12-12 double cove edge, 17-D.16, 19-D.3 travertine, 12-4 to 12-5
water absorption, 4-3 double pencil round edge, 17-D.16, drip stone, defined, 23-10
dentil course, defined, 23-9 19-D.3 drips
dentil, defined, 23-9 double radius edge, 17-D.16, 19- defined, 23-10
derrick, defined, 23-9 D.3 granite, 5-4
design considerations, 3-3, 17-10 dovetail L straps, 14-D.23 limestone, 6-4
detrital sedimentary stone, 1-1 dovetail slot, defined, 23-9 marble and onyx, 7-4
diabase, 5-9 dovetail split-tail straps, 14-D.23 quartz-based stone, 8-3
diamond dovetail straps, 14-D.23 serpentine, 9-4
as abrasive, 21-29 dovetail twisted straps, 14-D.23 slate, 10-3 to 10-4
defined, 23-9 dowelling, 21-8 soapstone, 11-3
dressing, 21-53 dowels, 14-D.23, 14-D.24 travertine, 12-4
hardness, 17-10, 17-12, 21-2 defined, 23-9 dry assembly of countertops, 17-5
diamond gang sawn finish, 12-7 granite, 5-3 dry cleaning, 21-84
diamond gauged finish, 10-9 marble, 7-3 to 7-4 dry climate and limestone exterior,
diamond match pattern, 7-D.3 non-ferrous, 10-3 3-4
defined, 23-9 onyx, 7-3 to 7-4 dry pack, defined, 16-2
diamond wire brushes, 21-37 quartz-based stone, 8-3 dry seam, defined, 23-10
diamond wire saw, defined, 23-9 serpentine, 9-4 dry stack, defined, 23-10
die, 23-7, 23-18, 23-19 slate, 10-3 dry stack veneer, 14-D.22
defined, 23-9 stainless steel, in stair treads, dry weight and specific gravity, 4-4
digital inventory management, 13-D.6 to 13-D.8 to 4-5
defined, 23-9 stair treads, 13-D.6 to 13-D.8 dry-lay, 13-1, 14-3
digital layout application, defined, down washed lighting, 14-17 dry-pack mortar, 13-8 to 13-9, 13-
23-9 downward crack, repairs, 21-44 12 to 13-13, 14-6 to 14-7
digital templating, defined, 23-9 drafted margin (British), defined, drywall, mold and mildew, 16-2
dimension stone 23-9 dual finish, defined, 23-10
defined, 23-9 drains, 21-20 Dupont edge, 17-D.16, 19-D.3
flexure testing, 4-7 drawings, shop durability, defined, 23-10
"Dimension Stone Anchorage; countertops, 17-3 durability of exterior application, 3-
Theory, Practice, & granite, 5-2 to 5-3 4
Components," 21-18 limestone, 6-2 dust restrictions, 21-26
diorite, 5-9 marble, 7-2 Dutchman, defined, 23-10
disc hangers for soffits, 14-D.18 onyx, 7-2 dyes, 21-7
disclaimer, suggested, xii quartz-based stone, 8-2 dynamic coefficient of friction, 4-9
dishing, marble and onyx, 7-21 serpentine, 9-2
dispensing tools, 21-43 slate, 10-2
distortion of stone in exterior soapstone, 11-2 E
application, 3-4 travertine, 12-2 Earth Day, v
documentation of customer dressing, defined, 21-48, 21-53, 23- eased edge, defined, 23-10
communication, 17-2 to 17-3 9, 23-10 eaves, defined, 23-10
dolomite, 6-8 to 6-9, 7-8 drilling edge chiseling tool, defined, 23-10

© 2022 Natural Stone Institute Index • Page 25-7

edge profiles, 19-D.3 expansion bolts for soffits, 14-D.18 mortar bed, 14-5 to 14-6
countertops, 17-4 defined, 23-11 pedestal system, 14-6
defined, 23-10 expansion gaskets, 18-1 sand bed, 14-6
finishing, 17-5 expansion joints, 13-6 traffic after installation, 14-5
edge treatment for stone tile defined, 21-19, 23-11 exterior stone cleaning, 21-79 to
countertops, 17-9 exterior cubic stone coping and 21-80
edges, tolerances, 22-6 walls, 18-2 exterior stone maintenance, 21-79
efflorescence, 13-19, 14-17, 21-20 exterior stone veneer, 14-D.9 exterior stone selection, 4-10
to 21-21, 21-22, 21-81 to 21-82 granite, 5-4, 5-6 exterior stone stresses, 3-3 to 3-4
defined, 23-10 limestone, 6-7 exterior stone veneer
granite, 5-13 to 5-14 location, 14-9 adhered veneer, 14-13 to 14-14
limestone, 6-14 to 6-15 marble and onyx, 7-4, 7-7 blind connections, 14-D.5
marble and onyx, 7-19, 7-20 quartz-based stone, 8-3, 8-6 colors, 14-2
quartz-based stone, 8-13 to 8-14 serpentine, 9-4, 9-8 corners, standard, 14-D.9
serpentine, 9-15 to 9-16 slate, 10-6 expansion joints, 14-D.9
slate, 10-12 to 10-13 soapstone, 11-3 extraction testing for heavy
subsurface water, 21-26 travertine, 12-4, 12-6 to 12-7 metals, 2-4
travertine, 12-14 exposed edges fabrication, 14-2
elastic distortion and exterior countertops, 17-6 finishes, 14-2
application, 3-4 furniture and tops, 19-1 independently supported, 14-11
elastomeric sealant for countertops, showers, residential, 16-10 to 14-12
17-7, 17-9 showers, residential, 16-D.10 installation, 14-11 to 14-14, 14-
electrical power, commercial and steam rooms and showers, 16- D.1 to 14-D.7
historical restoration, 21-85 10 rebated bearing, 14-D.6
electrical properties of crystalline exposed face, defined, 23-11 reglets, 14-D.9
quartz, 8-8 exterior application restraint anchorage, 14-D.7
elemental composition, oceanic vs. considerations, 3-3 to 3-4 split-tail anchor, 14-D.2
continental stone, 1-3 diagnostic considerations, 21- stacked, 14-12
elevation, defined, 23-10 24 steel T, 14-D.1 to 14-D.3
embellishments, corner, 17-4 durability, 3-4 stone relief, rebated bearing,
enameled cast iron sinks, support inappropriate stones, 3-4 14-D.6
details, 17-D.8 test data, 3-4 vertical surfaces, 14-11 to 14-
encrinal marble, defined, 23-10 exterior cubic stone coping and 14
end match pattern, 7-D.3 walls eye rod and dowel, 14-D.25
end slip pattern, 7-D.2 backup walls, 18-1
energy and atmosphere, viii bond stones, 18-1
engineered stone, defined, 23-10 bonding, 18-1 F
engineering, 14-11 color, 18-1 fabricated, defined, 23-11
entablature, 23-7, 23-8, 23-12 coping details, 18-D.1 fabrication
defined, 23-10 expansion gaskets, 18-1 countertops, 17-5
entasis expansion joints, 18-2 cubic sills, 18-3
defined, 23-10 fabrication, 18-1 exterior cubic stone coping and
free-standing columns, 14-D.13 finishes, 18-1 walls, 18-1
epidote, in marble, 7-9 flashing details, 18-D.1 furniture and tops, 19-2
epoxy, 21-7 full mortar method, 18-2 quartz-based stone, 8-11
adhesives and patching joint width, 18-2 shower partitions, 16-5
materials, 21-41 load-bearing walls, 18-1 showers, residential, 16-10
properties, 21-49 oil-based putty, 18-1, 18-2 steam rooms and showers, 16-
epoxy resin, 21-8 parapet details, 18-D.1 10
countertops, 17-7, 17-9, 17-10 preparation, 18-2 toilet partitions, 16-3
defined, 23-10 exterior pavers tolerances, 22-5 to 22-6
erection, defined, 23-10 color, 14-5 urinal partitions, 16-4
etched, defined, 23-10 concrete subsurface, 14-5 to 14- window stools, 18-3
etching, 21-23 6 face size, tolerances, 22-5
ethics, xiv flexural strength, 14-5, 14-6 face, defined, 23-11
exfoliation, defined, 23-11 installation, 13-D.1 to 13-D.2, fall off. See remnant (23-21)
expansion anchor, 14-D.1, 14-D.4 14-5 to 14-6 fascia, defined, 23-11
defined, 23-11 joints, 14-5 feed rate, defined, 23-11

Page 25-8 • Index © 2022 Natural Stone Institute

feldspar, 5-8, 17-12 fire resistance dimension stone, 4-7
defined, 23-11 limestone, 6-13 limitations, 4-7
felsic stone, 1-3 marble and onyx, 7-17 slate, 4-7
ferruginous, defined, 23-11 quartz-based stone, 8-12 thickness, 21-18
fiberglass backing, defined, 23-11 serpentine, 9-15 flint, 8-7, 8-9
fiberglass mesh backing, 13-18, 14- slate, 10-11 floor drains, 16-D.6 to 16-D.7
16, 21-8 to 21-9 soapstone, 11-6 floor installation
adhesive, countertops, 17-11 travertine, 12-13 marble and onyx, 7-5 to 7-6
field identification, 21-5 fireplace facings serpentine, 9-6 to 9-7
field measurements for countertops, details, 14-D.19, 14-D.20 floor machines, 21-27 to 21-28
17-3 to 17-4 header, 14-D.19, 14-D.20 attachments, 21-27
field repair, 13-2, 14-3 hearth, 14-D.19, 14-D.20 diamond honing and polishing,
fieldstone, defined, 23-11 installation, 14-15 21-27
filled finish (travertine), 12-10 leg, stone, 14-D.20 drive plates, 21-28
filler strip (backer rod), defined, mantel, stone, 14-D.19 floating heads, 21-28
23-3 mantel, wood, 14-D.20 mono-rotary machines, 21-27
fillers masonry fireplace, 14-D.19, 14- planetary machines, 21-27 to
anchor prep, 14-6 D.20 21-28
maintenance, 21-76 surround, stone, 14-D.19 rigid heads, 21-28
filling, defined, 23-11 surround, wood, 14-D.20 floor-mounted shower partitions,
fine rubbed finish, 3-2, 5-7 fissures 16-6
fines, defined, 23-11 countertops, 17-11 floor-mounted toilet partitions, 16-
finish, defined, 23-11 defined, 23-11 D.1
finished work, protection of, 13-17 flagstone, defined, 23-11 flooring
to 13-18 flamed finish (thermal finish), 3-2 adjacent floors and damage, 21-
finishes, 3-2, 13-3 defined, 21-6, 23-26 25
countertops, 17-2 granite, 5-7, 21-62 alkalinity, 14-7
cubic sills, 18-3 limestone, 6-10 cast-in-place concrete, 13-5
exterior cubic stone coping and flashing, 14-4 cementitious backer units, 13-
walls, 18-1 flashing and limestone, 6-4 11
exterior pavers, 14-5 flashing details, exterior cubic cleaning
flooring, 14-8 stone coping and walls, 18-D.1 marble and onyx, 7-6
foot traffic, 14-1 flat installation of stone tile serpentine, 9-6
furniture and tops, 19-2 countertops, 17-9 color, 14-8
granite, 5-6 to 5-7, 5-10, 21-61 flat strap hangers for soffits, 14- concrete subsurface, 14-9
to 21-62 D.18 concrete, cast in place, 13-5
identification, 21-5 to 21-6 flatness, tolerances, 22-6 defined, 23-12
limestone, 6-10, 21-58 fleuri cut, 23-27. See also cross cut deflection of, 13-5, 14-8, 14-9
marble, 21-58 defined, 23-11, 23-12 finishes, 13-3, 14-8
marble and onyx, 7-14 filling, 3-2 float the floor, 21-54
non-planar, 13-6 marble and onyx, 7-16 grout, 14-7
pavers, 14-1 serpentine, 9-13 heated floor systems, 13-16 to
precast concrete panels, 20-1 travertine, 12-11, 24-4 13-17, 14-10
quartz-based stone, 8-10 and voids, 13-19 high-traffic exteriors, 3-4
serpentine, 9-12 veneer cutting, 7-D.1 hollow sound, 13-18
shower partitions, 16-5 flexural strength, 4-6. See also installation, 13-D.3 to 13-D.4,
slate, 10-3, 10-9 modulus of rupture 14-8 to 14-10
soapstone, 11-3 defined, 23-12 installation methods, 14-7
stair treads, 14-13 granite, 5-11 installation references, 13-14
stone veneer panels, 20-1 limestone, 6-12 joint width, 13-5 to 13-6
thresholds, 14-11 marble and onyx, 7-17 lighting, 13-19
toilet partitions, 16-3 pedestal supported support marble and onyx, 7-6
translucence, 7-21 systems, 13-13 moisture, 13-18
travertine, 12-7, 21-58 quartz-based stone, 8-11 refinishing, abrasive bonds, 21-
urinal partitions, 16-4 serpentine, 9-13 32 to 21-34
window stools, 18-3 slate, 10-10 serpentine, 9-6 to 9-7
finishing tools, 21-43 travertine, 12-12 slate, 10-10
fire ratings, 14-10 to 14-11 flexure testing strength considerations, 4-7

© 2022 Natural Stone Institute Index • Page 25-9

 thickness, 13-2 tube steel supports, 19-D.1 sealing, 21-64
traffic after installation, 7-6, 9- surface preparation, 21-62
G
6, 14-7 to 21-63
transitions, 13-18 gabbro, 5-9, 21-15 countertops, 3-5 to 3-6
travertine, 12-11 gabbro, defined, 23-12 cubic sills, 18-3
wood subfloor, 14-9 gallet (British), defined, 23-12 damaged stone, repairing, 5-3
fluorite, hardness, 21-2 gang saw, 5-10, 7-16, 9-13 defined, 21-15, 23-13
flute, defined, 23-12 defined, 23-12 density, 5-11, 24-4
fossils, 6-9 to 6-10 garnet, 5-9 drips, 5-4
fracture, defined, 23-12 gauge edging, 21-59 to 21-60
fracturing See also calibration effective techniques, 21-15 to
crystalline quartz, 8-7 to 8-8 defined, 23-12 21-16
texture of quartz-based stone, 8- generic movement joints, defined, efflorescence, 5-13 to 5-14
9 21-19 enhanced, 5-15
frame construction geographic methods, 13-17 epoxy filling, 5-15
heated floor systems, 14-10 geographical variation, 13-17, 14- expansion joints, 5-6
window stools, 18-D.2 17 exterior application, 3-4
free-standing units, shower geological classification, sealers, exterior cubic stone coping and
partitions, 16-6 21-69 walls, 18-1
freestone, defined, 23-12 Gissen, David, v face filling, 5-15
freeze/thaw cycles and exterior glass seam finishes, 5-4, 5-6 to 5-7, 5-10
applications, 3-4 See also dry seam fire resistance, 5-12
freeze/thaw issues, 21-24 defined, 23-12 fleuri cut, 3-2
friction, 13-4 to 13-5 gloss meter, defined, 23-12 flexural strength, 5-1, 24-41
frieze, 23-7, 23-8, 23-10 gloss, variation in, 13-19, 14-17 flooring, 5-10
defined, 23-12 gneiss, 5-9, 21-15 gabbro, 21-15
front-end loader, defined, 23-12 defined, 23-12 genuine, 1-4
full bullnose edge, 17-D.16, 19-D.3 grain, defined, 23-12 geological classification, 5-8 to
full mortar method granite 5-9, 21-70
steam rooms, 16-9, 16-11 abrasion, 5-11 gneiss, 5-9, 21-15
steam showers, 16-9, 16-11 abrasion resistance, 5-12, 24-4 hardness, 5-9, 5-12
exterior cubic stone coping and absorption of stone, 5-11, 24-4 identification, 21-15
walls, 18-2 adhesive, 5-3 joint width, 5-8
cubic sills, 18-4 anchorage, 5-7 lippage removal, 21-59
furniture, moving, 21-25 anchors, 5-3 mineral components of, 5-8 to
furniture and tops ashlar facing, 5-8 5-9
base design, 19-1 back-checking, 5-4 minimum safety factors, 5-7
bevels, 19-1 backs of pieces, 5-4 modulus of elasticity, 5-11
color, 19-2 bacteria, 5-14 modulus of rupture, 5-11, 24-4
conference table, 19-D.1, 19- bed width, 5-8 moisture absorption, 5-12
D.2 bending strength, 5-12 moldings, 5-4
exposed edges, 19-1 black granite, 5-9, 23-4 mortar, 5-3
fabrication, 19-2 bolted connections, back- mortar setting of, 5-5
finishes, 19-2 checking, 5-4 orthoclase feldspar, 5-8
installation, 19-2 carving, 5-4 orthoquartzite vs., 5-9
laminated aprons, 19-1 caulking, 5-6 packing and loading, 5-5
marble and onyx, 19-1 cleaning, 5-7 panel, 5-4
oil-based putty, 19-1 coefficient of thermal physical properties, 5-10 to 5-
overhangs, 19-1 expansion, 5-11 11, 24-4
plywood subtops, 19-1, 19-D.1 color, 5-9 pitting, 5-14, 17-12
quirk miters, 19-1 commercial definition, 23-13 plagioclase feldspar, 5-8
radius of rounded edges, 19-1 composition of, 5-8 to 5-9 polyester filling, 5-15
sealing, 19-1 compressive strength, 5-11 to 5- protection of, 5-6 to 5-8
sizes, 19-2 12, 24-4 quartz, 5-9
slate, 19-1 countertop polishing quartzite vs., 5-9
spans, 19-1 cleaning, 21-64 radon, 5-14
thickness, 19-1 equipment, 21-62 refinishing, surface preparation,
travertine, 19-1 polishing, 21-64 21-59
refinishing, 21-63 to 21-64

Page 25-10 • Index © 2022 Natural Stone Institute

 refinishing and polishing stone and, ix to x hairpin precast anchor, 14-D.25
considerations, 21-61 green colored stone, 14-16 half bullnose edge, 17-D.16
edging, 21-59 to 21-60 adhesives for, 13-18 halite, defined, 23-13
equipment, 21-59 green references, xi handheld machines
grinding, 21-60 greenstone, defined, 23-13 variable speed machines, 21-28
honing, 21-61 grind, defined, 23-13 pad drivers, 21-28 to 21-29
lippage removal, 21-59 grinding hardness, 21-2 to 21-3
other finishes, 21-61 to 21- granite refinishing and absolute, 21-3
62 polishing, 21-60 crystalline quartz, 8-7
polishing, 21-61 machine control, 21-48 defined, 21-2, 23-13
process, 21-58 to 21-59 MTL refinishing and polishing dolomite, 6-9
sealing, 21-61 first grinding, 21-54 to 21- foot traffic, 14-1
transition step, 21-60 55 limestone, 6-9
resin filling, 5-15 light grinding, 21-55 to 21- Mohs scale, 17-10, 17-12, 21-2,
resin-treated, 3-6 56 24-2
rigid resin diamond abrasives, grinding tools, 21-43 pavers, 14-1
21-47 grout pyrite, 7-10
safety factors, 5-12 to 5-13 acrylic modified portland sealers, 21-69
sampling, 5-10 cement grout, 14-8 soapstone, 11-5
sawn backs, 5-9 adhesion problems, 21-26 stair treads, 14-13
scientific definition, 23-13 color, 13-9 to 13-10, 14-8 hazing, 21-22, 21-26
sealant joints, 5-6 to 5-7 countertops, 17-9 head, defined, 23-13
sealants, 5-3 defined, 23-13 header for fireplace facings, 14-
sealers, 3-5 to 3-6 flooring, 14-7 D.19, 14-D.20
seams or cracks, 21-48 grout inspection, 21-24 hearth for fireplace facings, 14-
seismic considerations, 5-13 horizontal applications, 13-9 to D.19, 14-D.20
seismic loads, 5-13 13-10 hearth stone, defined, 23-14
sizes, 5-10 joint width, 14-2 hearth, defined, 23-14
staining, 5-9, 5-13 to 5-14 latex modified portland cement heat retention of soapstone, 11-5
stair treads, 14-13 grout, 14-8 heated floor systems, 13-16 to 13-
storage, 5-5 maintenance, 21-76 17, 13-D.4
strength, 5-11 to 5-12 polymer modified portland high angle of incidence for lighting,
texture, 5-10 cement grout, 14-8 13-19
thickness, 5-7, 5-10 sanded portland cement grout, high traffic environments,
thresholds, 14-11 14-7 diagnostic considerations, 21-24
tinting, 5-15 staining, 14-8 high-traffic floor areas, 13-4
turbo-style resin diamond stains, 21-22, 21-26 exterior, 3-4
abrasives, 21-47 steam rooms, 16-9, 16-12 interior, 3-5
usage tips, 5-10 steam showers, 16-9, 16-12 historic restoration
veneer cutting, 5-10 unsanded portland cement additional resources, 21-121 to
veneer facing, 5-9 grout, 14-7 to 14-8 21-122
washes, 5-4 veneer cavities, 14-4 labor restrictions, 21-87
water absorption, 24-4 guillotine, defined, 23-13 payment, 21-88
weep tubes, 5-6 guillotining of slabs, 8-11 rules and regulations, 21-85
wind loads, 5-13 gypsum, 14-16 work approval, 21-88
window stools, 18-3 formation from calcite, 7-12 hollow sounds, 14-1 to 14-2, 21-26
granite and quartzite hardness, 21-2 horizontal surfaces, 13-18
Giallo Ornamental, 21-15 gypsum-based underlayment for flooring, 13-18
Kashmir, 21-15 stone tiles, 13-5 honed, defined, 23-14
Santa Cecilia, 21-15 gypsum molding plaster, honed finish, 3-2, 18-1, 19-2
granitic lava, 1-3 serpentine, 9-7 countertops, 17-2
granitization, 5-9 gypsum wall board defined, 21-5, 21-75
granular, defined, 23-13 exterior stone veneer, 14-D.8 granite, 5-6, 21-61 to 21-62
granular bed method, 13-14 interior cladding, 14-D.10 to limestone, 6-10
gravity load and exterior 14-D.11 marble and onyx, 7-3, 7-14
applications, 3-3 MTL, 21-58
green building , v to xi serpentine, 9-12
history, v to vii H slate, 10-9

© 2022 Natural Stone Institute Index • Page 25-11

 travertine, 12-7, 12-10 America) water resistance, 3-5
honing defined, 23-14 interior cladding
granite refinishing and publications, 6-1 anchorage, 14-14 to 14-15
polishing, 21-61 impregnators (penetrating sealers), anchors, wire, 14-D.10
machine control, 21-48 17-12 to 17-13 beveled block joint, 14-D.16
MTL refinishing and polishing, defined, 21-6 to 21-7, 23-14 bracket detail, 14-D.15
21-56 to 21-57 inches to millimeters, 24-1 butt joint, 14-D.16
honing pads, miscellaneous, 21-36 incise, defined, 23-14 column, free-standing
honing tools, 21-43 Indiana Limestone Institute of anchors, 14-D.12
hooked bolt, 14-D.25 America (ILI) battered splay, 14-D.14
horizontal applications defined, 23-14 entasis, 14-D.13
ASTM standards, 4-3 publications, 6-1 joints, 14-D.13 to 14-D.14
installation, 14-1 to 14-14 inscription, defined, 23-14 corner block joint, 14-D.16
interior surfaces, 3-5 inspection, 14-3 corner cove joint, 14-D.16
horizontal surfaces for repairs, 21-43 corner detail, 14-D.16
abrasion resistance, 13-4 installation crypt, 14-D.15
carving, 13-2 attachment method, 21-17 external corners, 14-D.16
cementitious backer units, 13- cold weather, 12-6 fire rated wall, 14-D.11
11 condition, maintenance, 21-76 gypsum wall board, 14-D.8, 14-
colors, 13-3 countertops, 17-5 to 17-6 D.10 to 14-D.11
finishes, 13-3 cubic sills, 18-4 installation, 14-14 to 14-15
friction, 13-4 to 13-5 existing installation, 21-17 to internal corners, 14-D.16
grout, 13-9 to 13-10 21-18 metal studs, 14-D.10, 14-D.11
hollow sound, 13-18 exterior installation, molded joint, 14-D.16
membranes, 13-7 maintenance, 21-76 molded trim, 14-D.12
sizes, 13-3 exterior stone veneer, 14-11 to quirk miter joint, 14-D.16
stone edges, 13-6 14-14 rabbeted joint, 14-D.16
stone selection, 13-1 furniture and tops, 19-2 rosette detail, 14-D.15
thickness, 13-2, 13-3 granite, 5-6 to 5-7 rosette fasteners, 14-D.15
hornblende, 5-9, 11-5 high rise cladding, stone slide, 14-D.15
hot mop, defined, 16-2 maintenance, 21-77 strap anchored, 14-D.8
hot-tub environments, diagnostic interior installation, wall facing details, 14-D.10 to
considerations, 21-24 maintenance, 21-76 14-D.11
humidity and exterior applications, limestone, 6-5 to 6-7 wet areas, 14-16
3-4 location, maintenance, 21-76 wire anchored, 14-D.8
hydrated lime marble and onyx, 7-5 to 7-7 interior panels
limestone, 6-3 mechanical anchors, 21-18 adhered systems, 14-15
travertine, 12-3 precast concrete panels, 20-2 anchored systems, 14-14 to 14-
hydraulic cleaning, 21-84 quartz-based stone, 8-5 to 8-6 15
hysteresis (thermal), 14-16 serpentine, 9-5 to 9-8 installation, 14-14 to 14-15
defined, 23-14 shower partitions, 16-5 to 16-6 interior stone base, details, 14-D.17
marble and onyx, 7-21, 7-19 to showers, residential, 16-10 to interior veneer
7-20 16-11 cement backer board, 14-D.8
slate, 10-4 to 10-6 gypsum wall board, 14-D.8
soapstone, 11-3 to 11-4 marble and onyx, 7-6
I steam rooms and showers, 16- restraint anchorage, 14-D.8
Iceland Spar, 7-11 11 to 16-12 serpentine, 9-7
IEC (International Electrotechnical stone tile countertops, 17-9 intermediate stone, Andesite, 1-3
Commission), 2-3 stone veneer panels, 20-2 International Electrotechnical
igneous, defined, 21-1 tile, 21-18 Commission (IEC), 2-3
igneous rock, 1-1 toilet partitions, 16-3 International Organization for
cleaning and maintenance, 21- tolerances, 22-7 to 22-8 Standardization (ISO), 2-3
78 travertine, 12-5 to 12-7 inward crack, for repairs, 21-44
geological classification, 21-70 urinal partitions, 16-4 iron oxides as cementing material,
pitting, 17-12 window stools, 18-4 1-6
igneous stone, formation, 1-4 interior application ISO (International Organization for
igneous, defined, 23-14 considerations, 3-4 to 3-5 Standardization), 2-3
ILI (Indiana Limestone Institute of selection criteria, 3-4 to 3-5 ISO/IEC Guide 25, 4-2

Page 25-12 • Index © 2022 Natural Stone Institute

 Roman arch, 23-22 abrasion resistance, 6-13, 24-4
isolation joint, defined, 21-19, 23- kitchen layouts and countertops, absorption of stone, 6-12, 24-4
14 17-D.1 to 17-D.2 anchorage, 6-6 to 6-7
shop drawings, 17-D.17 anchors, 6-4
knife edge, 17-D.16, 19-D.3 atmospheric agents, 6-13
J back-checking, 6-4
J.O.S. system, 21-84 backs of pieces, 6-4
jamb, 23-14 L Beaumaniere, 21-12
jasper (chert), 8-9 L bar, 14-D.25 bolted connections, back-
jet washed finish, 5-7 L straps, 14-D.23 checking, 6-4
joinery L stud and disc, 14-D.24 carving, 6-5
alignment, 21-20 L-spline anchors, 14-D.18 caulking, 6-7
layout for countertops, 17-4 labor assignment, 14-1 clasts, 6-8
joint, defined, 23-14 labor restrictions, 21-87 clay, 6-9
joint filler laminated aprons for furniture and cleaning, 6-7, 21-14
countertops, 17-7, 17-9 tops, 19-1 coefficient of thermal
stone tile countertops, 17-2 laminated edge, 17-D.16, 19-D.3 expansion, 6-12
joint filling, 17-6 lamination, defined, 23-14 cold weather and installation, 6-
joint sealants, 14-8 to 14-9 laser, defined, 23-14 6
maintenance, 21-76 lathe, defined, 23-15 color, 6-10
joint width, 13-5 to 13-6, 14-9 to lavatory tops, 3-5 compressive strength, 6-12, 24-
14-10 See also countertops 4
countertops, 17-6 backsplashes, 17-D.12 contact with soil, 6-15
exterior cubic stone coping and vanities, 17-D.11 countertops, 17-2
walls, 18-2 layout for countertops, 17-5 Crema Europa, 21-12
granite, 5-4, 5-9 joinery layout, 17-4 cubic sills, 18-3
marble and onyx, 7-4 lead buttons, defined, 23-15 damaged stone, repairing, 6-2
pavers, 14-2 Leadership in Energy and dampproofing, 6-11
quartz-based stone, 8-3 Environmental Design (LEED), deicing chemicals, 6-13
serpentine, 9-4 vii, viii to ix defined, 23-15
showers, residential, 16-7 to 16- leather finish, countertops, 17-2 dense
8, 16-11 LEED (Leadership in Energy and defined, 21-12
slate, 10-3 Environmental Design), vii, viii effective techniques, 21-12
stone tile countertops, 17-9 to ix density, 6-12, 24-4
tolerances, 21-20, 22-7 legs for fireplace facings, 14-D.20 drips, 6-4
travertine, 12-4 length and area, conversion ratios, efflorescence, 6-14 to 6-15
jointing scheme, defined, 23-14 24-2 expansion joints, 6-7
joints lewis, defined, 23-15 exterior application, 3-4
sink, 17-D.4 lewis pins exterior cubic stone coping and
slate, 10-3 defined, 23-15 walls, 18-1
types of, 21-18 to 21-19 granite, 5-4 finishes, 6-10
width tolerances, 21-20, 22-7 limestone, 6-5 fire resistance, 6-13
joints, free-standing column, 14- marble and onyx, 7-4 flexural strength, 6-12, 24-4
D.13 to 14-D.14 quartz-based stone, 8-4 flooring, 6-13
exterior pavers, 14-5, 14-6 serpentine, 9-5 fossiliferous, 6-9 to 6-10
granite, 5-4 slate, 10-4 geological classification, 6-8 to
pressure relieving, 14-D.6 travertine, 12-4 6-10, 21-70
joints, open, 13-13 to 13-14 light colored stones hardness, 6-8, 6-13
mortar, 13-9 horizontal applications, 6-6
portland cement, 14-7 hydrated lime, 6-3
K setting beds, 13-18 installation, 6-5 to 6-7
light foot-traffic, 13-4 metamorphosis to calcite, 7-9
kaolinite, defined, 23-14 modulus of elasticity, 6-12
kerf, 5-4 interior, 3-5
lighting, 13-19 modulus of rupture, 6-12, 24-4
defined, 23-14 moldings, 6-4
rebated kerf, 23-21 commercial and historical
restoration, 21-85 mortar, 6-3, 13-9, 14-7
Kessler abrasion testing, 4-8 mortar setting of, 6-6
keystone limestone
abrasion, 6-12 packing and loading, 6-5
defined, 23-14

© 2022 Natural Stone Institute Index • Page 25-13

 panel thickness, 6-4 See also dead load absorption of stone, 24-4
physical properties, 6-11 to 6- defined, 23-15 acid reaction, 7-11
12, 24-4 load cell, defined, 23-15 anisotropy, 7-11 to 7-12
plastic setting pads, 6-6 load-bearing walls, 18-1 chemical properties, 7-10 to
porous lug sill, defined, 23-15 7-11
defined, 21-12 cleavage, 7-11
effective techniques, 21-12 color, 7-11
protection of, 6-8 M composition of, 7-11
repairing, 21-13 to 21-14 machine finish, defined, 23-15 compressive strength, 24-4
sampling, 6-11 machine gauged finish, 10-9 crystals, 7-10 to 7-11
sand, 6-3 machine tooled finish density, 24-4
sealant joints, 6-7 limestone, 6-10 flexural strength, 24-4
sealants, 6-3 travertine, 12-7 Iceland Spar, 7-11
seismic loads, 6-14 mafic stone, 1-3 modulus of rupture, 24-4
sizes, 6-11 magnesite, 6-8, 7-10, 9-10, 11-5 optical character, 7-11
snow melting chemicals, 13-19 magnetite, 5-9, 9-11 physical properties, 24-4
stain prevention, 6-4 maintenance thermal hysteresis, 7-12 to
staining, 6-14 to 6-15 additional resources, 21-121 7-13
stair treads, 14-13 commercial cleaning and water absorption, 24-4
storage, 6-5 sealing, 21-78 to 21-79 carving, 7-5
strength, 6-12 to 6-13 countertops, 17-12 to 17-13 caulking, 7-7
tensile strength, 6-11 current products and cleaning, 7-7
texture, 6-10 procedures, 21-21 coefficient of thermal
thermal expansion, 6-15 defined, 21-75, 23-15 expansion, 7-17
thickness, 6-10 to 6-11 purpose and benefits, 21-75 to color, 7-8 to 7-9, 7-13
thresholds, 14-11 21-76 commercial definition, 23-15
usage tips, 6-11 residential cleaning, 21-77 to compressive strength, 4-4, 7-17
veining, 6-10 21-78 countertops, 3-6, 17-1
veneer cutting, 6-11 specifying, 3-8 cramps, 7-3 to 7-4
washes, 6-4 mantels for fireplace facings, 14- crystallizers, 21-36
water, 6-4 D.19, 14-D.20, 23-14 cubic sills, 18-3
water absorption, 24-4 mantle (Earth), 1-2 damaged stone, repairing, 7-2
weep tubes, 6-7 marble and onyx defined, 23-15
white masonry cement, 6-3 See also MTL density, 7-17, 24-4
white portland cement, 6-3 (marble/travertine/limestone) diamond match pattern, 7-D.3
wind loads, 6-14 abrasion, 7-17 dishing, 7-21
window stools, 18-3 abrasion resistance, 7-17 to 7- distortion of stone, 7-12
limitations 18, 24-4 dolomitic marble, 7-8 to 7-9
precast concrete panels, 20-1 abrasive finish, 7-3 abrasion resistance, 24-4
stone veneer panels, 20-1 absorption of stone, 7-17, 24-4 absorption of stone, 24-4
limonite, 8-9 accessory mineral variation, 7- compressive strength, 24-4
line (edge) polisher, defined, 23-15 10 density, 24-4
liner blocks for countertops, 17-11 adhesive, 7-3 flexural strength, 24-4
liners, defined, 23-15 anchorage, 7-7 modulus of rupture, 24-4
lintel, 23-21 anisotropic-hysteretic effects, 7- physical properties, 24-4
defined, 23-15 12 to 7-13 water absorption, 24-4
lippage back-checking, 7-4 dowels, 7-3 to 7-4
countertops, 17-6, 17-7 backs of pieces, 7-4 drips, 7-4
defined, 23-15 blend pattern, 7-D.2 efflorescence, 7-19, 7-20
horizontal applications, 13-6 bolted connections, back- end match pattern, 7-D.3
pavers, 14-3 checking, 7-4 end slip pattern, 7-D.2
removal of, 21-25 book match pattern, 7-D.3 expansion joints, 7-7
slate, 10-3 breccia, 21-14 exterior cubic stone coping and
tolerances, 21-20, 22-7 brecciated veneer patterns, 7- walls, 18-1
vertical surfaces, 14-10 D.3 face dimensions, 7-16
lithogeochemistry, 4-1 to 4-2 burning, 21-13 finishes, 7-3, 7-14
lithosphere, 1-2 calcite fire resistance, 7-17
live load abrasion resistance, 24-4 fleuri cut, 7-16

Page 25-14 • Index © 2022 Natural Stone Institute

 flexural strength, 7-17, 24-4 21-36 marble blocks, 7-15
flooring, 14-5 defined, 21-34 to 21-35 Marble Institute of America (MIA),
finishes, 7-14 primary depositional features, defined, 23-16
installation, 7-5 to 7-6 7-9 masonry, defined, 23-16
geological classification, 7-8 to protection of, 7-7 to 7-8 masonry backup for interior
7-13, 21-70 pyrite, 7-10 cladding, 14-14
geological origin, 7-9 to 7-10 quarry blocks, 7-14 to 7-15 masonry cement
green, 9-8 to 9-9, 9-10 quarter match pattern, 7-D.3 limestone, 6-3
adhesive, 13-19 repairing, 21-13 to 21-14 travertine, 12-3
group A, 7-15 Rosso, 21-14 masonry construction and window
flooring, 14-5 Rosso Levanto, 21-15 stools, 18-D.2
furniture and tops, 19-1 sampling, 7-14 masonry fireplace, 14-D.19 to 14-
pavers, 14-4 sealant joints, 7-7 D.20
group B, 7-15 sealants, 7-3 matched stone samples, 3-7
flooring, 14-5 seismic considerations, 7-18, 7- matched-vein patterns, 3-3
pavers, 14-4 20 Material Safety Data Sheet
group C, 7-15 to 7-16 shims, 7-4 (MSDS), defined, 23-17
furniture and tops, 19-1 side slip pattern, 7-D.2 mechanical repairs, 21-8
group D, 7-16 sizes, 7-14 mechanical systems, anchors, 14-
furniture and tops, 19-1 soundness classification, 7-15 14 to 14-15, 21-18
hardness and flooring, 7-18 to 7-16 membranes, 13-7
honed finish, 7-3 squareness, 7-16 pavers, 14-3 to 14-4
honing powders, 21-36 staining, 7-19, 7-20 to 7-21 metaconglomerates, 8-7, 8-9
hysteresis, 7-19 to 7-20, 7-21 stair treads, 14-13 metal backup for exterior stone
Iceland Spar, 7-11 storage, 7-5 veneer, 14-D.3
installation, 7-5 to 7-7 strength, 7-17 metal edges, 13-11
curing compounds, 7-5 stylolites, 7-9 to 7-10 metal frame for sink hole, 17-D.10
tamping, 7-5 Tennessee Pink, 21-14 metal studs
thin-set method, 7-6 texture, 7-13 interior cladding, 14-14 to 14-
insulating materials, 7-18 thermal conductivity, 7-17 15, 14-D.10
interior veneer, 7-6 thermal expansion, 7-20, 7-21 exterior stone veneer, 14-D.2,
Italian, 7-10 thickness, 7-14, 7-16 14-D.5
liquid polishes, 21-36 thresholds, 14-11 metamorphic, defined, 21-1
magnesite, 7-10 toilet and shower metamorphic rock, 1-2
marble blocks, 7-15 compartments, 7-6 cleaning and maintenance, 21-
marble, composition of, 7-8 to translucence, 7-20, 7-21 78
7-13 usage tips, 7-14 defined, 23-16
microfractures, 7-12 variegated types, 21-14 geological classification, 21-70
modulus of elasticity, 7-17 vein cut, 7-16 metamorphic stone, 1-6 to 1-7
modulus of rupture, 7-17, 24-4 veining, 7-14 metaquartzite, 8-8
moldings, 7-4 veneer cutting, 7-14 to 7-15, 7- metamorphism, defined, 23-16
mortar, 7-3 D.1 metaquartzite, 8-7, 8-8
mortar setting of, 7-5 to 7-6 veneer patterns, 7-D.2 to 7-D.3 mica, hardness, 21-2
onyx voids, 7-9, 7-10 to 7-11 microcrystalline, defined, 23-16
color, 7-13 vugs, 7-10 to 7-11 milling, defined, 23-16
composition of, 7-13 wall tile, 7-6 miter
geological origin, 7-13 washes, 7-4 defined, 23-16
travertine and, 7-13, 12-8 n1 water absorption, 7-18, 24-4 quirk miter, 23-21, 22-D-App B
"orange peel", 21-13 water vapor permeability, 7-17 miter joint, countertops, 17-D.3
packing and loading, 7-5 weathering, 7-18 mixing tools, 21-43
panel thickness, 7-4 weep tubes, 7-7 mixing types of stone, 3-3
pavers, 14-4 white Carrara, 21-13 mockups, 3-6, 5-2, 6-2, 7-2, 8-2, 9-
physical properties, 7-16 to 7- white marble 2, 10-2, 12-2, 14-3
17, 24-4 defined, 21-13 defined, 23-16
polished finish, 7-3 effective techniques, 21-13 horizontal applications, 13-1
polishing pastes, 21-36 wind loads, 7-18 soapstone, 11-2
polishing powders window stools, 18-3 testing of, 20-1
characteristics of, 21-35 to wire anchors, 7-4 moderate foot-traffic, 13-4

© 2022 Natural Stone Institute Index • Page 25-15

 interior, 3-5 13-15 consistent MTL group
modular, defined, 23-16 concrete subsurface bonding, Crema Marfil, 21-11 to 21-
modular stone tiles, 3-3, 3-7 to 3-8 13-11 to 13-12 12
modulus of elasticity expansion joint, 13-D.1 defined, 21-11
defined, 23-16 flooring, 14-8 effective techniques, 21-12
granite, 5-11 heated floor systems, 13-17 general notes, 21-13
limestone, 6-12 limestone setting, 14-7 consistent variegated MTL
marble and onyx, 7-17 membrane, 13-D.1 group
precast concrete panels, 20-1 movement joint, 13-D.1 Botticino, 21-14
quartz-based stone, 8-11 portland cement, 14-6 defined, 21-14
serpentine, 9-13 reinforcement, 14-5 effective techniques, 21-14
stone veneer panels, 20-1 reinforcement, 14-6 edging, 21-54
travertine, 12-12 separate from subfloor, 13-15 to lippage removal, 21-53, 21-54
modulus of rupture, 4-6 13-16 polishing, frankfurt, 21-30
See also flexural strength thin bed, 13-15 to 13-16 refinishing and polishing
defined, 23-16 thin-set, 13-D.1, 13-D. 3, 14-6 edging, 21-54
granite, 5-11 to 14-7 first grinding, 21-54 to 21-
limestone, 6-12 wood frame subfloor, 13-D.3 55
marble and onyx, 7-17 wood subfloor, 13-D.3 honing, 21-56 to 21-57
quartz-based stone, 8-11 mortar bed weight, 13-5 initial honing, 21-56
serpentine, 9-13 joints light grinding, 21-55 to 21-
slate, 10-11 granite, 5-5 56
travertine, 12-12 limestone, 6-6, 8-5 lippage removal, 21-53, 21-
Mohs scale, 5-9, 17-10, 17-12, 24-2 marble and onyx, 7-6 54
defined, 21-2, 23-16 serpentine, 9-7 other finishes, 21-58
moisture, flooring, 14-7 pointing mortar polishing, 21-57 to 21-58
moisture penetration, 13-18 granite, 5-3 preparation, 21-53 to 21-54
steam rooms and showers, 16-8 limestone, 6-3 refinishing, 21-55
moisture proofing, steam rooms marble, 7-3 sealing, 21-58
and showers, 16-12 onyx, 7-3 variegated MTL group, 21-14
moisture sensitivity, 13-18 quartz-based stone, 8-3 mudstone, 1-5
mold and mildew serpentine, 9-4 mullion, defined, 23-17
cementitious backer units, 16-2 setting mortar
drywall, 16-2 granite, 5-3
molded joint, 14-D.16 limestone, 6-3 N
moldings marble, 7-3 National Building Granite Quarries
defined, 23-16 onyx, 7-3 Association (NBGQA)
granite, 5-4 quartz-based stone, 8-3 defined, 23-17
limestone, 6-4 serpentine, 9-3 to 9-4 publications, 5-2
marble and onyx, 7-4 setting of stone National Building Museum, v
quartz-based stone, 8-3 granite, 5-5 National Sanitation Foundation,
serpentine, 9-4 limestone, 6-6 See NSF International
slate, 10-3 to 10-4 marble and onyx, 7-5 to 7-6 National Tile Contractors
soapstone, 11-3 quartz-based stone, 8-5 Association (NTCA), defined,
travertine, 12-4 serpentine, 9-6 23-17
monolithic, defined, 23-16 mortar joints natural bed, defined, 23-17
mortar slate, 10-5 natural cleft, defined, 23-17
defined, 23-17 travertine, 12-6 natural cleft finish, 3-2, 19-2
dry-pack, 13-8 mosaic, defined, 23-17 slate, 10-9
dry-set, 13-8 to 13-9 movement joints, 13-6, 14-9 natural stone, defined, 23-17
pointing mortar, slate, 10-3 defined, 23-16 Natural Stone Institute (NSI), i
setting mortar, slate, 10-3 exterior pavers, 14-5 defined, 23-17
setting of stone, travertine, 12-5 pavers, 14-2 code of ethics, xiv
to 12-6 MSDS (Material Safety Data membership, xv
thin-set, 13-8 to 13-9 Sheet), defined, 23-17 publications, 3-8, 4-10
mortar bed, 13-D.3 MTL (marble/travertine/limestone) statement of position on sealers,
bond coat, 13-D.1 See also marble and onyx; 3-5 to 3-6
bonded to subfloor, 13-14 to limestone; travertine NBGQA

Page 25-16 • Index © 2022 Natural Stone Institute

 defined, 23-17 countertops, 17-1 acrylics, 21-40 to 21-41
publications, 5-2 defined, 23-18 cyanoacrylate (CA) glues, 21-
neat cement, 5-7 geological classification, 21-70 41 to 21-42
See also back parging; parge oolitic limestone, defined, 23-18 epoxy, 21-41
defined, 23-17 open-faced quarry, defined, 23-18 general notes, 21-42
negative flow, defined, 16-2 organization websites, iv hybrids, 21-42
Neolite, 4-9 orthoclase, hardness, 21-2 polyester resins, 21-40
neutral cleaners, 21-84 orthoquartzite vs. granite, 5-9 urethane, 21-41
niche, defined, 23-17 OSHA (Occupational Safety and patina, defined, 23-18
NIOSH (National Institute for Health Administration), defined, patterned and matched panels, 3-3
Occupational Safety and Health), 23-18 pavers
defined, 23-17 out-crop, defined, 23-18 coefficient of friction (COF),
noise restrictions, 21-26 outriggers, defined, 23-18 14-3
nonferrous anchors, cramps, and outward crack, repairs, 21-44 defined, 23-18
dowels, 8-3 overburden, defined, 23-18 dry-pack mortar, 13-12 to 13-13
nonstaining mortar, defined, 23-17 overhangs, 23-6 finishes, 13-3
nonstick mastic compound, 10-5 defined, 23-18 granular bed method, 13-14
Normandy edge, 17-D.16, 19-D.3 furniture and tops, 19-1 hollow sound, 14-1 to 14-2
notch, defined, 23-17 thickness, 19-1 installation methods, 13-17
NSF International, 2-3 to 2.4 oxalic acid, 21-13 joint width, 13-5, 14-2
NSF Material Requirements defined, 23-18 lippage, 14-3
(Standard 51), 2-3 to 2.4 polishing powders, 21-35 membranes, 14-3 to 14-4
NSF/ANSI standards, 2-6 pedestal systems, 13-13, 13-D.2
NSI (Natural Stone Institute), i sand installation, 13-D.2
defined, 23-17 P thickness, 14-2 to 14-3
code of ethics, xiv palletize, defined, 23-18 underlayment limitations, 13-5
membership, xv pan, steel for stair treads, 13-D.6, paving, defined, 23-18
publications, 3-8, 4-10 13-D.8 pebble, clast size, 1-5
statement of position on sealers, panel, defined, 23-18 pebble conglomerate, 1-5
3-5 to 3-6 panel deformation, 21-19 pedestal, 23-7, 23-9, 23-19
NTCA (National Tile Contractors panels defined, 23-18
Association), defined, 23-17 precast concrete, 20-D.1 to 20- pedestal system and exterior
D.2 pavers, 13-13, 13-D.2, 14-6
coefficient of thermal pediment, defined, 23-18
O expansion, 20-1 PEL (permissible exposure limit),
obsidian, defined, 23-17 color, 20-1 defined, 23-18
occupants' access, commercial and compressive strength, 20-1 pencil round edge, 17-D.16, 19-D.3
historical restoration, 21-86 finishes, 20-1 percussion drilling, defined, 23-19
Occupational Safety and Health installation, 20-2 perforated wall, defined, 23-19
Administration (OSHA), defined, limitations, 20-1 pergola, defined, 23-19
23-18 modulus of elasticity, 20-1 perimeter joints, defined, 21-19
oceanic stone, 1-2 to 1-3 physical properties, 20-1 permeability, sealers, 21-69
off fall. See remnant (23-21) shear strength, 20-1 permissible exposure limit (PEL),
Office of the Federal sizes, 20-1 defined, 23-18
Environmental Executive, v tensile strength, 20-1 personal protective equipment
offset butt joint, 14-D.9 testing mockups, 20-1 (PPE)
ogee, defined, 23-17 thickness, 20-1 defined, 23-19 to 23-20
ogee edge, 17-D.16, 19-D.3 showers, residential, 16-8 for repairs, 21-40, 21-43, 21-45
ogee roundover edge, 17-D.16, 19- parallel vs. perpendicular testing, 4- petrography, 4-1
D.3 3 pH, 21-3
oil-based putty parapet, defined, 23-18 cleaners, 21-36 to 21-37
cubic sills, 18-3, 18-4 parapet details for exterior cubic phenocryst, defined, 23-19
exterior cubic stone coping and stone coping and walls, 18-D.1 phyllite, 5-9, 10-7 to 10-8
walls, 18-1, 18-2 parge. See also back parging; neat picked, hand-hewn, rock face
furniture and tops, 19-1, 19-2 cement finish, 3-2
wet areas, 16-1 defined, 23-18 picture framing, 21-32, 21-55
window stools, 18-3, 18-4 particle names (clast sizes), 1-5 pilaster, defined, 23-19
onyx, 7-13 patching materials, 21-39 pillowed, defined, 23-19

© 2022 Natural Stone Institute Index • Page 25-17

pit quarry, defined, 23-19 polishing pastes, 21-36 marble and onyx, 7-7 to 7-8
pitch faced finish, 5-7 time, 21-36 quartz-based stone, 8-6
defined, 23-19 polishing tools, 21-43 serpentine, 9-8
pitched stone (pitch faced), defined, right-angle polisher, 21-47 slate, 10-6
23-19 polishing wheel marks, 13-19, 14- soapstone, 11-4
pits, 21-23 17 travertine, 12-7
pitting of granite, 5-14, 17-12 poly-epoxy, properties, 21-49 pumice, defined, 23-20
planed finish, 3-2 polyester, properties, 21-49 pyrite, 7-10
slate, 10-9 polyester-based resin adhesives, pyroxene, 11-5
plastic lime hydrate 21-8
quartz-based stone, 8-3 polyester resin, 17-9, 17-10
slate, 10-3 pool environments, diagnostic Q
plastic setting pads considerations, 21-24 quarried stone, defined, 23-20
limestone installation, 6-6 porosity of stone and exterior quarrier, defined, 23-20
travertine installation, 12-6 applications, 3-4 quarry, defined, 23-20
plate tectonics, 1-3 to 1-4 porous limestone quarry block
platner edge, 17-D.16, 19-D.3 defined, 21-12 defined, 23-20
plinth, 23-7, 23-9, 23-18 effective techniques, 21-12 marble and onyx, 7-14 to 7-15
defined, 23-19 porphyry, defined, 23-19 quarry run, defined, 23-20
plucked finish portico, defined, 23-19 quarry sap, defined, 23-20
defined, 23-19 portland cement, 14-6 quarrying, x
limestone, 6-10 light colored stones, 14-7 quarter match pattern, 7-D.3
travertine, 12-7 portland cement mortar, 13-8, 13- quarter-point loading and flexural
plug anchors, 14-D.24 16 strength test, 4-7
plumbing sealants, wet areas, 16-1 positive flow, defined, 16-2 quartz
plutonic, defined, 23-19 poultices, 21-52 composition of, 8-7
plywood subfloors, 13-11, 14-10 defined, 23-19 defined, 23-20
mortar bed, 13-D.3 for stains, 21-82 to 21-83 granite, 5-9
plywood subtops, 19-1 PPE (personal protective hardness, 17-10, 17-12, 21-2
pointed finish. See bush-hammered equipment) quartz-based stone
finish defined, 23-19 to 23-20 abrasion resistance, 8-12, 24-4
pointing, defined, 23-19 for repairs, 21-40, 21-43, 21-45 absorption of stone, 8-11, 24-4
polished finish, 3-2, 19-2 preassembled units, defined, 23-20 anchorage, 8-5 to 8-6
countertops, 17-2 precast, defined, 23-20 anchors, wire, 8-3
defined, 21-5, 21-75, 23-19 preparation back-checking, 8-4
granite, 5-6 exterior cubic stone coping and backs of pieces, 8-3
limestone, 6-10 walls, 18-2 bolted connections, back-
marble and onyx, 7-3, 7-14 showers, residential, 16-8, 16- checking, 8-3
serpentine, 9-12 11 caulking, 8-6
travertine, 12-7, 12-10 steam rooms and showers, 16-9 cleaning, 8-6
polishing pressure relieving joints, 14-D.6 color, 8-9
defined, 23-19 pressure washing, 21-84 compressive strength, 8-11, 24-
granite countertops, 21-64 pricing stone, 3-7 to 3-8 4
granite refinishing and primer, defined, 23-20 cramps, 8-3
polishing, 21-61 privacy partition crystalline quartz, 8-7 to 8-8
MTL refinishing and polishing, See also urinal screens damaged stone, repairing, 8-2
21-57 to 21-58 defined, 23-20 defined, 23-20
polishing compounds, defined, 23- producer, defined, 23-20 density, 8-11, 24-4
19 profile wheel, defined, 23-20 dowels, 8-3
polishing cream, defined, 23-19 project samples, 3-6 drips, 8-3
polishing pads projections, defined, 23-20 efflorescence, 8-13 to 8-14
defined, 23-19 promotional samples, color expansion joints, 8-6
miscellaneous, 21-36 consideration, 3-6 fabrication, 8-11
types of, 21-35 to 21-36 prospecting, defined, 23-20 finishes, 8-10
polishing powders protection of stone fire resistance, 8-12
bricks, 21-30 finished work, 13-17 to 13-18 flexural strength, 8-11, 24-4
characteristics of, 21-35 granite, 5-6 to 5-8 geological classification, 8-6 to
marble, 21-34 to 21-35 limestone, 6-8 8-9

Page 25-18 • Index © 2022 Natural Stone Institute

 hardness and flooring, 8-12 defined, 23-21 serpentine (during fabrication),
installation, 8-5 to 8-6 density, 24-4 9-2
main groups of, 8-7 flexural strength, 24-4 slate, 10-2
modulus of elasticity, 8-11 hardness for flooring, 8-12 soapstone, 11-2
modulus of rupture, 8-11, 24-4 modulus of rupture, 24-4 sticking, 9-2
moldings, 8-3 physical properties, 24-4 travertine, 12-2
mortar, 8-3, 8-5 water absorption, 24-4 repairs
packing and loading, 8-4 quirk joint, 14-D.9 adhesives, consistency, 21-45
physical properties, 8-11 to 8- quirk miter joint, 14-D.9, 14-D.16 chips, 21-44
12, 24-4 quirk miters, 19-1 color matching, 21-46
plastic lime hydrate, 8-3 defined, 23-21 damage types, 21-43
protection of, 8-6 tolerances, 22-D-App B downward crack, 21-44
safety factors, 8-12 to 8-13 quoin, defined, 23-21 finishing, 21-46
sampling, 8-1 to 8-2, 8-10 identification, 21-7 to 21-9
sealant joints, 8-6 inspection, 21-43
sealants, 8-3 R inward crack, 21-44
seismic considerations, 8-13 rabbet, defined, 23-21 macro-cracks, 21-45 to 21-46
seismic loads, 8-13 rabbeted joint, 14-D.9, 14-D.16 maintenance, 21-76
sizes, 8-10 radius edges, 17-D.16, 19-D.3 micro-cracks, 21-45
staining, 8-13 to 8-14 undermount sink support, 17- outward crack, 21-44
storage, 8-4 D.8 preparation, 21-45
strength, 8-12 radius of rounded edges, 19-1 seams or cracks, 21-48
tensile strength and thickness, radon, granite, 5-14 suggestions, 21-44
8-10 rain screen, defined, 23-21 upward crack, 21-43
texture, 8-9 to 8-10 raked joint, defined, 23-21 reprise, defined, 23-21
thermal expansion, 8-14 random ashlar, 23-3 resin, defined, 23-21
thickness, 8-10 random slab, defined, 23-21 resin-impregnated slabs, 17-11
thin wall tile, 8-5 rebated kerf, defined, 23-21 resin impregnation, 21-7
tolerances, 8-10 recess, defined, 23-21 resin patching sticks, defined, 23-
usage tips, 8-10 recrystallization. See crystallization 22
veneer, 8-5 recrystallized limestone, defined, resin polishing, defined, 23-22
washes, 8-3 23-21 resined slab, defined, 23-22
water absorption, 24-4 refinishing resort environments, diagnostic
weep tubes, 8-6 Crema Marfil, 21-11 considerations, 21-24
wind loads, 8-13 defined, 23-21 resources
quartz pebble conglomerates, 8-7, Noce Travertine, 21-11 mechanical anchors, 21-18
8-8 to 8-9 reglets tile, 21-18
quartz sandstone, 1-5 n10 defined, 23-21 restoration
quartzite, 8-7, 8-8, 23-21 exterior stone veneer, 14-D.9 additional resources, 21-121
abrasion resistance, 24-4 flashing, 6-4 budgetary concerns, 21-72
absorption of stone, 24-4 limestone, 6-4 defined, 21-51, 21-75, 23-22
compressive strength, 24-4 reinforcement, defined, 23-21 masking and protecting, 21-52
defined, 21-15 reinforcement techniques for to 21-53
density, 24-4 countertops, 17-11 previous restoration, 21-21
effective techniques, 21-15 to reinforcements, identification, 21-7 surface preparation, 21-51
21-16 to 21-9 restraint anchorage, 14-D.7
flexural strength, 24-4 relief, defined, 23-21 expansion bolts, 14-D.8
geological classification, 21-70 relief angle connection, 14-D.4 exterior stone veneer, 14-D.7
granite vs., 5-9 relieving angle-clip, 14-D.24 interior stone veneer, 14-D.8
hardness for flooring, 8-12 relieving arch, defined, 23-21 return, defined, 23-22
identification, 21-15 remnant, defined, 23-21 return head, defined, 23-13
modulus of rupture, 24-4 repairing damaged stone reveal
physical properties, 24-4 countertops, 17-11 to 17-12 defined, 23-22
water absorption, 24-4 granite, 5-3 free-standing column, 14-D.14
quartzitic sandstone limestone, 6-2 ribbons, 10-8
abrasion resistance, 24-4 marble, 7-2 defined, 23-22
absorption of stone, 24-4 onyx, 7-2 rift
compressive strength, 24-4 quartz-based stone, 8-2 defined, 23-22

© 2022 Natural Stone Institute Index • Page 25-19

 testing in relation to direction marble and onyx, 7-5 geological classification, 21-70
of, 4-3 quartz-based stone, 8-5 hardness for flooring, 8-12
rigidity, 21-19 serpentine, 9-5 modulus of rupture, 24-4
riprap, defined, 23-22 slate, 10-5 physical properties, 24-4
riser, 23-25, 23-27 soapstone, 11-4 texture, 8-10
rock travertine, 12-5 water absorption, 24-4
defined, 23-22 salt attack, 21-4 sawed edge, defined, 23-23
vs. stone, 1-1 saltwater environments, 21-24 sawed face, defined, 23-23
rock cycle, 1-7, 1-8 sample specification language, xvii sawing countertops, 17-5
rock-faced finish to xviii sawn finish, 3-2
defined, 23-22 samples, 14-3 granite, 5-7
granite, 5-7 defined, 23-23 limestone, 6-10
marble and onyx, 7-14 granite, 5-2 travertine, 12-10
rocked edge, 17-D.16, 19-D.3 horizontal applications, 13-1 sawyer, defined, 23-23
rodding, 21-8 limestone, 6-1 to 6-2 scabbing (dressing), defined, 23-9
See also reinforcement marble, 7-1 to 7-2 scaling, travertine, 12-14
countertops, 17-11, 17-D.5 onyx, 7-1 to 7-2 schist, 5-9, 9-9, 9-11, 10-8
defined, 23-22 quartz-based stone, 8-1 to 8-2 defined, 23-23
Roman arch, defined, 23-22 serpentine, 9-1 to 9-2 scotia, defined, 23-23
rosette detail, interior cladding, 14- slate, 10-1 to 10-2 scratches, 21-23
D.15 soapstone, 11-1 to 11-2 pressure scratches, 21-23
rosette fasteners, interior cladding, travertine, 12-1 to 12-2 removal of, 21-23
14-D.15 sampling, 3-6 to 3-7 screed, defined, 23-23
rough back, defined, 23-22 granite, 5-10 sculpture, defined, 23-23
rough finish, 19-2 large projects, 3-6 to 3-7 sea-floor spreading, 1-3
rough sawn finish limestone, 6-11 sealant joints
defined, 23-22 marble and onyx, 7-14 granite, 5-6
exterior cubic stone coping and number, 3-6 to 3-7 limestone, 6-7
walls, 18-1 quartz-based stone, 8-10 marble and onyx, 7-7
marble and onyx, 7-14 serpentine, 9-12 quartz-based stone, 8-6
rubbed finish, 5-7 slate, 10-9 serpentine, 9-8
defined, 23-22 travertine, 12-10 to 12-11 slate, 10-6
rubber bristle brushes, 21-37 sand travertine, 12-6
rubble, defined, 23-22 clast size, 1-5 sealants
rustication, defined, 23-23 grout, 14-7 backer rods, 14-9
limestone, 6-3 cubic sills, 18-3, 18-4
marble, 7-3 defined, 23-23
S onyx, 7-3 fungicide, 14-8
saddle (threshold), defined, 23-26 portland cement mortar, 14-6 furniture and tops, 19-1, 19-2
safety factors travertine, 12-3 granite, 5-3
compressive loads, 4-5 sand bed installation, 13-D.2, 14-6 joint sealants, 14-8 to 14-9
quartz-based stone, 8-12 to 8-13 sand grain composition, 1-5 limestone, 6-3
seismic loads sand rubbed finish, 10-9 marble, 7-3
granite, 5-13 sandblasted finish, 3-2 oil-based organic, 14-8
limestone, 6-14 defined, 23-23 onyx, 7-3
quartz-based stone, 8-13 granite, 5-7 primers, 5-6, 6-7, 7-7, 8-6, 9-8,
travertine, 12-13 to 12-14 slate, 10-9 10-6, 11-4, 12-6, 14-8
wind loads sandblasting, 21-84 quartz-based stone, 8-3
granite, 5-13 sanded finish, defined, 21-6 serpentine, 9-4
limestone, 6-14 sandstone, 1-5, 8-7, 8-8 silicone, 13-10, 14-8
marble and onyx, 7-18 See also quartz-based stone slate, 10-3
quartz-based stone, 8-13 abrasion resistance, 24-4 soapstone, 11-4
serpentine, 9-14 to 9-15 absorption of stone, 24-4 staining, 13-19, 14-8 to 14-9,
slate, 10-12 compressive strength, 24-4 14-16 to 14-17
travertine, 12-13 to 12-14 defined, 21-16, 23-23 surface sealers, 14-10
salt density, 24-4 travertine, 12-3
granite, 5-7 effective techniques, 21-16 urethane, 13-10
limestone, 6-5 flexural strength, 24-4 window stools, 18-3, 18-4

Page 25-20 • Index © 2022 Natural Stone Institute

sealers sedimentary rock, 1-1 to 1-2 insulator, 9-14
actives, 21-68 geological classification, 21-70 interior veneer, 9-7
appropriateness, 21-69 to 21-70 sedimentary stone, clastic, 1-4 to 1- limitations, 9-11
carriers, 21-68 5 marble and, 9-8 to 9-9
coatings, 21-67 to 21-68 seismic considerations modulus of elasticity, 9-13
color-enhancing impregnators, granite, 5-13 modulus of rupture, 9-13, 24-4
21-67 marble and onyx, 7-18, 7-20 Mohs scale, 21-15
commercial clients, 21-71 to quartz-based stone, 8-13 moldings, 9-4
21-72 serpentine, 9-15 mortar, 9-3 to 9-4
countertops, 17-6, 17-12 slate, 10-12 mortar setting of, 9-6
defined, 21-6, 23-23 travertine, 12-14 packing and loading, 9-5
exteriors, 21-70 to 21-71 self-leveling underlayment for physical properties, 24-4
field tests, 21-72 to 21-74 stone tiles, 13-5 protection of, 9-8
film-forming sealers, 21-23, 21- serpentine safety factor, 9-14 to 9-15
67 to 21-68 See also MTL sampling, 9-12
finished appearance, 21-71 (marble/travertine/limestone) sand, 9-6
flooring, 14-7 abrasion resistance, 9-13, 9-14, sealant joints, 9-7
fluoropolymers, 21-68 24-4 sealants, 9-4
general characteristics, 21-68 to absorption of stone, 9-13, 24-4 seismic considerations, 9-15
21-69 adhesive, 9-4, 13-18 to 13-19 setting beds and water, 9-6
granite, 21-61, 21-64 anchorage, 9-7 sizes, 9-12
impregnating repellents, 21-67 anchors, 9-4 staining, 9-16
impregnating sealers, 21-80 asbestos content, 9-3 storage, 9-5
introduction, 21-67 back-checking, 9-4 strength, 9-14
maintenance, 3-8, 21-71, 21-72 backs of pieces, 9-4 texture, 9-12
MIA statement, 3-5 to 3-6 bolted connections, back- thickness, 9-12
penetrating sealers, 3-5, 21-67 checking, 9-4 toilet and shower
performance expectations, 21- carving, 9-5 compartments, 9-7
71 caulking, 9-8 usage tips, 9-13 to 9-14
points to remember, 21-74 cleaning, 9-8 vein-cut, 9-13
residential and commercial color, 9-11 to 9-12 veining, 9-11 to 9-12
interiors, 21-70 composition of, 9-9 veneer cutting, 9-13
residential clients, 21-71 compressive strength, 9-13, 24- vertical surfaces, 14-16
resin-impregnated slabs, 17-11 4 wall tile, 9-7
sealer components, 21-68 countertops, 17-1 washes, 9-4
sealer selection, 21-72 cramps, 9-4 water absorption, 9-14, 24-4
silicone-based chemicals, 21-68 damaged stone, repairing during water and installation, 9-6
solvent-based coatings, 21-68 fabrication, 9-2 weathering, 9-14
staining, 21-70 damaged stone, repairing during weep tubes, 9-8
Standard 51, 2-4 installation, 9-3 wind loads, 9-14 to 9-15
timing, 21-80 defined, 21-15, 23-24 setter, defined, 23-24
topical sealers, 17-12, 21-23, density, 9-13, 24-4 setting, defined, 23-24
21-80 dowels, 9-4 setting beds, stair treads, 13-D.6 to
VOC tolerance, 21-72 drips, 9-4 13-D.8
water-based carriers, 21-68 effective techniques, 21-15 setting space, defined, 23-24
sealing efflorescence, 9-15 to 9-16 shading variation in stone tile
defined, 23-23 expansion joints, 9-8 countertops, 17-9
furniture and tops, 19-1 finishes, 9-3, 9-12 shale, 1-5
MTL refinishing and polishing, fire resistance, 9-15 defined, 23-24
21-58 fleuri cut, 9-13 shear, defined, 23-24
seam filler material for countertops, flexural strength, 9-13, 24-4 shear strength
17-7, 17-9, 17-13 floor installation, 9-6 to 9-7 precast concrete panels, 20-1
seam setter flooring, 9-13 to 9-14 stone veneer panels, 20-1
countertop repair, 21-46 geological classification, 9-8 to sheet applied bonded membrane,
defined, 23-23 9-11, 21-70 defined, 16-2
seam width, countertops, 17-6 gypsum molding plaster, 9-7 shellac, polishing powders, 21-35
seams, granite, 21-48 hardness, 9-9, 9-14, 21-15 shelves, 17-D.14
sedimentary, defined, 21-1, 23-24 installation, 9-5 to 9-8 shims, 14-9 to 14-10, 14-D.23

© 2022 Natural Stone Institute Index • Page 25-21

 countertops, 17-5 stone ceiling, 16-8 window stools, 18-3
repair, 21-46 stone tile slab, defined, 23-24 to 23-25
defined, 23-24 details, 16-D.10 slab production table, 24-2
interior stone base, 14-D.17 elevations, 16-D.9 slab stock, 13-1
plastic, 14-D.23 exposed edges, 16-10 defined, 14-1
marble, 7-4 fabrication, 16-10 slab warp, allowable lippage, 17-7
onyx, 7-4 installation, 16-10 to 16-11 slate
slate and, 10-5 joint width, 16-11 abrasion resistance, 10-11, 24-4
stainless steel, 14-D.23 polished finish, 16-10 absorption of stone, 10-11, 24-4
shop drawings preparation, 16-10 to 16-11 adhesive and panel installation,
countertops, 17-3 sizes, 16-10 10-5
defined, 23-24 soundness, 16-10 anchorage, 10-6
granite, 5-2 to 5-3 thickness, 16-10 anchors, 10-3
horizontal applications, 13-2 side slip pattern, 7-D.2 back-checking, 10-4
kitchen layouts and countertops, siderite, 6-8, 9-10 to 9-11 backs of pieces, 10-4
17-D.17 sidesplashes, 17-D.13 bolted connections, back-
limestone, 6-2 silica checking, 10-4
marble, 7-2 cementing material, 1-5 calcium carbonate and weather
onyx, 7-2 defined, 23-24 resistance, 10-13
quartz-based stone, 8-2 silicates, 1-1 caulking, 10-6
serpentine, 9-2 siliceous, defined, 23-24 cleaning, 10-6
slate, 10-2 siliceous stones color, 10-7, 10-8
soapstone, 11-2 acid attack, 21-3 to 21-4 compressive strength, 10-10,
travertine, 12-2 defined, 21-2 24-4
shop ticket, defined, 23-24 sealers, 21-70 countertops, 17-2
shot ground finish, 5-7 sill, defined, 23-24 cramps, 10-3
shot sawed, defined, 23-24 silt, clast size, 1-5 damaged stone, repairing, 10-2
shower pan, defined, 16-2 siltstone, 1-5 defined, 23-25
shower partitions defined, 23-24 density, 10-10, 24-4
color, 16-5 simulated stone, defined, 23-24 dowels, 10-3
details, 16-D.5 sink flange, 17-D.8 drips, 10-3 to 10-4
elevations, 16-D.4 sink mounts, 17-4 efflorescence, 10-12 to 10-13
fabrication, 16-5 sinks expansion joints, 10-6
finishes, 16-5 cast-iron, 17-3 exterior panel installation, 10-5
floor-mounted, 16-6 support details, 17-D.8 to 17-10 finishes, 10-3, 10-9
free-standing units, 16-6 site access, commercial and fire resistance, 10-11
installation, 16-5 to 16-6 historical restoration, 21-86 flexural strength, 10-10, 24-4
sizes, 16-5 sizes flexure testing, 4-7
soundness, 16-5 cubic sills, 18-3 flooring, 10-10
types, 16-5 exterior pavers, 14-5 formation, 10-7
waterproof pan receptor types, furniture and tops, 19-2 furniture and tops, 19-1
16-D.4 granite, 5-10 geological classification, 10-6
shower receptors, 16-D.4 limestone, 6-11 to 10-8, 21-70
showers, residential marble and onyx, 7-14 hardness, 10-11
color, 16-8, 16-10 precast concrete panels, 20-1 installation, 10-5 to 10-6
details, 16-D.8 quartz-based stone, 8-10 interior panel installation, 10-5
elevations, 16-D.6 to 16-D.7 serpentine, 9-12 lippage, 10-3
stone slab shower partitions, 16-5 modulus of rupture, 10-11, 24-4
anchors, 16-8 showers, residential, 16-10 moldings, 10-3 to 10-4
exposed edges, 16-8 slate, 10-9 mortar, 10-3
fabrication, 16-7 stair treads, 14-14 mortar joints, 10-6
installation, 16-8 steam rooms and showers, 16- mortar setting of, 10-5
joint width, 16-7 to 16-8 10 packing and loading, 10-4
panels, 16-8 stone veneer panels, 20-1 panel thickness, 10-3
polished finish, 16-8 thresholds, 14-11 phyllite, 10-7 to 10-8
preparation, 16-8 toilet partitions, 16-3 physical properties, 10-10 to
sizes, 16-7 travertine, 12-10 10-11, 24-4
soundness, 16-7 urinal partitions, 16-4 plastic lime hydrate, 10-3

Page 25-22 • Index © 2022 Natural Stone Institute

 protection of, 10-6 hardness, 11-5 splashes and stone tile countertops,
quality, 10-7 heat retention, 11-5 17-9
safety factors, 10-12 installation, 11-3 to 11-4 splay, 23-27
sampling, 10-9 magnesite, 11-5 defined, 23-25
schist, 10-8 micas, 11-5 splines
sealant joints, 10-6 mineralogy, 11-5 countertops, 17-11
sealants, 10-3 moldings, 11-3 for toilet partitions, 16-D.1
seismic considerations, 10-12 packing and loading, 11-3 spline joint reinforcement at sink,
sizes, 10-9 physical properties, 11-5 to 11- 17-D.4
soundness, 10-10 6 split, defined, 23-25
spandrel thickness, 10-3 protection of, 11-4 split face ashlar, 14-D.21
staining, 10-13 sampling, 11-1 to 11-2 split faced finish, 5-7
storage, 10-4 sealants, 11-4 split-faced stone, defined, 23-25
strength, 10-11 steatite, 11-5 split-tail anchor, exterior stone
texture, 10-8 talc, 11-5 veneer, 14-D.2, 14-D.3
thermal conductivity, 10-11 washes, 11-3 split-tail straps, 14-D.23
thickness, 10-9 soffit hanger, 14-D.24 splitting of slabs, 8-11
usage tips, 10-10 soffits spot or spotting, defined, 23-25
veining, 10-8 back anchors, 14-D.18 spreader bar, defined, 23-25
wall facing thickness, 10-3 defined, 23-25 spreading devices/tools, 21-43
washes, 10-3 to 10-4 disc hangers, 14-D.18 spring clip, 14-D.25
water absorption, 4-3, 10-11 to expansion bolts, 14-D.18 spring clip with collar, 14-D.25
10-12, 24-4 flat strap hangers, 14-D.18 springer, 23-14, 23-22
weather resistance, 10-12 L-spline anchors, 14-D.18 square feet to square meters, 24-1
weep tubes, 10-6 stone, installation, 14-14, 14-15 square meters to square feet, 24-1
wind loads, 10-12 solid-state transformation, 1-1 squareness, tolerances, 22-5
sling, defined, 23-25 solvents, 21-84 stacked bond, defined, 23-26
slip joint, defined, 23-25 sound attenuation membranes, 13-7 stain prevention with travertine, 12-
slip resistance, 4-1, 4-9, 21-75 soundness 3 to 12-4
slip sill defined, 23-25 staining
See also lug sill marble and onyx, 7-15 to 7-16 granite, 5-13 to 5-14
defined, 23-25 shower partitions, 16-5 grout, 14-8
slurry, defined, 23-25 showers, residential, 16-10 marble and onyx, 7-19, 7-20 to
smooth finish steam rooms and showers, 16- 7-21
defined, 23-25 10 quartz-based stone, 8-13 to 8-14
limestone, 6-10 urinal partitions, 16-4 sealants, 13-19, 14-8 to 14-9
travertine, 12-7, 12-10 wet areas, 16-1 serpentine, 9-16
snapped edge. See guillotine (23- source of supply slate, 10-13
13) granite, 5-2 travertine, 12-14
snow melting chemicals, 13-19 limestone, 6-1 stains
soapstone marble, 7-1 accelerators, 21-40
absorbency, 11-6 onyx, 7-1 biological stains, 21-81, 21-83
caulking, 11-4 quartz-based stone, 8-1 efflorescence, 21-22, 21-81 to
chemical reactivity, 11-5 serpentine, 9-1 21-82
chlorite, 11-5 slate, 10-1 eradication of, 21-22
cleaning, 11-4 soapstone, 11-1 etch marks, 21-81
color, 11-6 travertine, 12-1 fire and smoke damage, 21-81
countertops, 17-2 spall, defined, 23-25 flammable materials, 21-83
damaged stone, repairing, 11-2 spalls, 21-23, 21-26 food and beverage, 21-21
defined, 23-25 spandrel, 23-14, 23-22 grout stains, 21-22
dolomite, 11-5 defined, 23-25 hazing, 21-22
drips, 11-3 spandrel beam, 23-27 identifying causes, 21-21 to 21-
electrical properties, 11-6 spans 22
expansion joints, 11-3 countertops, 17-4 ink stains, 21-81, 21-83
finishes, 11-3 furniture and tops, 19-1 inorganic metal stains, 21-81,
fire resistance, 11-6 specific gravity, 4-1, 4-3 21-82
geological classification, 11-4, specification language, sample, xvii oil-based stains, 21-80 to 21-81,
21-70 to xviii 21-82

© 2022 Natural Stone Institute Index • Page 25-23

 organic stains, 21-81, 21-82 stone tile straps, twisted, 14-D.23
paint stains, 21-81, 21-82 to 21- exposed edges, 16-10 straps, two way, 14-D.23
83 fabrication, 16-10 stratification, defined, 23-26
poulticing, 21-82 to 21-83 full mortar method, 16-11 strength, 4-1
rust, 21-21 grout, 16-12 exterior application, 3-3
soiling, 21-22 installation, 16-11 to 16-12 limestone, 6-12 to 6-13
subsurface water, 21-26 marble groups, 16-10 marble and onyx, 7-17
water spots and rings, 21-81 moisture proofing, 16-12 quartz-based stone, 8-12
stair tread edge, 17-D.16, 19-D.3 polished finish, 16-10 serpentine, 9-14
stair treads sizes, 16-10 slate, 10-11
abrasive hardness, 14-13 soundness, 16-10 travertine, 12-13
color, 14-14 steam, effects of, 16-11 to uniformity, 4-3
deflection of, 14-13 16-12 units of measure, 4-5
details, 13-D.6 to 13-D.8 thickness, 16-10 strength testing, 4-5 to 4-9
finishes, 14-13 thin-set method, 16-11 string course, defined, 23-26
granite, 14-13 steam, effects of, 16-9, 16-11 to 16- stringers, steel, for stair treads, 13-
hardness, 14-13 12 D.8
installation, 13-D.6 to 13-D.8, steel pan, for stair treads, 13-D.6, stripping, defined, 23-26
14-13, 14-14 13-D.8 structural contraction and exterior
limestone, 14-13 steel stringers, for stair treads, 13- applications, 3-3 to 3-4
limitations, 14-13 D.8 structural distortion and exterior
marble, 14-13 sticking, 7-15 n11, 21-8 applications, 3-4
setting, 13-D.6 to 13-D.8 defined, 23-26 structural flaws and resin-
sizes, 13-17 stiles for toilet partitions, 16-3, 16- impregnated slabs, 17-11
slip resistance, 14-13 D.1 to 16-D.2 structural support, consultants, 21-
stainless steel dowels, 13-D.6 to stone 26
13-D.8 defined, 23-26 stud walls, 14-14 to 14-15
thickness, 13-17 product of nature, 3-1 stun marks, 21-13
traffic after installation, 14-13 rock vs., 1-1 stylolites, 7-9 to 7-10
stairs, 13-17 size of and cost, 3-7 defined, 23-26
abrasion resistance, 13-4 stains, 21-26 subcontractor responsibilities, 17-3
Standard 51 and stone, 2-4 thickness, 3-7 subduction, 1-3
standard set method, window weight, 13-5 subflooring
stools, 18-4 stone base, installation, 14-15 concrete, 13-14 to 13-15
standards, importance of, 2-1 stone behavioral groups frame construction, 13-5
standards organizations, 2-1 additional resources, 21-121 plywood, 13-11, 13-15 to 13-
static coefficient of friction, 4-9 defined, 21-11 16, 14-10
wet tests, 4-9 stone formation, 21-1 to 21-2 wood, 13-15
steam rooms and showers stone in green building, ix to x sub-slab, 13-D.1
color, 16-10 stone paving and underlayment substrate
color, 16-7 limitations, 13-5 high moisture, 21-26
details, 16-D.8 stone samples, 3-6 maintenance, 21-76
elevations, 16-D.6 to 16-D.7 stone slab layout countertops, 17-3 tolerances, 22-8
stone slab stone tile countertops, 17-2 subtops, 17-3, 17-D.8
ceilings, 16-9 installation, 17-9 outdoor kitchens, 17-13
fabrication, 16-7 stone types stone tile countertops, 17-9
full mortar method, 16-9 identification, 21-17 supply source
grout, 16-9 location, 21-17 granite, 5-2
installation, 16-9 mixing, 3-3 limestone, 6-1
moisture proofing, 16-8 stone units, preparation, 13-18 marble, 7-1
polished finish, 16-7 stool, 23-24 onyx, 7-1
sealing, 16-8 defined, 23-26 quartz-based stone, 8-1
sizes, 16-7 straight edge, 17-D.16, 19-D.3 serpentine, 9-1
soundness, 16-7 straps, "L", 14-D.23 slate, 10-1
steam, effects of, 16-9 straps, "Z", 14-D.23 soapstone, 11-1
stone ceiling, 16-7 straps, cramp, 14-D.23 travertine, 12-1
thin-set method, 16-9 straps, dovetail, 14-D.23 support, defined, 23-26
ceilings, 16-12 straps, split-tail, 14-D.23 support anchorage for exterior

Page 25-24 • Index © 2022 Natural Stone Institute

 stone veneer, 14-D.7 slate, 10-9 to 14-7
support documentation, samples, 3- travertine, 12-10 thin-stone pavers
7 textured finish, defined, 23-26 stair treads, 14-13
support systems, pedestal thermal (flamed) finish, defined, structural qualities, 4-3
supported, 13-13 21-6 water absorption, 4-3
surface plane, tolerances, 22-8 thermal conductivity of marble and three-sided adhesion, 13-10, 14-9
surface protection for countertops, onyx, 7-17 thresholds, 13-17
17-12 to 17-13 thermal expansion abrasive hardness, 14-11
surface sealers, 13-7 to 13-9 exterior applications, 3-4 color, 14-11
vertical surfaces, 14-10 marble and onyx, 7-20, 7-21 damage prevention, 21-25
surface treatments, 21-6 to 21-7 quartz-based stone, 8-14 defined, 23-26
surround for fireplace facings, 14- thermal finish, 3-2 exposed edges, 14-11
D.20 defined, 23-26 fabrication, 14-11
sustainability, vii to ix, x granite, 5-7 finishes, 14-11
limestone, 6-10 full mortar method, 13-D.5
weakening of stone, 6-10, 8-10 granite, 14-11
T thermal insulation, 14-10 hardness, 14-11
T, stainless steel or extruded thick beam behavior, 5-12 installation, 14-11, 14-12
aluminum, 14-D.1, 14-D.2, 14- thick bed, coursed ashlar, limestone, 14-11
D.3 installation, 14-13 marble, 14-11
T-31 back anchor, 14-D.23, 14- thickness sizes, 14-11
D.24 countertops, 17-4 stone abutment in floors, 14-7,
talc, 9-10, 11-5 cubic sills, 18-3 14-11
hardness, 21-2 exterior pavers, 14-2, 14-5 thickness, 14-11
tannin-containing woods flooring, 14-5 thin-set method, 13-D.5
limestone, 6-5 furniture and tops, 19-1 traffic after installation, 14-11
travertine, 12-5 granite, 5-7, 5-10 varying bed depth mortar
TCNA (Tile Council of North interior flooring, 14-3 method, 13-D.5
America), 13-14 limestone, 6-11 white portland cement, 14-11
defined, 23-26 marble and onyx, 7-14 tiebacks, wire, 14-D.25
Handbook for Ceramic, Glass, measuring, 21-18 tiger's eye, 9-10
and Stone Tile Installation, overhangs, 19-1 tile
21-18, 21-19 pavers, 14-2 to 14-3 defined, 14-1, 23-27
Technical Bulletins, "Dimension precast concrete panels, 20-1 installation, 14-15
Stone Anchorage; Theory, quartz-based stone, 8-10 mixing, 3-3
Practice, & Components", 21-18 serpentine, 9-12 modular, 3-3
temperate climate and limestone showers, residential, 16-10 selection, 13-1
exteriors, 3-4 slate, 10-9 thickness, 13-2
template, defined, 23-26 stair treads, 13-17 Tile Council of North America
tensile strength steam rooms and showers, 16- (TCNA), 13-14
precast concrete panels, 20-1 10 defined, 23-26
stone veneer panels, 20-1 stone veneer panels, 20-1 Handbook for Ceramic, Glass,
terrazzo thresholds, 14-11 and Stone Tile Installation,
defined, 23-26 tolerances, 22-5 21-18, 21-19
plugs, 21-30 translucence, 7-21 tile reinforcement for stone tile
testing travertine, 12-10 countertops, 17-9
knowing when required, 2-2 water absorption, 4-3 tile width for stone tile countertops,
when not available, 2-2 window stools, 18-3 17-9
testing mockups thin bed mortar, 14-9 tilt shop cart, defined, 23-27
precast concrete panels, 20-1 thin sections, 4-1 tin oxide, defined, 23-27
stone veneer panels, 20-1 thin stone, defined, 23-26 toilet and shower compartments
texture thin veneer, 14-D.21 ceiling-hung, 7-6, 9-7
defined, 23-26 thin-bed mortar, 13-16 corrosion-resistant angles, 7-6,
granite, 5-10 thin-set method 9-7
limestone, 6-10 steam rooms, 16-9, 16-11 dowel fastenings, 7-6, 9-7
marble and onyx, 7-13 steam showers, 16-9, 16-11 marble and onyx, 7-6
quartz-based stone, 8-9 to 8-10 window stools, 18-4 serpentine, 9-7
serpentine, 9-12 thin-set mortar, 13-8 to 13-9, 14-6 toilet partitions

© 2022 Natural Stone Institute Index • Page 25-25

 ceiling channel, 16-3 travertine sampling, 12-10 to 12-11
ceiling-hung, 16-D.1 See also MTL sand, 12-3
color, 16-1 (marble/travertine/limestone) scaling, 12-14
fabrication, 16-3 abrasion resistance, 24-4 sealant joints, 12-6
finishes, 16-3 absorption of stone, 24-4 sealants, 12-3
floor-mounted, 16-D.1 adjacent to water, 12-4 setting mortar, 12-3
installation, 16-3 anchorage, 12-6 sizes, 12-10
sizes, 16-3 anchors, 12-3 stain prevention, 12-3 to 12-4
splines, 16-D.1 as type of limestone, 12-8 staining, 12-14
stiles, 16-3, 16-D.1 to 16-D.2 back-checking, 12-4 storage, 12-5
tolerances backs of pieces, 12-4 stun marks, 21-13
alignment, 22-7 to 22-8 bolted connections, back- texture, 12-10
anchors, 22-6 checking, 12-4 thickness, 12-10
applicability, 22-3 carving, 12-5 tufa, 12-9
asymmetrical bilateral caulking, 12-7 tuff, 12-9
tolerances, 22-1 to 22-2 clay balls, 12-9 usage tips, 12-11
bilateral tolerances, 22-1 to 22- cleaning, 12-7 vein cut, 12-11
2 cold weather and installation, veining, 12-10
bullnose edge, 22-D-App B 12-6 vertical surfaces, 12-6
chamfer edge, 22-D-App B color, 12-10 voids, 13-19
defined, 22-1 composition of, 1-6, 12-8 to 12- washes, 12-4
edges, 22-6 9 water absorption, 24-4
fabrication, 22-5 to 22-6 compressive strength, 24-4 water and installation, 12-5
face size, 22-5, 22-D-App B countertops, 17-2 weep tubes, 12-7
flatness, 22-6 cross cut stones, 12-11 white masonry cement, 12-3
formatting differences, 22-2 damaged stone, repairing, 12-2 white portland cement, 12-3
installation, 22-7 to 22-8 dampproofing, 12-14 tread, 23-25
joint width, 21-20, 22-7 defined, 21-12 to 21-13, 23-27 defined, 23-27
limit tolerances, 22-2 deicing chemicals, 12-13 trim, defined, 23-27
lippage, 21-20, 22-7 density, 24-4 triple waterfall edge, 17-D.16, 19-
percentage tolerances, 22-2 distinguished from onyx, 7-13 D.3
quartz-based stone, 8-10 drips, 12-4 troubleshooting, vertical surfaces,
quirk miter, 22-D-App B effective techniques, 21-13 14-16 to 14-17
squareness, 22-5 efflorescence, 12-14 tufa, 12-9
substrate, 22-8 expansion joints, 12-6 to 12-7 tuff, 12-9
surface plane, 22-8 filling, 12-11 tumbled finish, 3-2
symmetrical bilateral finishes, 12-7, 12-10 defined, 23-27
tolerances, 22-1 fleuri cut, 3-2, 12-11, 24-4 limestone, 6-10
thickness, 22-5 flexural strength, 24-4 MTL, 21-58
tiles, 14-1 furniture and tops, 19-1 slate, 10-9
unilateral tolerances, 22-2 geological classification, 12-8 travertine, 12-7
tooled finish, 7-14 to 12-10, 21-70 twisted straps, 14-D.23
defined, 23-27 hardness, 12-13, 21-2 two-way straps, 14-D.23
topaz, hardness, 21-2 horizontal applications, 12-6 tympanum, 23-18
topical sealers, 21-23 hydrated lime, 12-3
traffic after installation, exterior installation, 12-5 to 12-7
pavers, 14-5 modulus of rupture, 24-4 U
transition strips, 13-11, 13-18 moldings, 12-4 U clamp bars, 14-D.25
damage prevention, 21-25 mortar joints, 12-6 U cramp straps, 14-D.23
translucence, 3-1 packing and loading, 12-5 ultimate capacity, defined, 23-27
color, 7-21 panel thickness, 12-4 uncoupling membranes, 13-7, 14-3
crystal structure, 7-21 paving stone, 12-6 undercut back anchors, 14-D.24
defined, 23-27 physical properties, 12-12, 24-4 undercut, defined, 23-27
marble and onyx, 7-20, 7-21 plastic setting pads, 12-6 underlayment, self-leveling, 13-5
surface finish, 7-21 pointing mortar, 12-3 undermount sink support, 17-D.8
thickness, 7-21 portland cement, 12-5 unfilled finish, 12-10
transverse strength. See flexural protection of, 12-7 uniformity, 4-3
strength reflection, 13-19 uniformity of material, relative

Page 25-26 • Index © 2022 Natural Stone Institute

 value of, 3-1 blend pattern, 7-D.2 vug, defined, 23-27 to 23-28
unit, defined, 23-27 book match pattern, 7-D.3
W
United States Green Build Council diamond match pattern, 7-D.3
(USGBC), vii to viii end match pattern, 7-D.3 wainscot, defined, 23-28
units of measure for strength, 4-5 end slip pattern, 7-D.2 wall tie, defined, 23-28
upward crack, repairs, 21-43, 21-44 marble and onyx, 7-D.2 to 7- wall tile
urethane D.3 adhesive
adhesives and patching quarter match pattern, 7-D.3 marble and onyx, 7-6
materials, 21-41 side slip pattern, 7-D.2 serpentine, 9-7
properties, 21-49 veneer, adhered, installation, 14-13 marble and onyx, 7-6
urinal partitions to 14-14 serpentine, 9-7
color, 16-4 veneer, dry stack, 14-D.22 walls
details, 16-D.3 veneer, independently supported, bearing, defined, 23-28
fabrication, 16-4 installation, 14-11 to 14-12 cavity, defined, 23-28
finishes, 16-4 veneer, stacked damage prevention, 21-25
installation, 16-4 installation, 14-12 durability of installation, 3-4
sizes, 16-4 shims, 14-10 warranty provision, suggested, xii
soundness, 16-4 veneer, stone-faced, 20-D.1 to 20- wash, 23-7
urinal screens, 16-D.3 D.2 defined, 23-28
defined, 23-27 coefficient of thermal washes
USGBC (United States Green expansion, 20-1 granite, 5-4
Build Council), vii to viii color, 20-1 limestone, 6-4
utilities compressive strength, 20-1 marble and onyx, 7-4
power source, 21-25 finishes, 20-1 quartz-based stone, 8-3
water discharge and disposal, limitations, 20-1 serpentine, 9-4
21-25 modulus of elasticity, 20-1 slate, 10-3 to 10-4
water supply, 21-25 physical properties, 20-1 soapstone, 11-3
UV light exposure shear strength, 20-1 travertine, 12-4
resin-impregnated slabs, 17-11 sizes, 20-1 wastage, 3-3
outdoor kitchens, 17-13 tensile strength, 20-1 related to cost, 3-7
testing mockups, 20-1 waste management, viii to ix
V thickness, 20-1 water absorption, 4-4
vacuum cups, defined, 23-27 installation, 20-2 water and serpentine installation, 9-
vacuum lifter, defined, 23-27 veneer, thin, 14-D.21 6
vanities, 17-D.11 vertical surfaces water control slopes, 21-20
variegated materials, 3-1 anchors and accessories, 14- water damage, 21-24
variegated MTL group D.23 to 14-D.25 water discharge, commercial and
defined, 21-14 exterior stone veneer, 14-11 to historical restoration, 21-86
effective techniques, 21-14 14-14 water jet, defined, 23-28
vein, defined, 23-27 interior, 3-5 water misting, 21-84
vein cut, 23-3, 23-11 shop drawings, 14-1 to 14-2 water recycling system, defined,
defined, 23-27 vitrification 23-28
marble and onyx, 7-16 See crystallization water repellent, defined, 23-28
serpentine, 9-13 defined, 21-64 water resistance
travertine, 12-11 VOCs (volatile organic interior application, 3-5
veneer cutting, 7-D.1 compounds), 21-40 limestone, 6-4
vein trend in stone tile countertops, sealers, 21-68 water stop, spline type, 14-D.9
17-9 voids, 21-23 water supply, commercial and
veined materials, 3-1 maintenance, 21-76 historical restoration, 21-85 to
veneer, defined, 23-27 travertine, 13-19 21-86
veneer cutting volatile organic compounds water table, defined, 23-28
fleuri cut, 7-D.1 (VOCs), 21-40 water vapor, 3-4
granite, 5-10 sealers, 21-68 water vapor permeability of marble
limestone, 6-11 volcanic rock, cleaning and and onyx, 7-17
marble and onyx, 7-D.1 maintenance, 21-78 water-jet finish, defined, 23-28
serpentine, 9-13 volume water-jet flamed finish, 3-2
vein cut, 7-D.1 conversion ratios, 24-2 waterfall edge, 17-D.16, 19-D.3
veneer patterns measurement, 4-4 to 4-5 waterproof membranes, 14-4
waterproof pan receptor types, 16-

© 2022 Natural Stone Institute Index • Page 25-27

 D.4 limestone, 14-13, 16-1, 18-1, Z straps, 14-D.23
waterproofing 18-3
showers, residential, 16-D.8, marble, 14-11, 14-13, 18-1, 18-
16-D.10 3
steam rooms, 16-12, 16-D.8 stair treads, 14-13
steam showers, 16-12, 16-D.8 thresholds, 14-11
waxing, 7-15 n12 wet areas, 16-1
defined, 23-28 window stools, 18-3
wear, defined, 23-28 windload and exterior applications,
wear resistance, 4-1 3-3
weathering, 21-24 window stools
chemical, 1-1 to 1-2 bonding, 18-3
defined, 23-28 color, 18-3
websites, organizations, iv corrosion-resistant metals, 18-3
green references, xi details, 18-D.2
wedging, defined, 23-28 fabrication, 18-3
weep holes finishes, 18-3
defined, 23-28 frame construction, 18-D.2
granite, 5-6 installation, 18-4
limestone, 6-7 masonry construction, 18-D.2
marble and onyx, 7-7 oil-based putty, 18-3, 18-4
placement, 15-3 sealants, 18-3, 18-4
quartz-based stone, 8-6 sizes, 18-3
serpentine, 9-8 standard set method, 18-4
showers, steam rooms, and thickness, 18-3
steam showers, 16-9, 16-12 thin-set method, 18-4
slate, 10-6 wire "goose neck" anchor, 14-D.25
travertine, 12-7 wire lace anchor, 14-D.25
weep holes, showers, 16-7 wire loop anchor, 14-D.21
weight wire sawing, defined, 23-28
conversion ratios, 24-2 wire tieback, 14-D.25
mortar bed, 13-5 wood
stone, 13-5 chemically treated, 6-5, 12-5
well-rounded grain (sand), 1-5 skids, 6-5, 12-5
wet areas, 13-18, 14-16 tannin-containing, 6-5, 12-5
anchors, 16-1 wood studs, 14-15
definitions, 16-2 wood subfloor
diagnostic considerations, 21- heated floor systems, 13-D.4,
24 14-10
evaluation of, 21-20 to 21-21 mortar bed, 13-D.3
interior cladding, 14-16 work, considerable, i to 25-28
oil-based putty, 16-1 work platforms, commercial and
plumbing sealants, 16-1 historical restoration, 21-85
soundness, 16-1 wythe, defined, 23-28
white portland cement, 16-1
wet/dry testing, 4-4
wet/dry vacuums, 21-37 X
wet set, defined, 16-2 X-ray diffraction (XRD), 4-1
wet weight and specific gravity, 4-4
to 4-5
White House, greening of, vi to vii Y
white portland cement
cubic sills, 18-3 Young's modulus. See modulus of
exterior cubic stone coping and elasticity
walls, 18-1
granite, 14-11, 14-13, 18-1, 18-
3 Z
light colored stones, 13-18 Z bar, 14-D.25

Page 25-28 • Index © 2022 Natural Stone Institute