Seismic Retrofit Training

For Building Contractors & Inspectors

PARTICIPANT HANDBOOK
Seismic Retrofit Training
For Building Contractors & Inspectors

Cover Photo: Hale House (1887)

Heritage Square Museum
Los Angeles, California

Photo Credit: Timothy P. McCormick, P.E.

PARTICIPANT HANDBOOK
 ABOUT THIS TRAINING COURSE

The City of Los Angeles, and the Structural Engineers Association of Southern California (SEAOSC)
created a task force to study the reason for the widespread damage in the 1994 Northridge Earthquake.
The task force concluded that one primary cause of damage was the lack of quality control in the design,
construction, and inspection of wood frame buildings. The Federal Emergency Management Agency
(FEMA), State of California Office of Emergency Services (OES), City of Los Angeles, SEAOSC and the
Building Industry Association (BIA) joined forces to provide additional training in seismic-resistant
construction. This course is one outcome of their cooperative effort.

This course seeks to teach building contractors and building inspectors the correct methods for doing
typical seismic retrofits that have been designed by an engineer or architect or described in a prescriptive
standard. The course will not teach one how to design a seismic retrofit, but rather how to properly
implement the design.

Woodward Clyde Federal Services and the Hazard Mitigation Technical Assistance Partnership, Inc.
created this manual and course update. The new course includes some elements of the original course
prepared by Wiss, Janney, Elstner Associates, Inc. and Organizational Learning Systems, Inc. Revisions to
the manual and course content are primarily the work of the private instructional team of experts FEMA
originally hired to teach the course. The FEMA instructional team members are:

Ariel Babikian, Former Technical Specialists Manager, California Office of Emergency Services

George D. Calkins, Esq., Cox, Castle & Nicholson, LLP

Richard Chylinksi, FAIA, Professor of Architecture, California State Polytechnic University, Pomona

Stephan A. Kiefer, C.B.O., Building Official, City of Dublin, California

Timothy P. McCormick, P.E., Director, Anchor L.A. Program, City of Los Angeles
Editor-in Chief

The authors express sincere appreciation to Jeanne Perkins, Patrick McClellan, Linda Noson and Anthony
Qamar for their valuable contributions to the earth science portion of Earthquake Basics.

The authors have presented the information in this manual as a one-day seminar to several thousand
building contractors and inspectors throughout the State of California. The seminars were presented
under the sponsorships of FEMA, OES, BIA, International Conference of Building Officials (ICBO), the
Association of Bay Area Governments (ABAG), Pacific Coast Building Conference (PCBC), and the State of
California Department of Insurance.

The California Earthquake Authority sponsored the addition of a new section to this FEMA manual,
namely Retrofitting Post and Pier Houses. This section creates a new prescriptive standard for floor
support systems that are common in the northern coastal regions of California and elsewhere. The
Hazard Mitigation Technical Assistance Partnership, Inc. created this section through James E. Russell,
Building Code Consultant.

COURSE INFORMATION LIMITS

Any opinions, findings, conclusions or recommendations expressed in this manual do not necessarily
reflect the views of the Federal Emergency Management Agency, California Office of Emergency
Services, California Earthquake Authority, Building Industry Association, Structural Engineer’s
Association of California, City of Los Angeles or any other sponsors of the seminar training. The
authors of this manual are solely responsible for its content. Additionally, neither the creators,
sponsors nor authors of this manual make any warranty, expressed or implied, nor assume any legal
liability or responsibility for the accuracy, completeness, or usefulness of any information, product,
or process included in this manual. Users of information from this manual assume all liability arising
from such use.
 Table of Contents i

Table of Contents
Page

v....... List of Figures 27 ...Reduced Code Values Table

28 ...Success of Plywood Sheathing for Shear Walls
1.. INTRODUCTION – 1 29 ...Wood Structural Panel Shear Walls
...How to Install the Lumber
3.. Course Overview ... ....Use the Proper Lumber Species
.. Training Objectives ... ....Effect of Lumber Species on Strength Table
4.. The Reasons That Owners Retrofit 30 ... ....Determine Existing Lumber Species
.. Many Buildings Need Retrofitting ... ....Use the Proper Size Stud
5.. Retrofit Prescriptive Standards 31 ... ....Install Proper Size Blocking
6.. Prescriptive Retrofit Standards Work 32 ... ....Properly Locate the Holdown Stud
.. When to Hire Professional Help 33 ... ....Use the Proper Lumber Grade and Size
of Holdown Studs
7.. EARTHQUAKE BASICS – 2 ... ....Effect of Lumber Grade on
Holdown Capacity Table
9.. Earthquake Basics ... ....Avoid Mechanical Penetrations
.. Earthquakes & Faults 35 ... ....Evaluate Existing Lumber
11.. Proximity To Faults 36 ... ....Provide Adequate Ventilation
.. Surface Geology Effects 37 ...How To Install The Sheathing
12.. Inertia Forces ... ....Use The Specified Wood Structural Panel
.. Effect of Height on Building Movement ... .... ....Oriented Strand Board
13.. Period of Vibration 38 ... .... ....Plywood
14.. Horizontal Force Distribution 39 ... ....Use The Proper Thickness & Number of
.. Base Shear and Cripple Walls Plies
.. Horizontal Force-Resisting System ... ....Use The Proper Panel Grade
15.. Seismic Load Path in the Building 40 ... ....Locate Panel on the Center of Framing
.. Gravity Force-Resisting System Member & Blocking
41 ... ....Use the Proper Size Panel
17.. SHEAR WALLS - 3 ... ....Mark Location of Studs on Panels
... ....Maintain Fire Resistive and Sound-
19.. Getting the Big Picture Rated Construction
.. .... What is a Shear Wall? 42 ... ....Provide Ventilation at Cripple Wall Sheathing
.. .... Where Should Shear Walls Be Located? 43 ...How To Install The Fasteners
21.. .... What Types of Forces Do Shear ... ....Use Common Nails
Walls Resist? ... ....Use the Proper Length of Common Nail
23.. .... What Are The Functions of 44 ... ....Why Common Nails Are Important
a Shear Wall? ... ....Common vs. Box Nails Table
.. .... How Shear Walls Provide Strength 45 ... ....Use Full Headed Nails
24.. Combining Different Material Strengths 46 ... ....Install Nails Flush to Sheathing
25.. Shear Walls are like Wood I-Beams ... ....Provide Proper Sheathing Edge Distance
26.. How Shear Walls Provide Stiffness ... ....Center the Nails in the Framing Member
.. .... Stiffness and Aspect Ratios and Blocking
26.. Allowable Aspect Ratio Table 47 ... ....Check for Splitting of Lumber During Nailing
27.. Lessons Learned from the Northridge ... ....Remove All Improperly Installed Nails
Earthquake ... ....Provide Proper Edge Nailing
... ....How To Nail A Shear Wall Table

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 Table of Contents ii

49 .. CONNECTIONS - 4 69 .. Foundation Condition

.. .... Deterioration
51 ...Connections Resisting Uplift Forces .. .... Foundation Cracking
52 ... ....Types of Holdowns 70 .. Foundation Embedment
... ....Importance of Proper Installation .. Foundation Retrofit
53 ... ....Common Holdown Installation Errors .. .... Capping
54 ... ....Installation Errors for Bolted Holdowns .. .... Replacement
... .... ....Improper End Distance .. .... Parallel Systems
... .... ....Oversized Bolt Hole
... .... ....Undersized Washers 71 .. RETROFITTING POST & PIER HOUSES - 6
... .... ....Substitution of Lag Screws for
Through Bolts 73 .. Why Earthquakes Damage Post & Pier Houses
... .... ....Countersinking Nut & Washer 75 .. New Prescriptive Retrofit Method
55 ... .... ....Insufficient Depth of Embedment .. Partial Perimeter vs. Continuous Foundation
For Anchor Rods 76 .. How Partial Perimeter Equals Continuous
... .... ....Substitution of Holdown Anchor Type Foundation
... .... ....Untightened Nuts 77 .. Moisture Effects on Wood Materials
56 ...Connections Resisting Shear Forces 78 .. Holdown Anchors are Needed
... ....Fastener Types in Shear Connections 79 .. Transferring Forces to the Partial Foundations
57 ... ....Shear Connections in the Load Path 82 .. Evaluating Existing Conditions
... ....Non-Standard Framing .. When you Need an Architect & Engineer
58 ... ....Connections at Top Plates 83 .. Partial Perimeter Retrofits Require More
59 ... ....Connections at Sole Plates Attention to Detail
60 ... ....Connections at Sill Plate .. Building Inspection Requirements
61 ... ....Locating Drilled-In Anchors .. Seismic Retrofitting Flood Prone Structures
... .... ....Provide Proper Edge Distance in the
Concrete and Wood 85 ... NON-STRUCTURAL ELEMENTS - 7
... .... ....Provide Proper End Distance in the
Sill Plate 87 .. Chimneys
... .... ....Provide Proper Depth of Embedment 88 .. Building Appendages
in the Concrete 89 .. Veneer
62 ... .... ....Use the Proper Length of Anchor 90 ... Gas Lines
... .... ....Use Plate Washers 91 ... Water Heaters
...Installing Mechanical Anchors 92 ... Tanks
63 ...Installing Adhesive Anchors 93 ... Other Types of Nonstructural Items
... ....Carefully Clean the Hole .. FEMA’s Nonstructural Manual
... ....Use All-Threaded Rod
... ....Completely Fill the Hole in the Sill Plate 95 ... SAFETY & LEGAL – 8
with Adhesive
... ....Install the All-thread Rod with the Plate 97 ... Safety On The Job Site
Washer and Nut Attached .. .... Wear Protective Clothing
... ....Wait Until Fully Cured Before Tightening .. .... Read and Follow MSDS
... ....Follow Safety Requirements .. .... Rope Off Dangerous Areas
64 ...Installing Side Plates .. .... Do Not Disturb Asbestos
...Interior Post to Girder Connections 99 .. Seismic Retrofit Legal Perspectives
...Putting It All Together .. Earthquake Legal Basics
.. .... Duty to Understand Earthquake Forces
65 FOUNDATIONS – 5 100 .. .... Agencies Have No Liability for Inspections
.. .... Prescriptive Standards
67 ...Foundation Types 101 .. .... Preconstruction Conferences
68 ...Foundation Material .... .... Statutes of Limitations

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 Table of Contents iii

102 .. .... Unlimited Exposure for Personal Injury 113 Keeping Track of the Work
.. Shear Walls . ..... ....Notification of Existing Conditions
.. .... Use Prescribed Wood and Shear Wall 114 ......Change Orders
Dimensions . ..... ....Inspections
.. .... Nailing Patterns ...... ....Photographs
103 .. .... Coordination is Important .....Getting Help
.. .... OSB 115 A Word About Warranties
.. .... Plywood Strength ......When Should A Contractor Quit A Project
.. .... Use Specified Nails
.. .... Nailing Patterns 117 GLOSSARY
104 .. .... Economics of Framing Affect Quality
.. .... The Liability in Nailing Problems 123 APPENDIX
.. Connections
.. .... Holdowns .... A City of Los Angeles Prescriptive Standard
.. ... Beware of Nonstandard Framing .... B Real Estate Disclosure Requirements
105 .. ... Proper Anchor Bolt Assembly .... C Full Scale Nail Charts
.. ... Protection from Fumes .... D Pre-Drilled Hole Sizes
.. Foundations and Miscellaneous Elements .... E Partial Perimeter Foundation Details
.. ... Need Effective Communication .... F Water Heater Bracing Illustrations
.... G Home Improvement Contract Form
.. ... Prejob Walk Through
.... H Legal Aspects of Construction Administration
106 .. ...Identify Differing Site Conditions ... I What Did You Learn
.. ...Legal Standards and Manufacturers’ Specs
.. ...Continuity of Foundation
.. ...Shoring ***
.. ...Concrete Quality and Owner Consultation
107 .. Non-Structural Elements
.. ...Care in Specification of Bracing
109 .. A Contractor's Legal Relationship with the
Customer
.. ...Understanding the Owner’s Concerns
.. ... .. Money Limitations
110 .. ...Disruption to the Occupants
.. ...Schedule
.. ...Background Information
.. Limiting A Contractor’s Liability
.. ...Necessary Documentation for Each Project
.. ... .. Liability Insurance
.. ... .. Project File and Documentation

111 .. ... .. Employee and Subcontractor Screens

.. ... .. Applicable Local Codes
.. ... .. Preconstruction Walk Through
.. ...The Importance of a Clear Written Contract
.. ... .. Scope of Work Is Important
.. ... .. Termination Options
.. ... .. Exculpatory Provisions
.. ... .. Liability Revolution
.. ... .. Additional Work
.. ... .. Get A Lawyer's Help with Your Contract
.. ... .. Key Contract Provisions

113 .....Good Set of Plans

.....Building Permit

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Table of Contents iv

Seismic Retrofit Training

 List of Figures v

List of Figures
Abbreviation Table for Figure Credits

APA-EWA - The Engineered Wood Association ABAG- Assoc. Of Bay Area Governments
EERI - Earthquake Engineering Research Institute WJE - Wiss, Janney, & Elstner Associates
FEMA - Federal Emergency Management Agency Chylinski - Richard Chylinski, FAIA
ICBO - International Conference of Building Officials Ferrell- Elizabeth Ferrell, AIA
ISANTA - International Staple and Nail Tool Association Kiefer - Stephan A. Kiefer, C.B.O.
SBA - Structural Board Association McCormick - Timothy P. McCormick, P.E.
SEAOC - Structural Engineers Association of California Mehlmauer- George E. Mehlmauer

FIGURE NUMBER FIGURE CREDIT PAGE

1-1: Typical Simple Structure House ..................................................... McCormick ................................... 5

1-2: Hillside Homes ................................................................................ Wayne Durand ............................. 6
2-1: Strike-Slip Fault Diagram................................................................. ABAG ............................................. 9
2-2: Thrust Fault Diagram....................................................................... ABAG ............................................. 9
2-3: Major Plates of the World................................................................ EERI............................................... 9
2-4: State of California Index Map......................................................... ICBO .............................................. 10
2-5: Location of Focus and Epicenter .................................................... Jim Gregori ................................... 11
2-6: Factors Affecting Earthquake Forces.............................................. McCormick ................................... 11
2-7: Liquefaction Failure......................................................................... EERI............................................... 11
2-8: Inertia Forces .................................................................................... WJE................................................ 12
2-9: Height & Weight Relationship......................................................... Chylinski ...................................... 12
2-10: Cyclic Motion of Building................................................................ McCormick ................................... 13
2-11: Chimney Vibration Failure.............................................................. FEMA............................................. 13
2-12: Porch Vibration Failure.................................................................... FEMA............................................. 13
2-13: One & Two Story Differences ......................................................... FEMA............................................. 13
2-14: Horizontal Force Resisting System................................................. WJE................................................ 14
2-15: Cripple Walls .................................................................................... WJE................................................ 14
2-16: Base Shear Damage .......................................................................... FEMA............................................. 14
2-17: Complete Load Path......................................................................... WJE................................................ 15
2-18: Missing Sill Plate Connection ......................................................... FEMA............................................. 15
2-19: No Shear Walls at Garage................................................................. Chylinski ...................................... 15
2-20: Steel Moment Frame ....................................................................... McCormick ................................... 15
2-21: Gravity Force Resisting System....................................................... WJE................................................ 15

3-1: Typical Shear Wall............................................................................ WJE................................................ 19

3-2: Location of Shear Wall..................................................................... McCormick ................................... 20
3-3: Horizontal Alignment of Cripple Walls ......................................... McCormick ................................... 20
3-4: Vertical Offset of Shear Walls......................................................... WJE................................................ 21
3-5: Shear Wall over Floor Beam ............................................................ McCormick ................................... 21
3-6: Shear Force on 3-Ply Plywood ......................................................... City of Los Angeles ...................... 21
3-7: Uplift Forces on Shear Wall............................................................. City of Los Angeles ...................... 21
3-8: How Shear Wall Length Changes Shear & Uplift .......................... McCormick ................................... 22
3-9: Two Functions of a Shear Wall....................................................... McCormick ................................... 23
3-10: Lumber Strength Failure ................................................................. City of Los Angeles ...................... 23
3-11: Sheathing Strength Failure ............................................................. City of Los Angeles ...................... 23
3-12: Fastener Strength Failure................................................................ FEMA............................................. 23
3-13: Different Material Stiffness Properties ......................................... McCormick ................................... 24
3-14: Different Maximum Displacements .............................................. McCormick ................................... 24
3-15: Comparison of Wood Shear Wall to Wood “I” Beam.................... McCormick ................................... 25
3-16: Drywall Failure ................................................................................. City of Los Angeles ...................... 28
3-17: Stucco Failure ................................................................................... City of Los Angeles ...................... 28
3-18: Narrow Panel Failure ........................................................................ City of Los Angeles ...................... 28
3-19: Success of Full Plywood Coverage................................................... City of Los Angeles ...................... 28
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 List of Figures vi

FIGURE NUMBER FIGURE CREDIT PAGE

3-20: Stronger Douglas Fir-Larch............................................................... McCormick ................................... 30

3-21: Weaker Hem Fir ................................................................................ McCormick ................................... 30
3-22: Earthquake Damage with 2-inch Adjoining Stud........................... City of Los Angeles ...................... 30
3-23: Cripple Wall Blocking ....................................................................... McCormick ................................... 31
3-24: 3-Inch Blocking .................................................................................. McCormick ................................... 31
3-25: Reinforced Window Openings in Shear Wall................................. McCormick ................................... 31
3-26: Blocking for Opening Reinforcement ............................................. McCormick ................................... 31
3-27: Too Close to Wall End...................................................................... McCormick ................................... 32
3-28: Too Far From Wall End.................................................................... McCormick ................................... 32
3-29: Acceptable Holdown Location for Shear Walls at Corner ............ McCormick ................................... 32
3-30: Lumber Grade Stamps ..................................................................... WWPA ........................................... 33
3-31: Unregulated Penetrations ............................................................... McCormick ................................... 33
3-32: Regulated Penetrations.................................................................... McCormick ................................... 34
3-33: Non-Engineered Limits for Mechanical Penetrations.................. City of Los Angeles ...................... 34
3-34: Wood Decay ...................................................................................... FEMA............................................. 35
3-35: Termite Damage ............................................................................... FEMA............................................. 36
3-36: Crawl Space Ventilation .................................................................. McCormick ................................... 36
3-37: Oriented Strand Board Panel Construction................................... SBA. ............................................... 37
3-38: Plywood Panel Construction........................................................... APA - EWA..................................... 38
3-39: Panel Grade Stamp ........................................................................... APA - EWA..................................... 39
3-40: Install Sheathing Vertical or Horizontal ........................................ SBA ................................................ 40
3-41: Cripple Wall Ventilation.................................................................. McCormick ................................... 42
3-42: Box Label for Common Nails .......................................................... Golden State Nail Company ....... 43
3-43: Sample Nail Gun With Flush Attachment..................................... McCormick ................................... 45
3-44: Nail Head Differences...................................................................... ISANTA.......................................... 45
3-45: Earthquake Damaged Shear Wall ................................................... City of Los Angeles ...................... 45
3-46: Nails That Are Too Close / Overdriven .......................................... FEMA............................................. 46
3-47: Nails that Missed.............................................................................. McCormick ................................... 47

4-1: Uplift Force In Holdown.................................................................. WJE................................................ 51

4-2: Floor-to-Floor Holdown ................................................................... McCormick ................................... 52
4-3: Improperly Bent Strap ..................................................................... Kiefer............................................. 52
4-4: Proper Installation ........................................................................... Anthony De Mascole & Assoc..... 52
4-5: Two 2x4s vs. One 4x4...................................................................... FEMA............................................. 53
4-6: Nail Edge Distances.......................................................................... McCormick ................................... 53
4-7: Holdowns at Each End of Shear Wall............................................. McCormick ................................... 53
4-8: Improper End Distance ................................................................... FEMA............................................. 54
4-9: Oversized Bolt Hole.......................................................................... City of Los Angeles ...................... 54
4-10: Smaller Washers............................................................................... City of Los Angeles ...................... 54
4-11: Countersunk Nut and Washer in Holdown Stud.......................... McCormick ................................... 54
4-12: Lack of Embedment for Holdown Anchor..................................... City of Los Angeles ...................... 55
4-13: Untightened Nut Found in Earthquake Damaged Building ........ FEMA............................................. 55
4-14: Shear Connections ........................................................................... WJE................................................ 56
4-15: Building Damage From Shear Connection Failure ....................... FEMA............................................. 56
4-16: Shear Load Path................................................................................ SEAOC........................................... 57
4-17: Balloon Framing ............................................................................... SEAOC........................................... 57
4-18: Framing Clips at Top Plate .............................................................. City of San Leandro ..................... 58
4-19: Use of Palm Nailer............................................................................ City of San Leandro ..................... 58
4-20: Splice for Single Top Plates ............................................................. McCormick ................................... 58
4-21: Sole Plate Connection...................................................................... McCormick ................................... 59
4-22: Double Sole Plates............................................................................ McCormick ................................... 59
4-23: Longer Length Sheathing ................................................................ McCormick ................................... 59
4-24: Earthquake Damaged Sill Plate....................................................... City of Los Angeles ...................... 60
4-25: Mechanical Anchor .......................................................................... Kiefer............................................. 60
4-26: Adhesive Anchor .............................................................................. FEMA............................................. 60
4-27: Side Plate To Connect Sill Plate to Concrete Stem Wall............... Kiefer............................................. 60
4-28: Concrete Edge Distance Failure...................................................... FEMA............................................. 61
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 List of Figures vii

FIGURE NUMBER FIGURE CREDIT PAGE

4-29: Proper End Distance for 5/8" Sill Plate Anchors ........................... SEAOC........................................... 61
4-30: Misaligned Sill Plate......................................................................... Gregori .......................................... 61
4-31: Improper Countersinking ............................................................... FEMA............................................. 61
4-32: Sill Plate Anchor Options ................................................................ Kiefer............................................. 62
4-33: Square Plate Washer......................................................................... McCormick ................................... 62
4-34: Nylon Brush in Hole ........................................................................ City of Los Angeles ...................... 63
4-35: Blowing Out Dust Fines .................................................................. City of Los Angeles ...................... 63
4-36: Installing Adhesive........................................................................... City of Los Angeles ...................... 63
4-37: Anchor Side Plate ............................................................................. Kiefer............................................. 64
4-38: Interior Post Strengthening............................................................. Kiefer............................................. 64

5-1: Partial Foundation............................................................................ FEMA............................................. 67

5-2: Post & Pier Foundation .................................................................... Robert Bruce................................. 67
5-3: Interior Posts & Girders ................................................................... WJE................................................ 67
5-4: Continuous Interior Footing........................................................... Brian Kehoe .................................. 67
5-5: Two-Pour System.............................................................................. WJE................................................ 68
5-6: Failure of Two-Pour Joint ................................................................ FEMA............................................. 68
5-7: Unreinforced Brick Foundation Wall ............................................. McCormick ................................... 68
5-8: Stone Foundation Wall.................................................................... McCormick ................................... 68
5-9: Deteriorated Mortar Joints In Foundation Wall ........................... McCormick ................................... 69
5-10: Foundation Wall Damage................................................................ EERI............................................... 69
5-11: Foundation Cracks ........................................................................... EERI............................................... 69
5-12: Foundation Wall Crack .................................................................... FEMA............................................. 69
5-13: Foundation Embedment ................................................................. WJE................................................ 70
5-14: Capping Existing Foundations........................................................ WJE................................................ 70
5-15: Foundation Replacement ................................................................ FEMA............................................. 70
5-16: Parallel System ................................................................................. McKelvey Construction............... 70

6-1: Typical Existing Post & Pier Type House ....................................... James E. Russell ........................... 73
6-2: House with Braced Posts Along Perimeter .................................... James E. Russell ........................... 74
6-3: Plan View of Partial Perimeter System .......................................... Ferrell............................................ 76
6-4: Elevation - Floor Joists Parallel to Wall.......................................... Ferrell............................................ 78
6-5: New Metal Strap Reinforcement .................................................... James E. Russell ........................... 79
6-6: Girder Connection to New Foundation Stem Wall....................... Ferrell............................................ 80
6-7: Elevation - Floor Joists Perpendicular to Wall............................... Ferrell............................................ 80
6-8: Strap for Joists Splice ....................................................................... Ferrell............................................ 81
6-9: Strap for Plate Splice........................................................................ Ferrell............................................ 81

7-1: Reinforced Chimney Failure ........................................................... City of Los Angeles ...................... 87

7-2: Braced Chimney Failure .................................................................. City of Los Angeles ...................... 87
7-3: Chimney Replacement..................................................................... FEMA............................................. 87
7-4: Porch Roof Collapse ......................................................................... Anthony De Mascole & Assoc..... 88
7-5: Porch Roof Straps and Bracing ........................................................ WJE................................................ 88
7-6: Fallen Brick Veneer .......................................................................... City of Los Angeles ...................... 89
7-7: Automatic Shutoff Valve ................................................................. Mehlmauer................................... 90
7-8: Overturned Water Heater................................................................ FEMA............................................. 91
7-9: Braced Water Heater ........................................................................ Mehlmauer................................... 91
7-10: Pre-Packaged System........................................................................ Lee Clifton.................................... 91
7-11: Tank Bracing ..................................................................................... WJE................................................ 92
7-12: Earthquake Damaged Air Conditioning Units............................... City of Los Angeles ...................... 93
7-13: Dresser Fell On Bed ......................................................................... McCormick ................................... 93
7-14: Broken Glass in Kitchen .................................................................. FEMA............................................. 93

8-1: Proper Respirator.............................................................................. McCormick ................................... 97

8-2: Asbestos Heating Duct in Seismic Retrofit Work Area................. McCormick ................................... 97
**
Seismic Retrofit Training
List of Figures viii
 Introduction 1

1 INTRODUCTION
by Timothy P. McCormick, P.E.

Seismic Retrofit Training

 2 Introduction

Seismic Retrofit Training

 Introduction 3

COURSE OVERVIEW

This course describes retrofit methods for light wood frame buildings that
have structural weaknesses for resisting earthquakes. The training focuses on
understanding how these retrofit methods work and how to install them. It
also shows how to avoid making typical retrofitting errors. This course is not
intended to teach you how to design a retrofit, but rather how to implement
one. Much of this information is also useful for other types of work, such as
the construction of new houses or apartment buildings.

This training will benefit:

• Contractors who wish to learn how to do seismic retrofit work or wish to

improve their current seismic retrofitting skills.
• Building Inspectors who are responsible for checking seismic retrofit work.
• Plan Reviewers who approve designs for the seismic retrofit of wood
structures.
• Property Owners who want to retrofit their wood frame buildings.
• Realtors who need to understand the earthquake weaknesses of existing
dwellings and ways to retrofit them.
• Lenders and Insurers who need to understand the seismic weakness of
existing buildings and the retrofit methods that reduce their risks.
• Construction Attorneys who need to understand proper installation and
retrofit techniques.

Although this course was developed in California, there are over 30 of the
nation’s states that are exposed to damage by earthquakes. Many of these
states have wood frame structures similar to those in California. As a result,
the retrofit techniques discussed in this course have widespread importance.

TRAINING OBJECTIVES

By the end of this training, you should be able to:

• Generally explain how shaking damages wood frame structures during an

earthquake.
• Identify the key components of a retrofit (shear walls, holdowns,
foundation, anchor bolts, sill plates & other connections).
• Describe how the components connect together to form a proper seismic
retrofit.
• Compare and contrast the different material types available for each
component of a retrofit.
• Recall the installation steps for each component.
• Recognize the typical errors made during installation and how to avoid
making them.
• Understand basic methods for reducing earthquake hazards of chimneys,
water heaters, tanks, building appendages, gas lines, brick veneer, and
other nonstructural items.
• List basic safety measures to consider when doing retrofit work.
• Recognize areas of potential liability related to construction and ways to
avoid or reduce liability.
• Generally explain the building permit requirements, warranties, and
liabilities related to seismic retrofit work.

Seismic Retrofit Training

 4 Introduction

THE REASONS THAT OWNERS RETROFIT

There are many reasons for retrofitting. Owners who occupy the building
may retrofit to ensure the safety of their family. Landlords may wish to avoid
future loss of income from a vacant and damaged building. Many insurance
companies will not write earthquake or homeowner’s insurance until needed
retrofitting is done. Some cities and counties mandate seismic retrofits when
alterations reach a specific dollar amount or enough square footage is added
to the building.

Special real estate transfer rules exist in California for residential dwellings.
If the structure was built prior to January 1, 1960 and it contains one to four
living units of conventional light-frame construction, the transferor must
disclose any of the following deficiencies they are aware of:

• The absence of anchor bolts securing the sill plate to the foundation.
• The existence of perimeter cripple walls that are not braced with plywood,
blocking, or diagonal metal or wood braces.
• The existence of a first-story wall or walls that are not braced with plywood
or diagonal metal or wood braces.
• The existence of a perimeter foundation composed of unreinforced
masonry.
• The existence of unreinforced masonry dwelling walls.
• The existence of a habitable room or rooms above a garage.
• The existence of a water heater that is not anchored, strapped, or braced.

The transferor is also required to disclose any material information within

the transferor’s actual knowledge regarding any corrective measures or
improvements taken to address the items listed above. See the California
Government Code Section in Appendix B for full details.

MANY BUILDINGS NEED RETROFITTING

California Government Code Section 8897 says, “… there are approximately

1,200,000 homes in the State of California which may not be bolted or
anchored to their foundations or do not have adequate cripple wall bracing.”
These homes were generally built prior to the 1950’s and can represent one-
half of the existing housing stock. Because there will be many houses that
will need retrofitting, contractors who know how to do the work correctly
will be in great demand!

Question: Why are we concerned with housing?

Answer: Because the Northridge earthquake in January 1995 caused

more than 48,000 housing units to become uninhabitable in Los
Angeles and Ventura counties. Previously the Loma Prieta earthquake
in October 1989 caused more than 16,000 housing units to be
uninhabitable throughout the Monterey and San Francisco Bay areas.
Approximately one-fourth of the total uninhabitable housing units in
the Loma Prieta earthquake was from buildings with one-to-four
dwellings.

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 Introduction 5

RETROFIT PRESCRIPTIVE STANDARDS

When you build a new house, you have two ways to design the framing. The
first method is to have an engineer or architect create the design. The second
is to follow the conventional construction provisions of the Uniform Building
Code (UBC). Similarly, there are two ways in which a seismic retrofit can be
designed for light wood frame houses. The owner or contractor could hire an
architect or an engineer to design the retrofit. There are many houses that
have complications that will require an engineer or architect to design the
retrofit. Another way to retrofit a house is to use a prescriptive standard.

One or two story wood frame dwellings with no more than four units are
usually simple structures (Fig.1.1). Retrofitting them often includes such
items as bolts in the sill plate and plywood on the cripple walls. Engineers
and building officials have developed guidelines to install these and other
items needed for a seismic retrofit. These guidelines are called “prescriptive
standards”.

Even though prescriptive methods are limited to residential buildings

containing one to four units, there are several good reasons to have these
standards:

1. There are large numbers of one-to-four unit wood frame buildings

that have structural weaknesses.

2. The seismic retrofit for many of these structures are simple to

install for contractors and many homeowners.

3. Prescriptive standards permit building owners to seismically

retrofit simpler buildings without having to hire an architect or
engineer to prepare drawings. Although professional advice is
generally desirable and frequently required, prescriptive standards
may allow appropriate cost savings. This will make retrofitting
more desirable.

Fig. 1.1 - Typical Simple Structure House

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 6 Introduction

PRESCRIPTIVE RETROFIT STANDARDS WORK

The Northridge Earthquake taught us that wood frame homes properly

retrofitted according to prescriptive standards suffered little to no earthquake
damage and remained intact on their foundation. Past earthquakes, including
the Northridge earthquake, also showed us that houses retrofitted incorrectly
can be damaged just as much as those that were not even retrofitted.

Incorrect or incomplete retrofits can give the homeowner a false sense of

security as to how well the home will resist an earthquake. Keep this in mind
as we focus on CORRECT methods of installing retrofits that will be effective
in reducing the damage to buildings during the next earthquake.

“ Incorrect retrofit installations are as bad as having “NO RETROFIT AT ALL! ”

WHEN TO HIRE PROFESSIONAL HELP

Since seismic retrofit technology is an evolving process, the participant needs

to understand and follow the most current seismic retrofit standards. The
authors developed this course using the best available information on the
subject at the time. However, this information cannot substitute for
professional advice. The services of an architect, civil, structural or
geotechnical engineer is frequently required. You will learn more about this
throughout the course.

Because the use of prescriptive standards for retrofit work is generally limited
to one-to-four unit wood frame residential buildings, commercial and larger
residential buildings require the expertise of an engineer or architect to
design the seismic retrofit. This is also true for buildings constructed on
steeply sloping lots. (Fig. 1.2)

Fig.1.2 - Hillside Homes Require an Architect or Engineer to Design the Retrofit

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 Earthquake Basics 7

2 EARTHQUAKE BASICS

by Richard Chylinski, FAIA

Timothy P. McCormick. P.E. and
Stephan A. Kiefer. C.B.O.

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 8 Earthquake Basics

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 Earthquake Basics 9

EARTHQUAKE BASICS
This section will give you a basic understanding of the nature of earthquakes
and how earthquake forces affect buildings. The more you understand how
buildings respond to earthquake forces, the better you will understand what
parts of the building resist these forces and how to properly install these
structural components.

EARTHQUAKES AND FAULTS

Earthquakes are perceptible movements of the earth's surface. The primary

cause of earthquakes is the rupture of faults in the earth's crust and the
associated rapid slip on these faults. Large and damaging earthquakes are
caused by rupture of faults that are tens to hundreds of miles long. If the
fault rupture extends to the surface, we see movement on a fault (surface
rupture). But strong earthquakes can occur when the fault rupture does not
extend to the surface as seen in both the 1989 Loma Prieta and the 1994
Northridge earthquakes in California.

Fault rupture of the ground generates vibrations, or waves, in the rock that
we feel as ground shaking. Because faults are weaknesses in the rock,
earthquakes tend to occur over and over on these same faults. Most of the
major faults in the United States, particularly in California, are strike-slip
faults. For these types of faults, the rupture extends almost vertically into the
ground and the ground on one side moves past the ground on the other side Fig. 2.1
of the fault. (Fig. 2.1) California’s largest fault, the San Andreas, is a strike-
slip fault formed where two large chunks of the earth's crust, or plates, move
past each other.

Another type of fault is the thrust fault where ground on one side of the fault
moves up and over adjacent ground (Fig. 2.2). These faults are much more
common in the Los Angeles area than in the Bay Area because the San
Andreas Fault makes a large bend to the west there before heading
northwest. This bending causes thrust faults in southern California.

Farther north, these same two crustal plates are pushing against each other,
with the Pacific Plate diving under the North American Plate along large
plate-boundary thrust or “subduction zone” faults (Fig. 2.3). Thus, Oregon,
Washington and Alaska are all subject to huge earthquakes caused by this
movement, in addition to the more common strike-slip earthquakes. The Fig. 2.2
1964 Good Friday Alaska earthquake was an example of one of these plate-
boundary earthquakes.

Fig. 2. 3
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 10 Earthquake Basics

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 Earthquake Basics 11

PROXIMITY TO FAULTS
The magnitude of an earthquake is frequently given as a number on the
Richter scale. This scale measures the amplitude of ground motion. Local
ground motion from the earthquake will depend on the distance from the
fault source to the building and the surface geology under the building.

Earth scientists use certain terms to define seismic distances. The point at
which the slippage occurs is called the focus, or hypocenter. The distance
from this hypocenter to the surface of the earth is termed the focal depth.
The point directly above the hypocenter is called the epicenter ("epi" being
Greek for "above"). The locations of earthquakes are frequently given by their
epicenter (Fig. 2.5).
Fig.2.5 Location of Focus and Epicenter
Earthquakes release energy along the entire portion of the ruptured fault
surface. Because of this, the distance between the building and the fault
source is more important that the distance to the actual epicenter. The Index
Map on the left shows the active fault zones in California. The 1997 Uniform
Building Code uses this information to determine when earthquake forces on
buildings must be increased due to fault proximity (Fig. 2.4). Calculated
earthquake forces can increase up to 100 per cent for buildings near large
faults.

SURFACE GEOLOGY EFFECTS

Surface geology can amplify the earthquake ground motion. The same
districts in San Francisco that were strongly damaged in the great San
Francisco earthquake of 1906 were also damaged in the 1989 Loma Prieta
earthquake. These damage-prone districts are built on bay mud sites that can
amplify ground shaking by a factor of 6 when compared to sites on rock.
Sandy soils can amplify shaking by a factor of 2 (Fig.2.6).

Behind the garage shown in Fig. 2.7 is a stream that saturated the soil with
water. The building moved and settled because the earthquake shaking
“floated’ the soil grains in the water and the soil was able to flow. This type
of ground failure is called liquefaction. When special soil problems like
liquefaction or landslides may occur, a geotechnical engineer should be hired Fig. 2.7 Liquefaction Failure
for advice.

Fig. 2.6 Factors Affecting Earthquake Forces Seismic Retrofit Training

 12 Earthquake Basics

INERTIA FORCES
Inertia is the tendency for an object at rest to remain at rest, or of an object in
motion to remain in motion. Force is the energy required to move or accelerate
the object. Inertia forces move or accelerate an object and they are
proportional to the object's weight. Seismic forces on buildings are inertia
forces.

Consider a person standing in the bed of a pickup truck. If the pickup truck
accelerated rapidly, inertia would tend to keep that person's body in its
original location. Similarly, if the pickup truck decelerated, the person would
be thrown forward. (Fig. 2.8) The same reaction occurs in a building when the
ground moves. The building moves back and forth, with the bottom of the
building moving with the quake and the top tending to remain in place. Now
imagine two persons in the back of a pickup truck: one weighing 100 pounds
and the other 200 pounds. As the truck accelerates, the individual that weighs
200 pounds would be pushed back with twice as much inertial force as the
person who weighs 100 pounds.

For another example, let’s assume that there are two tract homes. They are
side by side on the same street and identical except that one has an asphalt
Fig. 2. 8 shingle roof and the other has a heavy clay tile roof. Because clay tiles weighs
more than asphalt shingles, the home with the clay tile roof will experience
higher inertia forces from the earthquake and, most likely, suffer more
damage.

EFFECT OF HEIGHT ON BUILDING MOVEMENT

The effects of earthquake forces on buildings are related to both the weight
and height of the building. The higher the building’s weight is above its
support base, the further the top of the building will move under the same
earthquake force. Using the left side of Figure 2-9, imagine a one-story building
with a height of 14 feet. Let’s say the inertia force of the earthquake moved
the top of the building 1 inch (HD1). If you put additional weight on that
building, the top of the building will move more. Let’s say it moved 1-½ inches
(HD2).

Using the right side of Figure 2-9, imagine the same type of building that is
two stories or 24 feet high. The top of the building may now move 2 inches.
The top of the heavier building may move 3 inches. The greater the height,
and/or the greater the weight of a building, the more the building will move
during an earthquake.

ELEVATION

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 Earthquake Basics 13

PERIOD OF VIBRATION
Earthquakes send out shock waves that travel in all directions up to the
surface of the earth. These waves impart horizontal and vertical forces to
earth-supported structures. Because buildings are designed to continuously
support vertical loads from their own weight and use, they tend to better
resist these vertical forces and move up and down safely with the ground.
However, horizontal force waves cause buildings to move laterally and vibrate
back and forth during an earthquake. Unless the building is properly
constructed, these horizontal forces will cause damage.

The time an object takes to vibrate back and forth one complete cycle is
known as its period of vibration. The period of vibration is one of the most
important factors determining how a structure will respond to ground
shaking. For one or two-story wood frame buildings, the period of vibration is
about ½ a second. This means that these buildings will go through their
complete cycle of seismic motion about two times per second. For an Fig. 2. 11 - Chimney Vibration Failure
earthquake with strong ground shaking that lasts 15 seconds, the building
will go through this cycle approximately 30 times (Fig. 2-10).

Because periods of vibration depend on weight and height, portions of

building with different weights and heights will move separately unless all
portions of the building are properly connected and tied together. Common
examples of different portions of buildings with these problems are
chimneys, porches and stories with differing heights (Fig. 2.11-2.13).

Fig. 2.12- Porch Vibration Failure

Fig. 2.13- One & Two Story Differences

Fig. 2. 10 Cyclic Motion of Building

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 14 Earthquake Basics

HORIZONTAL FORCE DISTRIBUTION

Newton’s Second Law of Motion states that force equals mass times
acceleration. When the earthquake’s sudden movement of the ground
accelerates the mass of the building, horizontal forces are created in the
building. These forces are distributed throughout the building and are
concentrated where the weight is: the floors, roofs and walls.

Consider the two-story building in Figure 2.14. The arrow at the roof
represents the seismic force from both the roof weight and one-half of the
weight of the walls between the second floor and roofline. The arrow at the
second floor represents the seismic force of both the second floor weight and
Fig. 2.14 one-half of the weight of the first and second story walls. The arrow at the
first floor represents the force at the first floor that is similarly calculated.
The arrow at the foundation level is the sum of all these forces that must be
transmitted safely into the ground.

BASE SHEAR AND CRIPPLE WALLS

A cripple wall is a wall that is less than full story height. The cripple wall
usually occurs between the first floor and the foundation and is generally the
most vulnerable part of older buildings (Fig.2.15). These cripple walls are
weak because they are typically sheathed with only stucco or horizontal wood
siding on the exterior side of the wall. These sheathing materials are weak
wall-bracing methods for seismic loads. You will learn more about this in the
section on “Shear Walls”.

Because seismic forces in the building accumulate all the way down to the
ground, they are greatest at the base of the building. The seismic force at base
of the building is called the base shear. Earthquakes often damage buildings
Fig. 2.15 at this level (Fig. 2.16). For buildings with cripple walls, this means that the
weakest part of the building must resist the greatest force. This is why
retrofit standards require strengthening of the cripple walls.

HORIZONTAL FORCE-RESISTING SYSTEM

The horizontal force-resisting system is composed of both horizontal and

vertical parts. The horizontal parts are the roof and the floor structures.
These parts are called diaphragms. The vertical elements are the walls that
span between the horizontal elements. These walls are called shear walls. You
will learn more about these in the section on Shear Walls.

To be effective, each part of the horizontal force-resisting system must be

adequate and properly connected to the other parts in the system. For
example, the roof diaphragm must be strong enough to safely resist the
Fig. 2.16 Base Shear Damage seismic loads. Also, the connections from the roof diaphragm to the shear
walls below must be strong enough to give the force to the shear wall. Shear
walls at the base of the building must be securely connected to the footing
and the footing must be adequate. To have an effective horizontal force-
resisting system, there must be a continuous load path. That is, there must
be no weak elements between the top and bottom of the structure.

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 Earthquake Basics 15

SEISMIC LOAD PATH IN THE BUILDING

The load path can be thought of as a chain. It is only as strong as its weakest
link. The roof and floor diaphragms and shear walls are two links in the
chain. The connections between the roof, walls, floors and foundation are
additional links. These additional links serve as the connective points that
complete the chain. The connections are just as important as the diaphragms
and shear walls themselves. The seismic loads imparted on a building must
successfully pass through all of these elements in order to reach the ground
and effectively resist an earthquake’s damaging forces. In other words, the
load path or chain must be continuous and complete. There can be no weak
Fig. 2. 18 Missing Sill Plate Connection
links in the load path chain (Fig. 2.17).

Fig. 2.19 No Shear Walls At Garage

Fig. 2.17

When a part of the load path is weak or missing, damage will occur during an
earthquake. If the sill plate is not connected to the foundation wall, the
ground will move and leave the building behind (Fig. 2.18). A building
without shear walls like the one in Figure 2.19 can collapse. When there is
not enough room for an adequate shear wall (e.g. a wall with many large
windows), an engineer or architect must design a special frame to resist the
horizontal forces, These frames are called moment frames.

Fig. 2.20 Steel Moment Frame

GRAVITY FORCE-RESISTING SYSTEM

Some of the elements of a gravity or vertical force-resisting system can and

will be used to resist the horizontal loads. In the gravity force-resisting
system there are live and dead loads transferred from the wood roof rafters to
the walls; the live and dead load from the floor loads are transferred to the
cripple walls, and then to the foundations where they are resisted by the soil
below them.

Alterations to the lateral system should not compromise the ability of the
gravity force-resisting system to support these loads. The purpose of the
Fig. 2.21
horizontal force-resisting system is to enable the gravity force-resisting
system to maintain its support of the structure during earthquakes and
windstorms.

***

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 16 Earthquake Basics

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 Shear Walls 17

3 SHEAR WALLS
by Timothy P. McCormick, P.E.

Seismic Retrofit Training

 18 Shear Walls

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 Shear Walls 19

SHEAR WALLS

This section provides an introduction to shear walls and how they resist
earthquake and wind forces. This section also shows how to properly construct
the shear walls and the parts that make them up. With this knowledge,
contractors can build proper shear walls and inspectors can recognize the errors
untrained contractors make.

GETTING THE BIG PICTURE

WHAT IS A SHEAR WALL?

Shear walls are vertical elements of the horizontal force resisting system. They are typically
wood frame stud walls covered with a structural sheathing material like plywood.
When the sheathing is properly fastened to the stud wall framing, the shear wall
can resist forces directed along the length of the wall. When shear walls are
designed and constructed properly, they will have the strength and stiffness to
resist the horizontal forces. (Fig. 3.1)

Fig.3.1 - Typical Shear Wall

WHERE SHOULD SHEAR WALLS BE LOCATED?

Shear walls should be located on each level of the structure including the crawl space. To form
an effective box structure, equal length shear walls should be placed
symmetrically on all four exterior walls of the building. Shear walls should be
added to the building interior when the exterior walls cannot provide sufficient
strength and stiffness or when the allowable span-width ratio for the floor or roof
diaphragm is exceeded. For subfloors with conventional diagonal sheathing, the
span-width ratio is 3:1. This means that a 25-foot wide building with this subfloor
will not require interior shear walls until its length exceeds 75 feet unless the
strength or stiffness of the exterior shear walls are inadequate. (Fig. 3.2)

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 20 Shear Walls

Fig.3.2 - Location of Shear Walls

Shear walls are most efficient when they align vertically and are supported on
foundation walls or footings. When shear walls do not align, other parts of the
building will need additional strengthening. Consider the common case of an
interior wall supported by a subfloor over a crawl space and there is no
continuous footing beneath the wall. For this wall to be used as shear wall, the
subfloor and its connections will have to be strengthened near the wall. For new
construction, thicker plywood or extra nailing and connections can be added. For
retrofit work, existing floor construction is not easily changed. That’s the reason
why most retrofit work uses walls with continuous footings underneath them as
shear walls. (Fig. 3-3)

Break in Load Path

Exterior Shear
Wall Interior Shear
Wall

Interior Partition

Cripple Wall

Floor must support Shear Wall Continuous Load Path

Fig. 3-3 Horizontal Alignment of Cripple Walls

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 Shear Walls 21

Fig. 3.4 -Vertical Offset of Shear Walls

Another type of alignment problem occurs when the ends of shear walls do
not align from story to story. This condition creates the need for extra framing
members and connections in the walls for holdown devices. Holdown devices
must transfer the uplift from the shear wall to framing members that can
resist it. When full height studs are not available, special connections must be
added. These connections must assemble enough of the structure’s framing to
resist the uplift. (Fig. 3-4, 3.5)

WHAT TYPES OF FORCES DO SHEAR WALLS RESIST?

Fig.3.5 - Shear Wall Over Floor Beam
Shear walls resist two types of forces: shear forces and uplift forces. Connections to the
structure above transfer horizontal forces to the shear wall. This transfer
creates shear forces throughout the height of the wall between the top and
bottom shear wall connections. The strength of the lumber, sheathing and
fasteners must resist these shear forces or the wall will tear or “shear” apart
(Fig. 3-6).

Fig. 3.6 – Shear Force on 3-Ply Plywood Fig. 3.7 - Uplift Forces on Shear Wall

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 22 Shear Walls

Fig 3.8 - How Shear Wall Length Changes Shear & Uplift

Uplift forces exist on shear walls because the horizontal forces are applied to
the top of the wall. These uplift forces try to lift up one end of the wall and
push the other end down. In some cases, the uplift force is large enough to tip
the wall over. Uplift forces are greater on tall short walls and less on low long
walls. Bearing walls have less uplift than non-bearing walls because gravity loads
on shear walls help them resist uplift. Shear walls need holdown devices at each
end when the gravity loads can not resist all of the uplift. The holdown device
then provides the necessary uplift resistance.

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 Shear Walls 23

WHAT ARE THE FUNCTIONS OF A SHEAR WALL?

Shear walls must provide the necessary lateral strength to resist horizontal
earthquake forces. When shear walls are strong enough, they will transfer these
horizontal forces to the next element in the load path below them. These other
components in the load path may be other shear walls, floors, foundation walls,
slabs or footings.

Fig. 3.10 -Lumber Strength Failure

Fig. 3.9

Shear walls also provide lateral stiffness to prevent the roof or floor above from
excessive side-sway. When shear walls are stiff enough, they will prevent floor
and roof framing members from moving off their supports. Also, buildings that
are sufficiently stiff will usually suffer less nonstructural damage. (Fig. 3.9)

HOW SHEAR WALLS PROVIDE STRENGTH

Fig. 3.11 -Sheathing Strength Failure

The strength of the shear wall depends on the combined strengths of its three components:
lumber, sheathing and fasteners. Later in this section you will learn how each
component effects the strength and how strength is lost by improper
installations. When all of the components are properly in place, the shear wall
can provide its intended strength.

For shear wall sheathing, the 1994 Uniform Building Code (UBC) permits the use
of gypsum wallboard, cement plaster, fiberboard, wood particleboard, plywood
and oriented strand board. Previous editions of the UBC also allowed wood lath
and plaster, horizontal and diagonal sheathing for shear walls. All of these
sheathing materials provide different strengths. The UBC shows these strengths
in pounds per foot of wall length.

Fasteners for shear wall construction may be staples, screws or nails. Denser
lumber species provide stronger fastener strengths. Values for shear wall
strengths assume a dense lumber species like douglas fir-larch or southern pine.
Thicker framing members also increase wood structural panel sheathing
strengths.

Fig. 3.12 – Fastener Strength Failure

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 24 Shear Walls

COMBINING DIFFERENT MATERIAL STRENGTHS

Older editions of the building code allowed the combination of strengths for
different materials on the same shear wall. If a wall was sheathed inside with
gypsum wallboard and outside with portland cement plaster, the allowable
shear strength became the combined strength of the two materials. Before
this code provision was deleted in the 1976 Uniform Building Code, several
buildings were built under this errant concept and are at a fraction of the
strength that the original design intended. Buildings designed with gypsum
wallboard or portland cement plaster in combination with structural wood
panels will have the same problem. Different sheathing materials do not
combine strengths. This is true on the same wall. It is also true for different
walls of the same level of the building.

Material strengths cannot combine because different sheathing materials

reach their ultimate strength at different wall displacements. Shear walls
braced with cement plaster and gypsum wallboard reach their ultimate
strength at about one-half inch of movement of the top of the wall. After this
point, gypsum wallboard buckles off the studs, frequently leaving its fasteners
in place. Portland cement plaster has similar behavior. Structural wood panels
reach their ultimate strength when the top of the wall moves about 1½
inches. This means that plywood will share seismic loads with portland
cement plaster or gypsum wallboard when the top of the wall moves less than
one-half inch. When earthquake forces cause more than ½-inch
displacements, the wood structural panel sheathing will have to resist the
entire load. Some earthquakes will cause top of wall displacements greater
than ½-inch. When they do, the sheathing material that stays on the walls the
longest will have to resist the total seismic load. Normally, this sheathing
material will be wood structural panel. (Fig. 3.13 & 3.14)

Wall Displacement

Different Maximum
Displacements
Fig. 3. 13
Fig. 3.14
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 Shear Walls 25

SHEAR WALLS ARE LIKE WOOD I-BEAMS

Wood structural panel shear walls behave like cantilevered wood I-beams.
Just as wood I-beams use their flanges to resist bending, wood structural
panel shear walls use their end studs. Both wood I-beams and wood structural
panel shear walls use their sheathing web to resist shear forces. Because of
their size, wood structural panel shear walls must fasten their sheathing to
intermediate wall studs to prevent it from buckling. The stiffness of shear
walls constructed with wood structural panels depends on four things:

1. The size and species grade of the end studs

2. The thickness and grade of the sheathing

3. The diameter of the sheathing fasteners

4. The amount of slip in any holdown device

Figure 3-15 – Comparison of Wood Shear Wall to Wood I-Beam

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 26 Shear Walls

HOW SHEAR WALLS PROVIDE STIFFNESS

The stiffness of the shear wall, just like its strength, depends on the combined
stiffness of its three components: lumber, sheathing and fasteners. The size
and grade of end stud(s), thickness and grade of sheathing, and the sheathing
fastener diameter determine how flexible a wood shear wall will be. When
present, holdown devices also contribute to the overall stiffness of the shear
wall. If holdown devices stretch or slip, the top of the shear wall will move
horizontally. This horizontal movement adds to the movement allowed by the
lumber, sheathing and fasteners. Any additional movement from the holdown
will reduce the effective stiffness of the shear wall.

STIFFNESS AND ASPECT RATIOS

Shear walls provide stiffness in large part by the ratio of their height to width. Long
short walls are stiffer than tall narrow ones. For a wall of constant height, the
stiffness will grow exponentially as the wall length increases. To help control
stiffness, the UBC requires a minimum wall length for any given wall height.
This allowable dimension ratio changes for each type of sheathing material
and its construction. Wood structural panels can have smaller shear wall
lengths than cement plaster or gypsum wallboard. When this sheathing is
fastened at all of its edges, the UBC also permits smaller shear wall lengths.

1994 Uniform Building Code - Wood Frame Shear Values

Maximum
Allowable Minimum
Height-
Material Shear, Width for 8 Foot
To-Width
lbs/ft High Wall
Ratio
gypsum lath & plaster 100 1½:1 5 feet-4 inches

gypsum wallboard-unblocked 100-145 1½:1 5 feet-4 inches

gypsum wallboard-blocked 125-250 2:1 4 feet -0 inches

Fiberboard 125-175 1½:1 5 feet-4 inches

portland cement plaster-unblocked 180 1½:1 5 feet-4 inches

portland cement plaster-blocked 180 2:1 4 feet-0 inches

diagonal sheathing-conventional 300 2:1 4 feet-0 inches

diagonal sheathing-special 600 3½:1 2 feet-4 inches

wood structural panels & particleboard 140-870 3½:1 2 feet-4 inches

Table 1 – Allowable Aspect Ratios
• Allowable shear values for gypsum lath and wallboard must be reduced 50% in Seismic Zones 3
and 4.
• The 1997 Uniform Building Code reduces the maximum allowable height-to-width ratios to 1:1 for
conventional diagonal sheathing and 2:1 for special diagonal sheathing, wood structural panels
and particleboard in Seismic Zones 3 and 4.

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 Shear Walls 27

LESSONS FROM THE NORTHRIDGE EARTHQUAKE

After each major earthquake, scientists and engineers study the performance
of structures so that building codes may be evaluated and improved as needed.
After the 1994 Northridge Earthquake, the City of Los Angeles and Structural
Engineers of Southern California formed a joint task force to re-evaluate
several seismic provisions of the building code for wood frame buildings. The
task force recommended significant changes to the design and construction of
wood frame shear walls. These changes included lowering the allowable
height-to-width ratios and shear strength values.

The following table shows the former (UBC) and new (LABC) code provisions
that the City of Los Angeles and many Southern California communities
adopted following the Northridge Earthquake.

1994 Uniform Building Code

City of Los Angeles Building Code Amendments (LABC)
Wood Frame Shear Wall Construction
Maximum
Allowable Shear,
Shear Wall Height-
lbs./ft
Sheathing Material To-Width Ratio
UBC LABC UBC LABC
gypsum lath & plaster 100 30 1½:1 1:1

gypsum wallboard-unblocked 100-145 30 1½:1 1:1

gypsum wallboard-blocked 125-250 30 2:1 1:1

fiberboard 125-175 0 1½:1 -

portland cement plaster-unblocked 180 90 1½:1 1:1

portland cement plaster-blocked 180 90 2:1 1:1

plywood -3 ply panels 200-770 150-200 3½:1 2:1

plywood & OSB- 3/8 inch 200-730 150-200 3½:1 2:1

particleboard 140-870 175 3½:1 2:1

diagonal sheathing-conventional 300 300 2:1 2:1

diagonal sheathing-special 600 600 3½:1 2:1

wood structural panels 200-870 150-650 3½:1 2:1

Table 2- Reduced Code Values

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 28 Shear Walls

SUCCESS OF PLYWOOD SHEATHING

The most important lesson that the Northridge Earthquake taught us about
wood frame shear walls was the good performance of plywood sheathing.
Shear walls sheathed with plywood performed significantly better than
other sheathing materials such as gypsum wall board or portland cement
plaster. The apartment building shown below in Figure 3.19 had minimal
damage from the Northridge Earthquake because of its extensive use of
shear walls sheathed with plywood.

The best plywood sheathing is Structural 1 grade with a minimum of four-

ply panel construction. Three-ply plywood panel construction tore at its
inner ply seam. For this reason, prescriptive standards often specify five-ply
plywood for shear wall sheathing.

Fig. 3.16 - Drywall Failure

Fig. 3.17 -Stucco Failure

Fig. 3-18-Narrow Panel Failure Fig. 3. 19 – Success of Full Plywood Coverage

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WOOD STRUCTURAL PANEL SHEAR WALLS

This part of the Shear Walls section will discuss the components of wood
structural shear walls, their correct installation and the effects on seismic
performance when they are improperly installed. The components examined
will be lumber, sheathing, and fasteners. Holdown devices and shear transfer
connections will be discussed in the next section, “Connections.”

How to Install the Lumber

USE THE PROPER LUMBER SPECIES

The lumber of choice in California for new construction is usually douglas fir-
larch. Some hem-fir is used for pressure treated sill plates. Older buildings used
foundation grade redwood for sill plates and some used redwood for all framing
members. Shear walls constructed with hem-for or redwood are weaker than
shear walls constructed with douglas fir-larch.

Density of the lumber species determines how well the sheathing fasteners will
hold. Shear walls constructed with lower density lumber do not hold fasteners
as well as shear wall constructed with denser lumber. The Uniform Building
Code requires an 18% strength reduction for walls built with the less-dense hem-
fir and a 35% reduction for open grain redwood. The following table shows some
of the different allowable shears based on the species of the lumber framing.

Wood Nail Spacing

Common Allowable Shears, lbs./ft.
Structural at Panel
Nail Size Based on Lumber Species
Panel Edges
Douglas fir- Redwood
Panel Grade Thickness Hem-Fir
larch Open Grain
Structural 1 15/32 inch 8d 4 430 355 280
Structural 1 15/32 inch 8d 3 550 450 360

Structural 1 15/32 inch 10d 3 665 545 430

Table 3- Effect of Lumber Species on Strength

There are two types of redwood species for strength considerations: open grain
and close grain. Because lumber in a covered structure is not always visible or
accessible, verification of the grain pattern in existing buildings may be difficult
or unreliable. For this reason, structural designers commonly use the 35%
reduction for the less dense open grain. When verification of the denser close
grain is possible, shear wall strength values may use a 18% reduction like hem
fir. Older buildings are more likely to have close grain from old growth trees.

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DETERMINE EXISTING LUMBER SPECIES

Structural designers normally assume that existing lumber is douglas fir-larch.

When retrofit work uncovers existing redwood or hem fir lumber, contractors
and inspectors should notify the structural designer so that additional shear
wall strength can be provided. Otherwise, hem fir framing will provide only 82
percent and the redwood will provide only 65 percent of the shear wall
strength intended. (Figs. 3.20 & 3.21)

Prescriptive standards for retrofit work generally do not consider the effect of
different lumber species. Although not required in such standards, additional
sheathing fasteners are recommended for the softer lumber species. The use
of 10d commons at 3 inches on center in redwood or 8d common at 3 inches
on center in hem-fir is equivalent to the a prescriptive standard of 8d
commons at 4 inches on center in douglas fir-larch framing. See the shaded
Fig. 3. 20 Stronger Douglas Fir-Larch portions in Table 3- Effect of Lumber Species on Strength.

When termite or fungus damage requires the repair or replacement or existing

framing members, contractors should use douglas fir-larch lumber to replace
all studs, blocking, sill and top plates. Douglas fir-larch should be used for both
pressure treated and non-pressure treated lumber. Denser lumber always
means better fastener strength and as a result, stronger shear walls.

USE THE PROPER SIZE STUD

The 1994 Uniform Building Code requires 3-inch nominal width (2½ net)
framing at adjoining panel edges when 6d, 8d and 10d short nails are spaced 2
inches on center or 10d long nails are spaced 3 inches or less on center.
Fig. 3. 21 Weaker Hem Fir Original diaphragm testing by the American Plywood Association (APA)
showed that framing members split at ultimate loads when sheathing nails are
closely spaced. APA Tests also showed that shear walls are 17% stronger when
3-inch framing is used throughout.

The minimum edge distance for common nails is 5/8 for 6d, ¾ for 8d and 7/8
for 10d. This edge distance should be provided in all framing members and
blocking. If an engineer were to use this UBC criteria to design the connection
of two adjoining pieces of sheathing to a framing member, nail edge distance
requirements in the framing member and sheathing would always require a
minimum 3-inch nominal width framing member. Although thicker framing
members are not always required by the minimum standards of the building
code, using 3-inch nominal width framing at ALL adjoining panel edges will
generally increase shear wall strength.

Sometimes it is difficult to install 3-inch nominal width framing in existing

construction. An acceptable alternative to 3-inch nominal width framing is to
Fig 3.22 Earthquake damage with bolt a new stud to the existing stud at the adjoining panel edge. The number
2 inch adjoining stud of bolts required depends on the shear wall strength and lumber species. For
the prescriptive standard, connecting the two studs with ½ inch bolts at 12
inches on center or 5/8 bolts at 16 inches on center will properly join the
studs.

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INSTALL PROPER SIZE BLOCKING

All of California and portions of Washington, Oregon, Nevada, Utah, Idaho,

Montana, and Wyoming are in Seismic Zones 3 or 4. For shear walls in these
seismic zones, all edges of wood structural panels must be fastened to framing
members or blocking. Blocking must be provided when adjoining panel edges
are unsupported between framing members. This situation occurs when the
wall heights exceed available panel lengths, panels are installed horizontally,
around wall openings or at existing cripple walls. When sheathing panel edges
are not fastened, the shear wall is only one-third as strong when all edges are
fastened. (Figs 3.23 & 3.24)

Just like vertical studs, the nailing surface of the blocking for adjoining panels Fig. 3.23 - Cripple Wall Blocking
should be a minimum of 2½ width to provide proper fastener edge distance in
the sheathing and blocking. However, unlike framing members, blocking can be
installed flatly if it provides the minimum penetration depth for the fasteners.
Flat installation of blocking provides more nailing surface and better edge
distances.

When blocking is installed flatly, a minimum thickness of 1½-inch lumber

should be used to nail sheathing with 6d and 8d common nails. Larger nails, like
the 10d common, require 1¾-inch thick lumber to provide the full strength of
the nail. When 1½-inch flat blocking is used for 10d common nails, shear walls
will lose 16 percent of their strength.

Blocking is also provided in shear walls when shear walls are designed with
openings. Blocks are installed between the studs in line with the top and bottom
Fig. 3.24 - 3 Inch Blocking
of the openings. Metal straps are nailed to the blocks to reinforce the opening.
These metal straps usually require 2½-inch minimum width blocking for the 2
rows of 16d common or sinker nails. When the metal straps are fastened with
16d common nails, the blocking must also be at least 2 inches thick. When 1½-
inch flat blocking is used for 16d common nails, opening reinforcement straps
will lose 23 percent of their strength. (Fig. 3-25 & Fig. 3.26)

Fig. 3.26 – Blocking for Reinforcement

Fig. 3.25 Reinforced Window Openings in Shear Wall

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PROPERLY LOCATE THE HOLDOWN STUD

The length of a shear wall is measured horizontally along the sheathing between
wall ends or the framing members with holdown devices. Studs for holdown
devices should be located as far apart as practical. Framing members for
holdown devices should not be notched for larger obstructions like plumbing or
countersunk for washers or bolt heads.

Fig. 3.27 - Too Close to Wall End Fig. 3.28 -Too Far From Shear Wall End

Fig. 3.29 - Acceptable Holdown Location for Shear Walls at Corner

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 Shear Walls 33

USE THE PROPER LUMBER GRADE

& SIZE OF HOLDOWN STUDS

When an engineer designs the connection of a holdown device to a framing

member, the grade and size of the lumber helps determine how much uplift the
framing member can take. For example, “Construction” grade 2 x 4 studs can
take a maximum 4,540 pounds of seismic uplift. “Stud” grade 2 x 4 studs can
take only 3,140 pounds. The maximum seismic uplift for “Stud” grade 4 x 4
studs is 7,330 pounds. The grade of douglas fir-larch for the holdown stud can
determine the available strength of a holdown devices. The shaded portions in
Table 4 show when the lumber grade or species controls the allowable value.

When holdown devices are installed on new framing members, contractors and
inspectors should verify that the proper grade and size of lumber is used. Fig. 3.30 - Lumber Grade
Otherwise, the holdown may be attached to a framing member that is too weak Stamps
to resist the required uplift. This will result in lower shear wall strengths.

Tension,
Compression, lbs
lbs
Holdown Stud Douglas Fir- Catalog
Sill or Sole Plate
Product Size Larch Grade Value Net 8 Ft.
Section Stud Hem
DF-L
fir

No. 1 12,078 7,695

No. 2 10,288 7,209

HD 8A 4x4 Construction 7,460 7,753 6,840 4,961 7,656

Standard 4,473 6,327

Stud 5,905 5,965

Table 4-Effect of Lumber Grade on Holdown Capacity

AVOID MECHANICAL PENETRATIONS

Many wood frame residences have poor coordination of structural and

mechanical installations. Structural designs are completed and approved long
before mechanical subcontractors begin to design their systems. Residential
mechanical designs often call for penetrations in shear walls. These
penetrations can seriously weaken shear walls and stricter notching and cutting
limits should be followed than given in the building code for non-shear walls.

As a result of buildings damaged in the Northridge Earthquake, the City of Los

Angeles amended its building code to provide stricter limits on mechanical
penetrations in wood frame shear walls. These limits effectively remove large
electrical conduits, plumbing and heat vents from wood frame shear walls. The
following code section and illustration from the Los Angeles Building Code show Fig. 3.31 – Unregulated Penetrations
the recommended limits.

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“2314.5.8 Mechanical Penetration of Wood Shear Walls and Plate

Members. The maximum accumulated length of openings in a shear
wall shall not exceed 20% of the wall length. Plumbing, electrical, and
other mechanical penetrations of the top or bottom plate framing
members shall be limited to Figure 23-1-Y-1.

EXCEPTION: Openings or penetrations may exceed this amount where

designed and shown on the approved drawings.”

Fig. 3..32-Regulated Penetrations

FIGURE 23-I-Y-1

1 "Ν
1 ¼” d. 1Max. Bored Hole
NOTCHES MIN. 6' - 0" O.C. 4 MAX. BORED HOLE "
1 1 2 MIN.

"
1 1 2 MAX.

"
3 1 2MAX. 10" MIN. 10" MIN.
" d
11 4x 16 GA. STRAP w/ 6-10 COMMON NAILS EA. END @ EA. PLATE
(STRAP NOT REQ'D FOR SILL PLATE)

2 x 4 DBL. TOP PLATE

2 x 4 or 3 x 4 SILL PLATE SIM.

2” d. Max. Bored Hole

NOTCHES MIN. 6' - 0" O.C. 2" ΝMAX. BORED HOLE "
2 1 2 MIN.

2" MAX.

"
5 1 2 MAX. 1' - 0" MIN. 1' - 0" MIN.

" d
1 1 4x 16 GA. STRAP w/ 8-10 COMMON NAILS EA. END @ EA. PLATE
(STRAP NOT REQ'D FOR SILL PLATE)

2 x 6 DBL. TOP PLATE

2 x 6 or 3 x 6 SILL PLATE SIM.

3” d. Max. Bored Hole

NOTCHES MIN. 6' - 0" O.C. 3" ΝMAX. BORED HOLE "
3 1 2 MIN.

3" MAX.

Fig. 3.33 - Non-Engineered Limits for Mechanical Penetrations

"
5 1 2 MAX. 1' - 0" MIN. 1' - 0" MIN.

" d
1 1 4x 16 GA. STRAP w/ 11-10 COMMON NAILS EA. END @ EA. PLATE
(STRAP NOT REQ'D FOR SILL PLATE)

Fig. 3.33- Non-Engineered Limits for Mechanical Penetrations

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 Shear Walls 35

EVALUATE EXISTING LUMBER

Both the existing and new framing should be free of wood decay. Wood decay is
frequently referred to as dry rot. This is a misnomer. Rotted wood may be dry
when it is found, but wood actually rots when it is too wet. Fungi that feed on
the carbohydrates, cellulose, and lignin that make up the wood primarily cause
rot. Such fungi are always present in wood but require high moisture content to
become destructive. When wood dries out, the fungi cease to deteriorate the
wood fibers. (Fig. 3.34)

When the retrofit work is being performed, the contractor should check for
sources of water intrusion and wood-earth clearances. Water should not
continuously saturate wood and any wood should be at least 6 inches above any
soil. When existing soils are regraded to provide proper wood-earth separation,
contractors should be careful not to create new drainage problems or undermine
any existing footings. If adequate separation between earth and wood cannot be
provided, the contractor should seek the advice of the building official and
engineer or architect.

Therefore, if wood is kept dry, it will not rot. Rotted wood is always a sign that
the moisture content is--or has been--too high. Common causes of dry rot are
close wood-earth contact, maladjusted lawn sprinklers, excessive foliage
against the building, drain pipes that splash water onto framing, leaking
plumbing, inadequate ventilation in crawl spaces, excessive ground water
under the building and poor drainage.

Fig. 3.34 – Wood Decay

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Termites, powder post beetles, and other animal organisms can also seriously
weaken a structure. Infestation should be treated by a properly licensed and
experienced pest control service before the retrofit work begins. Damaged wall
framing should be removed and replaced. (Fig. 3.35)

Fig. 3.35 – Termite Damage

PROVIDE ADEQUATE VENTILATION

Adequate ventilation is one of the best ways to minimize potential wood decay
in the crawl space. Unless the crawl space is mechanically ventilated, the UBC
requires 1 square foot of vent openings in the cripple walls for every 150 square
feet of under-floor area. To provide cross ventilation, these openings should be
spaced evenly on at least two sides of the crawl space. New sheathing should
not reduce or cover existing ventilation openings. Additional ventilation should
be added when wood decay is present under prevailing conditions (Fig. 3.36).

Fig. 3. 36 – Crawl Space Ventilation

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HOW TO INSTALL THE SHEATHING

USE THE SPECIFIED WOOD STRUCTURAL PANEL

All types of wood structural panel sheathing have the same allowable shear
strengths in the UBC. Wood structural panels include all veneer plywood,
composite panels, oriented strand board and waferboard. The most common
structural panels are plywood and oriented strand board. When the term “wood
structural panel” is specified, the contractor may use oriented strand board or
plywood panels of the required thickness and grade.

ORIENTED STRAND BOARD

Oriented Strand Board (OSB) is a mat-formed panel product made of strands

bonded with exterior type resins under heat and pressure. OSB panels consist of
four or five layered mats. Most mills use uniformly thick strands up to 4-1/4"
long and 1" wide. Exterior or surface layers consist of strands aligned in the long
panel direction. Inner-layer layers consist of cross or randomly aligned strands.
OSB's strength comes mainly from the uninterrupted wood fiber, interleaving of
the long strands or wafers and degree of orientation of wafers or strands in the

Fig. 3.37 - Oriented Strand Board Panel Construction

surface layers. (Fig. 3.37)

Question: Can I substitute oriented strand board for plywood sheathing?

Answer: Some designers will specify plywood panels for sheathing

because oriented strand board expands more than plywood when exposed
to moisture. Wetting and expansion can cause fasteners to fracture the
surface of the sheathing. Fasteners whose heads are below the surface of
the sheathing due to panel expansion will cause premature failure of the
shear wall during seismic loading. When plywood is specified, no substitutions of
the less costly OSB should be made without the approval of the structural designer and
local building department.

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Professional engineers and architects can and often should design to more than
the minimum standards of the building code. When they do, their specifications
must be followed. For example, California law states that licensed architects are
not responsible for damages caused by unauthorized changes to their plans or
specifications. This provision includes changes made by plan reviewers and
building inspectors without the architect’s consent.

PLYWOOD

Plywood is a panel of laminated veneers (plies) constructed in an odd number of

layers. Layers may consist of one or more plies laminated with parallel grain
direction. Each layer is positioned perpendicular to the adjacent layer to equalize
strain, reduce splitting, and minimize warping. Outer layers generally have the
outer layers oriented parallel to the long dimension of the panel. Plywood must
have a minimum number of plies and layers for each thickness range. For
example, 15/32 inch Structural 1 plywood must have at least 4 plies and 3 layers.
Non-Structural 1 plywood of the same thickness can have 3 plies. (Fig. 3.38)

Fig. 3.38 - Plywood Panel Construction

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 Shear Walls 39

USE THE PROPER THICKNESS & NUMBER OF PLIES

Normally, the strength of shear walls sheathed with wood structural panels
comes from the strength of the sheathing fasteners. However, instead of
fastener failure, some shear walls constructed with 3/8-inch plywood tore at
their inner ply seam during the Northridge Earthquake. This is the first time
this type of failure was documented. Using thicker panels with additional
plies should allow fasteners to reach their strength limit before the sheathing
prematurely tears.

The minimum recommended thickness for wood structural panels is 15/32 of an inch.
For this thickness, both four-ply and five-ply plywood panels are commonly
available. Five-ply panels provide five plies and five layers while four-ply
panels provide four plies and three layers. The more plies and layers that are
used in plywood, the more overlapping occurs of defects and inner ply seams.
For this reason, some prescriptive standards recommend the use of five-ply
panel construction for plywood.

The following panel information was furnished by a major plywood

wholesaler and conforms to UBC Standard 23-2 (PS 1-83).

3-ply panel construction is used on 3/8 inch Structural 1, 3/8-inch C-D

Exposure 1 and ½-inch C-D Exposure 1.
4-ply panel construction is used on ½-inch Structural 1 (Southern
Pine) and 5/8-inch C-D Exposure 1
5-ply panel construction is used on ½-inch Structural 1 (Douglas Fir)
and 5/8-inch Structural 1.

The panel thickness shown is nominal. Use 3/8 for 11/32, ½ for 15/32 and
19/32 for 5/8-inch thickness.

Structural 1 plywood in ½-inch thickness is normally available in 4-ply

(Southern pine) panel construction because it is less expensive than the 5-ply
(Douglas fir). C-D Exposure 1 allows 3-ply in 5/8-inch thickness under UBC
STD. 25-9 but manufacturers typically construct the panel with 4 plies to
obtain the required thickness.

USE THE PROPER PANEL GRADE

The recommended panel grade for shear wall construction is Structural 1. Structural 1
is the premium grade of “CDX” and OSB panels. Structural 1 Rated Sheathing
has increased cross-panel strength and shear properties and all plies use
special improved grades. The allowable panel rigidity of Structural 1 is almost
twice other structurally rated sheathing. Because of its properties, Structural
1 shear walls are ten percent stronger than other similar fastened structural
use sheathing. (Fig. 3.39)

The common phrase “CDX” refers to a plywood panel constructed with

exterior glue that has “C” grade veneer on its face and “D” grade veneer on its
back. This typical construction panel is used for subfloors and roofs. Roofs
and floors generally have several panels resisting the seismic forces and
therefore require lower shear strength. In contrast, shear walls generally use Fig. 3. 39 – Panel Grade Stamp
few panels to resist these same forces and the demand on individual panel
strength and stiffness is greater than floors or roofs. For retrofit work,
remember to install each panel with the grade stamp visible for the building
inspector.
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LOCATE PANEL ON THE CENTER OF

FRAMING MEMBER & BLOCKING
Panel edges should be centered on all framing members with a 1/8-inch space
between them. The spacing allows for future panel expansion and contraction
from moisture and temperature changes. If panels are not properly spaced,
expansion will cause buckling. Buckling reduces shear wall performance and can
damage wall finishes.

Panel edges should be centered on framing members and blocking to provide

proper fastener edge distance in both the lumber and sheathing. The greater the
fastener edge distances in the lumber and sheathing, the better the shear wall
will perform. Fasteners installed too close to the edge of the sheathing, blocking
or framing member have no value.

Question: Do I Need to Install the Sheathing Perpendicular to the Framing

Members?

Answer: Unlike unblocked floor and roof diaphragms, shear wall

strength values in the UBC do not change with orientation of the
panel. Either vertical or horizontal placement of the individual panel
is acceptable. Most panels are installed vertically to avoid the added
expense of blocking. (Fig. 3.40)

Question: Can I Place the Sheathing on the Inside of the Wall?

Answer: Sheathing for shear walls may be placed on either the
interior or exterior face of the wall framing. Wood structural panel
sheathing is usually placed on the exterior for new construction and
the interior for retrofit work. For new construction, work of other
trades, like insulation and electrical is generally easier when the
interior is accessible. For retrofit work, the interior wall surfaces are
usually cheaper to replace. The shear wall will have the same strength
with the sheathing on either side of the wall.

vertical or
2 inch stud horizontal

3 inch stud

3 inch block

nail edges

Fig. 3.40 - Install Sheathing Vertical or Horizontal

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 Shear Walls 41

USE THE PROPER SIZE PANEL

Although the Uniform Building Code does not prescribe minimum dimensions
for individual panels on shear walls, a minimum width of 24 inches is
recommended to prevent any one local defect affecting performance. This
criterion is used for floor loads and is recommended for shear walls.

To follow the 1997 UBC recommendations of 2:1 aspect ratios in Seismic Zones
3 and 4, contractors should always install at least one full 4' x 8’ panel on any
standard eight-foot high shear wall. When the length of the shear wall exceeds
four feet, the end panels should be at least 24 inches.

MARK LOCATION OF STUDS ON PANELS

Retrofit work is usually done from one side of the wall. Panels are held in place
with a few nails until volume nailing is done later. Unlike new construction, the
number of fasteners that do not properly connect to the framing members or
blocking cannot easily be determined after the sheathing is in place. To reduce
the chance of improper fastening, contractors should mark the center of all
framing members, blocking and holdown end studs during sheathing
installation. After all panels are in place, a “chalk” line can be snapped on the
panels, which makes proper volume fastening easy.

MAINTAIN FIRE RESISTIVE AND

SOUND-RATED CONSTRUCTION

When retrofit work replaces existing wall finishes, any fire resistive
construction must be maintained. One-hour fire resistive and sound-rated
construction is required at walls separating dwelling units in the same building.
One-hour fire-resistive construction is also required throughout three story
apartments and when two story apartments have more than 3,000 square feet
on the second floor. Some apartments may also use two-hour walls to get more
allowable floor area. When these conditions exist, all required components of
the wall assembly must be replaced. The addition of plywood or OSB panels will
not affect the fire rating when attached directly to the framing and covered with
the appropriate fire-resistive materials.

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PROVIDE VENTILATION AT
CRIPPLE WALL SHEATHING

Many older homes do not have building paper under their horizontal siding
around the crawl space. This permits water to enter the cripple wall stud cavity.
Circular ventilation holes should be cut in the sheathing when new sheathing is placed on the
inside face of the cripple wall. Prescriptive standards specify the size and spacing of
the ventilation holes. The holes will permit water vapor to escape and will
permit inspectors to observe and test anchor bolts. Screens should be installed
over the ventilation holes to prevent animals from nesting in the newly
sheathed stud cavities. (Fig. 3.41)

New sheathing should not block existing vents. Where sheathing must be
placed where a ventilation or other opening is located, cut an opening for the
vent, install blocking around the vent opening and extend the length of shear
wall the width of the vent opening to the nearest stud.

Fig. 3.41-Cripple Wall Ventilation

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HOW TO INSTALL THE FASTENERS

USE COMMON NAILS

Nails are the preferred fasteners for several reasons. They cost less to install
than screws and are easier to install in volume due to pneumatic tools
commonly known as “nail guns”. Engineers prefer nails because they are
generally more ductile than screws. Better ductility mean better absorption of
seismic energy. When screw withdrawal properties are desirable, such as for
floor sheathing, ring-shank or screw-shank nails can be used instead.

Most structural designers specify common nails because of their improved

strength and stiffness over box, cooler or sinker nails. Common nails have larger
nail shank diameters than other nails. Although hot-dip galvanized box nails
may be used for plywood sidings, common nails are recommended to fasten wood
structural panel shear walls. (Fig. 3.42)
Fig. 3.42 –Box Label for Common Nails
Hand driven nails typically come in boxes labeled with the nail type. Boxes with
nails for nail guns sometimes show only the length, diameter and finish. To
verify the use of common nails, contractors and building inspectors must be familiar with nail
diameter requirements. For example, if a gun nail box says 2-3/8 x.113 Smooth
instead of 2-3/8 x.131 Smooth, the fastener is a 8d cooler nail instead of the 8d
common. This is a common construction error. Nail sizes and diameters are
shown in the Appendix.

USE THE PROPER LENGTH OF COMMON NAIL

Shortened 10d common nails, commonly referred to as short or plywood nails,

come in three lengths: 2-1/8, 2¼ & 2-3/8-inches. Only 11/32-inch thick panels
can use the shortest nail, 2-1/8-inch. Panels with thicknesses from 3/8-inch to
15/32-inch can use the 2¼-inch length nail. Panel thicknesses from ½-inch to
19/32-inch require the 2-3/8-inch length nail. Panel thickness equal to 5/8-inch or
thicker must use the full length 10d common (3 inches).

Question: Can I Use Shortened 10d Common Nails?

Answer: Unless otherwise specified, shortened 10d common nails, may

fasten wood structural panels in shear walls if they meet the minimum
penetration requirements. All nails must provide a minimum of 12
diameters penetration into the framing member or blocking.

Because of their shallower penetration, short nails are less likely to split
framing members but are more likely to withdraw. Check with the structural
designer before using these shortened nails.

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WHY COMMON NAILS ARE IMPORTANT

Because the head sizes of common and box nails are nearly identical, wood
structural panel sheathing fastened with these nails will reach the same
ultimate strength. The advantage of using common nails to fasten sheathing is
generally stiffness and not strength. Common nails have less slip than box nails
due to their increased shank diameter. Because shear walls must provide both
strength and stiffness, the use of box, cooler or sinker nails will reduce the
performance of the shear wall.

UBC Table 23-I-G, which uses stiffness to determine the allowable load values,
can be used to make the following stiffness comparison. For sheathing, four
common nails provide the same stiffness as five box or cooler nails. When shear
walls are constructed with box, sinker, or cooler nails, it will take 25% more
nails to make up the difference. However, additional nailing must follow the
requirements for minimum spacing and framing member sizes.

When additional nailing creates spacing of 6d or 8d at 2 inches on center or 10d

at 3 inches on center, 3 inch nominal width framing members are required at all
adjoining panel edges. When the original common nail spacing was equal or less
than 6d at 2 inches, 8d at 2½ inches or 10d at 3 inches, additional nails cannot
be used because of minimum spacing requirements. In these cases, additional
sheathing must be provided and is usually installed on the other side of the
same wall. Remember, it is easier in the long run to do it right the first time.

COMPARISON OF COMMON VS. BOX NAILS

Shank Diameter, Minimum Spacing Allowable Lateral Load, pounds
Nail Length, decimal inch and Penetration,
Size inches inches

Common Box Nail Common Box Common Box Box vs.

Nail Nail Nail Nail Nail Common

6d 2 0.113 0.099 1¼ 1c 63 51 0.81

8d 2½ 0.131 0.113 1½ 1¼ 78 63 0.81

10d 3 0.148 0.128 1e 1½ 94 76 0.81

Table 5 - Performance Losses for Nail Substitutions

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 Shear Walls 45

USE FULL HEADED NAILS

Most Contractors use nail guns to fasten wood structural panel sheathing (Fig.
3.43). The nails used in these tools come in clips that may or may not have full
heads. Some manufacturers clip the nail head to form clips with the nail shanks
side by side. This arrangement allows more nails per clip, reduces the frequency
of reloading and avoids intershank plastic from disabling the tool. Other
manufacturers use plastic to hold the individual nails far enough apart to allow
for full heads (Fig. 3.44).

Although present building code accepts altered heads, there are good reasons to
believe they are not as strong as full headed nails. Examination of plywood
shear walls damaged in the Northridge Earthquake showed the importance of
nail head size. Shear wall failure occurred at the panel edges. The panel edge
either failed by punching through at the nail head or withdrawal of the nail
itself in panel buckling. In both cases, the nail head size was a significant
element in the mode of failure. The smaller the nail heads size, the easier a
panel can buckle off the framing. (Fig. 3.45)

Fig. 3.45–Earthquake Damaged Shear Wall

Fig. 3.43 – Sample Nail Gun with Flush Attachment

Round-Head Nails Modified

(P-Nails) Round-Head Nails
(P-Nails)

Fig. 3.44 – Nail Head Differences

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 46 Shear Walls

Tests that established the strengths of wood structural panel shear walls used
hand driven nails with full heads. Some tests used casing nails. These tests
showed that shear walls with 8d casing nails are only 62 percent as strong as
ones with 8d box nails. Though the shank diameters of the two nails are the
same, the head area of the casing nail is only 27 percent of the box nail.
Smaller head areas provide smaller shear wall strengths.

INSTALL NAILS FLUSH TO SHEATHING

Some contractors and inspectors have expressed confusion about the actual
meaning of the 1994 UBC language “not fracture the surface of the
sheathing”. The 1997 UBC has clarified the language to state that the “head or
crown of the nail is flush the surface of the sheathing.” Nails installed with
their heads resting on but not into the sheathing can cause problems for
roofing and other finishes. Nails should be driven so that the top of the nail
is flush and not above the surface of the sheathing.

Because nails will try to pull through the thickness of wood structural panel
sheathing during an earthquake, nails should be driven flush with the surface
of the sheathing and not overdriven. Overdriven nails reduce the shear wall
strength by effectively reducing the thickness of the sheathing. At panel
edges, overdriven nails allow easier nail punch-through. At intermediate
studs, overdriven nails allow easier panel buckling. Nails are commonly
overdriven because of excessive air pressure or too long of a driving pin on
the nail gun. Hand driven nails are rarely overdriven unless a soft spot in the
framing member or blocking exists where the nail is installed. (Fig. 3.46)

When nailing sheathing, Contractors should operate their nail guns within the
manufacturer’s recommended pressure range and install flush nailing attachments as
required. Inspectors should reject all nails driven below the surface of the sheathing.
When the spacing and framing member thickness allow, nails should be
added to replace any overdriven nails.

PROVIDE PROPER SHEATHING EDGE DISTANCE

Fig. 3.46 – Nails That Are Too Close
to the Panel Edge and/or Overdriven
When nails are installed too close to the sheathing edge, the shear wall will
fail prematurely during seismic loading. The greater the edge distance, the
better the sheathing connection will perform. High-strength diaphragms are
created when several rows of nails are placed in wide framing members with
large edge distances. Although the 1994 UBC only requires 3/8 inch, the
minimum recommended edge distance for sheathing fasteners is ½ inch.
This will increase the strength of the connection.

CENTER THE NAILS IN THE

FRAMING MEMBERS & BLOCKING

To properly connect sheathing to framing, most nails should be located in the

center of the framing member whenever possible. Centering the nail is easy
to do on sill plates, sole plates and intermediate studs. Centering nails in the
uppermost top plate frequently requires oversized panel sheets. Centering
nails in framing members or blocking at adjoining panel edges is impossible.
To make up for the inability to center the nails at adjoining panel edges,
wider framing members and blocking are recommended at adjoining panel
edges.

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 Shear Walls 47

Most 8-foot walls today are framed at a height of 8 ft-0¾ inch to allow for the
gypsum wallboard on the ceiling. As a result, the common 8-foot sheet of
wood structural panel sheathing does not span the full height of the wall.
Frequently sheathing panels are installed vertically with one end flush to the
bottom edge of the sill or sole plate and the other end centered on the
uppermost top plate. This situation cannot easily be fixed by adding 3-inch
plates. Thicker plates require longer framing nails that are not readily
available and are more difficult to install. The best solution is oversized
sheets. Both oriented strand board and plywood come in 9 foot and ten-foot
lengths. When these lengths are used, shear transfer connections can be
eliminated if nailing is provided to the floor or roof-framing members.

CHECK FOR SPLITTING OF LUMBER DURING NAILING

All fasteners in wood must be installed without splitting of the lumber. There
are no exceptions. Existing lumber can be very dry and stiff. If needed to
prevent splitting, predrilling of holes at 75% of the nail diameter is required.

REMOVE ALL IMPROPERLY INSTALLED NAILS

To allow for proper inspection, all nails that miss, graze or connect to framing
members too close to their edges should be removed prior to inspection.
These nails have no allowable value and can mislead the Contractor or
Inspector into thinking the job was done right. Since the strength of shear
walls sheathed with wood structural panels comes mainly from the fasteners,
proper fastener location is of primary importance. (Fig. 3-37)

PROVIDE PROPER EDGE NAILING

For the shear wall to reach its intended strength, all sheathing edges of
individual panels must be fastened with the edge distance nailing
requirements. Intermediate studs must be fastened with the field nailing
requirements so that panel buckling does not occur. Remember that the end
of a shear wall is where the sheathing stops at either the wall corner or the
framing member with the holdown device. All sheathing must be fastened
with the closer edge distance spacing at every framing member that connects
to a holdown device.

The following nail locations apply to all wood structural panels shear walls.
“Edge Nail” refers to the closer nail spacing requirement of Uniform Building
Code Table 23-1-K-1. Field nailing should be used on the studs between panel Fig. 3.47 – Nails that Missed
edges except at framing members connected to holdown devices.

TABLE 5- HOW TO NAIL A SHEAR WALL

• Edge Nail the Holdown Stud(s)

• Edge Nail the Upper Top Plate
• Edge Nail the Sill or Sole Plate
• Edge Nail the Blocking for Individual Panel Edges
• Edge Nail the Blocking for Opening Reinforcement
• Field Nail the Studs Between the Panel Edges

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NOTES

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 Connections 49

4 CONNECTIONS
by Stephan A. Kiefer, C.B.O.

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 50 Connections

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 Connections 51

CONNECTIONS RESISTING UPLIFT FORCES

In the Shear Wall section you learned that a building must resist two types
of forces; shear and uplift. The horizontal forces acting on the top of a shear
wall not only create shear forces in the wall but will also create uplift forces
at the ends of the wall. Tall and narrow shear walls, in particular, have a
tendency to overturn due to uplift forces created when an earthquake
(lateral) force pushes the top of the wall. First, we will discuss those
connections used to resist uplift forces. (Fig. 4.1)

The shear wall’s tendency to overturn may be resisted by its own weight or
in combination with the weight of the structure above it. However, when
the uplift forces exceed the given weight on or in the wall, additional
resistance must be applied. This is done with the installation of metal
hardware typically identified as a holdown. There are no prescriptive
requirements in the Building Code for the installation of these holdowns.
The engineer or architect will specify the installation of holdowns when
anticipated uplift forces exceed gravity loads on the wall. Simply put, the
architect or engineer specifies when the installation of a holdown is
required.

Holdowns transfer uplift forces from the end of the wall through a floor to a
wall or foundation below. When an earthquake shakes a shear wall back
and forth, the shear wall will experience uplift forces on both ends, one end
at a time. It is for this reason that holdowns are typically required on both
ends of a shear wall and are connected to the end stud or post of the shear
wall. The added post is better able to resist the tension load from uplift and
the simultaneous compression load at the opposite end of the shear wall.

Fig. 4. 1

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TYPES OF HOLDOWNS

Holdowns that connect a shear wall to the foundation are bolted, screwed or
nailed to the end stud or added post. Retrofit holdowns are anchored to the
footings using a threaded rod that is connected to the holdown. The other
end of the rod is adhesive set into a hole that is drilled into the foundation
concrete. This rod transfers the uplift force from the wall down into the
foundation. This minimizes the wall’s tendency to overturn.

Holdowns that connect two walls through a floor come in pairs; one above
and one below. The holdowns are bolted, screwed or nailed to their
respective end stud or added post. The uplift forces are then transferred
from the wall above to the wall below through a threaded rod that is bolted
to the holdowns. (Fig. 4.2)

Similar to bolted holdowns, metal straps can be used as holdowns to

connect the end studs or added posts below the floor. The strap must be
long enough to pass through the floor framing and be attached to the end
studs or added posts so that the required number of nails or bolts are
provided between the strap and the end stud or added post both above and
below the floor. The strap should also be taut and straight to reduce slippage
Fig. 4.2 Floor-to-Floor Holdown (Fig. 4.3).

IMPORTANCE OF PROPER INSTALLATION

To better understand the importance of properly installed holdowns,

consider a tall and narrow shear wall that is 8 feet tall and 2 feet 3 inches
wide (height to width ratio of 3 ½ to 1). By applying an earthquake induced
horizontal load at the top of the wall, the wall will begin to overturn. For
every one inch that the bottom, left corner of the wall goes up, the upper,
right corner will move laterally a distance of 3 ½ inches.

Cyclic testing of wood shear walls has shown that lateral movement of as
Fig. 4. 3 Improperly Bent Strap little as 2 inches can cause loss of vertical support and therefore, cause
building collapse. Accounting for the height to width ratio of 3 ½ to 1, this
means that if a holdown at the bottom left corner of a shear wall slips as
little as 5/8 inch up, the building could suffer significant damage and
possible collapse!.

Proper installation becomes even more critical when you consider that even
a properly installed holdown will tend to allow some upward movement.
This inherent deflection can be attributed to:

1. Localized crushing of the wood fiber around the fasteners

2. Crushing of the sill or sole plate under the end stud.
3. Stretching of the metal holdown hardware.
4. Random nut spin or thread stripping during the earthquake.
5. Bending of the fastener (nail, screw or bolt)
6. Wood shrinkage
7. Additional rotation allowed from one-sided connection

Proper installation is essential. (Fig. 4.4) A number of things can go wrong

when installing holdowns. What follows is a discussion of some of the
more common problems and how to avoid them.
Fig. 4.4 – Proper Installation

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COMMON HOLDOWN INSTALLATION ERRORS

Holdowns should be installed as specified on the plans and following the

manufacturer’s installation instructions. Substitutions of holdown
hardware require the prior approval of the building department and the
design professional (engineer or architect). An errant substitution may not
provide the same resistance to uplift as originally intended.

When new holdown posts are specified, such as a 4x4 or 4x6, you should
not substitute the specified post with a doubled stud. The allowable
strength of a holdown is partly based on the cross-sectional area of the end
stud. The strength of the holdown is generally reduced by attaching it to two
2x studs (3 inches) instead of the specified solid post (3 ½ inches). (Fig. 4.5)

When nailing on straps used as holdowns, the minimum required edge Fig. 4.5 – (2)- 2X4 vs. (1) 4X4
distance must be maintained. The minimum required edge distance
depends on the size of nail used. Nails should be installed no closer to the
edge of the wood member than ½ the minimum required embedment depth SHEATHING HOLDOWN
of the nail (see Table 23-G of the Uniform Building Code). For example, if STRAP
the nail’s minimum embedment depth is 1-3/4 inches, the nail should be
installed no closer than 7/8 inch from the edge of the wood member. (Fig.
HOLDOWN
4.6) STUD

Shear wall end studs or posts should normally be one full piece for the
height of the wall. This is necessary because the end stud or post must be 16d
COMMON
capable of resisting tension due to the uplift forces. Otherwise, additional NAIL
connections will be needed inside the wall to transfer the uplift forces.
7/8"

When plans specify the installation of new posts in an existing or new wall, MINIMUM REQUIRED
the posts should be installed at the ends of the wall. As you now know, EDGE DISTANCE

tension or uplift loads occur at the ends of a shear wall. Unless otherwise
approved by the engineer or architect, holdowns should be located as close Fig. 4.6 – Nail Edge Distances
to the ends of the shear wall as practical. (Fig. 4.7)

Fig. 4.7 Holdowns at Each End of Shear Wall

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INSTALLATION ERRORS FOR BOLTED HOLDOWNS

• Improper End Distance

With respect to the holdown location on the post, the bolts attaching the
holdown to the post should be located per the manufacturer’s installation
instructions. In general, the first bolt should be at least seven bolt
diameters from the bottom of the post. This minimizes the chances of the
bolt ripping right through the end of the post during an earthquake (Fig.
4.8).

• Oversized Bolt Hole

The post bolt holes must not be oversized. If the hole is bigger than the
bolt, the bolt will move before it engages the wood and will be much more
likely to split the post. The building code allows the hole in the end stud to
Fig. 4.8 Improper End Distance be a maximum 1/16-inch oversized. The proper drill bit size must be used
so that the hole is no larger than 1/16 inch bigger than the bolt diameter
(Fig. 4.9).

• Undersized Washers
In addition, washers should always be used where the bolt head or nut bears
directly on wood. This typically occurs on the post side that is opposite the
holdown. Square plate washers should be used instead of round malleable
washers. This will help better prevent the bolt pulling through the end stud
during an earthquake (Fig. 4.10).

• Substitution of Lag Screws for Through Bolts

When through bolts are specified, lag screws should not be used. A lag
screw, even if it is the same diameter, will not have the same strength as a
through bolt.

• Countersinking Nut & Washer

Post bolts should never be countersunk into the post unless the installed
Fig. 4.9 Oversized Bolt Hole post is at least one size larger than that specified. For instance, if the plan
calls for a 4x4 post and it becomes necessary to countersink the bolt head, a
4x6 post should be used. This allows for an additional 2 inches of post
thickness in which to countersink the bolt head (Fig. 4.11).

Fig. 4.10 Smaller Washers

Fig. 4.11 Countersunk Nut and Washer in Holdown Stud
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 Connections 55

• Insufficient Depth of Embedment for Anchor Rods

Holdown rods anchored into the foundation should be embedded as
required by the manufacturer or structural design. The rods should only be
embedded into sound concrete or reinforced masonry. Unlike a typical
anchor bolt, the holdown rod must resist uplift forces. The loads imposed
on a holdown rod are generally greater than those imposed on a typical
shear wall anchor bolt. Holdown anchors that are not installed to the
proper depth and at the minimum edge distance will not perform as
intended during an earthquake (Fig. 4.12).

Fig. 4.12 Lack of Embedment for Holdown Anchor

• Substitution of Holdown Anchor Type
Wedge or Expansion type anchors should not be substituted when chemical
(adhesive) anchors are specified. For holdowns, these anchors do not
generally perform as well as adhesive anchors during the cyclic uplift
loading caused by earthquakes.

• Untightened Nuts
The nut must be tightened securely on the holdown rod. If not properly
tightened, the wall will begin to uplift during an earthquake before it
engages the holdown. This movement can split both the sill plate and the
holdown post. When the nut is not properly tightened, shear wall
overturning will cause damage to the building (Fig. 4.13).

Fig. 4.13 Untightened Nut Found in Earthquake Damaged Building

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 56 Connections

CONNECTIONS RESISTING SHEAR FORCES

A typical wood-framed building has many connections where shear forces
are present. All of these connections are links in the shear load path. Just as
with the uplift forces, these shear forces must be adequately resisted in
order to minimize building damage (Fig. 4.14). No matter how heavy the
gravity load, friction alone is not an effective way to create a load path.
Remember that the heavier the gravity load, the greater the inertia and
resulting shear force.

Two pieces of wood that are butted together can be easily pulled apart if not
connected by some type of splice. Similarly, two pieces lying one on the
Fig. 4.14 Shear Connections other can be slid past each other if not properly connected (Fig. 4-15). In
wood framing, all connections need to have a nail, screw or bolt connecting
two pieces together. Proper shear connections are created with
combinations of fasteners, blocking and hardware such as framing anchors.

FASTENER TYPES IN SHEAR CONNECTIONS

For nailed connections to be effective, the nails need to penetrate the wood
a minimum depth. To accomplish this, the specified nail length must be
used in all wood connections. It is also important to use the proper
diameter nail (common vs. box) and avoid splitting the wood while nailing.

Screws should not be randomly substituted for nails. While screws provide
superior holding power in tension, they have reduced ductility. Ductility is
necessary to prevent brittle fracture during cyclic loading. Always consult
the architect/engineer and the local building official when considering this
substitution.

Fig. 4.15 Building Damage from Shear Connection Failure during an Earthquake
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 Connections 57

SHEAR CONNECTIONS IN THE LOAD PATH

There are many breaks in the continuity of a conventional platform-framed

building, particularly if it rests on cripple walls. Shear forces created by the
earthquake must be effectively transferred through these breaks in order for
the load path to be complete. The following elements must connected to
each other to develop this complete path.

1. Roof and ceiling must be attached to the top plate(s).

2. Top plate must be attached to the sheathing.

3. Sheathing must be attached to the sole plate.

4. Sole plate must be attached to the floor framing.

5. Floor framing must be attached to the top plate(s).

6. Top plate(s) must be attached to the sheathing.

7. Sheathing must be attached to the foundation sill plate.

8. Foundation sill plate must be attached to the foundation.

When these elements are properly connected, they form an unbroken load
path from the roof and floor diaphragms to the ground. Figure 4-16 shows
forty-four (44) elements in this shear load path.

NON-STANDARD FRAMING

When evaluating an existing building for possible retrofit, it is important to

identify non-standard framing. Balloon framing is one type of non-standard
framing. Balloon framed structures were common on the East Coast and
Midwest until recently. Some older buildings on the West Coast are also
balloon framed. In balloon framing, the intermediate floor framing joists are
face nailed directly to the studs. The studs are continuous from top to
bottom of the building. This creates a load path discontinuity between the
floor diaphragm and shear wall. When encountering this or any other type of
non-standard framing, an architect or engineer should be consulted. (Fig. 4-
17)

BOUNDARY NAILING
WALL TIE @ 48'' SHEAR NAIL TO BLOCKING
BOUNDARY NAILING
4'' MAX TO BLOCKING

1'-0'' MIN
EDGE NAILING
2x BLOCKING
2x FLOOR JOIST
W/4-16d COMMON 2x BLOCKING @ 48''
10' C

Fig. 4. 16 Shear Load Path

Figure 4.17 Balloon Framing

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CONNECTIONS AT TOP PLATES

Walls built today usually have doubled top plates on which the roof, ceiling
or floor framing above rests. On some older buildings, only a single top
plate was installed. The top plate(s) is where the shear wall sheathing is
nailed and where the shear forces transfer from the roof, ceiling or floor
diaphragm. For adequate transfer of forces, it is necessary to attach the top
plate to the rim joist or blocking above.

Code conventional framing requires that each joist be attached to the top
plate with 3-8d toenails. This amount of attachment may not be adequate
for shear forces in the plane of the wall. Since it is difficult to determine if
Fig. 4.18 Framing Clips at Top Plate there is sufficient existing toe-nailing, metal right angle clips (framing clips)
should be nailed into the top plate(s) and the rim joist or blocking. This will
strengthen the shear connection between the floor framing and the shear
wall below. (Fig. 4.18)

These shear connections should be installed at the required spacing along

the entire length of the wall. Spacing will depend on the given design value
of the clip and the prescriptive or engineered retrofit design that is being
used. For shallow 2x6 or 2x8 joists, it may be difficult to attach the clip into
the rim joist or blocking and top plate. The use of a pneumatic palm nailer
will make this installation easier in difficult access areas. (Fig. 4.19)

Splices in double top plates should be properly lapped and the laps should
be well nailed. If a double top plate is notched or cut (say for a plumbing
vent), metal straps should be added across the notch to restore its tension
Fig. 4.19 Use of Palm Nailer capacity. When splices of double top plate are not properly built or if there
is only one discontinuous top plate, a metal strap should be nailed across
the splice to provide the necessary continuity. (Fig. 4.20)

20 GAGE GALVANIZED SIX- 8d COMMON

STEELSPLICE PLATE NAILS EACH SIDE
STEEL SPLICE
PLATE

3"

SINGLE TOP
PLATE 6"
STUD

SINGLE TOP PLATE

Fig. 4.20 Splice for Single Top Plates

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CONNECTIONS AT SOLE PLATES

At the bottom of a shear wall, the attachment of the sole plate and the floor
decking to the floor framing accomplishes the shear transfer from the shear
wall and the floor diaphragm to the floor framing below. When nails or lag
screws resist shear, they must be sufficiently long enough to penetrate
through the sole plate and floor sheathing into the framing member below.
(Fig. 4-21)

For full load values, Table 23-G of the Uniform Building Code specifies the
minimum penetration required of nails into the framing member. When the SOLE PLATE NAILING
nail penetration falls below Table 23-G values, the allowable load for the nail FOR SHEAR TRANSFER
is reduced proportionally up to 50% of its value. When nail penetration falls
below 6 nail shank diameters, the allowable load value is zero. For this
reason, nails often cannot transfer shear forces through thick sheathing.

If the wall framing is exposed above the floor, as in new framing that has
not yet had plaster or drywall attached, the nails can be installed from
above. However, in some retrofit situations, the wall framing above is not
(or cannot be) exposed. In this case, it may be possible to add framing clips
where the underside of the floor and the rim joist or blocking meets. Short
joist hanger nails should be used to attach the clips to the joist or blocking.
Longer nails or wood screws should be used to penetrate up through the
floor decking and into the sole plate above.

In some multiple story buildings, double sole plates may be encountered.

The second sole plate may have been installed to act as a form for poured-in-
place lightweight concrete or gypsum sub-floor material. Where this occurs,
it is important to maintain a load path through both plates. In new
construction, this is accomplished by nailing the first sole plate and second Fig. 4.21 Sole Plate Connection
sole plate with a sufficient number of nails specified by a design
professional. In existing construction, it may be necessary to use extra long
nails or screws through both plates so that the fastener has enough
penetration into the framing member below. (Fig.4.22)

Another way of accomplishing the shear transfer from a wall and floor above
into the wall below is to use longer sheets of wood structural panels. By
spanning full sheets from the rim joist or blocking above to the rim joist or
blocking below, the panel serves as a direct load path from one shear wall to
the other. This reduces the number of links in the chain and eliminates the
MAX

need for framing clips. Remember to install the four rows of nails (as
4''

illustrated) to provide a load path from the floor diaphragm as well as the
wall above and always provide the recommended gap between panel edges
MAX
4''

to allow for expansion. New construction requires even larger gaps for
shrinkage of the rim joist or blocking. (Fig. 4.23)

Fig.4-23 Longer Length Sheathing

Fig. 4.22 Double sole plates

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CONNECTIONS AT SILL PLATES

Because shear loads are cumulative as they work their way down a building,
they are greatest at the base of a building. Shear loads are transferred from
the shear wall into the foundation through the sill plate. Consequently, the
sill plate must be attached to the foundation with anchor bolts or plates.
Before the load enters the anchor bolt or plate, it must successfully pass
through the sill plate. Sill plates should be in good condition and free from
cracks. If a cracked or split sill plate is encountered, it should be replaced
before proceeding with the retrofit (Fig. 4-24).

Sometimes existing anchor bolts in the sill plate are too few in numbers or
size or are rusted through under the sill plate. Some older buildings did not
bolt their sill plates to the concrete stem wall. In these cases, special retrofit
Fig. 4-24 Earthquake Damaged Sill Plate
anchors must be used to strengthen the sill plate connection. New sill plate
anchors are installed in two ways: drilled-in anchors through the sill plate or
side plates that connect the sill plate to the foundation concrete or masonry.
Side plates are used when there is not enough room to stand a drill motor
on top of the sill plate (Fig. 4.25-27).

Drilled-in anchors come in two types: mechanical and adhesive. Adhesive

anchors have the advantage of working in lower strength existing concrete.
They are more expensive to install than mechanical anchors and require
greater quality control during installation. Mechanical wedge anchors are
easier to install but require generally greater concrete strength due to the
concentration of stresses at the expansion clip. When sufficient concrete
strength exists, either adhesive or mechanical anchors may be used.
Generally the strength of both anchor types in concrete is greater than their
strength in the wood sill plate.

All anchoring products should be installed per the manufacturer’s

installation instructions. Some products require special inspection as
defined in Chapter 17 of the Uniform Building Code. Always check with the
Fig. 4.25 Mechanical Anchor manufacturer and the local building official to determine if special
inspection is required.

Fig. 4.26 Adhesive Anchor

Fig. 4.27 Side Plate to Connect Sill Plate to Concrete Stem Wall

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LOCATING DRILLED-IN ANCHORS

• Provide Proper Edge Distance in the Concrete and Wood

Drilled-in anchors require a minimum edge distance in concrete. The
manufacturer’s recommendations will specify the minimum amount
required for each diameter anchor. Anchors without sufficient edge distance
will fail in earthquakes and sometimes, even during installation (Fig 4.28).
When obstructions require the hole be drilled at slight angle, make sure that
the bottom of the hole still has the minimum edge distance. This is
particularly important when using mechanical anchors. Normally, drilled-in
anchors should be installed near the center of the sill plate (Fig. 4-29). This
will furnish the minimum required 1-½ bolt diameter edge distance in the Fig. 4.28 Concrete Edge Distance
wood. For 2 x 6 sill plates, this will generally provide adequate edge distance Failure
in the concrete.

When foundation walls of a house are located slightly out of position,

builders will sometimes adjust the wood wall location. They do this by
partially overhanging the sill plate at the edge of the foundation wall (Fig.4-
.30). If such a condition is encountered during retrofit, an architect or
engineer should be consulted. If the overhang is severe or the required edge
distances in the concrete, masonry or wood is not provided, a special repair
or connection may be needed to effectively transfer the shear loads.

• Provide Proper End Distance in the Sill Plate

Additional anchors should be installed within 12 inches but not closer than 7
bolt diameters from the end of each sill plate piece.
5'' MIN 5'' MIN
12'' MAX
5'' MIN

12'' MAX 12'' MAX

12'' MAX
5'' MIN

2'' MAX Fig. 4-30 Misaligned Sill Plate

AT CORNER AT INTERSECTION AT SPLICE

Fig. 4-29 Proper End Distance for 5/8-inch Sill Plate Anchors

• Provide Proper Depth of Embedment in the Concrete

To safely resist their shear loads, both adhesive and mechanical anchors need
a minimum depth of embedment in the concrete. The manufacturer’s
recommendations will show the minimum embedment depths required.
When holes are drilled deeper than required, nuts and plate washers should
be installed on the mechanical and adhesive anchors before they pass
through the sill plate. This will prevent the anchor from sinking too deep
into the hole. If the anchor settles too deep in the hole, it should be left in
place and another anchor installed nearby. When plate washers and nuts are
countersunk into the sill plate, the reduced plate thickness weakens the Fig. 4. 31 Improper Countersinking
connection (Fig. 4.31).

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• Use the Proper Length of Anchor

When edge distance permits, drilled-in anchors can be installed directly through
the blocking added for cripple wall strengthening but longer anchors are needed
to provide the minimum depth of embedment in the concrete. Longer anchors are
also required when sill plates are full two inches thick. This commonly occurs in
older buildings (Fig. 4.32).

PROVIDE MINIMUM
RECOMMENDED
EMBEDMENT DEPTH

MAINTAIN MINIMUM
EDGE DISTANCE IN
CONCRETE AND WOOD

Fig. 4.32 Sill Plate Anchor Options

• Use Plate Washers

To further reduce the chances of the sill plate splitting during an earthquake,
square plate washers should be used instead of round washers. Round malleable
washers tend to fold up and split the sill plate during an earthquake, especially
when the sill plate hole is oversized. During the 1994 Northridge earthquake, sill
plates often split or pulled through anchor bolts. The square plate washer is more
effective in creating a good friction connection between the sill plate and the bolt.
It also makes tightening of expansion anchors easier (Fig. 4.33).

INSTALLING MECHANICAL ANCHORS

Mechanical anchors attach to the concrete through friction by mechanically

Fig. 4.33 Square Plate Washer expanding or “wedging” against the concrete. These types of anchors are effective
if the concrete is in good shape and the minimum edge distance is maintained.
The proper diameter hole is essential to allow the anchor to properly engage.
Normally it is the nominal diameter of the anchor. Sometimes the bolt will not
engage due to air or powder pockets in the area of the expansion wedge. This will
be apparent when the bolt will not torque to the required strength. When this
happens, the bolt should be abandoned and a new bolt should be installed nearby
in a new hole.

Wedge anchors have a required torque to properly set them in concrete. For sill
plate anchors, the range is generally 50-120 ft-lbs. The use of plate washers will
help reach the required torque without excessive compression of the sill plate
under the washer. Follow the manufacturer’s recommendation for the required
torque and use a calibrated torque wrench.
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 Connections 63

INSTALLING ADHESIVE ANCHORS

• Carefully Clean the Hole

Unlike mechanical anchors, adhesive anchors attach to the concrete
chemically; they glue to the concrete. These products usually come in a two-
part tube applicator and are readily available. Because the products create a
chemical bond between the anchor rod and the concrete, it is extremely
important that the hole be properly drilled and cleaned. The product must
adhere directly to the concrete surface and not to residual dust that might
be left in the hole after drilling. Carefully clean the hole as required by the
manufacturer. The hole must be properly brushed and blown out prior to
adhesive installation (Fig. 4.34 & 4.35).

• Use All-threaded Rod

Although these products chemically bond to concrete, they will NOT
chemically bond to the anchor rod (steel). Therefore, threaded rod is Fig. 4.34 Nylon Brush in Hole
required for all adhesive-anchoring systems. This allows the product to
engage the threads and create a good mechanical bond to the rod.

• Completely Fill the Hole in the Sill Plate with Adhesive

Most adhesive products require holes in the concrete that are oversized 1/8-
inch larger than the all-thread diameter rod. This creates oversized holes in
wood sill plates because the limit is only 1/16-inch. To remedy this, enough
adhesive should be placed in the hole to overflow the sill plate once the rod
is installed. This will allow the sill plate to immediately engage the anchor
rod during an earthquake and allow it to transfer shear forces directly into
the rod, thus reducing the chances of the sill plate splitting (Fig. 4.37).

• Install the All-thread Rod with the Plate Washer and

Nut Attached
The washer and nut should be placed on the rod prior to installing the rod
since the adhesive extruding from the top of the sill plate will make it
difficult, if not impossible to install the washer and nut at a later time.

• Wait Until Fully Cured Before Tightening Fig. 4.35 Blowing Out Dust Fines
Adhesive anchor installations will need to cure for several hours before they
can be tested. Always check manufacturer’s requirements for minimum set
and cure time. The time will vary depending on the product used and the
temperature.

• Follow Safety Requirements

A final word of caution on the use of adhesive anchors: you need to protect
workers and the people living in the building from the fumes. Check with
the manufacturer to find out which product is appropriate for the use and
what precautions, will be needed. You will learn more about this in the Fig. 4.36 Installing Adhesive
section on Safety & Legal..

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INSTALLING SIDE PLATES

When installing these plates, follow the manufacturer’s installation

instructions carefully (Fig. 4.37). Unless otherwise approved, lag screws
require pre-drilling to avoid splitting the sill plate during seismic loading.
Lag screws require pre-drilling even if you intend to use a pneumatic
wrench. Be careful not to overtighten the lag screw during installation. This
will “strip” out the hole. To prevent damage to the hole, never drive the lag
screws with a hammer.

Lag screws require two different diameter pre-drill holes. The larger
diameter pre-drill hole is for the solid shank portion of the screw. This hole
should be drilled the same diameter as the screw itself. The second hole is
the pre-drill hole for the threaded portion. This hole must be smaller than
Fig. 4.37 – Anchor Side Plate the threaded diameter in order for the lag screw to grip the wood. Required
pre-drill hole sizes for both lag screws and nails are shown in the Appendix.

INTERIOR POST TO GIRDER CONNECTIONS

There is a misconception that the strength of the crawl space can be

increased by adding gussets, straps, or bracing to the interior posts. In a
house with a properly braced perimeter cripple wall, elaborate post
connections will not provide any benefit. The posts need only a simple
toenail connection at the top and bottom to keep them from shifting during
an earthquake (Fig. 4.38).

When seismic strengthening is being performed in the underfloor crawl

space, you should inspect the post connections and provide toenails, small
straps, or clips only when there is no existing connection. When you are
unsure about the condition, have an engineer evaluate it. If the perimeter
Fig. 4.38 Interior Post Strengthening of the house is properly braced, there should be very little movement at the
top of these posts.

PUTTING IT ALL TOGETHER

By carefully following the plans and the manufacturer’s specifications and

installation instructions, and by following these tips and guidelines, you will
significantly reduce the number of weak links in the load path chain. When
installing a retrofit, understand the objective. By understanding the load
path and realizing the importance of maintaining a complete and
continuous load path from top to bottom, you will be able to complete a
more effective and possibly a more economical retrofit.

***
.

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 Foundations 65

5 FOUNDATIONS
by Richard Chylinski, FAIA
and Timothy P. McCormick, P.E.

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 Foundations 67

FOUNDATIONS
Let's assume that the retrofit has been done correctly from the roofline to
the top of the foundation. The shear walls have the proper thickness of
plywood, adequate plys, plenty of common nails, anchor bolts, and hold-
downs. Everything has been done correctly, including the connection
between the shear wall and the foundation. However, if the foundation
cannot resist the forces imposed on it, there is still a problem. As noted,
the horizontal force will tend to make the building or wall slide or
overturn. If the foundation is not adequate, it will be the weak link in the
continuous load path, and the wall or building could be damaged.

In determining whether or not the foundation can resist the horizontal

forces that are transferred to it, it is necessary to investigate foundations in Fig.5.1 – Partial Foundation
terms of type, material, condition, and embedment.

FOUNDATION TYPES

Residential foundation systems can be divided into six general categories:

• No foundation

• Partial foundation
Fig.5.2 – Post & Pier Foundation
• Post and pier throughout

• Perimeter footing with interior posts

• Continuous perimeter and interior footings

• Continuous footings with a slab floor on grade.

With no foundation, or too small a partial foundation, the horizontal forces

in the building cannot be transferred safely into the ground (Fig. 5.1).
There is a similar discontinuity in the load path with a post and pier Fig.5.3 –Interior Posts & Girders
foundation (Fig. 5.2). You will learn more about post and pier systems in
the next section, Retrofitting Post and Pier Type Houses.

When a building has a continuous perimeter footing, the horizontal force

can transfer from the shear wall to footing and then into the ground.
Interior supports are usually posts and girders or continuous cripple walls
(Fig. 5.3 & 5.4). Unless there are shear walls above, these systems provide
vertical support only and are not part of the horizontal force-resisting
system. They are simply part of the gravity force-resisting system.

Fig.5.4 Continuous Interior Footing

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 68 Foundations

Contractors frequently pour slabs in a two-step process with the footing being
the first pour and the slab being the second pour. (Fig. 5.5) When the joint
between the two pours is not properly cleaned and prepared, there will be a
poor connection between the concrete layers. The problem is often discovered
after an earthquake causes horizontal sliding between the pours. Typical
remedies for this condition include installing vertical steel reinforcing dowels
that tie the slab to the footing. These remedies must be designed by an
architect or engineer.

Fig.5.6 –Failure of Two-pour Joint

Fig.5. 5

FOUNDATION MATERIAL
The foundation would normally consist of one or more the following
materials :
• concrete
• concrete block
• brick
• stone.
If the concrete block is fully grouted and reinforced, it will tend to act as
concrete. If it is not grouted or reinforced, it will act as brick or stone

Continuous concrete footings and foundation walls are the best material type.
Fig.5.7 – Unreinforced Brick This is one reason their presence is required in some prescriptive standards.
Foundation Wall Expansion anchors require concrete and are not approved for connections to
masonry.

Some adhesive anchor products can be used for reinforced masonry.

Reinforced masonry is not as strong as concrete but when fully grouted is
strong enough to resist the seismic loads of light wood frame buildings.
Hollow masonry is usually unreinforced.

When the foundation walls or footings are constructed with any unreinforced
material such as stone or pre-1933 brick, retrofitting requires the expertise of
an engineer or architect. Many engineers believe that unreinforced masonry
materials cannot adequately resist seismic loads. Common retrofit methods
for unreinforced masonry foundations include replacement, new parallel
systems or strengthening by pneumatically placed concrete (shotcrete or
Fig.5. 8- Stone Foundation Wall gunite).

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 Foundations 69

FOUNDATI3ON CONDITION

There are two concerns for the foundation condition: deterioration and
cracking.

Deterioration
Deterioration of the foundation wall is normally visible to the naked eye.
Before beginning work, a visual inspection of the foundation walls can find
excessive concrete or masonry cracking and weathering . Mortar in reinforced
masonry should be well pointed and tooled. Existing concrete should be
smooth and without separation or exposure of stone aggregates. Poorly
finished and consolidated concrete frequently suffers later from excessive Fig.5.9 – Deteriorated Mortar
weathering. If parging or repointing cannot repair the wall, a full foundation Joints in Foundation Wall
retrofit is required. You will learn more about this later in this section.

Foundation Cracking
When concrete foundation walls are constructed without expansion joints,
hairline crackling will normally occur. Cracks that are wider at the top than at
the bottom are often caused by expansive soil. When the crack is wider at the
bottom than at the top, there is likely a problem with soil settlement. These
problems can prevent the seismic loads from safely dissipating through the
soil (Fig. 5-11).

The effects of expansive soils are best reduced with deepened footings and
control of adjacent watering. Keeping roof and surface water away from
Fig.5.10 – Foundation Wall Damage
footings is always a good idea since settlement can also occur with excessive
water in the soil. Underpinning, roof gutters with downspouts to yard drains
and new concrete paving can help alleviate expansive soil problems. The
presence of expansive soils or foundation settlement indicates the need for
professional advice. Geotechnical engineers specialize in solving these
problems.

Depending on the size of the crack, concrete cracking can be repaired with
various epoxy or cementitious mortars. These products require special
inspection and careful quality control by the approved applicator. These
products should be used only under the qualified advice of an engineer or
architect.

Question: When is a crack in the footing something to be concerned about?

Fig. 5.11
Answer: An architect or engineer should be consulted if the crack
is greater than 1/8 of an inch, you can see all the way through the
crack, or if it appears that the crack was caused by settlement or the
thrust of expansive soils (Fig. 5.12).

Fig. 5.12 Foundation Wall Crack

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 70 Foundations

FOUNDATION EMBEDMENT

Footings must be embedded deep enough into the ground so that the
foundation can safely resist the vertical and horizontal loads imposed upon
it. Shear walls impart compression and sliding forces to the footing. Usually
the deeper the footings are, the better the soil condition is and the better
the foundation can resist these loads. When poor embedment exists, the
load path is incomplete and the building can simply slide along the ground
surface.

Foundation embedment is measured below the undisturbed ground surface

and does not include the depth through loose topping soils that are
commonly added for the garden. The minimum required embedment depth
for the footing is based on the number of floors supported and the soil
condition. If the existing foundation depth is less than 12, 18 or 24 inches
for 1, 2 or 3-story buildings respectively or there is evidence of expansive
soils, an architect or engineer should be consulted. (Fig. 5.13)

FOUNDATION RETROFIT

Several options exist to retrofit the buildings footings and foundation walls:
• capping
• replacement
• parallel systems

Fig. 5.14 Capping simply means that concrete is placed over or alongside the existing
foundation wall. An engineer or architect must specify the reinforcing steel,
anchor bolts and connections between the existing foundation wall and the
new capping. The embedment of anchor bolts and placement of reinforcing
steel generally follow the standards for new construction. For unreinforced
masonry, some of the bricks or stones are removed to help interlock the
capping to the existing wall. To provide proper curing of the capping,
existing brick foundation walls must be well saturated with water before
any shotcrete or gunite is installed over them. Capping is popular when
owners wish to maintain the appearance of masonry foundation walls
(Fig.5.14).

Replacement involves shoring up the building and putting in a complete or

Fig.5.15 Foundation Replacement partial perimeter footing and stem wall. This method is frequently used to
reset houses that fell off their foundation during an earthquake but
remained intact (Fig. 5.15) Shoring can be omitted when replacement is
done in small sections at a time. The latter technique is popular for
occupied structures.

Parallel systems are systems of new structural elements that create a

parallel horizontal force-resisting system at the foundation level. These
systems are designed by an engineer or architect. The new structural
elements are typically located near the exterior walls. A sample system
using large concrete columns is show in Figure 5.16.

***

Fig. 5.16 Parallel System

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 Retrofitting Post & Pier Houses 71

6 RETROFITTING
POST & PIER HOUSES
by James E. Russell, P.E.

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 72 Retrofitting Post & Pier Houses

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 Retrofitting Post & Pier Houses 73

RETROFITTING POST AND PIER HOUSES

This section describes a prescriptive method for the seismic retrofitting of a

specific type of existing housing that is supported along its perimeter walls by a
series of wood posts set on top of individual concrete pier pads. This type of
construction is commonly referred to as a “post and pier” foundation. Post and
pier houses are very susceptible to damage because they have an inadequate
bracing system to resist earthquake forces below the first floor level. An effective
bracing system can be provided by installing new “L” shaped partial perimeter
foundations at each corner, properly connected to the existing first floor framing,
or with a combination of new partial foundations and new braced cripple walls
connecting the existing floor to the new cripple walls.

WHY EARTHQUAKES DAMAGE

POST AND PIER HOUSES

In other sections of this manual you have learned about the importance of a
complete load path to resist earthquake forces and how wood structural panel
sheathing properly nailed to wall framing members with anchor bolts connecting
the wall to a continuous foundation are used to provide that resistance. Two
major weaknesses occur in the load path of houses supported by a post and pier
foundation. One is the absence of sheathed walls below the first story exterior
walls. The other is the absence of an adequate foundation under those perimeter
walls.

A typical post and pier house uses wood posts spaced at 4 to 8 feet apart along the
exterior perimeter walls to support the vertical loads from the floor and walls
above. The top ends of these posts are typically toe-nailed to a wood girder that is
part of the floor framing. The bottom ends of the posts are usually supported on
individual foundation pads, often called pier blocks. These pier blocks are usually
concrete, in a pyramid shape, with a square flat top surface where the post is
supported. The bottom of the post is typically toe-nailed to a wood block
embedded in the top of the pier block. The pier block may or may not have a
larger square concrete pad below it embedded in the ground.

Fig.6. 1 Typical Existing Post & Pier Type House

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 74 Retrofitting Post & Pier Houses

The weakness in this system is that the posts and their top and bottom
connections provide very little resistance to horizontal forces caused by an
earthquake. Without a bracing system, the posts will topple over and the house
will collapse to the ground.

Sometimes wood bracing installed in an “X” or “V” shaped pattern may

interconnect the existing posts. These braces are typically nailed or bolted to the
top and bottom of each post. This type of bracing may have been used as part of a
repair of previous earthquake damage or as an attempt to provide some
earthquake bracing. Although this type of bracing does add some resistance when
compared to posts without any braces, it has too little strength to prevent damage
and possible collapse at this level when subjected to strong earthquake shaking.
(Fig. 6.2)

Fig.6. 2 House with Braced Posts along Perimeter

The weakness in this braced system is primarily at the pier pad level. Here the
connection between the bottom of the post and top of the pier must resist
horizontal loads transmitted by the braces. If a traditional toe-nailed connection
is all that is present, it will quickly be overwhelmed and the bottom of the post
will slide off the top of the pier pad. This results in a loss of vertical support for
the post and leads to a collapse similar to that for an unbraced post system.

Merely adding stronger connections at the bottom of the post such as a metal post
base that is embedded in the pier pad and nailed or bolted to the post is also
insufficient. The forces generated by the braces will then push on the pier pads
and can cause them to slide or possibly overturn. Either one of these two effects
will induce damage into the post and brace system causing it to degrade and
possibly fail. A more reliable and stable retrofit method is needed for post and
pier type foundations than is provided by this type of bracing.

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 Retrofitting Post & Pier Houses 75

NEW PRESCRIPTIVE RETROFIT METHOD

The prescriptive seismic retrofit standards contained in the Appendix of this

manual are applicable to houses that have existing perimeter foundations and
cripple walls. However, these standards require that a completely new
continuous foundation be installed along all the exterior walls, or that a retrofit
using a partial perimeter foundation must be designed by a licensed architect or
engineer and be approved by the local building official. The prescriptive methods
and details described in this section are consistent with the Uniform Code for
Building Conservation (UCBC) and City of Los Angeles standards and use a partial
perimeter foundation system to provide equivalent earthquake resistance below
the first floor level. Permission to use this partial perimeter system without a
specific design prepared by a licensed design professional must always be
obtained from the local building official.

PARTIAL PERIMETER VS. CONTINUOUS FOUNDATION

Where a continuous foundation exists or is added, the primary retrofit
elements used in the UCBC, are also parts of the partial perimeter system.
They include:

Ÿ A foundation constructed with a concrete footing and either a poured

concrete or grouted masonry stem wall.
Ÿ Foundation sill plates and sill bolts with plate washers.
Ÿ Sheathed cripple wall with connections between the wall and floor
framing.

Note that a new cripple wall is not always necessary. A new foundation stem
wall can be extended to the underside of the existing floor framing depending
on how high the existing floor is above the surrounding exterior grade.
Generally, if the floor is more than 3 feet above grade at any point, a cripple
wall will be necessary.

Several additional retrofit elements are needed for a partial perimeter system
that do not occur in the UCBC prescriptive standards. They include:

Ÿ New holdowns at the ends of new sheathed cripple walls.

Ÿ Straps to connect the existing floor framing beams and joists together and
to connect them to the new partial foundations and cripple walls. These
are load path elements needed to compensate for the use of a partial
foundation system compared to a continuous foundation system

Certain elements of a partial perimeter retrofit must be stronger or larger than

those prescribed in the UCBC. They include:

Ÿ Nails used to attach plywood to the cripple wall framing must be 10d
common instead of 8d common.

Ÿ The minimum width of the new footing for a one-story house must be 15
inches rather than 12 inches.

Ÿ All foundation sill bolts must be 5/8-inch diameter instead of 1/2-inch, and
their spacing is reduced from 6 or 4 feet on center to 2-’6” or 2’-0” on
center.

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HOW PARTIAL PERIMETER

EQUALS CONTINUOUS FOUNDATION

The standard retrofit method for a house with an existing continuous

foundation and cripple walls adds wood structural panels in sections along all
the perimeter cripple walls and prescribes a minimum number of sill bolts
connecting the foundation sill plate to the continuous foundation. Except for
houses with existing brick or other unreinforced masonry foundations, the
foundation itself should not need to be strengthened. The foundation’s
primary task is to resist the sliding forces transferred from the foundation sill
bolts into the foundation, and to provide sliding resistance against the
surrounding soil equal to or greater than the sum of all the sill bolt forces.

The bottom surface of the foundation resists these forces by friction between
it and the ground. In addition, the vertical face of the foundation that is
below the ground surface also participates in that resistance by pushing
against the adjacent soil. Sliding friction and lateral bearing against the soil
are the final link in the load path. The amount of surface area a foundation
must provide to resist a specific amount of earthquake load is based on the
characteristics of the soil that determine its sliding and lateral bearing
resistance.

Chapter 18 of the Uniform Building Code provides numerical values for sliding
and lateral bearing resistance of various soil types. The minimum depth,
width and lengths of foundation used in the partial perimeter system are
based on soils having the least resistance. Based on calculations, a continuous
foundation is not required to provide the necessary resistance for average
sized houses up to two stories in height. The minimum foundation consists
of four separate, 15 inch wide “L” shaped footings, one at each of the building
corners.

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Fig. 6.3 Plan View of Partial Perimeter Foundation System
 Retrofitting Post & Pier Houses 77

For a one-story house the length of each leg of the “L” must be 8’-0” and for a
two story house each leg must be 12’-0”. Four sill bolts are required along each
leg of the one story house foundation and five bolts must be provided along
each leg of the two-story house foundation to attach the new foundation sill
plate.

When a post and pier house has its existing floor framing within 3 feet of the
ground surface, constructing a new cripple wall above the new partial
foundation should not be necessary. The existing floor joists and girders can
be directly connected to the new foundation sill plate. However, for floor
framing located higher than this, a new continuously sheathed cripple wall
located above the entire length of each of the new “L” shaped foundations will
be needed. The length of sheathing provided by the partial perimeter system
is equivalent to the length provided by the multiple individual sheathed
sections prescribed in the UCBC retrofit standards for a house with a
continuous foundation and cripple wall.

MOISTURE EFFECTS ON WOOD MATERIALS

The partial perimeter system was specifically developed to address existing
post and pier houses. It recognizes that post and pier type foundations are
commonly found in coastal geographical locations where moisture content of
the air and the ground are very high for much of the year. High moisture
levels can have a very undesirable effect on wood framing members and will
also decrease the strength of nailed or bolted connections in the wood.

One of the most important considerations when retrofitting any wood framed
building is to examine all the existing wood members to be used in the load
path and determine if they need to be replaced because of fungus infections,
commonly called “dry rot”, that destroy the wood fibers. Fungus infections
flourish in wood when it remains wet and recur where it goes through cycles
of wetting and drying. Such conditions are more likely to occur in damp
climates, where post and pier construction is quite common, so particular
attention must be paid to inspecting all existing wood members used in the
retrofit of these houses. Unlike a house with a continuous perimeter
foundation and cripple wall, where the underfloor space is fully enclosed and
weather protected, the underfloor area of a partial perimeter foundation
retrofit is open to the exterior along a substantial length of the perimeter.

Another aspect of wood exposed to damp climates is that the moisture content
of wood does not remain stable. Instead, it undergoes cycles where it is very
moist and then dries. As moisture content changes, wood fibers alternately
swell and shrink and this changes the holding power of nails and the tightness
of bolts in the wood. This condition is addressed in the Building Code by the
use of a “Wet Service Reduction Factor” to reduce the strength of nailed and
bolted connections. All the retrofit connections in the prescriptive partial
perimeter system involving nails or bolts in wood have been adjusted to lower
their strength to 75 percent of normal to account for this effect. This is the
principal reason that 10d nails are needed to attach sheathing to cripple wall
framing, and why 5/8-inch sill bolts are typically used.

The type of sheathing prescribed for use on the cripple walls of a partial
perimeter system was chosen to address the moisture exposure issue.
Exterior grade plywood is specified because it has a very high durability for
exposure to moisture. Plywood rather than Oriented Strand Board, known as
OSB, was selected because OSB has different moisture expansion
characteristics that make it less desirable for use where its moisture content is
expected to vary. For a more detailed discussion of sheathing materials see
the Shear Walls section titled How to Install Sheathing.

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 78 Retrofitting Post & Pier Houses

HOLDOWN ANCHORS ARE NEEDED

The purpose of holdown anchors and their proper installation are discussed in
the part of the manual titled Connections Resisting Uplift Forces and in the
section on Shear Walls. Holdowns are generally needed either when a shear
wall is very tall with respect to its length or when vertical loads from the weight
of the building above, carried by the wall, are insufficient to offset the
overturning force generated by the horizontal earthquake load the wall is
resisting.

In the partial perimeter system, holdowns are used at each end of the new
cripple walls. The reason holdowns are not required by the other prescriptive
standards when retrofitting a house with a continuous foundation, is that the
entire wall length can be engaged as part of the resistance to uplift. Using a
partial perimeter system results in shorter wall lengths and less resistance.

The holdowns shown in Elevations D and E in the Appendix must provide at

least 2,500 pounds resistance to earthquake loading. A variety of products can
provide this capacity. The drawings depict one type of holdown that uses bolts
through the cripple wall end posts and a bolt embedded in the new foundation.
Similar holdowns using special screws instead of bolts may be used if the local
building official approves them and they provide an equivalent minimum
capacity. Other types of holdowns that use nails to connect to the post may
also be used, but typically they require a post height of at least 24 inches. In
addition, all nailed type holdowns have limitations on how close they can be
placed to the corner of a concrete foundation and some may not be able to
provide the minimum required capacity.

Seismic Retrofit Training Fig. 6.4

 Retrofitting Post & Pier Houses 79

In addition to the holdown anchor which connects the new posts at each end
of the cripple wall to the foundation, a strap shown in Elevation D must be
added at each end on the transverse wall sides to tie the new posts to the
existing floor framing above. This is needed because the transverse walls are
parallel to the floor joists and, therefore, do not carry enough dead load to
adequately resist the uplift forces. The strap completes the load path between
the holdown post and the floor framing so that the floor will not lift off the
new cripple wall.

TRANSFERRING FORCES TO
THE PARTIAL FOUNDATIONS

Another unique aspect of a partial perimeter system is that connections are

required to transfer earthquake forces into the new foundations and cripple
walls that are located only at each corner of the building. Essentially, each of
the four new “L” shaped foundations are isolated from each other and
therefore must be connected to the entire length of floor that lies between
them to collect all of the forces in the existing floor system. With a
continuous foundation, this kind of discontinuity does not exist, so none of
the special ties and straps shown in the foundation/cripple wall elevations of
the partial perimeter system are prescribed in other prescriptive standards.

Along the exterior perimeter of the floor, between the new corner
foundations, where the ends of two pieces of an existing floor girder are
spliced over a post, that splice must be reinforced with a new metal strap
nailed or bolted to both pieces (Fig. 6.5). The details in the Appendix show
both the bolted and nailed connection. The girder is used to drag forces along
the edge of the floor into the new cripple wall or foundation at each end of
the wall line and the strap provides this load path connection. Similarly,
where existing floor joists are parallel to the exterior wall, a strap is needed at
any joist splice occurring between the two corner foundations.

Fig.6. 5 New Metal Strap Reinforcement

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 80 Retrofitting Post & Pier Houses

A very important load path connection also must be provided at the end of each
new partial cripple wall/foundation segment. The existing girder must be very
securely connected to the new foundation or cripple wall to fully transfer the
entire load along the edge of the floor that lies beyond the new partial
foundation. When a new cripple wall is not needed, the Elevation E-1 view
shows an anchor bolt embedded in the foundation stem wall secured to an “L”
shaped 12 gage connector. The long leg of the connector is nailed to the girder
(Fig. 6.6).

Where a new cripple wall is provided there are two options. The best solution
is to use the existing girder as the top plate of the new cripple wall. If the
Fig 6.6 Girder Connection to New girder extends as a single piece the full length of the new cripple wall, no
Foundation Stem Wall connection is necessary. However, if the girder has an existing splice location
within the length of the cripple wall, the typical girder splice shown in the
Appendix details must be provided at that location.

If using the existing girder as the cripple wall top plate is not feasible, and it is
cut flush with the end of the new cripple wall, a metal strap connecting the
girder to the top plate of the new cripple wall must be provided as shown in
Elevation E (Fig. 6.7). Because this connection will be subject to both tension
and compression forces, it is very important that the girder end be carefully cut
so that it will tightly fit against the new cripple wall or foundation. Also, to
provide enough surface area to make this nailed splice connection and not
interfere with the row of nailing along the top edge of the plywood, the new
cripple wall top plate must be a minimum 4x4 member instead of using a
typical double 2x4 top plate.

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 Retrofitting Post & Pier Houses 81

One further consideration at this connection is that the vertical face of the
girder and the new top plate must align because the strap should not be kinked
or bent. A misalignment of 3/4 inch or less can be accommodated by installing
plywood of the appropriate thickness on the face of the existing girder to make
it flush with the new top plate. If this plywood shim is installed, the length of
the 10d nails used in the strap must be increased to provide a minimum of 1-
1/2 inches of penetration into the girder. Given the complexity of this
connection, the use of the existing girder for the top plate of the new cripple
wall is the preferred method.

Along the walls where the existing floor joists are parallel to the new
foundation and cripple wall, the same concept of a continuous member applies.
As shown in Elevation D, the end joist must be a single piece that extends the
full length of the new foundation. This end joist must continue at least to the
next perpendicular girder line beyond the end of the new foundation, where it
may be spliced as shown in the Detail G (Fig.6.8).

Fig. 6.8 Strap for Joist Splice

Also along this wall, another strap must be provided to tie together the new
double 2x top plates of the cripple wall where they are interrupted by the
existing girders framed over new support posts. This connection is shown in
Section C (Fig. 6.9).

Fig. 6.9 Strap for Plate Splice

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EVALUATING EXISTING CONDITIONS

The first step in any retrofit project is to carefully examine the existing building
and its site to determine the extent of any unique conditions that exist for that
building on its specific site. Some situations will preclude the use of a
prescriptive method and instead will need the services of an experienced
design professional. The condition of the existing wood framing, particularly
along the perimeter walls must be checked for fungus or insect damage and all
damaged wood must be replaced.

WHEN YOU NEED AN ARCHITECT AND ENGINEER

There are several important limitations on the use of the prescriptive partial
perimeter system. Houses that are on a sloping site, where one side or end of
the building is substantially higher above grade than other portions of the
building, should not use this system. If the ground surface along the perimeter
walls has a slope that exceeds 1 foot vertical in every 10 feet of horizontal
distance, special structural considerations are necessary to accomplish an
effective retrofit. Some sloping sites may need to be evaluated by a
geotechnical engineer to establish the potential risk of landsliding or other
forms of ground failure.

Houses that are over two stories in height or that exceed the maximum width
and length dimensions shown on the prescriptive plan are too large to rely on
prescriptive methods to provide adequate earthquake protection. The
maximum height of new foundations are limited to 4 feet 6 inches measured
from the bottom of the footing, and new cripple walls are also limited to a
maximum of 4 feet in height. Retrofitting buildings where these limits are
exceeded requires the professional services of a licensed architect or engineer.

The prescriptive method also assumes that the building is not located on soils
that are subject to liquefaction during earthquake shaking or where highly
plastic clay soil exceeds 25 feet in depth. Maps indicating locations of
liquefiable soils are available in some cities and counties, and the local building
departments will usually be aware of or have special foundation requirements
in areas of highly plastic clay soils.

The prescriptive method should not be used for buildings located within 5
kilometers (approximately 3 miles) of a known active earthquake fault. Maps
have been published by the International Conference of Building Officials for
the entire State of California identifying these locations called “Near Source”
areas. The 1997 Uniform Building Code requires that all buildings inside these
areas be designed to resist larger forces than were used to develop the details
used in the partial perimeter foundation system.

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PARTIAL PERIMETER RETROFITS REQUIRE

MORE ATTENTION TO DETAIL
Constructing a partial perimeter foundation system for a post and pier type
house, involves much more work than installing new sheathing, foundation
sill plate anchors, and miscellaneous framing anchors, which is typically all
that is needed for houses with an existing continuous foundation and cripple
walls. Prior to beginning to excavate for the new concrete footings, a system
of shoring must be installed to adequately support the house where some of
the existing posts and piers must be removed. Proper shoring is not only a
major safety concern but it also serves to prevent damage to existing interior
and exterior finishes like plaster that are intolerant of even small changes in
the level of the supporting floor.

Preparing to pour the new concrete foundations involves accurately placing

new anchor bolts and holdowns as well as installing the needed reinforcing
steel. The formwork for the vertical stem wall must be strong enough to
contain the concrete as its is poured and vibrated to form a solid mass
without voids. If the optional masonry stem wall is used, proper knowledge
of mixing and placing mortar are essential to its proper construction.

If the existing floor level is close enough to the ground, a cripple wall may
not be needed on top of the new foundation wall, but in this case the top of
the new foundation must be very carefully leveled before it is poured. All of
the remaining work, including installing a new cripple wall if required,
requires good carpentry skills to provide all of the additional nailed and
bolted connections this system requires.

BUILDING INSPECTION REQUIREMENTS

The local building inspection authority will determine the exact number and
types of inspections needed during the construction. Some jurisdictions may
require a preconstruction inspection to determine if a prescriptive method is
appropriate or if conditions exist that need the services of an architect or
engineer. Typically inspections are performed prior to pouring any concrete
or grouting of any masonry. In addition, a framing inspection will be needed
during which the nailing of any cripple wall sheathing, the proper
installation of plate washers on sill bolts and the installation of holdowns
and other connections will be verified. A final inspection may also be
necessary to determine that exterior weather protective surfaces have been
properly installed over the new cripple walls.

SEISMIC RETROFITTING FLOOD-PRONE STRUCTURES

Some elevated residential structures will be located in both earthquake and

flood hazard zones. For these buildings, seismic retrofit work must also be
compatible with the latest standards for flood construction as contained in
Part 59 of Title 44 of the Code of Federal Regulations.

FEMA’s National Flood Insurance Program produces community maps that

designate special flood hazard areas inundated by 100-year floods. The local
community map repository should be consulted for complete information on
base flood elevations before starting any new construction of partial or full
perimeter foundation walls.
***

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 Non-Structural Elements 85

7 NON-STRUCTURAL ELEMENTS

Edited by
Timothy P. McCormick, P.E.

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NON-STRUCTURAL ELEMENTS

CHIMNEYS

The first nonstructural item to be considered is the chimney. There are two
types of chimneys:

1. Masonry- reinforced or unreinforced

2. Stud Framed with metal flue.

Stud framed chimneys can be made with wood or metal studs.

Many older residences have chimneys constructed with unreinforced masonry

such as brick or stone. Because these chimneys are not reinforced with steel and
their mortar tends to deteriorate over time, they usually have little strength to
Fig. 7.1 Reinforced Chimney Failure
resist earthquakes.

Even moderate earthquakes can cause extensive chimney damage. The portion of
the chimney above the roofline is usually the first part to fail. Chimneys can
break apart all the way to the firebox (Fig7-1). Whether masonry chimneys are
reinforced or braced to the roof structure, few construction methods have
improved their performance during earthquakes (Fig. 7.2).

Cracks in the chimney flue liner allow hot gases to leak into the wall or roof
framing and start a fire. Therefore, a thorough inspection of the chimney after
any significant earthquake will be necessary to identify any hidden or less
obvious cracks. Video camera inspections and smoke tests may be required.

Question: What can you do with “unreinforced” brick chimneys?

Answer: There is one basic method for dealing with unreinforced

brick chimneys: Fig 7.2 Braced Chimney Failure
REPLACE THE CHIMNEY!
Bracing of chimneys has been ineffective in preventing their failure during
earthquakes. While replacement of the chimney is a costly solution, it is also the
most effective technique to prevent damage (Fig. 7.3). In some cities, such as Los
Angeles, full or partial replacements may by the only accepted method. Always
check with the local building department for details and information.

Partial replacements remove all of the brick above the firebox. The chimney is
then replaced with a reinforced masonry chimney or metal stud framed chimney
with a metal flue. This method has often been used to repair earthquake
damage. This less-expensive method removes most of the potential problem.

Fig. 7.3 Chimney Replacement

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BUILDING APPENDAGES
All portions of the building, including those attached to the outside, experience
horizontal earthquake forces. Most houses either have a porch, a deck, an
exterior staircase, or other type of framing that is attached to the outside of the
house. Few of the appendages are stiff or strong enough to resist the earthquake
forces by themselves. Therefore, they need to be braced or adequately attached
to the house to resist the earthquake forces.

If the appendage is not braced on its own or adequately attached to the house, it
will collapse during an earthquake. This creates a falling hazard if the
attachment is a roof. Since most of the attachments are located near the doors,
Fig. 7. 4 Porch Roof Collapse.
it can also create a hazard for exiting the house if the attachment collapses.

Building appendages are usually connected to the house using nails, lag screws,
braces or straps.

Nails are typically used to connect the existing house to the building framing for
resisting gravity loads. However, nails may not be a sufficient method of
attaching for horizontal type forces that also cause withdrawal (pull out).

Lag screws connect a roof or porch to the house in order to resist lateral
earthquake forces. An architect or engineer may specify lag screws to attach the
ledger to the framing of the house. The lag screw must be anchored into a stud
Fig. 7. 5 for it to be effective. It will be necessary to drill pilot holes to locate the studs.

Straps are used when a simple attachment detail is not adequate to hold the
porch or roof to the house. If the length of the appendage is more than its
width, the architect or engineer may require straps at the ends of the appendage
to resist the horizontal swaying of the appendage. This is similar to the
requirement for holdowns for a shear wall.

Straps or brackets are used to prevent roof overhangs or elevated porches from
becoming unstable if they sway too far during the earthquake. If the swaying is
too great, the columns or posts supporting the outside ends will become
unstable or detach. Many of the posts have little or no attachment to the roof or
floor deck.

An architect or engineer may specify a strap or bracket to allow the post to

move without separating from the roof or floor deck. This does not increase
the strength of the post to resist earthquake forces. The only way to increase
the strength of these posts is by adding diagonal braces. If the braces are not
installed correctly, they will not be effective (Fig. 7.5).

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VENEER

Another nonstructural item is veneer. Many houses have a layer of brick or

stone veneer attached to the outside face of the exterior walls. Older houses
may not have any attachment of the brick veneer to the wall except for a layer of
mortar between the brick and the building paper.

If the attachment of the veneer to the house framing is not adequate, the bricks
may become dislodged during the earthquake causing the bricks to fall (Fig. 7.6).

New houses will have the veneer attached to the framing with wire ties
Fig. 7.6 Fallen Brick Veneer
embedded in the mortar joint. Even with wire ties in place, they may not be able
to adequately restrain the bricks from falling out because they are:

Too widely spaced and the bricks may fall out between the ties.
Corroded or deteriorated.
Attached to the wall with nails that are too small or short.
Mortar may have deteriorated so that the tie will pull out of the mortar
joint.

Mortar, especially older mortar, has very little strength for resisting earthquake
forces, because mortar deteriorates year after year if not well maintained. When
the spacing between the ties is too far, then the force on the ties as they try to
restrain the bricks from falling out could exceed the strength of the tie.

Question: What can you do to limit the hazards associated with brick or stone
veneer?

Answer: In order to limit the hazards associated with a brick or stone

veneer, you should:

1. Add new anchors for the veneer.

2. Remove the veneer.
3. Do nothing unless the architect or engineer and owner decide that
the veneer is a hazard.

The first option is adding additional restraints to the veneer to re-anchor the
bricks or stone to the framing. The bracing must be spaced regularly in both
horizontal and vertical directions. The restraints are intended only to prevent
collapse of the entire section of the veneer. Since it is not practical to add
restraints at every piece of veneer, adding the ties is not a guarantee that all of
the veneer will remain intact during the earthquake. Some stones or bricks may
become dislodged and fall during the earthquake shaking. The ties are intended
only to prevent collapse of the entire section of the veneer.

The second option is the most effective: remove the veneer. If the bricks are
removed, the area must be replaced with an exterior wall covering. The
replacement should be weather tight and securely attached to the building
framing.

The third option is to leave the veneer. The owner, engineer, or architect may
decide that a section of veneer is not a problem.

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GAS LINES

Gas lines are a nonstructural item that can pose a serious risk if damaged during
an earthquake. Fires often erupt following an earthquake because of broken gas
lines. Any spark can ignite the leaking gas and cause a potentially violent
explosion and fire. Installing automatic shutoff valves on the gas line can help
prevent these catastrophic fires. These valves can be attached on either the inlet
or outlet side of the gas meter for the building (Fig. 7.7).

The earthquake shaking causes the valve to stop the flow of gas. Most of the
time, the leaking gas dissipates so that there is less chance of a large quantity of
gas building up where a spark might develop. If there is a break in the line and a
spark develops, the gas remaining in the air can still start a fire. The shutoff
Fig. 7. 7 Automatic Shutoff Valve
valve makes sure that there is no additional fuel to feed the fire so that it is less
likely to get out of control.

In addition to the plumbing work required to put the valve on the gas line, the
valve must be rigidly attached to the building. If the valve is not rigidly attached,
someone could accidentally hit the valve, causing it to trip and shut off the gas
for the house.

In some jurisdictions, shut-off valves may no longer be an option. The City of

Los Angeles requires automatic shutoff valves to be installed when the cost of
alterations to a house exceeds $10,000 or upon sale of the residence.

Currently, there are several manufacturers that make automatic shutoff valves.
Any shutoff valve should be checked to verify that it meets the American Gas
Association’s standard. At the present time, this is the only standard available
for shutoff valves.

Installation requirements for shutoff valves vary by manufacturer. Some

manufacturers require that only approved contractors install the valves. Others
allow anyone to install them.

Installing shut-off valves may require a plumbing permit. Check with the
building department to find out their requirements for permits and
approved manufacturers.

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WATER HEATERS

One of the most common causes of fires associated with earthquakes is the
rupture of gas lines when the water heater overturns. Water heaters are
usually very tall, heavy (because they are filled with water) and narrow. These
characteristics make them vulnerable to tipping over during an earthquake
and starting a fire by breaking the attached gas or electrical line (Fig. 7.8).

Water heaters are usually set on the floor, or on a pedestal. Until recently, Fig. 7.8 Overturned Water Heater.
codes did not require water heaters to be braced. The earthquake shaking
produces lateral forces on the water heater at its center of gravity. The higher
the center of gravity, the less force will be necessary for the water heater to
overturn.

Question: How can you prevent a water heater from overturning?

Answer: To prevent the water heater from overturning:
1. Water heater must be braced at the top and the base.
2. Rigid connectors for the heater gas and water piping must be
replaced with flexible connectors.

Because earthquake forces can make a water heater shake in all directions, a
water heater must be braced at both the top and bottom. New water heaters
are installed on platforms.

The top brace is used to prevent the water heater from tipping over. The
bottom brace is necessary so that the base of the water heater will not move
far enough to shift and slide out when the earth is shaking. The State of
California has approved several typical details (Fig.7.9). There are other pre-
packaged systems that have been approved (Fig.7-10).
Fig. 7.9 Braced Water Heater
In the typical details for the smaller water heaters, plumber’s tape is
commonly wrapped around the top and base area of the water heater. Struts
are attached to the plumber’s tape and then anchored into the wall framing
using lag screws. EMT conduit works well as a strut. The ends can be
flattened and drilled to attach the lag screw or bolt. Sample details are
included in the Appendix.

For strapping of the water heaters, it is critical that:

• Plumber’s tape or strap is wrapped all the way around the water heater.
• Lag screws are anchored into a stud. The stud must be one that is
continuous from the sill plate to the top plate.
• Struts are used to brace the water heater to straight sections of walls.
Plumber’s tape only works in tension and has no strength to resist
compression.
• Lastly, gas and water connectors must be replaced with flexible
connectors and the flue should be braced. Flexible connections allow the
water heater to move several inches without breaking.

During an earthquake, a braced water heater will still make some movements
because of the slack and stretching of the straps. Even if the water heater
moves only a small distance, the connectors may break if the connections into
Fig. 7.10 Pre-packaged System

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the water heater are rigid. The break can cause the water to flood the area or
more seriously, cause a gas leak.

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TANKS

A water heater is a type of water storage tank. Many houses have tanks to
store liquids such as water or fuel. Natural gas is also stored in tanks. Usually
these tanks are located outside the house and are raised up off of the ground.
Like a water heater, these tanks are vulnerable to tipping over. Tanks that
contain any type of fuel are a concern because if they tip over and spill their
contents, they can ignite and cause a fire. The seismic retrofit of structural
elements like elevated tanks or roof mounted equipment requires the
expertise of an engineer or architect.

Question: What are the most important considerations when dealing

with elevated liquid storage tanks?

Answer: The two important considerations for elevated liquid storage

tanks are:

1. Brace the legs of the tank.

2. Provide a large enough concrete pad under the tank.

Bracing the legs of the tank is needed for the same reason as bracing the
cripple wall of a house. If the tank sways too far during the earthquake, the
legs can become unstable and the tank will fall over. Braces need to be
provided in both directions on each side of the tank (Fig. 7.11).

The concrete foundation pad is needed below the legs of the tank to spread
out the overturning force on the soil to prevent a soil failure that would cause
the tank to tip over. A single pad under the entire tank is preferred.

When casting the pad footing, be sure to cast in anchor bolts for attaching the
legs of the tank to the concrete. It is usually sufficient to place welded wire
fabric in the footing to prevent cracking but be certain it remains in the center
of the concrete during the pour.

Fig.. 7. 11

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OTHER TYPE OF NONSTRUCTURAL ITEMS

Houses contain many other items that can be a hazard to the occupants during
an earthquake. The two most important types of hazards are:

- Items that may fall and block exits.

- Items that may fall and injure someone.

Question: What are some examples of other non-structural elements?

Answer: Some examples of other non-structural elements are:

1. Architectural items like windows, doors, and roofing.
2. Mechanical and electrical equipment like furnaces, roof or window
mounted air conditioners, and chandeliers.
3. Furniture like book shelves, file cabinets, refrigerators, and wall
hangings.

Fig. 7.12 Earthquake Damaged Air Conditioning Units

FEMA’S NON-STRUCTURAL MANUAL

It is easy to brace most nonstructural items and to prevent them from falling
over during an earthquake. For more information about how to brace
nonstructural items, the Federal Emergency Management Agency has a
reference manual called:

“Reducing the Risks of Nonstructural Damage: A Practical Approach”.

This guide is available through FEMA or at government bookstores. It has

recently been updated to include findings from the Northridge Earthquake.

This nonstructural guide includes many standard details for bracing typical
nonstructural items in a house or business. A homeowner or a contractor can
install most of these techniques.

Some of the more complicated items have been designated as “Engineering

Required “. Bracing of these items are designed by an engineer because
engineering expertise is needed to calculate the expected earthquake force
generated by the item and the structural adequacy of the bracing that supports
the item.
***

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8 SAFETY & LEGAL

Legal by George D. Calkins, Esq.

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SAFETY ON THE JOB SITE

Safety on the job site is important for both you and your employees. Since
most retrofit work is done while the house is occupied, safety is also a
concern for the people living in the house. Here are some important safety
tips for protecting all of the people that could come into contact with the
project:

Wear Protective Clothing

Always use respirators whenever you’re working in a crawl space, performing
demolition work, drilling holes in wood or concrete, or using adhesive
anchors like epoxy. Dust masks are not a substitute for a good respirator.
Everyone should wear one. You need to check with the manufacturer of the
respirator and the manufacturer of any chemicals used to be sure that the
respirator is rated for your job. (Fig. 8.1)

Hard hats should be worn at ALL times, particularly in tight crawl spaces
where it is easy to bump into a floor joist or a protruding nail. Gloves should
be worn when working with adhesives like epoxy to avoid skin damage.

Read and Follow MSDS

Material Safety Data Sheets (MSDS) provide essential information on the safe
use of chemicals on a job site. OSHA requires that the MSDS sheets be
available for any chemicals that are present at the job site. MSDS sheets can
be obtained from the manufacturer of the chemical.

Rope Off Dangerous Areas

Use caution tape to keep people from straying into areas that may be
dangerous. Put barriers up at all times, particularly during breaks and at the Fig. 8.1 Proper Respirator
end of the day.

Do Not Disturb Asbestos

Houses built before 1980 may have asbestos insulation, particularly on
heating ducts. If it likely your will disturb the asbestos, notify the owner to
hire a qualified professional to remove it before your begin the retrofit work.
Otherwise you may be liable for a very expensive clean-up and the
contractor’s state license board may discipline you (Fig. 8.2).

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Fig. 8.2 Asbestos Heating Duct in Seismic Retrofit Work Area
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PART 1 SEISMIC RETROFIT

LEGAL PERSPECTIVES
By now you have reviewed materials in this manual relating to the
specific means and methods for conducting residential seismic retrofit projects.
You should be aware that there are important legal considerations relating to
how seismic retrofits are conducted. Contractors should be aware of the
following legal principles in their day-to-day pursuit of seismic retrofit projects.

In the Appendix of this manual is a form contract, which can be used as a

reference in preparing a seismic retrofit contract. The form must be adapted to
satisfy the unique requirements of each contractor's practice. It is intended to
be only a resource for contractors, and not a final contract form.

EARTHQUAKE LEGAL BASICS

It makes sense to perform your construction assignments in the best

manner possible in order to maintain and promote business. It makes obvious
sense from a legal perspective as well, as you'll see hereafter in this
presentation. Contractors are responsible for performing their construction
work correctly: A contractor is legally responsible for any damages resulting
from his/her negligent or substandard performance of his/her work. There has
been a profound liability revolution in California during the last 20 years arising
from poor construction of homes and condominiums. Owners and their
insurance companies have proven that they will pursue contractors to collect
their repair costs, if contractors perform their work contrary to the plans,
specifications and established industry standards.

The basic contractor standard of care includes the obligation to

understand and comply with applicable law, code provisions, regulations and
industry standards of care as well as with the contract, plans and specifications
applicable to your project. That duty includes the obligation to understand the
impact of earthquake forces upon homes, as well as the design and
construction techniques to appropriately address the impact of earthquake
forces upon homes.

• Duty To Understand Earthquake Forces

A contractor is legally responsible to understand earthquake caused

failures, including:

a. Base shear;

b. Earthquake overturning forces;

c. The lack of stability imposed by earthquake forces; and

d. Earthquake caused torsional rotation upon homes.

A contractor has the duty to properly perform his/her seismic retrofit work
as to both the gravity and horizontal resisting systems in homes.

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A contractor has an obligation to understand the following methods to

minimize earthquake failures:

a. Shear walls;

b. Brace frame methods of construction; and

c. Rigid frame construction methods.

• Agencies Have No Liability For Inspections

Contrast this basic contractor duty to the lack of any government legal duty
to properly inspect the building process. California Government Code Section
818.6 provides a basic immunity for local inspection agencies as follows:

A public entity is not liable for injury caused by its failure to make an
inspection, or by reason of making an inadequate or negligent inspection
of any property, other than its property . . . for the purpose of
determining whether the property complies with or violates any
enactment or contains or constitutes a hazard to health or safety."
(Emphasis added.)

A frequent misconception of inexperienced contractors is to believe that

government agencies are a source of responsibility concerning faulty construction.
There is no claim for negligent inspection against public agencies or their
employees. Public employees are equally liable with contractors for their
negligent conduct, other than negligent inspection of construction (See California
Government Code Section 820).

• Prescriptive Standards

There are two basic ways to design residential framing. The first method is
to have an engineer or architect create the design. The second is to follow
"conventional construction" provisions of the local building code. Similarly, there
are the same two ways in which a seismic retrofit can be designed for light wood
framed homes. An owner or contractor could hire an architect or engineer to
design the retrofit. Many homes have complications that will require an
engineer's retrofit design.

Often, what is needed for basic retrofit work are simple things like
foundation bolting and plywood shear walls that don't necessarily require the
expertise of an architect or engineer. Some communities offer classes for
homeowners on how they can perform seismic retrofit work themselves. For
these reasons, engineers and public agencies have developed general guidelines
that can be followed to complete seismic retrofits. These guidelines are often
called "prescriptive standards".

If a home satisfies certain clearly defined requirements, a contractor could

use the prescriptive standards adopted by the relevant local agency instead of a
plan specially prepared by an engineer or architect. HOWEVER, YOUR LOCAL
BUILDING DEPARTMENT MAKES THAT DETERMINATION, and . . . not you.

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Therefore, before starting a seismic retrofit project, a contractor is well

advised to check with the local building department to see if it has adopted a
seismic retrofit prescriptive standard. If such a standard exists, find out if the
building department is satisfied that the specific home in question meets the
requirements of the standard. When in doubt, consult the appropriate design
professional and/or building official to make the decision as to whether a seismic
retrofit can proceed by prescriptive standards, or whether a special plan by a
design professional is needed.

It is important to remember that the goal of a seismic retrofit program is

not an "earthquake proof home". Rather: the contractor is obviously targeting
improved safety and performance of the home in an earthquake. It should never
be stated that the home will be "earthquake proof", following a seismic retrofit
program.

California law at Business and Professions Code Section 5537 does not
prohibit any person from preparing construction plans, drawings or specifications
for a single family home or multiple dwelling (no more than four dwelling units),
of wood frame construction. That is, if the structure does not deviate from
"substantial compliance" with conventional framing requirements for wood frame
construction found in the most recent additional of Title 24 of the California
Code of Regulations, as defined by the applicable building code of the local
jurisdiction where the structure is located. Otherwise, the local jurisdiction will
require preparation of specific plans, drawings, specifications and/or calculations
for construction of the home and/or seismic retrofit, under direct supervision of a
licensed architect or registered engineer.

• Preconstruction Conferences

Preconstruction conferences can be a useful tool to avoid legal difficulties.

Under California Health and Safety Code Section 19872, an enforcement agency
may require that a contractor participate in a preconstruction conference. This
conference may be held prior to completion of plan checking concerning
submitted plans and specifications or receiving a building permit. The purpose of
the preconstruction conference is to review the plans to insure consistency of
building code interpretations, and the adequacy and sufficiency of plan details. It
is generally a useful practice for all concerned that local agencies require
preconstruction conferences.

• Statutes Of Limitations

A contractor should understand the applicable "statutes of limitations" that

apply to their liability exposure for seismic retrofit and other construction work.
There is a three year basic statute of limitations that applies to claims for damage
to real property arising from construction defects, following the time that an
owner knew or should have known that his/her property was damaged as a result
of the contractor's work. There is a two-year statute of limitations applicable to
recovery of damages arising from errors in design of construction projects. There
is a four-year statute of limitations for actions based upon breach of a
construction contract, whereby a lawsuit must be brought within four years of
damages arising from breach of the contract.

The law provides a four year statute of limitations for recovery for "patent",
or obvious, defects in construction, pursuant to which an action must be brought
within four years after "substantial completion" of the home that has the so-called
"patent defect". Likewise, an owner has ten years within which to file an action
for "latent", or undiscoverable, defects (without the aid of an expert), arising from
construction of the home following substantial completion.

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• Unlimited Exposure For Personal Injury

It should be understood that a contractor has a virtually unlimited exposure

period as to claims following completion of construction for personal injuries or
death arising from faulty construction. If construction of a project causes injury or
death, an action can be brought for personal injury more than ten years following
substantial completion of the project, but within one year following the actual
injury and/or death to the person.

There is an apartment building in Los Angeles that collapsed during the

Northridge earthquake which had been substantially completed in the early 1970s.
However, an action was permitted against the original developers, engineers and
contractors who built the project, even though the project had been substantially
completed almost 24 years before the events resulting in the 1994 collapse of the
apartment building. The length of time during which a contractor is exposed to
legal action should provide dramatic incentive for contractors to carefully monitor
the quality of their work on any given project.

SHEAR WALLS
• The “Code Minimum Syndrome”

It should be understood that a contractor building a home to code

requirements is sometimes not enough. The building code often follows changes
in engineering knowledge and construction practice by a matter of months or
years. Consequently, a local building code does not immediately track changes in
the local community standards of care applicable to construction, as they evolve.

An example is the changing "values" allowed for drywall and stucco

construction. Immediately after the 1994 earthquake, sound engineering practice
required less strength value to be allocated for drywall and stucco shear wall
construction than permitted under the then existing code. A contractor is
responsible to know, and follow, the evolving standards of practice in all of the
various areas of construction in which he/she is engaged, regardless of whether the
local code has caught up.

• Use Prescribed Wood And Shear Wall Dimensions

It is important that a contractor use the type of wood specified in the plans
for construction of framing, including shear walls. If the plans call for use of
Douglas Fir, then a contractor should not use Hem Fir. If the plans call for one half
inch or five ply plywood then that is the type of plywood that should be used by
the contractor for the construction of shear walls.

By the same token, contractors should not change the shear wall length or
locations from that specified in the plans without the approval of the engineer.
Nor should a contractor change the nail sizes or spacing from that specified in the
plans and specifications. Any such deviation, would constitute a violation of the
standard of care established in the plans and specifications, and the local codes
and established building practice, and would subject the contractor to liability
exposure.

If a contractor cannot install the specified length of shear wall, then he/she
should stop and call an engineer to design an appropriate resolution to the
problem. If the contractor installs a shorter length of wall (or even splits the shear
wall into two smaller components) the contractor will likely have reduced the
shear capacity of the wall, and it may be too flexible and violate the applicable
standard of care.

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• Coordination Is Important

Coordination among the trades is essential to effective construction of a

project. A contractor should not allow plumbing penetrations or electrical
penetrations through shear walls without the approval of an engineer and/or the
local building department. Contractors have a duty to be sure that the trades
coordinate their work effectively as well as comply with the applicable plans, code
and other standards of care

• OSB

Oriented strand board ("OSB") or other composite wood product panel may
not be equivalent to plywood for a particular location (i.e., "wet" climates). While
recent code changes have caused OSB to be deemed "equivalent" to plywood in
most instances, OSB may not be appropriate in environments where there is
substantial moisture in the air, such as locations near major bodies of water.

• Plywood Strength

The thickness and grade of plywood (as well as the size and number of
fasteners securing the sheathing to the framing) will determine the strength of a
plywood shear wall. It is prudent to always check with the local building
department and/or engineer before substituting any sheathing material. If a
contractor substitutes any material for the specified plywood, he/she may well be
liable if that replacement material does not have the strength to resist earthquake
forces possessed by the originally specified material.

• Use Specified Nails

A contractor should review the contract documents carefully and provide the
proper nail size for each location specified in the plans. The contractor should
not use nails other than those specified, without checking with an engineer
and/or the local building department. If nails other than common nails are used,
the connections will usually not satisfy strength requirements and will be
considered to be below the applicable standard of care in many instances. The
contractor should not use nails with clipped heads or apply coating to fasteners
prior to installation, as those conditions can reduce the nail's ability to resist pull
out.

Contractors should not substitute screws and staples for nails, unless an
engineer has specified a screw or staple type fastener, or the substitution has
been reviewed and approved by an engineer.

If the plans call for use of a ten-penny common nail, then contractor should
put those in and not an eight-penny box nail. There is a substantial "strength"
difference between ten-penny common and eight-penny box nails ( 63 lbs. vs. 94
lbs.). See the chart in the Appendix of this manual for different nail sizes.

• Nailing Patterns

If the contractor does not follow the nailing directions set forth in the plans,
he/she will reduce the capacity of the wall and expose the contractor to future
liability if the wall fails.

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• Economics Of Framing Affect Quality

A note about the "economics" of framing: piecework is often the method of

payment for those workers involved in the framing of homes. Such piecework
payment could be dangerous. The "typical carpenter" will be more concerned
with the speed of his/her work and that will often lead to loss of control of nailing
and general framing quality. Likewise, poor training and supervision can
substantially increase the risk of liability exposure to a contractor who pays
his/her workers on a piecework basis. A good contractor must resist the economic
temptation and tendency to downplay the quality of supervision, under such
conditions of piecework compensation.

• Nailing Patterns And The Liability Revolution

It must be remembered that a substantial contributor to the liability

revolution in California has been the failure of contractors to pay attention to the
nailing pattern and size requirements set forth in the construction plans and local
codes. Contractors are held to performing at least the code standard of care in
their work, and must be sure that the framing pattern requirements stated in the
local codes and the relevant project plans and specifications are followed in the
construction of seismic retrofit projects.

A contractor should not substitute hardware from a manufacturer that has

not been approved by the local building official and/or engineer.

CONNECTIONS

• Holdowns

A contractor should remember that for a hold down assembly to have the
required strength, the stud bolt holds in the end stud or added post must not be
oversized, and the stud bolts should not be counter sunk into the end stud or
post. Also, the stud bolts should be fitted with washers and tightened. Lag screws
should not be used as a substitute for through bolts, because the strength of lag
screws may be less than the strength of through bolts. By engaging in such
conduct, the contractor is again subjecting him/herself to liability exposure should
the structure fail.

• Beware Of Nonstandard Framing

In evaluating a structure before undertaking a seismic retrofit, the contractor

should contact an engineer when he/she sees a non-standard framing assembly in
the existing structure, since standard details may not work in such a structure.

"Balloon framing" is one type of non-standard framing. Balloon framed

structures were common in the Eastern United States between about 1850 until
1970. Some older buildings on the West Coast may have such balloon framing.

With balloon framing, the intermediate floor framing joists are face-nailed to
the studs. When retrofitting balloon framed houses, the same principles for
creating load paths apply. Blocking and connectors will be required at the roof
and intermediate floor lines to connect the floor sheathing to the shear walls. For
the connections to be effective, additional blocking must usually be added
between the floor joists to provide shear transfer nailing at the top and bottom of
the sheathing. A contractor will be held to this heightened standard of framing
care in such circumstances.

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• Proper Anchor Bolt Assembly

When contractors are installing anchor bolts, washers and nuts are required
on all anchors. Some building departments and engineers may require the use of
square cut plate washers instead of round malleable plate washers. The
contractor should make sure he/she knows which type of washer is required.

If the hole in the foundation sill is oversized, it will allow the sill to slide
before pushing against the bolt. This small amount of unwanted movement
during an earthquake can be enough to cause damage, usually in the form of
slipping to the sill, and will thereby expose the contractor to liability. A
contractor should never counter sink the washer and nut if the bolt is too short.
The anchor bolt will not be effective, and a contractor will be liable for installing
it incorrectly.

A contractor should likewise not drive lag screws into the framing with a
hammer. He/she should always screw them into place. There are many types of
anchor bolts and plate connections available. Before installing such materials, the
contractor should check with the building department and project engineer to
verify that the hardware used has been approved.

• Protection From Fumes

The contractor should always protect him/herself and his/her workers from
fumes when using chemical epoxy anchors. The contractor should check with the
manufacturer and the building department to find out, if an epoxy is appropriate
for use and as to what precautions should be used, such as which respirator
filters, protective clothing and ventilation will be needed. The contractor should
also check the manufacturer's literature for information on the flammability of
the epoxy.

FOUNDATIONS

• Need Effective Communication

The most significant legal consideration concerning the foundation areas of

homes during seismic retrofit projects is the need for effective communication by
contractors with their customers. Frequently contractors will observe conditions
other than those directly relating to their scope of work on the seismic retrofit
when they work under a home. They will see in many instances water leak
conditions, plumbing leaks, drainage problems, termite infestations, deterioration
and other conditions not specifically relating to their scope of work on a seismic
retrofit. Contractors must communicate to the owner such observed different site
conditions. Otherwise, he/she may assume legal responsibility for such
conditions.

• Prejob Walk Through

This heightens the importance of the prejob walk through which should be
conducted by contractors before they bid on seismic retrofit projects. Contractors
who fail to communicate the conditions that they observe risk liability as well as
risk inability to get paid for extra work arising from such conditions that should
have been observed and communicated.

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• Identify Differing Site Conditions

Leaking plumbing, leaks in roof areas, running surface water, as well as

hidden wood rot and split bottom framing members must be called out and
excluded from a contractor's work on a seismic retrofit. Such areas should also be
specifically included in the contract to set the scene for more compensation as a
change order. Such work would be outside of the traditional seismic retrofit scope
of work.

The bottom line is that notification to the owner of existing conditions is

essential for the contractor to avoid liability, and for the contractor to get paid for
extra work arising from such observed conditions.

• Legal Standards And Manufacturers' Specs

It is important to understand that standards of care applicable to contractors

can be partially defined by manufacturers' instructions for installation of their
products. Manufacturers will often attempt to shift the risk of installation of
their products to the contractor by prescribing specific methods for installation of
such materials. Courts will sometimes use such manufacturer's specifications as a
guide in measuring the legal responsibility of the contractor, along with the
applicable contract provisions, code and the project plans.

• Continuity Of Foundation

Foundations in the vicinity of all shear walls should be continuous. The

contractor should check with an engineer or building department to determine
whether any lack of continuity in the foundation will affect the ability of the
foundation to resist earthquake loads. It may be necessary to install new footings
under the outside walls of the house and connect them to the existing
foundation. Again, a contractor should contact an engineer where such may
appear to be required.

• Shoring

A contractor must provide adequate shoring for temporary construction

access before removing cripple stud walls, so that the home is not damaged
during construction. Again, the contractor will be held to the standard of not
weakening the structure while attempting to improve it.

• Concrete Quality And Owner Consultation

The strength of the concrete in the foundation can also deteriorate due to
reaction of the soil with the concrete over time. This usually can be seen if the
surface of the concrete is rough and appears to have been “eaten away”. An
engineer should check this before the contractor installs a retrofit.

It will be the obligation of the contractor to make certain that an engineer is

consulted, or at least that the owner should be informed of the need for such
consultation, and the contractor should document this communication to the
owner. Frequently a contractor will encounter the desire of an owner to restrict
his/her budget and to lower the cost of construction.

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NONSTRUCTURAL ELEMENTS

• Care In Specification Of Bracing

The contractor should not take responsibility for recommending bracing that
could be damaged during an earthquake. If an engineer or an architect specifies
bracing, the contractor should make sure that his/her contract says that he/she is
not responsible for future damage arising from such construction.

A contractor should not take responsibility for specifying the straps or braces
for such things as carport covers and/or water heaters. An engineer should be
consulted to design such installations. Likewise, a contractor should not take on
potential liability by recommending any particular type of veneer construction.
That should be the responsibility of an engineer and/or architect.

A contractor should not use a system or detail in his/her construction

activities that has not been approved by the relevant local building official. A
contractor should always check with the local building department to be sure as to
whether a particular system or detail has been so approved. This is particularly
applicable to bracing of water or propane tanks, water heaters, chimneys, and the
like.

End of Part 1

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PART 2 A CONTRACTOR'S LEGAL

RELATIONSHIP WITH THE CUSTOMER

Seismic retrofit contractors need to understand certain basic legal concepts

applicable to their relationship with their customers. First and foremost is the
need for a contractor to be an expert at communications with his/her customer,
subcontractors, the applicable local building department, his/her workers, the
architect and/or engineer, and the suppliers who provide material for any seismic
retrofit project.

The key is for the contractor to have an ability to talk with people and to
coordinate his/her activities to maximize his/her legal position on any project.
Also, the contractor should keep accurate records of what he/she is doing on any
given project including what is in his/her contract, as well as what he/she has to
do to perform that contract. All contractors should be aware of the standards
applicable to his/her work on any given project including:

a. The contract and the specifications designed for the

project;

b. The plans and other specific details applicable to the

contractor's work on the project;

c. The applicable building code;

d. Applicable trade association standards and manufacturer's

installation instructions;

d. Standards of care applicable to construction of such

projects in the location of each project worked on by the
contractor.

UNDERSTANDING THE OWNER'S CONCERNS

A contractor should be aware of the various concerns (sometimes
conflicting) of the homeowner in regards to seismic retrofit work. Going into
each job fully knowledgeable and prepared will help avoid any misunderstandings
with clients. Owners will be seeking advice on hiring contractors from a number
of sources, including local consumer organizations and the Contractor's State
License Board. Each contractor should know what the owners will be expecting.
He/she should also know what he/she must do to clearly set forth the scope of the
work that he/she is performing, as well as the limitations on a contractor's
responsibilities and liabilities. The contract documentation, particularly the
scope of work, is essential, as we will see shortly.

• Money Limitations

Most owners do not have a lot of money to perform retrofits. Some owners
will want to retrofit because it will make them feel safer. Others will be
retrofitting to meet some obligation, like a homeowner who wants to sell a house
for a better price, or to get earthquake insurance.

Whatever the reason, most homeowners will not want to spend any more
than is necessary to get the job done. Most owners will be getting several bids for
the retrofit work. A contractor should make a fair and reasonable bid based on a
clear contract. The Appendix contains a suggested form contract that could be
used as a basis for developing your own form contract. A contractor should not

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try to low-ball a bid hoping to "make it up with change orders". This is frankly a
dangerous fantasy. The owner may simply not have the money for change orders.

• Disruption To The Occupants

Most retrofit work will require some disruption to the occupants of the
building, including noise, loss of services, and/or inconvenience.

A contractor should work out an arrangement in advance with the owner to

let him know when the work may be disruptive. Owners do not like to suddenly
find out that their water or power has been temporarily turned off.

• Schedule

The owner wants to know when his/her house will be back to normal. A
contractor should clearly state the projected timeline for completion, and make
sure that the owner is aware of it. Also, the contractor should let the owner know
about anything that may cause a delay in the schedule.

• Background Information

Many homeowners will ask for information about their contractor's

experience. A contractor should be ready to provide references from previous
jobs, proof of bonding and insurance, as well as his/her contractor's license
number.

LIMITING A CONTRACTOR'S LIABILITY

One way a contractor can protect him/herself is to have the necessary
paperwork that explains what he/she will do and has done. Today many people
seem to be very anxious to pursue litigation if anything goes wrong. One of the
most important responsibilities of the contractor is to protect him/herself from
potential lawsuits. One way that a contractor can do this is to have the necessary
paperwork that explains what he/she has done.

• Necessary Documentation For Each Project

q Liability Insurance

The contractor should have an appropriate comprehensive general liability

insurance policy, or similar form of insurance. This should provide coverage to
the contractor, should he/she incur negligence and construction defect liability as
to work that he/she has performed for his/her customer. The contractor should
attempt to obtain an additional insured endorsement from each of the
subcontractors, adding him/her as an additional insured. Also, to the extent
possible, the contractor should make sure that each job site that he/she works on
is specifically identified on his/her liability insurance. This will provide specific
recognition by the contractor's carrier that it is providing liability coverage for
each of the projects that a contractor is working on.

q Project File and Documentation

A contractor should be sure that he/she has an appropriate file including the
contract, plans, correspondence and other relevant materials. He/she should
make sure that he/she keeps his/her file and notes as to any unusual job
circumstances so that his/her work is thoroughly documented. The better the
contractor keeps his/her file, the more likely that he/she will be able to cope with
any liability issues that come up after his/her work is completed.
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q Employee and Subcontractor Screens

The contractor should make sure that he/she carefully screens his/her
employees and subcontractors. He/she should be satisfied that they have the
capability to consistently perform the project in a good workmanlike manner,
which they have been hired to complete.

q Applicable Local Codes

The contractor should be sure that he/she understands the latest applicable
code and code interpretations that apply to the work in the specific jurisdiction
where he/she is working.

q Preconstruction Walk Through

It is very important that the contractor do a walk through of the project. If

the drawings are available, he/she should review them before the walk through.
Before bidding, each contractor must walk through the project area and be
thoroughly familiar with the existing conditions. This is essential for the senior
most executive with the retrofit company to be aware of these circumstances.

If an engineer designs the plans, he/she should be consulted by the

contractor if there any questions about the design or existing conditions. It
should be remembered that most engineers are not contractors and don't always
know what can be done from a practical standpoint on a retrofit project. The
contractor should use the walk through as an opportunity to identify any obvious
problems with the proposed work.

A contractor should not wait until he/she starts work and hope for a change
order. The engineer will say that he/she has seen the conditions before starting.
it is important to raise questions regarding existing conditions before starting
work.

• THE IMPORTANCE OF A CLEAR WRITTEN CONTRACT

The contractor should have a written contract stating exactly what work will
be done and how much the owner will pay for the work. Without a clear contract
it will be difficult to get paid extra for work that exceeds the scope of the original
agreement.

q Scope Of Work Is Important

The most important part of the contract is the scope of work provision. The
scope of work provision should carefully state what work the contractor is
performing, including reference to plans, specifications and applicable codes,
where appropriate. The scope of work section of the contract should just as
clearly state what is not in the contract; that is, what work is excluded and will
not be performed by the contractor. This provision particularly depends upon the
effectiveness of the prejob walk through by the contractor, and should include all
items which are noted, and which are not to be performed by the contractor. In
many instances this is the most important part of the contract, i.e the exclusions.

q Termination Options

The contract should also have carefully stated termination provisions. The
contract should state when, and under what circumstances, the contractor may
terminate his/her contract; that is for failure to pay progress payments, undue
interruption and interference by the owner, and similar such circumstances.

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q Exculpatory Provisions

The contract should also have exculpatory provisions relieving the

contractor from any liability for existing conditions on the site, which are not the
specific focuses of the contract. Such conditions may increase the scope of
required work on the part of the owner, once the contractor has identified them.

q Liability Revolution

The contractor should be aware that there has been an expansion of

construction defect claims against contractors and developers in the last 20 years.
These claims touch upon such things as inadequate framing, inadequate
plumbing, poor soils work, inadequate roof work and other workmanship claims,
including those claims involving window installation, waterproofing and the like.
The contract should have provisions citing the potential for these conditions and
that the owner understands that the contractor is not accepting responsibility for
such existing conditions which are uncovered during the course of performing the
actual work under the contract.

q Additional Work

The contractor should make it clear that if there are any such unforeseen
circumstances, which may indeed increase the scope of work on the project, that
the owner agrees to pay for any such additional work, which is requested by the
owner, and which is necessitated by hidden preexisting.

All participants in the construction industry have been increasingly

protecting themselves with appropriate insurance and contractual language to
help limit, cover or control the scope of their liability under their construction
contract. Retrofit work of this nature, often will involve conditions of poor
previous or original construction and other circumstances for which the
contractor does not want to be responsible. He/she should make that clear in
his/her contract!

q Get A Lawyer's Help With Your Contract

It is a good idea to contact an attorney who can prepare a standard form

contract for use. The contractor should work with the attorney to adapt the
contract to each job and its specific requirements.

q Key Contract Provisions

The sample contract form in the appendix may be a starting point. The following
is a listing of the key provisions that a retrofit contract should contain:

1. Scope of work, including plans and codes.

2. Time to complete project.

3. Price of work and payment schedule.

4. Subcontractor's names.

5. What's in and what's out of the contract, in terms of scope of work.

6. Change order provisions.

7. Termination provision.

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• GOOD SET OF PLANS

The contract should make reference to and incorporate the set of plans that
will be used on the project. All of the work (whether working from an engineer's
design or using a prescriptive standard) must have a workable set of drawings
showing the details of the building project with all retrofit work that is to be done
under the contract.

If an engineer or architect will not be involved, the contractor will be

responsible for obtaining a set of drawings. He/she can hire an engineer or
prepare drawings him/herself, only if they comply with an approved prescriptive
standard. If the contractor does prepare drawings, they obviously should be
checked with the Building Department to make sure they comply with the
existing prescriptive standards. Otherwise, an architect and/or engineer should
always prepare an appropriate set of plans.

The plans should make clear that they are tied to and coordinated with the
contract, and the contract should say so. The plans should be directed to specific
code provisions where appropriate. The project plans should include by name,
the design professionals who are responsible for them. The contractor should not
take responsibility for the plans and, should, where possible, state in the contract
that the design is separate and from the contractor's responsibility.

If there is no set of plans, then the contractor has no basis for bidding the
job, and the owner probably doesn't know when the job will be completed for
final payment. If there are any changes to the design that are needed because of
changes in scope, those should be shown on amended drawings.

• BUILDING PERMIT

All retrofit work requires a building permit. Even if the work is done
voluntarily, using a prescriptive standard, a building permit is necessary. Check
with the building department before starting to make sure that all necessary
permits are obtained.

KEEPING TRACK OF THE WORK

In addition to the above-referenced "starting documents" the contractor

must keep records of everything that happens during work on the project.
Following are some of the ways to document the course of the work,during the
project:

• Notification Of Existing Conditions

The contractor is only responsible for retrofit work that he/she actually does.
There may be other conditions in the home, as discussed above, that need repair,
or are not up to current standard. The contractor is not a building inspector
looking for problems. These areas should be specifically excluded from the work
scope or included in writing by change order for more pay.

Normally, building departments will not require that the entire building be
brought up to current code requirements. If there are obvious problems, such as
damage or decay to the structural members, the contractor should point them out
to the owner (especially if they present a potential danger). If the owner decides
to do something about the condition, then the contractor should get a change
order. Without that, the contractor should make clear that such conditions are
outside the scope of work of the contract, as discussed above.

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• Change Orders

The contractor should document in writing any changes that are requested
by the owner or engineer. This will be important, if there is a question about any
differences between the as built condition and the drawings. This is also
obviously important for the contractor to be able to obtain payment for any extra
work he/she performs. The contractor should be sure that he/she gives notice of a
potential claim for any additional work to the owner, and that the contract
supports the contractor's right to a change order, including increasing his/her
compensation and extending the time allotted for completing the work.

• Inspections

Having a building permit almost always requires some items to be checked

by the building inspector. The building inspector generally verifies (without
liability on his/her part) that the work is being done according to the approved
plans and according to the building code.

Inspections should be viewed as opportunities to learn what is being done

wrong before the work is rejected, the building fails or a claim is made. If there
are any errors that are not caught by the inspector, then the contractor alone is
responsible for the consequences; as the inspector is protected by immunities
built into the law. (See discussion above.)

Even if the inspection misses something, or passes it off as good enough,

that does not necessarily keep the contractor from being sued if something does
go wrong later. The contractor should keep a record of each day that the inspector
is on the job and what he/she checks and what his/her comments were.

If an engineer designs the job, the engineer may also come out to the site
and inspect the work. The contractor should also keep track of this information
and use it as an opportunity to discuss any unusual conditions.

If the contractor finds a problem and doesn't show it to the engineer, then
the contractor will be responsible for the consequences. It is in the basis best
legal interest of the contractor to communicate problems in construction to the
owner and his/her design professionals.

• Photographs

A picture is often "worth a thousand words". The contractor should take

pictures of existing conditions before starting work. If there is ever a question
about what a building looked like before retrofitting (or just to prove how bad the
existing construction was), the contractor will have evidence to support his/her
position regarding a potential change order.

Also, the contractor should take pictures of each part of the job as it is
completed. The contractor can use that photographic material to prove that the
work was completed and to show to potential future clients.

GETTING HELP

No one likes to admit that they do not know it all. Part of the contractor's
responsibility, as a professional, is to know when he/she needs assistance from
someone else. The contractor usually obtains during construction information
about various conditions that should alert the contractor to get advice from an
engineer or other professional, or at least the owner or relevant building
department.

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A WORD ABOUT WARRANTIES

There are no earthquake proof buildings. Even well designed buildings may
have some damage during an earthquake. Seismic retrofit of wood frame
buildings does not guarantee that the building won't be damaged during the next
earthquake.

Indeed, the contractor should understand that earthquake repairs are made
in order to effectuate safety measures. Sound engineering practice and code
compliance should produce a building that will protect occupants in a life/safety
situation, but the building and its contents may still be substantially damaged.

The contractor should also be aware that engineering practice is constantly

evolving regarding earthquake safety issues. The work that the contractor does
now may be obsolete in a few years when another earthquake occurs.

The contractor should not mislead the owner to believe that the house will
be undamaged during an earthquake. The contractor should explain to the owner
that seismic retrofits try to prevent severe damage to the homes by fixing obvious
weaknesses.

If the work is done carefully and correctly, however, the contractor can tell
the owner that the house should have less damage than a similar house that has
not been retrofitted. Older houses may have many other problems that are not
corrected by the retrofit (and aren't apparent at the time of the work). The
contractor does not want to take responsibility for the entire building, particularly
if the contractor only retrofitted a small part of the building, such as the cripple
walls.

A typical warranty will be one year for workmanship, but will also be ten
years (under law . . . even without an agreement) for latent defects. Whether the
contractor gives a warranty or not, he/she is exposed to liability for up to ten years
for property damage resulting from latent defects and four years for patent
defects, as defined above. Also, the contractor is responsible for three years, at a
minimum, for property damage resulting from negligent workmanship on the
contractor's
part, after the time the owner knew, or should have known, of any damage
resulting from a contractor's workmanship.

WHEN SHOULD A CONTRACTOR QUIT A PROJECT

The contractor should only quit a project when he/she has a right to quit.
The contractor has a right to quit when he/she recommends engineer's input on
safety issues and the owner refuses to obtain an engineer's input on the basis of
cost. The contractor should put language in his/her contract to give him a right to
quit, upon a fundamental unresolvable disagreement with the owner.

For a more thorough discussion of legal requirements, see the Supplement

titled “Legal Aspects of Construction and Administration” in the Appendix.

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GLOSSARY

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GLOSSARY OF ENGINEERING TERMS

Engineering terms often used in discussions of seismic design and retrofit.

Acceleration -The rate of change (increase or decrease) in velocity. As seismic

waves travel through the earth, the ground moves backward and forward
changing its velocity; acceleration is related to velocity and displacement.

Anchor Bolt - A cast-in place bolt used to connect the foundation sill to the
foundation.

Adhesive Anchor – An assembly consisting of a threaded rod, washer, nut,

and chemical adhesive for connections to existing concrete or brick
elements. Chemical adhesives may be epoxy, esters or acrylics.

Compression -When a wood member resists a pushing force along its axis on
each end towards its center, typical of columns, posts and holdown studs.

Connection - A point at which different structural members are joined to each

other or to the ground.

Cripple Wall - A wood stud wall less than full story height; typically
between the first floor and foundation wall.

Damage - Any economic loss or destruction caused by earthquakes.

Deflection - horizontal or vertical movement or displacement (See DRIFT)

Diaphragm - A horizontal or nearly horizontal structural element designed to
transmit horizontal or earthquake forces to the vertical elements of the
seismic resisting system.

Drift - Lateral deflection of a building caused by lateral forces.

Earthquake- A sudden motion or vibration in the earth caused by the abrupt
release of energy in the earth’s lithosphere. The wave motion may range
from violent at some locations to imperceptible at others.

Elastic - Capable of recovering size and shape after deformation.

Epoxy Anchor – a type of adhesive anchor using epoxy as the chemical
adhesive; SEE Adhesive Anchors

Expansion Anchor - An assembly containing a bolt, washer, and nut for

connecting to existing concrete elements. The base of the bolt is designed to
expand when properly set, wedging the bolt in a predrilled hole.

Fault - A fracture in the earth’s crust accompanied by a displacement of one

side of the fracture with respect to the other.
Floor Girder - A beam that supports floor joists.

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Foundation – As commonly used in residential construction, refers to the

masonry or concrete perimeter wall or slabs and footings that a house sits on. The
more accurate definition is the ground (rock or soil) that supports these systems.

Holdown - An element connected at the ends of the framing of a wall to prevent

uplift of the wall.

Horizontal - A direction parallel to the ground (sideways).

Inertia Force - A force generated by an object as it shakes. The force acts in the
opposite direction of the shaking and is related to the weight of the object and its
acceleration.

Intensity - The apparent effect that an earthquake produces at a given location.

In the United States, intensity is frequently measured by the Modified Mercalli
Index (MMI).

Joist –horizontal wood members that support floors or ceilings.

Lateral (Horizontal) Force Resisting System - The part of the structural system
that has been considered in the design to provide the required resistance to the
prescribed seismic forces: IE shear walls, braced or rigid frames, floor and roof
diaphragms and foundations.

Lateral Load (Force) - Side-to-side force(s) acting on a structure.

Load (Dead) - The gravity load created by the weight of all permanent structural
and nonstructural building components such as walls, floors, roofs, and the
operating weight of fixed service equipment.

Load (Live) - Moving or movable external loading on a structure. It includes the

weight of people, furnishings, equipment, and other things not related to the
structure. It does not include wind load, earthquake load, or dead load.

Magnitude, Earthquake - A measurement of the relative strength of the

earthquake shaking. Magnitude is often reported using the Richter Scale.

Mass - A quantity or aggregate of matter. It is the property of a body that is a

measure of its inertia taken as a measure of the amount of material it contains
that causes a body to have weight.

Mudsill / Foundation Sill / Sill Plate - The wood member that attaches to the
foundation.

Perimeter - The outer sides of a building.

Pier - A masonry or concrete column used as a beam support structure.

Pier Block - A pre-formed block of concrete used as a footing to support a post.

Post /Column - A load-bearing vertical member.

Racking - A movement that can distort a framework.

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Rafter - The roof support members.

Resonance - The amplification of a vibratory movement occurring when the

rhythm of an impulse or periodic stimulus coincides with the rhythm of the
oscillation (period). For example, when a child on a swing is pushed with the
natural frequency of a swing or when an earthquake shakes a building at its own
natural frequency.

Richter Scale - Named after its creator, the American seismologist Charles R.
Richter, a logarithmic scale expressing the magnitude of a seismic (earthquake)
disturbance in terms of its dissipated energy.

Seismic - Of, subject to, or caused by an earthquake or an earth vibration.

Seismic Forces - The assumed forces prescribed in the Uniform Building Code
related to the response of the building to earthquake motions to be used in the
design of a building and its components.

Seismic Hazard - Any physical phenomenon such as ground shaking or ground

failure associated with an earthquake that may produce adverse effects on
human activities.

Seismic Risk - The probability that social or economic consequences of an

earthquake will equal or exceed specified values at a site, at several sites, or in
an area during a specified exposure time.

Seismic Strengthening - Adding additional bracing, anchoring, or improvement to

a structure after the original construction is completed.

Shear - A deformation in which parallel planes slide relative to each other and
remain parallel.

Shear Wall - A wall, typically made of wood studs and wood structural panels,
built to resist lateral forces from wind or earthquake, acting in the direction of
the wall.

Sheathing - The material covering the surface of a wall.

Stiffness - Resistance to deformation of a structural element or system.

Strength - The capability of a material or structural member to resist or

withstand applied forces.

Stud - The vertical members in the walls.

Tension - When a connector or wood member resists a pulling force along its axis
such as a suspended ceiling or a holdown stud under uplift.
Top Plate - The horizontal members that fasten at the top of the studs and
support the rafters or joists.

Torque - The action or force that tends to produce rotation. In a sense, it is the
product of a force and a lever arm as in the action of a wrench twisting a bolt. IE
50 ft-lbs. is a force of 50 lbs. applied at the end of a 1 foot wrench to tighten a
bolt.

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Uplift - Force(s) acting to lift a structure or an element.

Velocity - the measure of speed and direction of an object

Vertical - A direction perpendicular to the ground.

Wall, Bearing - A wall providing support for vertical loads; it may be exterior or
interior.

Wall, Nonbearing - A wall that does not provide support for vertical loads other
than its own weight as permitted by the building code. It may be exterior or
interior.

***

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APPENDIX

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 Appendix A-1

Appendix A CITY OF LOS ANGELES

PRESCRIPTIVE STANDARD

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 Appendix A-3

CHAPTER 92

VOLUNTARY - EARTHQUAKE HAZARD REDUCTION

IN EXISTING WOOD FRAME RESIDENTIAL BUILDINGS
WITH WEAK CRIPPLE WALLS AND UNBOLTED SILL PLATES

SECTION 9201 C GENERAL

9201.1 Purpose. The provisions of this Chapter are intended to promote public safety and welfare by reducing the
risk of earthquake-induced damage to existing wood-framed residential buildings. The voluntary minimum
standards contained in this Chapter shall substantially improve the seismic performance of these residential
buildings but will not necessarily prevent all earthquake damage. When fully followed, these standards will
strengthen the portion of the structure that is most vulnerable to earthquake damage.

Prior to 1960, most wood frame residential buildings were built with raised wood floors supported by short wood
stud walls known as cripple walls. These cripple walls are typically braced with weak seismic materials such as
portland cement plaster or horizontal wood siding. In addition, wood frame buildings built under building codes in
effect prior to July 1938 were not required to be bolted to their foundations. Recent earthquakes have shown that if
a building has weak cripple walls or is unbolted, it may fall off its foundation even in moderate earthquakes. Fallen
buildings have collapsed, caught fire or needed extensive repairs to restore their occupancy.

This Chapter sets prescriptive standards for strengthening of underfloor enclosures that shall be permitted by the
Superintendent of Building without requiring plans or calculations prepared by an architect or an engineer. This
Chapter also provides a design standard for the use of alternate materials or an alternate method of construction in
lieu of the prescriptive standards. Construction documents for strengthening using alternate materials or methods
shall be prepared by an architect or engineer.

9201.2 Scope. The provisions of this Chapter may be applied to light wood frame Group R, Division 1 and Division
3 Occupancies with no more than four dwelling units when they contain one or more of the structural weaknesses
specified in Section 9203.1.

The provisions of this Chapter do not apply to the buildings or elements thereof, listed below. These buildings or
elements require analysis by an engineer or architect in accordance with Chapter 16 or other approved standards to
determine appropriate strengthening.

1. Buildings with a lateral force resisting system using poles or columns embedded in the ground.

2. Cripple walls that exceed four feet (1234 mm) in height.

3. Buildings exceeding three stories in height and any three-story building with cripple wall studs
exceeding 14 inches (360 mm) in height.
4. Buildings, or portions thereof, constructed on a concrete slab on grade or constructed on or into a slope
steeper than three horizontal to one vertical.

5. Buildings where the Superintendent of Building determines that conditions exist that are beyond the
scope of the requirements of this Chapter.

The standard details approved by the Superintendent of Building and these prescriptive provisions are not intended
to be the only acceptable strengthening methods permitted. Alternate details and methods shall be permitted when
approved by the Superintendent of Building. Qualified Historical Buildings shall be permitted to use alternate
building regulations or deviations from this Chapter in order to preserve their original or restored architectural
elements and features. See Chapter 84 for these standards.

9201.3 Alternative Design Procedures. When analysis by an engineer or architect is required or provided for a
building within the scope of this Chapter, such analysis shall be in accordance with all requirements of this Code
except as provided in this Chapter. The design shall provide strengthening for any structural weakness listed in

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Section 9203 that is at least equivalent to that provided by the prescriptive requirements of this Chapter with respect
to strength, deflection, and capacity. The Superintendent of Building may require that sufficient evidence be
submitted to substantiate such equivalence. The base shear may be determined in accordance with the following:

SECTION 9202 C DEFINITIONS

For the purpose of this Chapter, in addition to the applicable definitions, symbols and notations in this Code, certain
additional terms are defined as follows:

ADHESIVE ANCHOR is a fastener placed in hardened concrete or masonry that derives its holding
strength from a chemical adhesive compound placed between the wall of the hole and the embedded portion of the
anchor.

ANCHOR SIDE PLATE is a metal plate or plates used to connect a sill plate to the side of a concrete or
masonry stem wall.

CRIPPLE WALL is a wood-framed stud wall extending from the top of the foundation to the underside of
the lowest floor framing.

EXPANSION ANCHOR is a mechanical fastener placed in hardened concrete or assembled masonry,

designed to expand in a self-drilled or pre-drilled hole of a specified size and engage the sides of the hole in one or
more locations to develop shear and/or tension resistance to applied loads without grout, adhesive or drypack.

PERIMETER FOUNDATION is a foundation system which is located under the exterior walls of a
building.

SNUG-TIGHT is as tight as an individual can torque a nut on a bolt by hand using a wrench with a 10-
inch (254 mm) long handle and the point at which the full surface of the plate washer is contacting the wood
member and slightly indents the wood surface.

UNREINFORCED MASONRY includes adobe, burned clay, concrete or sand-lime brick, hollow clay or
concrete block, hollow clay tile, rubble, cut stone and unburned clay masonry walls in which the area of
reinforcement is less than 50 percent of the minimum steel ratios required for reinforced masonry.

SECTION 9203 C STRUCTURAL WEAKNESSES

9203.1 General. For the purpose of this Chapter, structural weaknesses shall be as specified below.

1. Sill plates or floor framing which are supported directly on the ground without an approved foundation
system.

2. A perimeter foundation system which is constructed of wood posts supported on isolated pad footings.

3. Perimeter foundation systems that are not continuous.

EXCEPTIONS: A. Existing single-story exterior walls not exceeding 10 feet (3084 mm) in
length forming an extension of floor area beyond the line of an existing continuous perimeter
foundation.
B. Porches, storage rooms and similar spaces not containing fuel-burning appliances.

4. A perimeter foundation system which is constructed of unreinforced masonry.

5. Sill plates which are not connected to the foundation or are connected with less than what is required by
Section 9204.3.1.

6. Cripple walls that are not braced in accordance with the requirements of Section 9204.4 and Table 92-A.

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SECTION 9204 C STRENGTHENING REQUIREMENTS

9204.1 General.

9204.1.1 Scope. The structural weaknesses noted in Section 9203 shall be strengthened in accordance with the
requirements of this section. Strengthening work shall be allowed to include both new construction and alteration
of existing construction. Except as provided herein, all strengthening work and materials shall comply with the
applicable provisions of this Code. Alternate methods of strengthening shall be allowed provided such systems are
designed by an engineer or architect and approved by the Superintendent of Building.

9204.1.2 Condition of Existing Wood Materials. All existing wood materials which will be a part of the
strengthening work shall be in a sound condition and free from defects which substantially reduce the capacity of the
member. Any wood material found to contain fungus infection shall be removed and replaced with new material.
Any wood material found to be infested with insects or to have been infested shall be strengthened or replaced with
new materials to provide a net dimension of sound wood at least equal to its undamaged original dimension.

9204.1.3 Floor Joists Not Parallel to Foundations. Floor joists framed perpendicular or at an angle to perimeter
foundations shall be restrained by either a nominal two-inch (51 mm) wide continuous rim joist or a nominal two-
inch (51 mm) wide full depth blocking between alternate joists in one- and two-story buildings, and between each
joist in three-story buildings. Blocking for multistory buildings must occur at each joist space above a braced
cripple wall panel.

Existing connections at the top edge of an existing rim joist or blocking need not be verified. The bottom edge
connection to either the foundation sill plate or top plate of a cripple wall shall be verified unless a supplemental
connection is provided. The minimum existing bottom edge connection shall consist of 8d toe nails spaced six
inches (152 mm) apart for a continuous rim joist or three 8d toe nails per block. When this minimum bottom edge
connection is not present, or is not verified, a supplemental connection shall be provided.

When an existing continuous rim joist or the minimum existing blocking does not occur, new 1c inch (29 mm)
wood structural panel blocking installed tightly between floor joists and nailed with 10d common nails at four inches
on center to the sill or wall top plate shall be provided at the inside face of the cripple wall. In lieu of 1c inch (29
mm) wood structural panel blocking, tight fitting, full or near full depth two inches nominal width (51 mm) lumber
blocking shall be allowed provided it does not split during installation. New blocking is not required where it will
interfere with vents or plumbing which penetrates the wall.

9204.1.4 Floor Joists Parallel to Foundations. Where existing floor joists are parallel to the perimeter
foundations, the end joist shall be located over the foundation and, except for required ventilation openings, shall be
continuous and in continuous contact with any existing foundation sill plate or top plate of the cripple wall. Existing
connections at the top edge connection of the end joist need not be verified; however, the bottom edge connection to
either the foundation sill plate or the top plate of a cripple wall shall be verified unless a supplemental connection is
provided. The minimum bottom edge connection shall be 8d toe nails spaced six inches (152 mm) apart. If this
minimum bottom edge connection is not present or is not verified, a supplemental connection shall be provided.

9204.1.5 Supplemental Connections. Supplemental connections shall provide sufficient strength to transfer the
seismic forces. Framing anchors of minimum 18 gauge steel and 12 approved fasteners may be considered to meet
this requirement when spaced 32 inches (813 mm) on center for one story buildings, 24 inches (610 mm) on center
for two story buildings and 16 inches (406 mm) on center for three story buildings.

EXCEPTION: A supplemental connection is not required when:

1. The structural wood panel sheathing extends from the sill plate to the rim joist or blocking
above.
2. The floor sheathing is nailed directly into the sill or top plate of the cripple wall.

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9204.1.6 Single Top Plate Ties. When a single top plate exists in the cripple wall, all end joints in the top plate
shall be tied. Ties shall be connected to each end of the discontinuous top plate and shall be equal to one of the
following:

1. 3-inch by 6-inch (76 mm by 152 mm) by 0.036-inch-thick (0.9 mm) galvanized steel and nailed
with six 8d nails at each end.

2. 1 2 inches (38 mm) by 12-inch (305 mm) by 0.058 inches (1.47 mm) galvanized steel nailed with
six 16d nails at each end.

3. 2-inch by 4-inch by 12-inch wood blocking nailed with six 16d nails at each end.

9204.2 Foundations.

9204.2.1 New Perimeter Foundations. New perimeter foundations shall be provided for structures with the
structural weaknesses noted in Items 1 and 2 of Section 9203.1. Soil investigations or geotechnical studies are not
required for this work unless the building shows signs of excessive settlement or creep.

9204.2.2 Foundation Evaluation by Engineer or Architect. Partial perimeter foundations or unreinforced

masonry foundations shall be evaluated by an engineer or architect for the force levels noted in Formula (92-1).
Test reports or other substantiating data to determine existing foundation material strengths shall be submitted for
review. When approved by the Superintendent of Building, these foundation systems may be strengthened in
accordance with the recommendations included with the evaluation in lieu of being replaced.

EXCEPTION: In lieu of testing existing foundations to determine material strengths and when approved
by the Superintendent of Building, a new nonperimeter foundation system, designed for the forces noted in
Formula (92-1), may be used to resist all exterior wall lateral forces.

9204.2.3 Details for New Perimeter Foundations. All new perimeter foundations shall be continuous and
constructed according to the standards for new buildings.

EXCEPTIONS: 1. When approved by the Superintendent of Building, the existing clearance between
existing floor joists or girders and existing grade below the floor need not comply with Section 2317.3.
This exception shall not be permitted when buildings are relocated on new foundations.
2. When approved by the Superintendent of Building, and when designed by an engineer or architect,
partial perimeter foundations may be used in lieu of a continuous perimeter foundation.

9204.3 Foundation Sill Plate Anchorage.

9204.3.1 Existing Perimeter Foundations. When the building has an existing continuous perimeter foundation, all
perimeter wall sill plates shall be connected to the foundation in accordance with Table 92-A and this section.

Anchors shall be installed with the plate washer installed between the nut and the sill plate. The nut shall be
tightened to a snug-tight condition after curing is complete for adhesive anchors and after expansion wedge
engagement for expansion anchors. The installation of nuts on all anchors shall be subject to verification by the
Superintendent of Building. Torque testing shall be performed for 25 percent of all adhesive or expansion anchors.
Minimum test values shall be 30 foot pounds (41 N-m) for 2-inch (12.7 mm) and 40 foot pounds (55 N-m) for e-
inch (15.9 mm) diameter anchors.

Anchor side plates shall be permitted when conditions prevent anchor installation vertically through the sill plate.
Anchor side plates shall be spaced as required for adhesive or expansion anchors but only one anchor side plate is
required on individual pieces of sill plate less than 32 inches (813 mm) in length. Wood structural panel shims shall
be used on sill plates for single plate anchor side plates when the foundation stem wall is from 3/16 inch (4.8 mm) to
3/4 inch (19 mm) wider than the sill plate. The shim length shall extend a minimum of two inches ( 50.8 mm) past
each end of the anchor side plate. Two plate anchor side plates shall be used when the total thickness of the required
shim exceeds 3/4 inch (19 mm).

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All anchor side plates which use lag or wood screws shall pre-drill the sill plate to prevent splitting as required by
Sections 2337.1.2 and 2339.1.2. Lag or wood screws shall be installed in the center of the thickness of the existing
sill plate.

Expansion anchors shall not be used in unreinforced masonry or concrete or masonry grout of poor quality.
Adhesive anchors shall be required when expansion anchors will not tighten to the required torque or their
installation causes surface cracking of the foundation wall.

9204.3.2 Placement of Anchors. Anchors shall be placed within 12 inches (305 mm), but not less than nine inches
(229 mm), from the ends of sill plates and shall be placed near the center of the stud space closest to the
required spacing. New sill plates may be installed in pieces when necessary because of existing conditions. The
minimum length of new sill plate pieces shall be 30 inches (762 mm).

EXCEPTION: Where physical obstructions such as fireplaces, plumbing or heating ducts interfere with
the placement of an anchor, the anchor shall be placed as close to the obstruction as possible, but not less
than nine inches (229 mm) from the end of the plate. Center-to-center spacing of the anchors shall be
reduced as necessary to provide the minimum total number of anchors required based on the full length of
the wall. Center-to-center spacing shall not be less than 12 inches (305 mm).

9204.3.3 New Perimeter Foundations. Sill plates for new perimeter foundations shall be anchored as required by
Section 1806.6.

9204.4 Cripple Wall Bracing.

9204.4.1 General. Exterior cripple walls, not exceeding four feet (1219 mm) in height, shall use the prescriptive
bracing method listed below. Cripple walls more than four feet (1219 mm) in height require analysis by an engineer
or architect in accordance with Section 1601.

9204.4.1.1 Sheathing Requirements. Wood structural panel sheathing shall not be less than 15/32-inch (12 mm)
thick. When used, plywood panels shall be constructed of five or more plies. All wood structural panels shall be
nailed with 8d common nails spaced four inches (102 mm) on center at all edges and at 12 inches (305 mm) on
center at each intermediate support with not less than two nails for each stud. Nails shall be driven so that their head
or crown is flush with the surface of the sheathing and shall penetrate the supporting member a minimum of 12 inch
(38 mm). When a nail fractures the surface, it shall be left in place and not counted as part of the required nailing.
A new 8d nail shall be located within two inches (51 mm) of the discounted nail and hand driven flush with the
sheathing surface.

EXCEPTION: No. 6 x 12 inch (38 mm) wood screws may be used for sheathing nailing when bracing
materials are installed on the interior face of studs and cement plaster or other brittle finishes are on the
exterior of the sheathed wall.

All horizontal joints must occur over nominal two-inch by four-inch (51 mm by 102 mm) blocking installed with the
nominal four-inch (102 mm) dimension against the face of the plywood. All vertical joints must occur over studs.
Vertical joints at adjoining pieces of wood structural panels shall be centered on existing studs such that there is a
minimum 1/8 inch (3.2 mm) between the panels. Nails shall be placed a minimum of 2 inch (12.7 mm) from the
edges of the existing stud. When such edge distance cannot be maintained because of the width of the existing stud,
a new stud shall be added adjacent to the existing and connected with 16d common nails at eight inches (206 mm)
on center. A minimum of three such nails shall be provided.

9204.4.2 Distribution and Amount of Bracing. See Table 92-A for the distribution and amount of bracing
required. Bracing for a building with three or more floor levels above cripple wall studs exceeding 14 inches (356
mm) in height must be designed in accordance with Chapter 16 of this code.

The braced panel must be at least two times the height of the cripple stud wall but not less than 48 inches (1219 mm)
in width. All panels along a wall shall be nearly equal in length and shall be nearly equally spaced along the length
of the wall. Braced panels at ends of walls shall be located as near the end as possible.

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Where physical obstructions such as fireplaces, plumbing or heating ducts interfere with the placement of cripple
wall bracing, the bracing shall then be placed as close to the obstruction as possible. The total amount of bracing
required shall not be reduced because of obstructions but the required length of bracing need not exceed the length
of the wall.

Underfloor ventilation openings shall be maintained in accordance with Section 2317.7. Braced panels may include
underfloor ventilation openings when the height of the solid portion of the panel meets or 75 percent of the height of
the cripple stud wall. When the minimum amount of bracing prescribed in Table 92-A cannot be installed due to
obstructions along any wall, the bracing must be designed by an architect or engineer in accordance with Section
9201.3.

9204.4.3 Stud Space Ventilation. When bracing materials are installed on the interior face of studs forming an
enclosed space between the new bracing and existing exterior finish, each braced stud space must be ventilated.
Adequate ventilation and access for future inspection shall be provided by drilling on two-inch to three-inch (51 mm
to 76 mm) diameter round hole through the sheathing nearly centered between each stud at the top and
bottom of the cripple wall. Such holes should be spaced a minimum of one-inch (25 mm) clear from the sill or top
plates. In stud spaces containing sill bolts, the hole shall be located on the center line of the sill bolt but not closer
than one-inch (25 mm) clear from the nailing edge of the sheathing.

When existing blocking occurs within the stud space, additional ventilation holes shall be placed above and below
the blocking or the existing block shall be removed and a new nominal two-inch (51 mm) by four-inch (102 mm)
block installed with the nominal four-inch (102 mm) dimension against the face of the plywood. For stud heights
less than 18 inches (457 mm) only one ventilation hole need be provided.

9204.4.4 Existing Underfloor Ventilation. Existing underfloor ventilation shall not be reduced without providing
equivalent new ventilation as close to the existing as possible. New sheathing may be installed around existing vent
openings in braced panels when the length of the panel is increased a distance equal to the length of the vent opening
or one stud space minimum.

EXCEPTION: For residential buildings with a post and pier foundation system where a new continuous
perimeter foundation system is being installed, ventilation shall be provided in accordance with this Code.

SECTION 9205 C QUALITY CONTROL

9205.1 Inspection by the Department. All work shall be subject to inspection by the Superintendent of Building
including, but not limited to:

1. Placement and installation of new adhesive or expansion anchors or anchor side plates installed in
existing foundations.

2. Placement of required blocking and framing anchors.

3. Installation and nailing of new cripple wall bracing.

The torque testing of sill plate anchors per Section 9204.3.1 shall be performed by the building inspector.

9205.2 Special Inspection. Special inspection is not required for sill plate anchors installed in existing foundations
regulated by the provisions of this Chapter. Any work may be subject to special inspection when required by the
Superintendent of Building or when so designated by the architect or engineer of record.

9205.3 Structural Observation. Structural observation is not required for work done under the prescriptive
provisions of this Chapter. When construction documents for strengthening are prepared by an architect or engineer
and alternate materials or methods are used, structural observation shall be provided as required in Section 1702.

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9205.4 Engineer's or Architect's Statement. When an alternative design is provided per Section 9201.3,
the responsible engineer or architect shall place the following statement on the approved plans:

1. AI am responsible for this building's seismic strengthening design for the underfloor
cripple walls and sill bolting in compliance with the minimum seismic resistance
standards of Chapter 92 of the Los Angeles Building Code.@

or when applicable:

2. AThe Registered Deputy Inspector, required as a condition of the use of structural

design stresses requiring continuous inspection, will be responsible to me as required by
Section 1701.1 of the Los Angeles Building Code.@

TABLE 92-A C SILL PLATE ANCHORAGE AND CRIPPLE WALL BRACING 1,2,3

Number of Stories above Minimum Sill Plate Connection and Maximum Amount of
Cripple Walls Spacing Wall Bracing
Adhesive or expansion anchors shall be 2-inch (12.7 Each end and not less
mm) minimum diameter spaced at six feet (1829 mm) than 50% of the wall
One Story maximum center to center. length.

Adhesive or expansion anchors shall be 2-inch (12.7 Each end and not less
mm) minimum diameter spaced at four feet (1219 mm) than 70% of the wall
maximum center to center; or 5/8 inch (15.9 mm) length.
Two Story spaced at six feet maximum center to center.
Adhesive or expansion anchors shall be 2- inch 100% of the wall
minimum (12.7 mm) diameter spaced at two feet eight length.
inches (813 mm) maximum center to center; or 5/8-
inch minimum (15.9 mm) diameter spaced at four feet
Three Story (1219 mm) maximum center to center.

1
Plate washers for use with adhesive or expansion anchors shall be two-inch (51 mm) by two-inch (51
mm) by 3/16-inch (4.8 mm) for 2-inch (12.7 mm) diameter anchors and 22-inch (64 mm) by 22-inch (64
mm) by 1/4-inch (6 mm) for 5/8 inch (15.9 mm) diameter anchors.
2
Existing sill plate anchor bolts shall be permitted to provide all or a portion of the sill plate connection
requirement if:
a. the anchor bolt is cast in concrete and in sound condition, and:
b. the diameter size and maximum spacing meets or exceeds the requirements of Table 92-A, and:
c. a new plate washer conforming to footnote 1 is installed, and:
d. the sill plate is connected to a snug tight condition and torque tested per Section 9204.3.1.
3
Anchor side plates shall be permitted when conditions prevent anchor installation vertically through the
sill plate.

***

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 Appendix B-1

Appendix B REAL ESTATE

DISCLOSURE REQUIREMENTS

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Appendix B-2

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 Appendix B-3

CALIFORNIA GOVERNMENT CODE

SECTION 8897.1-8897.5

Section 8897.1.

(a) After January 1, 1993, the transferor of any real property containing any residential dwelling built
prior to January 1, 1960, with one to four living units of conventional light-frame construction, as
defined in Chapter 25 of the 1991 Edition of the Uniform Building Code of the International
Conference of Building Officials, shall, as soon as practicable before the transfer, deliver to the
purchaser or transferee a copy of the “Homeowner’s Guide to Earthquake Safety” published
pursuant to Section 10149 of the Business and Professions Code and complete the earthquake
hazards disclosure regarding the property. The earthquake hazards disclosure shall clearly
indicate whether the transferor has actual knowledge that the dwelling has any of the deficiencies
listed in Section 8897.2.

(b) The transferor shall make the earthquake hazards disclosure as soon as practicable before the
transfer of title in the case of a sale or exchange, or prior to execution of the contract where the
transfer is by a real property sales contract, as defined in Section 2985. For purposes of this
subdivision, the disclosure may be made in person or by mail to the transferee, or to any person
authorized to act for him or her in the transaction, or to additional transferees who have requested
delivery from the transferor in writing.

(c) This article does not apply to any of the following:

(1) Transfers which are required to be preceded by the furnishing to a prospective transferee of a
copy of a public report pursuant to Section 11018.1 of the Business and Professions Code.
(2) Transfers pursuant to court order, including, but not limited to, transfers ordered by a probate
court in the administration of an estate, transfers pursuant to a writ of execution, transfers by a
trustee in bankruptcy, transfers by eminent domain, or transfers resulting from a decree for
specific performance.
(3) Transfers to a mortgagee by a mortgagor in default, transfers to a beneficiary of a deed of
trust by a trustor in default, transfers by any foreclosure sale after default, transfers by any
foreclosure sale after default in an obligation secured by a mortgage, or transfers by a sale
under a power of sale after a default in an obligation secured by a deed of trust or secured by
any other instrument containing a power of sale and, any subsequent transfer by a mortgagor
or beneficiary of a deed of trust who accepts a deed in lieu of foreclosure or purchases the
property at a foreclosure sale.
(4) Transfers by a fiduciary in the course of the administration of a decedent’s estate,
guardianship, conservatorship, or trust.
(5) Transfers from one coowner to one or more coowners.
(6) Transfers made to a spouse, or to a person or persons in the lineal line of consanguinity of one
or more of the transferors.
(7) Transfers between spouses resulting from a decree of dissolution of a marriage, from a decree
of legal separation, or from a property settlement agreement incidental to either of those
decrees.
(8) Transfers by the Controller in the course of administering the Unclaimed Property Law
provided for in Chapter 7 (commencing with Section 1500) of Title 10 of Part 3 of the Code
of Civil Procedure.
(9) Transfers under the provisions of Chapter 7 (commencing with Section 3691) or Chapter 8
(commencing with Section 3771) of Part 6 of Division 1 of the Revenue and Taxation Code.
(10) Transfers for which the transferee has agreed in writing that the dwelling will be demolished
within one year of the date of transfer.

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Appendix B-4

8897.2. (a) The transferor shall disclose any of the following deficiencies which are within the transferor’s
actual knowledge and material to the transaction, and which may increase a dwelling’s
vulnerability to earthquake damage:

(1) The absence of anchor bolts securing the sill plate to the foundation.
(2) The existence of perimeter cripple walls that are not braced with plywood, blocking, or
diagonal metal or wood braces.
(3) The existence of a first-story wall or walls that are not braced with plywood or diagonal
metal or wood braces.
(4) The existence of a perimeter foundation composed of unreinforced masonry.
(5) The existence of unreinforced masonry dwelling walls.
(6) The existence of a habitable room or rooms above a garage.
(7) The existence of a water heater which is not anchored, strapped, or braced.

(b) The transferor shall be required to disclose any material information within the transferor’s
actual knowledge regarding any corrective measures or improvements taken to address the items
listed in subdivision (a).
8897.3. (a) For the purposes of this chapter, if it is determined that retrofit work is appropriate to address
potential deficiencies listed in paragraph (1) or (2) of subdivision (a) of Section 8897.2, the following
standards shall be used:
(1) The foundation anchor bolt requirements of subdivision (f) of Section 2907 of Chapter 29
of the 1991 Edition of the Uniform Building Code of the International Conference of
Building Officials, or any local government modification which establishes equivalent or
higher requirements.
(2) The cripple wall bracing requirements of paragraph (4) of subdivision (g) of Section 2517
of Chapter 25 of the 1991 Edition of the Uniform Building Code of the International
Conference of Building Officials, or any local government modification which establishes
equivalent or higher requirements.
(3) The water heater bracing, anchoring, or strapping requirements to resist falling or
horizontal displacement due to earthquake motion of Section 19215 of the Health and
Safety Code.

(b) Any qualified historical building or structure, as defined pursuant to Section 18955 of the
Health and Safety Code, shall be permitted to utilize alternatives to the requirements of this
section, as provided by the State Historical Building Code (Part 2.7 (commencing with Section
18950) of Division 13 of the Health and Safety Code) and the regulations issued pursuant thereto.
8897.4. No transfer of title shall be invalidated on the basis of a failure to comply with this chapter.
8897.5. For the purposes of this chapter, the duty of the real estate licensee shall be limited to providing to
the seller a copy of the Homeowner’s Guide to Earthquake Safety for delivery to the prospective
transferee pursuant to Section 2079.8 of the Civil Code.

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 Appendix C-1

Appendix C FULL SCALE NAIL CHARTS

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Appendix C-2

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 Appendix C-3

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Appendix C-4

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 Appendix C-5

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Appendix C-6

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 Appendix C-7

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Appendix C-8

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 Appendix D-1

Appendix D PRE-DRILLED HOLE SIZES

Appendix D-2
 Appendix D-3

Less than 75% of nail diameter

 Appendix D-4

Threaded
Diameter
(Dt)
 Appendix E-1

Appendix E PARTIAL PERIMETER DETAILS

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 Appendix E-2

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 Appendix E-3

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 Appendix E-4

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 Appendix E-5

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 Appendix E-6

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 Appendix E-7

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 Appendix E-8

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 Appendix E-9

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 Appendix E-10

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 Appendix E-11

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 Appendix E-12

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 Appendix E-13

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 Appendix E-14

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 Appendix E-15

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 Appendix E-16

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 Appendix E-17

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 Appendix E-18

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 Appendix E-19

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 Appendix E-20

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 Appendix E-21

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 Appendix F-1

Appendix F WATER HEATER

BRACING ILLUSTRATIONS

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Appendix F-2

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 Appendix F-3

FLAT WALL BRACING

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Appendix F-4

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 Appendix F-5

CORNER BRACING

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Appendix F-6

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 Appendix G-1

Appendix G HOME IMPROVEMENT

CONTRACT FORM

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Appendix G-2

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 Appendix G-3

HOME IMPROVEMENT CONTRACT FORM

_________________ ("Owner") hereby retains ______________ Construction ("Contractor")
located at _______________, California, bearing California Contractor's License No. _________, to
construct the following described work of improvement (the "project"):

1. Description of Work. Contractor shall furnish all labor and materials necessary to
construct and complete in a good, workmanlike and prompt manner, pursuant to the project plans and
applicable law, the improvements to the project located at ______________, California (the "premises")
as described hereafter.

The following specifically described work is included:

a.

b.

c.

d.

e.

f.

g.

h.

i.

j.

k.

l.

All improvements and included in this Contract shall constitute the "work" of improvement as
to the premises.

The project shall be constructed with workmanship and materials which are timely approved
by the owner, which approval shall not be unreasonably withheld.

Owner shall timely communicate with the contractor to provide contractor an opportunity to
exercise such approval rights as appropriate as the project progresses.

The following items of work are not included in the work:

b.

c.

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Appendix G-4

d.

e.

f.

g.

h.

2. Construction Funds. The financing for this project shall be provided by an

appropriate loan to the owner from its lender whereby some other specified source of funds as
provided below:

The construction of this project shall be managed from the financial standpoint by the
_________________ Builders Control.

3. Property Lines. As the work will be completed within the confines of the existing
property where the premises is located, or has no responsibility to locate and point out property lines
to the contractor. There will be no need for a licensed land surveyor map on the property.

4. Price and Terms.

All of the above work is to be completed in a workmanlike manner according to the

standards, practices and applicable codes for the sum of $_____________. Contractor understands that
it is completing all necessary and appropriate seismic, energy conservation, heating and cooling
improvements pursuant to applicable law, and pursuant to all applicable standards and industry
practice.

Progress payments for the work are to be made in the course of terms and conditions
hereinafter set forth, upon owner's approval of completion of the work as to each indicated stage
indicated hereafter.

Amount of Work or Services

Amount of Payment
To Be Performed or Description
Of Any Material and Equipment
To Be Supplied

20% When Ready for Concrete

20% When Rough Framed
20% When Drywall is Installed
20% When Tile Completed
20% When Job Completed

5. Certificate of Completion Work.

Owner shall receive written certification from Contractor of completion of each day.
Owner has the right to retain an appropriate construction inspection service or consult to certify actual
satisfactory completion on each of the above-referenced stages of work, before any progress payment is
due, as stated hereinabove, which satisfactory completion shall not be reasonably withheld by owner
and/or its construction inspection service.

The entire amount of the agreed price under this contract has to be paid within 35
days after completion, as defined under California law.

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 Appendix G-5

6. Time for Commencement and Completion of Work.

The work shall commence within 10 calendar days after receipt of written notice from
Owner to Contractor to proceed (Notice to Proceed), and the work shall be substantially completed
within ___ calendar days thereafter. This schedule is subject to any unforeseen delays which are not in
anyway, the fault of the Contractor, and which are caused by acts of god, stormy weather, Owner
changes or Owner answers, and uncontrollable waiver of difficulties (all of which must be specifically
recognized by Owner in writing). Time is of the essence to this Contract. The above-stated substantial
completion schedule shall be substantially adhered to during the term of this Contract unless Owner
and Contractor agree in writing that a schedule modification is appropriate.
The term "substantial completion" as used herein, shall be defined as completion of
the work suitable to meet the requirements of the issuance of the Certificate of Occupancy or
Temporary Certificate of Occupancy by the City of _________ and/or approval of the Owner if no
Certificate of Occupancy is required for the improvement contemplated by this Agreement.

7. Liquidated Damages and Delay of Completion.

The Owner and Contractor agree in the event that the work, which is the subject of
this Contract is not substantially completed as defined herein by the scheduled completion date
following the Notice to Proceed, the amount by which Owner shall have been damaged although
substantial will be difficult to fix. The Contractor and Owner therefore agree that no liquidated
damages are appropriate and that the only remedy which Owner may have is for extension of time of
completion and that no damages for delays shall be awarded.

8. Contractor's Duty.

Subject to and in accordance with the terms and provisions of this Contract,
Contractor shall construct, equip and furnish for the Owner the within described work which is
described and reasonably inferable from the drawings herein described (and made a part hereof) as
fully and to the same extent as attached hereto. In connection therewith, Contractor shall provide and
furnish all materials, supplies, appliances, equipment, fixtures, tools, implements and all other
facilities and all labor, supervision, transportation, utilities, storage and all other services as and when
required for and in connection with the construction, furnishing, or equipment of the within described
work, pursuant to the Contract documents. The Contract documents shall mean this Contract, those
certain drawings and plans provided to the Contractor, including the purported general notes affixed
thereto, and as modified by any written change orders executed to this Contract by the Owner and by
the Contractor.

9. Contractor's Performance.

Contractor covets that the work which is does pursuant to this Contract shall be in
good and workmanlike and to the reasonable satisfaction of the Owner, and that all materials furnished
and used in connection therewith shall be new. Contractor shall cause all the materials and other parts
of the work to be readily available as and when required or daily ___________________ equipment of
the work provided for herein.

Contractor shall provide competent supervision as to all phases of the work, including
all of its subcontractors and suppliers, and Contractor shall cause the work to be performed in
accordance with the drawings, plans and specifications incorporated in this Contract, and all things
indicated are reasonably inferable therefrom. Contractor shall provide a schedule of the work to Owner
prior to or upon commencement of the work. If requested by Owner, Contractor shall also prepare and
furnish project manning charts for all key trades and schedules for the persons and delivery of all
material, together with periodic updating thereof.

The subcontractors who are retained by the Contractor to work on this project are:
______________, ________________, ______________.

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Appendix G-6

10. Contractor's Lien Releases.

Upon satisfactory payment being made for any portion of the work performed, under
applicable law, the Contractor shall refrain from any further payment being made, furnish to the
Owner in full and unconditional relief from any claim or mechanic's lien pursuant to Section 3114 of
the California Civil Code, for that portion of the work for which payment has been fully made.

11. Notice to Owner.

You, the homeowner (the "Buyer") have the right to require that your Contractor
furnish you with a performance and payment bond or use a joint control approved by the Registrar of
Contractors. You, the Buyer, may cancel this transaction at any time prior to midnight of the third
business day (in the case of disaster repairs, seventh business day) after the day of this transaction. See
the attached Notice of Cancellation form for an explanation of this right.

Owner hereby designates the following Builders Control Service ____________,

____________ and ____________, to administer payments to the subcontractors and suppliers on this
project.

12. Allowance.

From time to time after commencement of the performance of the work, Owner may
prepare and deliver to Contractor written communications of instructions for utilization of any
allowance items provided for hereinabove. Such allowance items include, as described above:
plumbing fixtures (________________); tile material (____________); floor covering
(__________________); in the amounts specified. Said amounts are all applied to the guaranteed
maximum cost of this project of _____________. In the event that the costs of performing the work,
included in the allowance items is less than the amounts set forth above, the guaranteed maximum
price for this Contract of __________ shall be reduced the amount of the allowance of amounts not
expended. Should the cost of performing said allowance work exceed the amounts set forth above,
then the Owner shall pay the Contractor such actual costs, pursuant to the Owner's specific written
instructions, and the guaranteed maximum amount of the Contract shall be increased to such extent.

13. Delay.

Contractor shall be responsible for timely completion of the project consistent with
the time limits set forth for the work herein. However, Owner shall also be responsible to cooperate in
good faith with the Contractor, and not to interfere with the Contractor's progress of the work. Owner
understands that Owner must provide timely input and counsel to the Contractor regarding inquiries
and directions to proceed where reasonably requested by the Contractor. Any delay which is solely
caused by acts of god, owner interference, stormy weather, labor trouble, acts of public bodies and/or
failure of Owner to make progress payments shall not be the responsibility of Contractor.

14. Extra Work.

Should the Owner direct any modifications or additions to the work covered by this
Contract, and should the Owner and Contractor agree that there is extra work involved, the cost shall
be added to the Contract price.

For the purpose of this "cost" is defined as a cost of extra subcontract work, labor and
materials, plus 10% of such "costs" for overhead, and plus 7 1/2% of such "costs" for profit. Changes in
the contract shall be evidenced by a writing signed by both parties. Contractor shall give adequate
notice in advance when any "extra" work is in his/her view being required so that he/she and Owner
can discuss the need for such work and the proper classification of such work, including appropriate
cost adjustments. There will not be any unusual ground conditions encountered as to the work. If
there are unforeseen conditions and circumstances which the Contractor discovers during the course of
demolition and/or construction of the work, then Owner shall receive timely notice of such and

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 Appendix G-7

Contractor and Owner shall negotiate in good faith any appropriate changes or additions to the work
necessitated by such unforeseen conditions.

15. Completion and Occupancy.

Owner agrees to sign and record an appropriate Notice of Completion within five
business days after completion of the project, which completion shall be established by agreement in
writing of the Owner and Contractor. If the work passes final inspection by the City of Los Angeles, but
the Owner fails to report the Notice of Completion within the time period above stated, then Owner
hereby appoints Contractor as Owner's agent to sign and record a Notice of Completion on behalf of
Owner. Under no circumstances may Contractor bar occupancy of the work by the Owner.

16. Contractor's Duties and Status.

Contractor bears the relationship of an independent contractor with Owner, and has
no fiduciary duty or other relationship of trust with the Owner. Contractor agrees with the Owner to
furnish his/her best efforts to cooperate with the Owner in furthering and expediting completion of the
work. Owner agrees to cooperate with Contractor, upon timely request, as to any and all inquiries and
explanations regarding the requirements on the project. Also, Owner shall cure the cooperation of the
Owner's architect and/or engineer with the progress of the work by the Contractor and such design
professionals shall not be allowed by the Owner to interfere with the work by the Contractor. If the
Owner requests that the work covered by the allowance be accomplished in such way that the costs will
exceed the allowance, Contractor shall promptly comply with the Owner's request, provided that the
Contractor first provides written notice to Owner that the Cost will exceed the allowance and that
thereafter the Owner will pay for the additional costs. The parties agree that appropriate
communications shall take place between Contractor and Owner to advance the Contractor's
responsibility assumed under the contract. It is understood that timely communication and
cooperation between Owner and Contractor are essential for timely completion of the work.

17. Damage to Work and Insurance.

Owner will procure at his/her own expense and before commencement of any work
hereunder, fire insurance and other casualty insurance with course of construction, vandalism and
malicious mischief clauses attached. Such insurance shall be in a sum at least equal to the contract
price with loss, if any, payable to the owner and any beneficiary or deed of trust covering the property,
which are met solely within the knowledge and concern of the Owner. Owner is to be named as an
additional insured on the Contractor's general liability insurance. If the work is destroyed or damaged
by an accident, disaster or calamity such as fire, storm, flood, landslide, subsidence or earthquake, or
theft or vandalism, the work done by the Contractor in rebuilding or restoring such work shall be paid
for by the Owner only if such involved extra work and the Contractor has no responsibility.

If the work is destroyed or damaged by an accident, disaster or calamity such as a fire,

storm, flood, landslide, subsidence or earthquake or by theft, or vandalism any work done by
Contractor in rebuilding or restoring the work shall be paid for y the Owner as extra work, only if such
involves extra work and the Contractor has no responsibility for such events of destruction.

The Contractor will maintain in full force the workers compensation insurance policy
and the a comprehensive general liability insurance policy in amounts not less than required by this
Contract and less than $300,000. Contractor shall furnish Certificates of Insurance to Owner before
commencing work showing that the Owner is added as an additional insured under such insurance,
including the comprehensive general liability insurance. This failure of the Owner to demand delivery
of such certificates shall not relieve Contractor of any obligation under this Contract.

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Appendix G-8

18. Right to Stop Work.

Contractor shall have the right to stop work if and only if (i) any payment under this Contract
shall not be timely made to Contractor under this Contract; (ii) contractor and owner have a
disagreement regarding the project, which the contract in good faith believes to be irreconcilable, or (iii)
owner substantially interferes with contractor's good faith and proper performance of work on the
project.

19. Limitations.

No action arising from or related to the Contract, or performance thereof, shall be commenced
by either party against the other more than five years after completion or cessation of the work under
this contract. This provision does not limit, change or eliminate the otherwise applicable statutes of
limitations available under California law, particularly those applicable to latent and patent defects.

20. Attorneys Fees.

If either party becomes involved in litigation arising out of this Contract, or the performance
thereof, the Court in such litigation, or in a separate suit, shall award reasonable costs and expenses,
including attorneys fees, to a party justly entitled thereto. In awarding attorneys fees, the Court will
not be bound by any Court fee schedule; but shall, if it is in the interest of justice to do so, award the
full amount of costs, expenses and attorneys fees paid or incurred in good faith.

21. Cleanup.

Upon completion of the work, Contractor shall remove debris and surplus material from
Owner's property, and leave Owner's property in a neat and broom clean condition.

22. Taxes and Assessments.

Taxes and special assessments of all descriptions will be paid by the Owner.

23. Notice.

Any notice required or permitted under this Contract, shall be given by ordinary mail at the
addresses contained in this Contract; but such addresses may be changed by written notice given by
one party to the other, from time to time. After a notice is deposited in the mail, postage prepaid, it
shall be deemed received in the ordinary course of time.

24. Prohibition of Assignments.

Contractor may not assign this contract or payment due under this Contract to any other party
without the written consent of the Owner.

25. Incorporation of Section 7159 of the California Business and Professions Code.
Section 7159 of the California Business and Professions Code, as amended by AB 2190,
effective January 1, 1992, and as reproduced in the last page of this form, is incorporated in this
Contract.

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 Appendix G-9

26. Changes in the Work.

Any alteration or deviation from the Contract documents hereby identified for performing the
work, involving extra costs of material or labor will be performed only upon written orders for same,
signed by each of the Owners (George and Cecilia Calkins), and will become an extra charge over the
guaranteed maximum sum of this Contract, only by Contractor following the procedures set forth in
this Contract. All such change orders shall be in writing. Any such changes in the work, shall only be
performed upon written communication by Contractor to Owner describing the changes, and upon the
Owner's execution of change orders giving Contractor specific authority to proceed, setting forth, in
detail, the nature of the requested change. Upon receipt by Owner of any executed change order,
Contractor shall within five days furnish to Owner a statement in writing setting forth in detail, with
suitable breakdown by trades and work classifications, the changes and the guaranteed maximum costs
attributable to the changes set forth in said change order request, including any proposed adjustment
in the scheduled completion date resulting from such change order requests. If Owner approves in
writing such changes, the guaranteed maximum cost and schedule will be adjusted, as set forth in such
written change order requests signed by the parties. Owner shall have the right to issue change orders
deleting portions, or entire categories, of materials and services from the work, and to reduce the
guaranteed maximum price of $50,000 by the amount of the materials and services attributable to such
deletion (together with the prorata portion of the Contractor's profit and overhead).

27. Applications for Payment.

At least five calendar days before the date of any scheduled payment under this Contract, as
hereinabove provided, Contractor shall provide to Owner an application for payment ("Application for
Payment") in form and substance satisfactory to Owner. Each application for payment shall be for a
sum specified hereinabove in this Contract (which provides for six payments upon completion of
specified portions of the work, including after job completion). Each application for payment shall
provide a specification of the exact work and materials provided by the Contractor, including an
accounting of the cost and value of the work and materials provided. Title to all work, materials and
equipment shall pass to Owner upon payment, and Contractor shall prepare and execute all documents
necessary to effect and perfect such transfer of title.

In each application for payment, Contractor shall certify that such application for payment
represents a reasonable statement of the actual costs payable to Contractor under the terms of this
Contract, and shall also certify as follows:

"There are no new mechanics or material liens outstanding at the

date of this Application for Payment. All due and payable bills with
respect to the work have been paid or are included in the amount
requested in the current application. Except for such bills not paid,
but so included, there is no known basis for the filing of any
mechanic's or material liens on the work. Waivers from all
subContractors and materialmen have been obtained in such form as
to constitute an effective waiver of the lien under the laws of the
State of California, to the extent payment made by Owner to
Contractor."

Contractor shall furnish with each application for payment waivers of liens for itself and each
of its subContractors and suppliers, and any such forms as required by Owner, Owner's title insurer,
Owner's construction lender, or Owner's permanent lender for the project (or any portion thereof), in
order to assure an effective waiver of mechanic's and material liens relating to the payment in
compliance with the laws of the State of California. Contractor shall furnish any supplemental waivers
of liens for itself and each of the subContractors and materialmen as may be reasonably required by the
Owner, the Owner's title insurer, or lenders to the full extent of the payments made by the Owner.

On or about three calendar days after submission of each such application for payment, Owner
shall make payment to Contractor in the appropriate amount, except the amounts as to which the
Contractor has failed to make provision of appropriate supporting data and other documents, as

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Appendix G-10

hereinabove provided, including appropriate lien releases. The payment of any application for
payment
by Contractor to Owner, including the final certificate for payment by Contractor to Owner, does not
constitute a waiver of any claim that Owner may have for defective or inadequate workmanship or
materials against the Contractor. Contractor agrees to timely pay all of his/her subcontractors and
materialmen as to the work in order to prevent the occurrence of any liens upon the subject premises
or property.

Owner has no obligation to pay any portion of the contract amount, pursuant to application for
payment or otherwise, if Contractor is in default as to any of its obligations hereunder or otherwise is
in default under any of the Contract provisions.

Owner reserves the right to make payment to Contractor and any subContractor by appropriate
joint check.

28. Termination of Contract. If Contractor shall fail to commence and perform

the work in accordance with the provisions of this contract, or shall fail to diligently prosecute the work
to completion, in a diligent, efficient, timely and workmanlike, skillful and careful manner, or
Contractor shall fail to timely make any payments to Subcontractors, materialmen or laborers, then
Owner shall have the right, if Contractor shall not cure any such default after fourteen days written
notice thereof, to:

(i) terminate the employment of Contractor hereunder;

(ii) take possession of and use all or any part of Contractor's materials, equipment,
supplies or other property of any kind used by Contractor in performance of the work
and to use such property in the completion of the work; or

(iii) complete the work in any manner the Owner deems desirable, including the
engaging of the services of other parties therefor.

Owner hereby reserves the right to terminate this Agreement without regard to default or
breach, and for convenience of the Owner, upon written notice to Contractor, effective immediately
unless otherwise provided in said notice. In the event of any such termination, Owner shall promptly
pay as the sole amount due the Contractor in connection with this project, all sums then due to
Contractor for work actually performed and completed to the date of the termination (except retained
sums which shall not be paid prior to 35 days following the date of termination).

29. Liens.

Contractor shall not voluntarily permit any laborers, materialmen, mechanics or other similar
liens to be filed or otherwise imposed on any part of the work or the property on which the work is
performed, provided that the specified payments are made by Owner to Contractor, or Owner is
excused for not making such payment, in accordance with the terms of this contract. If any such lien is
not discharged by Contractor forthwith, or the Contractor fails to file a bond in lieu thereof, Owner
shall have the right to pay all sums necessary to obtain such releases and discharge, and then deduct all
amounts so paid from the balance due the Contractor under this contract.

30. Title to Work.

Immediately upon performance of any part of the work, as between Contractor and Owner,
title thereto shall vest in Owner; provided, however, that vesting of such title does not impose any
obligations on Owner or relieve Contractor of any of its obligations hereunder.

Any provision hereof to the contrary, notwithstanding, Contractor shall observe, abide by and
perform all of its obligations hereunder in accordance with all applicable laws, rules and regulations of
all governmental authorities, having jurisdiction.

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 Appendix G-11

31. Contractor's Warranty.

Contractor represents and warrants that Contractor holds an active unencumbered Contractor's
license, to perform the services included in this contract, as required by law, and that Contractor shall
keep and maintain such license in good standing, and in full force and effect at all times while
Contractor is performing the work under this contract.

Contractor represents that he/she is fully capable (as will be all of his/her workman, suppliers
and subcontractors) to perform all aspects of the work described herein.

32. Defects.

Contractor shall reexecute any parts of the work that fail to conform with the requirements of
this Contract, and the Contractor shall remedy any defects in the work, materials or workmanship, due
to faulty materials or workmanship which appear within a period of one year from the final date of the
work hereunder, and Contractor shall replace, repair or restore any parts of the work that are injured,
or damaged by any such parts of the work that do not conform to the requirements of this Contract, or
that are injured or damaged by any defects in the work. Contractor's warranty herein shall be in
addition to and not in lieu of, any other remedies owner may have under this Contract, at law or in
equity for defective workmanship by the Contractor.

33. Dispute Resolution.

All claims, disputes and other matters in question between Contractor and Owner arising out
of or relating to the work of improvement herein under this Contract shall be first submitted to non-
binding mediation in order for the parties to attempt to settle the matter, and failing to achieve
settlement, all such disputes shall be decided by arbitration in accordance with the Construction
Industry Arbitration Rules of the American Arbitration Association then existing, before an appropriate
retired judge of the Los Angeles County Superior Court, as designated and chosen by the
JAMS/Endispute organization, or by mutual agreement of the parties.

34. Performance and Payment Bonds.

It is understood by the parties that the Owner, at the Owner's sole expense, may obtain a
performance bond assuring completion of the work without default by Contractor, and a payment bond
assuring payment of all subContractors, materialmen and suppliers of the Contractor. Contractor
understands that Owner may record said payment bond and file its contract with the Los Angeles
County Recorder's Office pursuant to applicable provisions of California law.

35. Acknowledgment by Owner that They Have Received the Notice to Owner Specified by
Section 7018.5 of the State Contractor's License Board.

The Owner acknowledges that it has received the Notice as specified by Section 7018.5 of the
California Business and Professions Code. Included in that Notice is Owner's acknowledgement of
complete text of Sections 70151, 70151.2, and 70159 of the California Business and Professions Code.
In no event shall the payment schedule herein provide for Contractor to receive nor shall Contractor
actually receive, payment in excess of 100% of the value of the work performed on the project at any
time.

DATED: _________________, 1996 By____________________________

DATED: ___________________, 1996 By____________________________

Owner

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Appendix G-12

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 Appendix H-1

Appendix H LEGAL ASPECTS OF

CONSTRUCTION ADMINISTRATION

by George D. Calkins, Esq.

Cox, Castle & Nicholson, LLP

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Appendix H-2

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 Appendix H-3

SUPPLEMENT REGARDING LEGAL ASPECTS

OF CONSTRUCTION ADMINISTRATION

I. INTRODUCTION AND OVERVIEW

A. Objectives of Contract Administration.

The purpose of this discussion is to address some of the legal issues confronted on
construction projects from the perspective of those working in the industry, insofar as that is possible.
These materials are presented from the perspective of a general contractor. We will refer to an
imaginary Company (a contractor) as we proceed in our discussion. The discussion will also address
the concerns of subcontractors and suppliers.

It is helpful to review the objectives of construction administration from the perspective of

those responsible for the project. Those objectives can be summarized as follows:

1. Generate appropriate project or development opportunities for the Company, consistent with
its capabilities.

2. Define the fundamental goals and objectives of the Company and work cooperatively with all
involved to timely and profitably complete the Company's projects.

3. Understand and implement the requirements and objectives for each construction project, to
the best of the Company's ability, while at all times addressing and documenting significant
issues which arise concerning the Company's ability to timely and profitably complete a
project.

4. Ensure that the Company's subcontractors perform their work in a timely manner in
accordance with the applicable construction schedules, agreements, plans and specifications.

5. Identify and resolve claims and disputes promptly when they arise, hopefully without the
need for litigation, arbitration or other time consuming, risky and costly legal measures.

6. If a dispute must be litigated, insure that the Company will have the necessary records and
evidence to effectively present its case, and prevail.

An appropriate approach to achieve these objectives is to implement an aggressive program of

project administration, including an effort to do each of the following:

1. Understand, in detail, the contents of the relevant contract documents;

2. Make certain that all contract documents are properly completed and signed;

3. Follow established procedures for preparation and implementation of each of the contract
documents (i.e., follow the rules for formation and completion of the contract requirements);

4. Avoid unwritten agreements, "side deals" and other informal practices which lead to
misunderstandings and disputes; and

5. Be thoroughly familiar with and understand the subcontracts relating to the project, maintain
solid communication with all the parties engaged in the project, and keep a well-documented
file regarding the project.

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Appendix H-4

In construction disputes, the single most common problem is the absence of contract
documentation to support your position. In any construction dispute which goes to litigation, the party
with the superior documentary record to support its position will be in a better position to win.
Careful contract administration can save the Company thousands of dollars in unnecessary legal fees
and discourage subcontractors, suppliers and other third parties from pursuing meritless claims and
litigation.

B. When a Lawyer is Needed.

As with most other things in life, there is a right time and wrong time to consult a lawyer. The
following is a nonexclusive listing of criteria as to when the Company ought to consider consulting its
lawyer, and when it shouldn't:

1. When the Company receives a communication from a lawyer indicating that he/she represents
a party involved in one of the Company's projects, is frequently a time when the Company
should consult its lawyer before proceeding.

2. If the Company is presented with documents appearing to be new, unusual or unforeseen

contract forms, additions, modifications or change orders, then consultation with the
Company's lawyer might be advised.

3. If the Company encounters conduct by another party on a project which appears to be quite
inconsistent with its previous experience, and the circumstances carry a substantial risk factor
for the Company, then consideration should be given to consulting the Company's lawyer.

4. If claims (in the several thousands of dollars) are made against the Company by anyone,
consult the Company's lawyer.

5. If the Company believes it should consider terminating a contractor or pulling off of a project,
because of circumstances or conduct which jeopardize a project or the Company's position,
then consideration should be given to consulting the Company's lawyer.

6. If the Company confronts circumstances which tend to raise substantial doubt in

management's mind as to whether the Company will receive payment for any portion of its
work on a project, then the Company probably needs to consider its options, in consultation
with its lawyer.

7. Day-to-day ups and downs in conduct of a project, which are not unusual, normally do not
require the attention of the Company's lawyer.

8. If management runs into personality problems with specific representatives of another party
on a project, consultation with the Company's lawyer is usually not indicated. Interpersonal
relationship problems should not generally be misinterpreted as a legal difficulty.

9. If difficulties persist, after the Company has made repeated efforts to resolve a problem by
informal consultation, then consideration should be given to asking the Company's lawyer to
undertake an appropriate strategy to deal with the situation, particularly if there is a
significant risk of a potential claim situation.

10. If a party takes some action to either place a lien on the project, stop the flow of construction
funds, or contact the Company's surety or insurer, such circumstances usually require the
involvement of the Company's lawyer.

11. Injuries or loss of property on a project, normally require consultation with the Company's
lawyer (and insurer) at some point.

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 Appendix H-5

12. If there is financial instability (of any owner or subcontractor) or disputes persist impacting
upon the potential profitability of the project for the Company, then consultation with the
Company's lawyer normally is important in addressing the situation.

C. Goal - Maximize Legal Position.

An important consideration with reference to the legal aspects of the Company's projects, is
how at all times to maximize the Company's legal position.

II. LEGAL ASPECTS OF ESTIMATION AND BIDDING

A. Bids and Quotes By the Company and Its Subcontractors.

The bid and negotiation process is often the beginning of the Company's involvement in a
project (i) as a contractor or (ii) with its subcontractors.

Invitations to bid are frequently published in local construction industry trade papers. Bidding
documents include the invitation (advertisement), instruction to bidders, bid forms, contract
documents and addenda affecting the bidding documents. All of these documents could have legal
implications and need to be examined and understood in that light.

Frequently, bid documents require that the bidder represent that it has read and understood
the documents, visited the site and familiarized itself with the conditions that may affect the project.
All of those representations have legal implications, should the Company or one of its subcontractors
later determine that it was mislead by the plans and specifications, or that it got into a contract which
proved unprofitable. Every representation and statement made by the Company during the bidding
process could come back to haunt it. Accordingly, the approach to any bidding process should be
carefully undertaken.

The instructions to bidders should be read very carefully by the Company and designated
subcontractors from the standpoint that the instructions set out the rules with reference to conducting
the bidding operation, and with reference to possible interpretation of the contract (once it is entered
into by the successful bidder). Frequently, the instructions state that requests from bidders for
interpretations or corrections in bidding documents should be addressed to a design professional who
is designated to be the final arbiter in such matters. Instructions also normally state that there can be
no substitution of material or equipment unless a written request is made within a specified number of
days before receipt of bids. Usually, such a request must contain a complete description of the
substitution so that the substituted equipment or material can be evaluated.

Furthermore, instructions quite typically require that the bidder give the design professional
representing the owner the estimated cost for each major item of work in his/her bid, the work to be
done by the bidder's personnel, the names of his/her subcontractors, and the names of the material and
equipment suppliers within a set period of time. Such statements and representations can have
significant legal representations later on.

The long and the short of it is that the Company should carefully approach the bidding
process. The handling of the bidding process could create substantial business difficulties for the
Company, which could have significant legal implications.

Not infrequently, the Company engages in a process of negotiation (in addition to or instead of
bidding) in the formation of subcontracts. The success of contract negotiations, whether involving
construction contracts or otherwise, depends upon many variables, most of which ultimately bear upon
the relative strengths and weaknesses of the parties.

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Appendix H-6

The basic goal in construction contract negotiations is an allocation of the risks between the
parties. The ability to identify and appraise these risks can move the parties closer toward an equality
of bargaining power, notwithstanding the above variables. Intelligent negotiation requires a thorough
understanding of the basis of construction contracting. This basic principle can be reduced to several
key issues which are invariably a part of every construction contract, including:

1. In determining which party should bear a particular risk, certain questions should be
answered:

a. Who is better able to recognize and assess the risk?

b. Who is better able to control the risk?

c. Who is better able to bear the consequences of the risk?

2. If the Company participates in a project as a potential subcontractor and provides an

oral quote for a particular contract, it can have significant legal implications.

3. Before submitting its bid to the owner the Company must know (to a high level of
certainty) what its costs will be to perform the work. To accomplish this, the Company solicits
and receives bid proposals from subcontractors for certain assigned portions of the work and
undertakes to estimate and perform other portions of the work itself. The Company should
always strive to assure that a subcontractor's bid proposal is in fact a definite offer to perform.
This bid will become an enforceable contract if the bid is accepted, as opposed to a naked price
quotation which courts have frequently viewed as preliminary negotiations.

Without contrary language appearing in the bid or invitation to bid (or some other enforceable
type of reliance by the contractor upon a subcontractor's bid) the subcontractor may, under traditional
contract formation rules, withdraw its bid at any time before a communication of acceptance by the
contractor. The amount of the subcontractor's proposal, the scope of his/her work and other conditions
to which the subcontractor commits, are critically important. Therefore, when the Company receives
and acts upon subcontractor quotations and proposals, it is in a predicament: It has no need or desire
to accept the proposal until it knows whether its own bid is accepted by the owner. This time lapse
between submission and owner acceptance or nonacceptance creates the risk, under traditional
contract law principles, that the subcontractor will withdraw its bid in the interim.

In an effort to deal with this risk and avoid disputes when a subcontractor withdraws its bid in
such a manner, contractors frequently require subcontractor offers to be firm or irrevocable for a
definite period of time after submittal.

A firm, irrevocable offer by a subcontractor has been found by courts to be a commitment

which is contractual in nature and legally enforceable as such. A subcontractor who fails to perform or
honor such a bid may be liable to the contractor for resulting damages incurred by the contractor.

B. When Is the Contractor Legally Bound?

Normally, when the Company receives a bid from a subcontractor, the subcontractor is legally
bound to perform the work as indicated in the bid documents, upon acceptance of the bid pursuant to
its procedures. Reliance by the Company upon the subcontractor's bid, in the form of acceptance or
some other conduct, is the point at which the subcontractor normally becomes legally bound.
Acceptance of the subcontractor's bid or any other form of reliance by the Company, is the point at
which the subcontractor's legal obligations under the contract become fixed.

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 Appendix H-7

It is extremely important, therefore, that the Company know from the outset what the bidding
and negotiation rules are, both formal and informal, and who will be conducting the bidding process
for the awarding authority. Appropriate business determinations should be made as to whether the
Company should bid the project. Risky contract circumstances should be clearly identified and
understood. To be aware of the potential problems, the Company should analyze any potential
contract, during the bid estimation stage to determine whether:

1. The time frame for performance of the construction is reasonable;

2. Time extensions are specified in the contract for excusable delays;

3. Time extension clauses are restricted to time or also provide for compensation;

4. No damages for delay provisions exist;

5. Scheduling and milestone requirements are reasonable;

6. Specifications appear to be adequately prepared so that reasonable bids can be prepared and
Construction undertaken based thereon;

7. Design appears to be adequate;

8. The guarantee provisions are reasonable; and

9. The owner bears the risk of sub-surface conditions.

As a part of such a review, the Company should also determine what risk allocation or
equitable adjustment clauses appear in the contract which are for the Company's benefit, and what
procedures for their enforcement exist.

Understanding of the current legal interpretations given to key clauses is also important. But
exceptions always exist in enforcement of "no damages for delay" clauses, and determination of what
types of work are subject to a "change order" clause.

C. Mistakes and Miscommunications In the Bid Process.

Under some circumstances, a mistake in preparing a subcontractor's bid can result in the
subcontractor being relieved of its obligations under a contract. A unilateral mistake, or one having to
do with an error in judgment, is less likely to result in the subcontractor being relieved of its
responsibilities once a bid is accepted and a contract formed with the awarding authority.

The right to terminate the contract is available to the subcontractor where there are instances
of mutual mistake; that is, both the subcontractor and the Company are mistaken on some point. Such
relief is also available for some forms of unilateral mistake.

It has been the law in California for quite some time that a bidder can withdraw his/her bid for
a unilateral clerical mistake which is not the result of neglect by the subcontractor, where prompt
notice was given to the awarding authority and the awarding authority suffered no damage, despite
inclusion in the invitation to bid of a statement that bidders "will not be released on account of errors".
Elsinore Union Elementary School Dist. v. Kastorff, (1960), 54 Cal.2d 380, 388-389.

A unilateral mistake by the Company, in most instances, cannot be the basis for a change in
the contract for the benefit of the Company. Mistakes in reading plans and specifications are normally
not the basis for relieving subcontractors from contract responsibilities. California law also provides
that no change shall be made in a bid because of a mistake.

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Appendix H-8

D. Prudent Practices In Taking Subcontractor Quotes.

Subcontractor quotes should be conducted pursuant to applicable law and the bid
specifications. Subcontractor quotes should be memorialized in writing. A complete file of the
circumstances surrounding receipt of a quote should be kept. The name of the party representing the
subcontractor providing the quote should be noted as well as the date and time of the conversation.
Quotes should be accepted only from subcontractors with whom the Company is familiar and as to
whom there exists a responsible track record. As always, the Company should work very hard to
maintain an accurate file of its subcontractor quote discussions, so that appropriate reference later on
can be made, should the need arise.

III. CONTRACT DOCUMENTS

A. What Is the "Contract", And What Isn't?

The orderly performance of complex construction contracts requires that fair and practical
methods of interpretation be available. This is necessary so that construction can proceed without
undue hardship upon the participants.

All of the elements which are included in the construction contract are pretty well known in
the construction industry as the "contract documents." According to the American Institute of
Architects, the contract documents consist of the owner-contractor agreement, the conditions of the
contract, the drawings, specifications, all addenda issued prior to execution and all modifications
issued after execution of the contract. These materials comprise the complete "Contract" for the
construction of a project.

The construction contract sets out the rights, responsibilities, relationships and liabilities of
the parties involved. The rules of interpretation of contracts, generally, apply to construction contracts
requiring that effect be given to the intention of the parties as gathered from the plain reading of the
entire contract, with ambiguities normally construed against the drafter. Clarity in drafting is a primary
tool by which to avoid litigation and disputes in connection with a contract.

A contractor's responsibility and liability is fixed by the terms of the contract. He/she is
obligated to perform according to those terms. The contractor cannot be burdened with obligations to
perform for which he/she did not originally contract. Questions obviously arise in great numbers as to
what the contractor agreed to do by his/her contract and what kinds of things are covered under the
provisions which call for changes in the work. The change order provision is an attempt to incorporate
a flexible provision in a fixed agreement to take into consideration unforeseen conditions which are
likely to present themselves during the course of work.

Field authorizations, letters, memoranda, communications from the owner's engineer, field
notes, diaries and other such documents, normally are not considered a part of the contract documents,
unless specifically incorporated within the construction contract itself. (In most government contracts,
the bid package, invitation to bidders, the bid, the contract, government regulations regarding labor and
equal employment opportunity, the standard specifications and the plans are normally incorporated in
the "contract.")

Detailed specifications, the most commonly used, describe the materials, dimensions and
locations of all elements of the final product. Those specifications attempt to represent the completed
construction project in such detail that the owner, contractor, architect and other interested parties all
agree on the exact physical properties of the final product, e.g., the exact formula to be followed in
mixing concrete, specific equipment to be utilized for the air conditioning system, and so on.

Outline specifications, as opposed to detailed specifications, are used by contractors to meet

the needs of the customer, usually an industrial owner, who needs warehouse or manufacturing
facilities or a combination of both, and would like to handle the entire program through a single
contractor who will design and build the facility on a cost-plus basis, or sometimes with a guaranteed
maximum price. The outline specifications merely designate broad features, such as major
construction or types of walls, type of electrical circuitry, and the type of air conditioning.

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 Appendix H-9

B. Specific Examples Of What Is Or Is Not Incorporated In The Contract.

Incorporated within every contract and subcontract, by operation of law, is an implied

covenant of good faith and fair dealing. Gray v. Bekins, (1921), 186 Cal 389, 394-395. That covenant
requires that neither party to the contract do anything which would hinder or interfere with the other
party's right to obtain the benefits of the contract. The implied covenant of good faith and fair dealing
is not a frequently used device in government work, but could be more frequently utilized where
agency representatives are acting in an arbitrary and unreasonable fashion.

If the Company is to "make its case" of being treated unfairly by a subcontractor, the Company
will do so by introducing correspondence and other documents, which support the proposition that the
subcontractor is behaving in bad faith and violating the implied covenant of good faith and fair dealing.
A "record" must be made of the conduct to succeed.

One of the first things the Company should do in reviewing a subcontract document is to
check it for completeness. Check the drawings against the drawing index. Check the specifications
against the specifications index. Before submitting a bid, ascertain that all addenda have been received.
On the occasion of signing a contract, the Company should follow the procedure generally accepted and
have all the contract documents executed in triplicate. Thereafter, the Company should attempt to
formalize all modifications to the contract by use of written change orders. Following all of these
procedures will eliminate the necessity for interpretation of what constitutes the contract documents
on any particular project.

A common practice among general contractors and owners, which can and does occasionally
lead to disastrous results, is the disassembling of the drawings and specifications for distribution to
subcontractors (such as electrical and mechanical). Architects and engineers expect that all of the
subcontractors will have reference to all of the drawings and specifications and be somewhat
conversant with them. Sometimes, information very important to the preparation of the
subcontractor's bid is on the architectural or structural drawings which they have not seen. While the
Company normally does not use all that many subcontractors on its typical projects, the Company
should make an effort, as a part of its plan to coordinate the work by subcontractors, to make certain
that all subcontractors have a complete set of the plans and specifications available for any project.

C. Change Orders And Field Authorizations.

Field authorizations, not executed by authorized officers of both the awarding authority and
the Company, are frequently ineffective documents. Yet, they can be construed as admissions against
the Company where field authorizations are issued to subcontractors, who rely thereon and perform
services. Field authorizations should be carefully utilized.

Probably the most frequently invoked clause in the standard form of construction contract is
the change order clause. This clause basically provides that the owner may order changes in the work,
after the basic contract is executed and demand specific performance without invalidating the contract.
This clause permits a job to continue toward completion under the basic contract while the owner and
contractor deal with new ideas or changed conditions. The changes may consist of additions or
deletions within the general scope of the work. The clause also provides for adjustment of contract
time and price based on the effects of the changes ordered. The change order is generally required to
be in writing and must be signed by the owner and/or the architect.

Construction contracts often involve changes within the general scope of the work:

(1) In the specifications;

(2) In the method or manner of performance of the work;

(3) In the government-furnished facilities, equipment, material, services or site; and

(4) Directing acceleration in performance of the work.

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Appendix H-10

In private work projects, changes most frequently arise over:

(1) Changed or concealed conditions on the job, such as work below ground;

(2) Increased costs due to changed conditions;

(3) Delays, stop work orders, etc.; and

(4) Extensions of time.

The most important factor in successfully negotiating a change order is to have a clear and
complete working knowledge and understanding of all resulting contract requirements with reference
to the scope of work and methods of performance.

Extra work is the most common type of change order. As used in connection with a
construction contract, it means work of a character arising outside, and entirely independent of, the
contract--something not required in its performance, not contemplated by the parties and not
controlled by the contract. Frank T. Hickey, Inc. v. L.A.J.C. Council (1954) 128 Cal.App. 676, 683.

Where extras are of a different character from the work called for in the contract and no price
is agreed upon for the extra work, the contractor is entitled to recover the entire "reasonable value" of
the extra work. The extra work ordered by the owner constitutes a change to the contract under the
scope of the work provisions of the contract. Also, the arbitrary deletion of a major portion of work by
the owner may entitle the contractor to his/her "loss of profits" in connection with the deleted work.

A contractor, who acting reasonably, is misled by incorrect plans and specifications issued by
the owner during the bid-process and who as a result, submits a bid which is lower than he/she would
otherwise have made, may recover damages for work necessitated by the incorrect plans and
specifications.

Another type of change commonly encountered by contractors is a demand on behalf of the

owner that the contractor perform the work by a method different from that specified in the contract
or, if no method is specified in the contract, different than that planned by the contractor in bidding
the project. This constitutes a change to the contract for which the contractor may be entitled to
recover the "reasonable value" of the extra costs attributable to such change. The theory of this
recovery is the same as extra work recovery discussed above.

"Constructive changes" broadly encompass all changes to the contract where the owner refuses
to acknowledge the change and therefore also refuses to issue a formal change order. For example, the
law is well established that the owner's unreasonable action, abusive discretion, overly strict
interpretation of the contract, or erroneous interpretation of the contract may constitute a "constructive
change" for which the contractor is entitled to extra compensation.

Most construction contracts contain a notice requirement to the effect that, as a condition
precedent to the contractor's right to recover on any claim against the owner, the contractor must give
prior written notice to the owner of the claim within a designated period time after the contractor
learns of the facts giving rise to the claim. Such notice provisions are generally applicable to claims for
extra compensation due to changes to the contracts. Inexcusable failure of the contractor to give the
requisite written notice of claim may be asserted by the owner in certain cases as a bar to the claim. It
is therefore strongly recommended that the Company routinely give the awarding authority or owner
written notice of claim or potential claim immediately upon becoming aware of factual circumstances
which may constitute the basis for a claim of extra compensation due to a change in the contract.

The notice provisions of a contract quite often purport to impose upon the contractor an
impossible burden of including in the notice of claim infinite details as to the factual basis and amount
of the claim. It is often impossible for the contractor to provide those factual details to the owner
within the time period designated by the notice of the claim requirements. The courts have therefore
held that substantial compliance with these notice requirements is adequate. Strict compliance with
such written notice requirements will not be required. There are certain exceptions to this rule, having
to do with the actual knowledge of the contractor, the contractor's breach of contract, and conduct by
the contractor constituting a waiver of the substantial compliance doctrine. However, failure to give
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 Appendix H-11

notice may not be imposed as a bar to a change order where it is shown that the awarding authority is
not prejudiced by the failure to give notice.

It is sometimes impractical to await the conclusion of the change order negotiations prior to
commencement of the extra work involved in the change to the contract. Therefore, as an alternative
to strict compliance with the written change order requirements, the contractor prior to commencing
extra work, should insist upon a written directive from the owner to proceed with the extra work.
Also, prior to or simultaneously with commencement of the extra work, the contractor should give the
owner written notice of the claim for extra compensation in connection with the extra work. The
contractor's written notice of claim should also include a confirmation of the owner's agreement to
waive the written change order requirements of the contract. In this manner, the owner will be
deemed to have waived the written change order requirements of the contract, and the contractor's
extra work claim will be preserved for a later pursuit against the owner.

The written change order provisions of a contract may be waived by the owner, if a course of
conduct on the project is adopted between the owner and the contractor inconsistent with the owner's
reliance upon a strict compliance with such written change order requirements. Howard J. White, Inc.
v. Varian Assoc., (1960), 178 Cal.App.2d 348, 353.

California law is well settled that a contractor is entitled to recover the entire reasonable value
of extra work performed for the owner, where the extras are of a different character from contract work
and no price is agreed upon for the extra work in the contract. Such major items recoverable under an
extra work claim include direct extra costs, including labor, equipment, materials, insurance premiums,
bond premiums and direct overhead. In addition, indirect extra costs, including home office overhead
are sometimes recoverable in the absence of a specific contractual provision to the contrary. In the
absence of a specific contractual provision to the contrary, the contractor is also entitled to recover from
the owner a reasonable percentage markup for profit attributable to the extra work claim. Finally,
deletion of a major portion of the work by the owner may entitle the contractor to recover his/her "loss
of profits" in connection with the deleted work.

If a change order is in an item of work covered by a contract unit price, and such change does
not involve a substantial change in the character of the work as that shown on the plans or included in
the specifications, an adjustment in payment will be made in accordance with an agreement between
the contractor and the Owner. If they cannot agree, the contractor shall proceed on the basis of extra
work based upon the actual costs incurred, and a specified provision with percentages as markup for all
overhead.

Frequently a contractor will sustain consequential damages and impact costs as a result of
contract changes by the owner. These damages are in addition to the extra compensation normally
paid to the contractor under the change order. If the owner demands that the contractor accelerate
his/her work because of changes to the contract, or the wrongful refusal of the owner to grant
extensions of time because of excusable delays in connection with the changes to the contract, such
circumstances may entitle the contractor to recover from the owner the extra costs attributable to the
acceleration. Furthermore, a contract change order by the owner may have the effect of severely
delaying, disrupting and hindering the operations and performance of the contractor on the project,
entitling the contractor to recover from the owner the extra costs and damages approximately caused by
the delay, disruption and hindrance. The delay, disruption and hindrance costs and damages can
include equipment, labor, labor
escalation, material escalation, extended direct and indirect overhead, extended insurance premiums,
interest on retention, extended maintenance costs, consequential inclement weather damages, and
other items. Moreover, a change may lose efficiency for the contractor, which itself may be
compensable in the form of extra costs and damages attributable to the loss of time and efficiency.

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Appendix H-12

D. Shop Drawings.

The Company may encounter circumstances where shop drawings are used with some
frequency on a project. Shop drawings are most normally used on building projects with reference to
construction activities concerning construction of a structure of the building. Shop drawings constitute
a contractor's recitation to the owner and the owner's architect of the contractor's understanding of
what is to be built. Shop drawings are a checking device by which the interpretation on the plans by
the subcontractor or contractor are reviewed by the owner and the architect.

IV. CONTRACT LEGAL ISSUES FOR CONTRACTORS

A. What Parts Of The "Contract Are Given Priority Over Other Parts?

There is no clear rule that can be safely relied upon to determine which of the contract
documents shall take priority in case of conflict or ambiguity within or among the documents. Often
the subject is resolved by an appropriate position being derived from the general conditions, standard
of specifications and/or other outlined specifications for conduct of the work.

As a matter of custom, but not invariably, architects who provide a specific solution for
resolution of conflict in their documents, prefer to have the specifications govern rather than the
drawings. Some architects provide that the most stringent or most costly, condition would govern.

In the complete absence of a precedence clause, the architect could settle this issue by written
interpretation in accordance with the procedures set forth and the general conditions of a contract.

Many of the inconsistencies, ambiguities and omissions in the plans and specifications are
discovered by estimators of the general contractor, various subcontractors and suppliers. The
contractor is required by the general conditions to report any errors which he/she may discover,
although he/she will not be responsible for damages resulting from such errors. During the bidding
period, however, he/she is not yet legally bound to the requirements of the general conditions.
Accordingly, a contractor's motivation in reporting errors is to obtain more accurate bidding
information.

Of serious potential concern are areas where inconsistencies are discovered during the
construction period. Often the area of concern will become apparent during the preparation of shop
drawings or in the field layout of dimensions. Any additional drawings or specification which will have
to be issued at this time to clarify such problems will be considered as modifications to the contract
and will often give rise to additional work charges to the owner. A contractor has the duty to seek
clarification of clear ambiguities, without which he/she is not entitled to the benefit of the rule that
ambiguities are to be resolved against the drafter.

Most contract provisions which are typed and not part of the forms, are in most instances
given precedence over the boilerplate form portions of the contract. In short, very special conditions
written by the awarding authority with reference to a specific project, are given precedence and priority
over the printed forms of standard specifications, such as the Green Book.

"What kind of information belongs on the drawings" and "What should be in the specifications?" Are
questions which frequently arise. As a general rule, information most effectively or most easily
conveyed in graphic or diagram form should be on the drawings, while material more efficiently or
conveniently transmitted by words, should be in the specifications. Drawings are very useful for
transmitting data relating to the arrangement, location, dimensions, and interrelationships, while
specifications are more suitable for describing quality, gauges, standards, guarantees, procedures and
manufacturers' names.

A general concept pretty well recognized among building contractors is that the general
contractor shall be solely responsible for all construction procedures and for coordinating all portions
of the work under the contract. He/she is also responsible for maintaining and supervising all safety
precautions and programs. Drawings and specifications prepared under the latest state of the art will
not violate that principle.
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 Appendix H-13

B. Ambiguity - Whose Problem?

Where a contract provision written by one of the parties is ambiguous, it normally will be
resolved against the party who drafted it. (A major exception to this is contracts drafted by
governmental entities. Such contracts are not interpreted by specific statutory requirements against
the government entity who drafted it.) In its practical application, the general rule that ambiguous
contracts are interpreted against their drafter, means that a contractor may rely upon his/her
interpretation of an ambiguous provision if his/her interpretation is reasonable, he/she did not
participate in the drafting of the particular contract clause and the clause is not so obviously or patently
ambiguous as to have imposed on the contractor a duty to seek clarification.

A contractor has the duty to seek clarification of patent ambiguities, failing which he/she is not
entitled to the benefit of the rule that ambiguities are to be resolved against the drafter.

The Parol Evidence Rule is a substantive rule of contract interpretation. It provides that where
two parties have reduced their agreement to a writing, which sets forth their complete agreement, all
prior negotiations and understandings whether written or oral are merged into the contract and cannot
be used to vary, contradict or add to the terms of the contract. The Parol Evidence Rule does not,
however, have any application to subsequent agreements or modifications of the contract. Also, there
are substantial exceptions to the rule, which indicate that the parties may submit to the court evidence
of their intentions and understandings at the time they entered into the contract.

C. Representatives Of The Company Should Be Aware of What's In the Contracts They Are
Signing And Use The Contracts To Their Maximum Benefit.

Not much legal insight or analysis is required to support the conclusion that the Company's
project managers should be thoroughly familiar with all contract documents, and be prepared to engage
representatives of the owner or awarding authority in discussions regarding contract interpretation,
based upon that detailed background knowledge. An understanding of the contract should be
undertaken as soon as possible, certainly before the first job or project meeting.

D. Scope Of Work Provisions.

Particular attention should be given at all times, particularly during bidding and during
contract administration, to what the scope of the work is under the agreement. This is a principle
which need not be restated.

The importance of this principle from a legal standpoint, has to do with the contractor's
reaction to extra work requests where contract additions or deletions substantially impact upon the
scope of work of the project.

Normally a contractor bids a job on the assumption that for the bid price he/she will perform
only the work called for by the contract. If additional work is added, he/she expects to be paid a sum in
addition to his/her bid price, regardless of whether the additional work is due to the architect's error,
the owner's oversight, or a desire to change and improve the project.

It is not uncommon for the owner to decide during construction of a project that he/she
wishes to add features not included in the original drawings and specifications or decide to delete
items from the drawings. If the contract reserves the right to the owner to make such changes and if
the magnitude of
the changes is not excessive (i.e., does not exceed the scope of the work) the contractor will be
obligated to comply with the change request. If the change is major, the contractor may contend that
the scope of the change is beyond what could have been contemplated by the parties at the time the
contract was signed, thus excusing him from the performance of the requested extras. Even if the
contractor is required to comply with the change, the amount by which the contract price is to be
increased or reduced, as a result of the change, may be disputed.

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Appendix H-14

If a dispute occurs, either over price or whether the work is extra, the parties first have an
obligation to bargain in good faith. In many instances a contractor will elect to proceed with the work
under protest after taking into account the extent of the claimed extra and the consequences of not
proceeding. If the dispute involves some aspect of the work that could not be performed later, such as
a request to wrap conduit before placing underground, the alternative to proceeding under protest may
be to shut down the job. That is a significant and difficult decision which must be carefully considered.

If owner-requested changes are of such a magnitude as to change the scope of the work, the
awarding authority may be considered to have abandoned the original contract. In such a situation the
contractor will be entitled to recover the reasonable value of the work performed in a civil action.
Excessive change orders may also constitute a breach of contract.

E. Time Extensions - Delay.

Most public and private construction contract disputes touch on the issue of delay. It is even
an issue in disputes centering on injury or extra work claims. Causes of delay are numerous and may
be the fault of the contractor, the awarding authority, both parties, or neither of them. When delays
are caused by natural conditions over which neither party has control, such as the weather, labor
relations problems and the like, neither party is at fault. The contractor is at fault when delay is due to
the failure to order materials on time, failure to make timely submittals of equipment to be used on the
project, inadequate coordination of subcontractors, and inadequate staffing of the job. Among delays
caused by the awarding authority are failure to give prompt inspection, delay in processing of
submittals, ordering extra work that delays the job, delay in processing extra work orders, and delay in
furnishing access to the job site.

Construction delays are frequently injurious to all parties. Injury to the contractor includes
direct job expenses, indirect costs (such as office expenses, salaries of home office personnel and the
like) and adverse impacts on profitability of the job for the contractor. Frequently damages for delay to
a awarding authority are very difficult to measure. The standard procedure is to determine damages to
be awarded to the awarding authority by application of a "liquidated damages clause".

When delay occurs, it is usually due to a combination of factors. Part of the delay may be due
to the fault of the contractor, part to the awarding authority, and part to weather, strikes or other
events that are not the direct responsibility of either party. Thus, there is a problem of apportionment
of damages for delay. Another part of the problem is determining the amount by which the delay in
one portion of the job contributed to the delay in the completion of the entire project. For example,
the contractor may claim the job was delayed by the architects failure to make a prompt selection of
colors. Architects, on the other hand, can argue that the delay in selecting colors did not prevent the
contractor from installing the roof.

One way to approach this type of problem is to determine whether the item of work is critical
to the progress of the project. For example, installation of anchor bolts may be a prerequisite to
pouring of a concrete slab. The slab must be poured before the job can proceed. Thus, a delay
centering on anchor bolts worth a few cents a piece can stop a project worth millions of dollars. On the
other hand, installation of the major component might not be very critical to the project's completion.
For example, a delay of 30 days (not due to rain) in installing a roof might not interfere with any other
trade and thus might not delay completion.

Given the supposition that a particular item of work is not on the critical path, accumulation of
delay for a number of such items is bound to affect the job's organization and efficiency, and thus,
ultimately delay completion of the entire project. If damages for delay are liquidated, calculation of the
amount is eased. It is then necessary to specify the day on which the project is to be completed,
calculate the total number of days of delay, minus the number of days for which the contractor is
excused for delay by rain, and other excusable reasons, and finally multiply the remaining days by the
liquidated damages figure.

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 Appendix H-15

The typical construction contract contains a provision that if the contractor is delayed by rain,
and other excusable events he/she will be entitled to an extension of time, if he/she files a request
within a certain number of days after commencement of the delay. The courts have held that if delay
is in part caused by the awarding authority, the contractor is entitled to an extension of time even if
he/she fails to request the extension in writing.

There is a division of legal authority in this state as to whether liquidated damages may be
apportioned when the delay is caused by both the contractor and the awarding authority. The only
California Supreme Court case on the issue stated, in language which was not material to the decision,
that a awarding authority is precluded from claiming liquidated damages when it caused a part of the
delay, even though the contractor may have caused most of the delay. Yet, there is a lower court
decision which indicated that liquidated damages may be apportioned and distinguishes the earlier
cases not allowing apportionment as involving those circumstances where there was not a contractual
provision for extension of time and those circumstances dealing with private contracts.

F. Interpretation And Reconciliation of Contract Provisions.

There are certain principles of contract interpretation which are of note. Ambiguous
provisions are interpreted against the drafter, except when the drafter is a public entity.

A basic rule of contract interpretation is that contracts are to be construed in accordance with
the objective intent of the parties. The objective, as opposed to subjective intent, is that intent which
one would infer from reading the contract. Subjective intent is the true intent or actual state of mind
of the party who drafted the particular contract provisions.

Courts frequently rely on various miscellaneous rules of contract interpretation. In many

instances such rules can be found to support several different and inconsistent results. For this reason,
it is often said that courts first determine the result and then determine the rule of interpretation
which supports it. Some of the miscellaneous rules frequently referred to in construction cases are:

1. Reasonable logical interpretation.

2. Normal meaning of words.

3. Look for the whole agreement, and not just parts of it.

4. Look for the order of precedence of a contract, and find those provisions of the contract which
are given clear preference over others, such as specifically typed provisions over printed
provisions.

5. Look for the principal purpose of the contract and follow that purpose.

6. Look for the usual custom and usage in the particular trade in question.

7. Examine what the course of dealing has been between the contractor and the awarding
authority in the past on the issue.

G. Termination And Quitting The Job.

Termination from a project is a very difficult decision. It is one invariably based upon a
calculation of what the impact of your decision will be when continuing with the project would be
unfair or impossible. Invariably, the awarding authority will accuse the Company of breaching the
contract, and will seek damages in the millions of dollars.

Several circumstances could result in a conclusion by a contractor that he/she should not
proceed. One such circumstance has to do with a situation in which the specifications are said to be
defective when they called for performance which is not possible.

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Appendix H-16

Actual impossibility exists when the contract cannot be performed according to the
specifications by the contractor or anyone else, because the specifications are erroneous or because
performance requirements cannot be achieved, or because requirements, although conceivably
attainable, cannot be attained without going beyond the existing state of the art. Aside from actual
impossibility there is a practical impossibility, which exists when the contract requirements are
impractical "because of extreme and unreasonable difficulty or expense in meeting them." Practical
impossibility exists when: (1) the work is not possible within the basic contract objective contemplated
by the parties; and (2) the cost and difficulty of performing the work renders completion commercially
senseless.

When performance is impossible, the risk of impossibility is allocated to one of the parties in
accordance with the various rules designed to impose the risk on the party which assumed that risk,
either expressly or otherwise. In some contracts, the risk of impossibility is expressly allocated to one
of the parties. As a general rule, the risk is allocated to the owner unless some special circumstance
indicates that the risk should be allocated to the contractor. The risk may be allocated to the
contractor where it is obvious, where the contractor warrants his/her ability to achieve a particular
performance requirement, where the contractor had superior knowledge respecting the possibility of
performance, or where the impossibility resulted from a shop design prepared by the contractor.

If the risk of impossibility is allocated to the owner, the contractor is entitled to recover the
fair value of the services performed prior to the termination of work, but is limited to a ratable portion
of the contract price. That is one situation in which termination of the contract by the contractor is
permissible.

One of the most important implied provisions in a contract is the warranty that the project can
be satisfactorily completed by following the specifications. Where that proves not to be true, the
contractor may be justified in terminating.

There are provisions implied by law in a contract which are "indispensable to effectuate the
intention of the parties" arising from the language of the contract and the circumstances under which it
was made. The intent of the contract must be obtained from the entire document, including
consideration of its subject matter and the purpose of its execution. The circumstances of the parties
when they made the contract, must prevail over the recitals therein, unless the intent so gathered runs
counter to the plain sense of the words in the agreement.

In every building contract, which contains no express covenants on the subject, there are also
implied covenants to the affect that the contractor shall be permitted to proceed with the construction
of the project in accordance with the other terms of the contract, without interference by the owner.
Such terms are necessarily implied from the very nature of the contract. A failure to observe them not
consented to by the contractor, constitutes a breach of the contract on the part of the owner, justifying
termination by the contractor. The foregoing circumstances arising from impossible to perform
conditions and breach of implied covenants of cooperation. Notwithstanding such, a decision to
terminate a contract by the contractor is one which should not be taken lightly.

When a owner orders a contractor to proceed with work that the contractor claims is not
included in the contract price, the contractor has a choice of abandoning the job, rescinding the
contract and suing for damages or proceeding under protest and later filing suit to recover for the cost
of extra work. A contractor can proceed under protest and not waive its claim for extra work
compensation. When the contract documents require a written protest specifying in detail the work
performed and the resulting cost, a protest letter that fails to comply with the contract requirements is
ineffective.

Related to the performance under the protest theory is the theory of economic duress which is
possibly subject to the doctrine of government immunity. Although no case has been found where the
theory has been successfully applied in a construction case, it may be useful to keep that theory in
mind, if a particularly difficult situation is confronted. Practically speaking, performance under protest
is normally preferred over termination of the contract.

If circumstances become very difficult, it is always a very good idea to have a documentary
record of the efforts to correct the situation and warnings to the owner.

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 Appendix H-17

In California, the failure of the awarding authority or owner to make progress payments under
the contract to the contractor will entitle the contractor to rescind the contract unless the failure is only
a minor deviation from the terms of the contract.

In determining whether the contractor would be justified in ceasing work and shutting down
the job, consideration must be given to whether the owner or awarding authority is justified under the
contract in ordering the contractor to do the work without additional compensation and, if not,
whether the order constitutes a breach of contract sufficiently material to excuse further performance
by the contractor. While the general rule is that a material breach of contract on one side excuses
further performance on the other side, there is very little legal authority to guide one in distinguishing
between a material breach and a minor breach. The safest course appears to be that when in doubt,
proceed under protest, unless the owner's alleged breach is so material that to follow the owner's
instructions would risk financial disaster to the contractor.

One case has held that, under the circumstances there, the contractor was justified in refusing
to proceed if the changes are of such great magnitude. Otherwise, the contractor must perform and
obtain subsequent judicial determination regarding his/her damages. If the changes are of great
magnitude, as requested by the awarding authority, the contractor is obligated to negotiate in good faith
for a satisfactory price and, having done so, is not required to continue performance of the basic
contract when there is no agreement.

Similarly, when a subcontractor fails to adequately perform, the Company should make every
effort to document its difficulties with the subcontractor, including providing substantial compliance
with the notice requirements under the provisions of the subcontract. The subcontractor provisions
regarding termination should be followed very closely, and only after substantial breach of a
subcontract, should the Company elect to terminate a subcontractor.

H. Keeping An Accurate Job File Is Very Important To Successful Administration Of A Project.

In order to maximize the Company's rights, a complete and accurate job file must be
maintained. Appropriate diaries must be kept by the appropriate employees, and frequent
communication should be engaged in with the owner where difficulties arise. When difficulties arise
the communication should begin in a timely fashion, both orally and in writing. Any arrangements
reached with the owner or awarding authority should be immediately documented in writing, if by no
other means than a letter directed to the awarding authority's
representative.

Efforts to keep in contact with the owner's representatives, including outside engineers, and to
document that contact in writing, may assist the Company in obtaining payment for its services, at
some later date. Efforts to completely document the file, at an early date, may prevent the need for
substantial expenditures of money to prove-up the Company's position after the fact.

I. It Is Important That The Company Understand The Awarding Authority's Application Of The
Contract Provisions And Where Appropriate Challenge Misapplication Of the Contract Provi-
sions By The Awarding Authority.

In keeping with the recommendation that the Company remain aware of the contract
provisions, project managers should work to understand the awarding authority's interpretation of the
contract documents. Project Managers should also be sure to document misapplication of the contract
provisions by the awarding authority, so that those misapplications can be addressed by informal
negotiation. If an awarding authority has a misunderstanding of the 25 Percent rule, or if it disagrees
regarding time delays, an immediate effort should be made to document those difficulties and an effort
should also be made to resolve them by informal negotiation, protest and/or documentation of the
dispute. Efforts to mediate differences of opinion should be made, including utilization of the
American Arbitration Mediation procedures, where applicable.

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Appendix H-18

J. Bond Requirements.

The subcontractor will be frequently required to put up performance and labor and material
bonds concerning its work.

The two most common types of bonds encountered in the construction industry are the
performance bond and the labor and material bond (also referred to as the payment bond). The
performance bond guarantees that the subcontractor will perform its contract. The "principal" may be a
subcontractor and the "obligee" the Company. Often the construction lender is also an obligee on a
performance bond, with reference to private work. A performance bond is often combined with a labor
and material bond at no additional premium.

Unlike a labor and material bond, a performance bond on which the subcontractor is the
principal, usually runs only in favor only of the Company.

The most common labor and material bond used in California is the payment bond. When an
owner of real property and a contractor enter into a fixed-price contract for construction, this price is
the monetary limit of the owner's obligation to the contractor regardless of the actual costs of the
improvement. The owner's obligation to supplier of labor, services, equipment or material is not
limited to the prime contract price. The mechanic's lien law does provide a means by which the
property owner may avoid paying more than the agreed contract price because of liens by unpaid
suppliers. To obtain the benefit of the statute, the owner must file the original contract and record a
bond in the office of the county recorder where the property is located before the work of improvement
is commenced.

K. Indemnity And Insurance.

A subcontractor may be asked by the Company to indemnify the Company for the
subcontractor's negligence in performing the project. Unless the indemnity provision specifically
provides for indemnification for the awarding authority's negligence, the indemnification runs only in
situations where the subcontractor is negligent, or if the Company and third parties are both negligent
(perhaps including the awarding authority as well).

It is often required in the Company's construction contracts that the subcontractor have
suitable liability insurance, builders' risk insurance and workmen's compensation insurance. The
purpose is to cover any injuries which are suffered by workmen on the project, and the affects of any
damage caused by the subcontractor or the Company's defective workmanship. Such insurance
normally does not provide coverage for damage to the Company's own work, but such coverage can be
approached by obtaining "completed operations" and "products liability" insurance. Such insurance is
very expensive. The Company can obtain insurance providing coverage for defective work by its
subcontractors, but not as to its own defective workmanship.

V. CONTRACT ADMINISTRATION

A. Follow The Contract Or Get Permission Not To Do So.

Whenever the Company confronts a situation where performance of a contract is difficult or

impossible, it should immediately communicate with the awarding authority or its agents in order to
obtain an appropriate change. Under no circumstance should the Company go forward with a change
of the proposed work without authorization, or least an effort to communicate with the awarding
authority in some follow-up form of protest. (See discussion above.)

Efforts should be made to ascertain from the awarding authority and its representatives, their
understanding of the way the work should proceed. If the Company believes that the awarding
authority and its representatives are in error, or if the awarding authority is improperly interfering with
the Company's performance, then appropriate communication should be had with the awarding
authority, and an appropriate protest lodged.

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 Appendix H-19

B. The Company's Project File Should Be Kept Complete.

The Company's time records, job diaries and job files should be kept up to date. All events and
developments should be memorialized in writing, particularly with reference to interaction with the
awarding authority and its agents. Any changes in the work should be documented. If changes cannot
be executed and entered into in a timely fashion before performing the work, the Company should at
least confirm in writing to the awarding authority requests for changes in the work.

C. Processing Payment Requests.

From a legal standpoint, the Company should make every effort to fully document all of its
payment requests. Complete copies of invoices, lien releases and other documentation should be
gathered together by the Company and presented with all payment requests. All time records,
subcontractors submittals, change order requests and other documents necessary to provide complete
documentation of the payment requests should be gathered together and presented with a payment
request. A complete file should be kept in chronological order of such payment requests, for ready use
should the Company determine it will need to pursue a claim in order to obtain payment.

D. Documentation Of Time Delays.

Project managers should make every effort to document each and every non-work day which
the Company confronts on a project. Each non-work day should be explained by some form of
reasonable excuse such as poor weather, owner interference or some other event outside of the control
of the Company. These events should be documented on a daily basis and summarized periodically.
Furthermore, the Company should make clear as soon as it can that it will be pursuing extra time to
finish the project due to excusable time delays.

E. Problems With Coordination.

The single word which best describes the role of the general contractor during construction is
that of the coordinator. Even if the Company only utilizes (in addition to its work force) a grading
subcontractor, framer, plumber, roofer, storm drain subcontractor, landscaper and electrical
subcontractor, the work of those subcontractors should be carefully scheduled, so that no time is lost
because of a lack of coordination. Proper coordination of the various groups involved in a construction
project occurs when the Company completes its construction tasks efficiently and expeditiously.

Successful coordination, involves the Company's reaction to the perceived need to continue to
introduce and master new methods and techniques of construction in order to conduct operations
more
efficiently. The coordination process involves the need to directly coordinate performance of highly
specialized and technical processes.

The central aspect of providing efficient coordination is having sufficient supervisory staff to
coordinate and provide general direction and supervision of the work and of the progress of the
subcontractors on the project. Appropriate procedures for implementing coordination among the
various interested parties should be undertaken. In that regard, the Company should maintain proper
records and prepare appropriate progress reports.

Construction pre-planning meetings and preparation of a detailed work schedule are tools for
the proper coordination of work. Prior to starting work, it is important for the estimators to meet with
the Company's project team for review of the estimates, drawings and specifications. The more
preplanning done by all elements of the Company's staff on a project, the better the coordination and
the less difficult are the potential claims by the awarding authority that the Company failed to
adequately coordinate the project, and thus delayed the project (thus subjecting the Company to
liquidated damages). Also, the Company can avoid claims for improperly constructive work, as a result
of failure to obtain appropriate coordination.

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Appendix H-20

F. Efforts Should Be Made To Communicate With The Subcontractor's Representatives With

Reference To Their Authority to Act, Extra Work and Time Extension Requests.

The Company's project manager should begin with the concept that communication with the
subcontractor is a high priority item. Such communication will help identify any misunderstandings
and potential disputes at an early stage, and hopefully generate a means for defusing those disputes.

Furthermore, a detailed understanding of contract provisions and aggressive interpretation of

those provisions (plus documentation of the positions taken by the Company), will assist the Company
in successful administration of the project. Also, there will be a minimization of delay and
maximization of the potential for recovery of compensation for extra work.

If the Company determines that a representative of the subcontractor, or one of its consultant,
is abusing his/her authority, every effort should be made to set the record straight, orally and in
writing, especially regarding the agent's misinterpretation of the plans and specification. Furthermore,
efforts should be made to at least create a record of that difficulty, should it be necessary to get into a
dispute later on.

Because of the implied covenant of cooperation and a potential exposure of third party
consultants for interference, a diplomatic but firm approach should be adopted where the Company
believes that representatives of the subcontractor are interfering with the Company's performance of
the work.

As always, project managers for the Company will be looking for areas of compromise and
ways to maximize cooperation with all other parties involved in a project, including the awarding
authority's consultants. An image of being a problem solver, and of delivering that which is promised,
will assist the Company in reaching its objectives. When the awarding authority's agents refuse to
cooperate, the Company should consider utilizing the above referenced techniques of controlling such
parties.

Use of the pre-job conference to size up the specific individuals representing subcontractors,
and thereafter formulating a strategy based on those initial impressions, may help the Company
appreciate at an early time exactly what problems its can anticipate in its dealings with representatives
of the subcontractors.

VI. SUBCONTRACT INFORMATION AND ADMINISTRATION

A. The Subcontract Agreement.

The typical subcontract form is based in part upon the AGC subcontract form.

The form retains the Company's right to terminate a subcontractor at any time, with or
without cause. If the termination is with cause, the Company stands to have far less exposure to the
subcontractor for termination payments.

An effort should be made in the subcontract to specifically state the scope of work for the
subcontractor and make clear the subcontractor's area of responsibility, particularly with reference to
preparatory work, temporary utilities and clean-up.

The subcontract form incorporates the provisions of the contract between the Company and
the awarding authority or owner so that the subcontractor is bound to the Company's agreement with
the awarding authority. It is wise to either use a separate dispute clause in the subcontract or
specifically provide that the dispute procedure of the prime contract is incorporated into subcontract.
The form specifically provides for an option that it may resolve disputes with the subcontractor by a
process of judicial reference procedures, thereby seeking expedited resolution of disputes before a
retired judge of the superior court.
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 Appendix H-21

The subcontract agreement form is effectively utilized, however, only if it is fully filled out and
signed. When signing up a subcontractor, by utilizing the subcontract agreement form, one should
make certain of the following:

1. Each of the blank spaces in the subcontract agreement relating to the specific details
concerning any project should be fully filled in. If any of the spaces are left blank, a dispute
could later arise regarding the parties' intent with respect to the information not provided.

2. One should make certain that each of the attachments referred to in the subcontract
agreement is, in effect, attached to the subcontract agreement.

3. One should also make certain that the subcontractor's initials appear on each page of the
subcontract agreement.

4. It is also important that the Company and subcontractor sign and fully fill out the signature
blocks at the end of the subcontract agreement.

There are usually many important features in the subcontract agreement, and project
managers should make an effort to be familiar with all of the them. A subcontract agreement will
typically provide answers to most of the issues which arise during construction.

Extras are only authorized when in writing under the subcontract. Also, the subcontractor is
required to provide full labor and material releases before receiving any progress payment from the
Company. The Company has the right under the form to terminate the right of the subcontractors. In
addition, the Company's subcontract form contains extensive indemnification provisions, essentially
requiring the subcontractor to indemnify the Company against any claim, as it may arise on the job site,
except those arising from the Company's own negligence. Also, the Company has extensive insurance
requirements for subcontractors, which should be vigorously enforced.

B. Processing Progress Payment and Final Payment Requests.

Payment processing is often the most important phase of subcontract administration.

The overriding objectives are:

1. To ensure that, by acceptance of payment, the subcontractor releases all claims for work done to
date, minus retention; and

2. To ensure that there are no third party lien or stop notice claimants who might retain a claim
against the property or against the Company after the subcontractor has been fully paid.

Before releasing a progress payment to the subcontractor, the Company should ensure that all
of the following have been done:

1. One should consult the list of preliminary notices that the Company has received; and the
subcontractor should be prepared to deliver a conditional release from each party which has
served a preliminary notice.

2. One should keep a record of any parties other than those serving preliminary notices who have
registered any kind of a claim regarding the project. A progress payment should not be released
until one is satisfied that these claims have been extinguished or waived, or that the
subcontractor will be solely responsible for them.

3. If any subcontractor is unionized, the Company should be certain that it knows the identify of
every union trust fund to which he/she is obligated to make contributions on behalf of his/her
workmen. Note that union trust funds are not obligated to serve a preliminary notice;
nevertheless, they have mechanic's lien rights. It is not unusual for a contractor to pay off a
lower tier contractor, only to discover that a union trust fund is asserting a mechanic's lien
claim on the property.

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Appendix H-22

4. The typical subcontract agreement gives the right to issue joint checks, payable to the
subcontractor and any unsatisfied claimants. One should not hesitate to use this device if there
is any doubt about the subcontractor's willingness to fairly pay his/her sub-contractors and
materialmen. (Note: To be effective, a joint check must be endorsed and payment in full for
material and labor covered by the check must be acknowledged by each of the endorsing parties.
Thus, it is critical that the joint check include an adequate recitation, prior to the endorsement,
waiving all lien and stop notice rights for labor and materials covered.)

It is possible to issue a joint check payable to more than two subcontractors and/or
materialmen. Post Bros. Construction Co. v. Yoder, (1977) 141 Cal. Rptr. 28. However, this practice can
lead to confusion regarding the respective entitlement of each joint payee to a portion of the proceeds.

5. To preserve the Company's status as a general contractor, checks to subcontractors should be

issued on its own bank account. One should avoid paying subcontractors and materialmen on
accounts which bear the name of any other related entity to the Company.

6. As an additional precaution, there generally should be a release paragraph on the back of each
check issued to subcontractors and materialmen. One form of release, which could be rubber-
stamped on the back of checks, would be as follows:

" The payee of this check, by endorsement hereon, acknowledges receipt of payment in full
for all work performed and material provided on Tract Nos. through and including
(date) and hereby releases and relinquishes all mechanic's lien, stop notice, and labor and
material bond rights it may possess for the performance of work and provision of materials
thereon. This release is for the benefit of, and may be relied upon by, the owner, the prime
contractor, the construction lender, and the principal and surety on any labor and material
bond. “

----------------------------------------------
(Endorsement)

7. Workmen who provide labor on a construction project are entitled to a mechanic's lien to secure
their claim for unpaid wages. They are not required to file a preliminary notice, and the
Company is usually not aware of their identities unless they audit the payroll records of the
subcontractor. Usually, it is impractical to require the subcontractor to provide lien releases
from all of its workmen. However, if there is any doubt about the solvency or reliability of the
subcontractor, one may wish to require such releases on particular construction projects.

8. In reviewing lien releases provided by the subcontractor, it is advisable to conduct a spot check
to verify the validity of the releases provided. It is not unheard of for a subcontractor to forge
the names of materialmen and of subsubcontractors in order to obtain a progress payment.
Spot checks can be done by telephone.

9. Generally, it is desirable to require the subcontractor to use release forms provided by the
developer or general contractor. However, in certain instances, the subcontractor may have
obtained releases on other forms provided by his/her materialmen and sub-subcontractors.
Following is a checklist one can use to determine whether an alternative form of release is
valid:
a. Does the title of the document contain the words "waiver" and "release"?
b. Does the form show the exact amount received?
c. Does the form show that the amount was received from the payor?
d. Does the form show the payee of the check?
e. Does the release specifically refer to the job on which work was performed or material
provided, and specifically name the owner?
f. Does the release form specifically state the date through which full payment is
acknowledged?
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 Appendix H-23

g. Does the form specifically state that the payee releases (whether conditionally or
unconditionally) pro tanto any mechanic's lien, stop notice, or bond right the payee
has on the referenced job?
h. Is the form dated?
i. Is the Company name of the releasor clearly shown in the signature block?
j. Is the release form executed by an authorized person, whose title appears on the
form?

If the release contains all of these items, it is generally valid. California Civil Code Section 3262.

C. Testing Lien and Stop Notice Claims.

Despite careful adherence to the payment procedures discussed above, the Company will
receive some lien and stop notice claims. Of course, not all such claims are valid; a significant
percentage of all lien and stop notice claims are procedurally defective in some way. Many lien claims
are filed in the hope that the Company will pay the claim just to get rid of the claim, without
scrutinizing its sufficiency.

The following points should assist one in evaluating lien and stop notice claims:

1. To be eligible for lien rights, the claimant must prove that it contributed to a reasonably
permanent work of improvement on the property. Services of a purely transitory nature, such
as trimming shrubs and mowing lawns, are insufficient to confer lien rights. Young v. Shriver,
(1922), 56 Cal.App. 653. By contrast, the installation of landscaping is sufficient to confer a
lien right. California Portland Cement Co. v. Wentworth Hotel Co., (1911), 16 Cal.App. 692.

2. The most important prerequisite to assertion of a lien right is that the material or labor
provided must have been used or consumed in the course of constructing a work of
improvement. California Civil Code Section 3110. If lumber is delivered to a jobsite, but is
subsequently removed by the owner or general contractor without being used in a work of
improvement on the site, the materialman has no lien right, even though he/she provided
lumber in good faith. California Portland Cement Co. v. Wentworth Hotel Co., (1911), 16
Cal.App. 692.

3. No lien rights attach when work on a planned project does not actually commence. For
example, a lumber dealer may not assert a lien for lumber which was milled to the order of a
prime contractor, where the work of improvement was never begun; similarly, an architect
cannot assert a lien for preparation of plans and specifications when the project was never
undertaken. MacDonald v. Filice, (1967), 252 Cal.App.2d 613.

4. Every mechanic's lien and stop notice claimant is required to prepare and serve a Preliminary
Notice before any lien or stop notice rights may be asserted. For claims against the owner, the
only exceptions are: (1) the prime contractor; (2) other contractors who deal directly with the
owner; (3) individual workmen who have a claim for unpaid wages; and (4) union trust funds.
For claims against the construction lender, the only exceptions are: (1) the prime contractor;
(2) individual workmen who have a claim for unpaid wages; and (3) union trust funds. If the
claim does not fit within these categories of exceptions, the failure to serve a properly
executed Preliminary Notice will render the mechanic's lien or stop notice unenforceable.
California Civil Code Section 3097.

5. The Preliminary Notice must be given no later than twenty days after the claimant has first
furnished labor, services, equipment, or materials to the jobsite. California Civil Code Section
3097(c). The service of a late Preliminary Notice will not completely destroy the claimant's
right to recovery, however. If a late notice is given, the notice will only give the claimant the
right to assert a lien for a period commencing twenty days prior to the service of the
Preliminary Notice. California Civil Code Section 3097(d).

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Appendix H-24

6. The Preliminary Notice must contain the following information:

a. A general description of the labor, services, equipment, or materials furnished, or to

be furnished;

b. If there is a construction lender, there must be an estimate of the total price of the
labor, services, etc., to be furnished;

c. The name and address of the person furnishing the labor, services, etc.;

d. The name of the person who contracted for purchases of the labor, services, etc.;

e. A description of the jobsite sufficient for identification; and

f. The following statement must appear in bold face type:

NOTICE TO PROPERTY OWNER

"If bills are not paid in full for the labor, services, equipment or materials furnished or
to be furnished, a mechanic's lien leading to the loss, through court foreclosure proceedings, of all or
part of your property
being so improved may be placed against the property even though you have paid your contractor in
full. You may wish to protect yourself against this consequence by (1) requiring your contractor to
furnish a signed release by the person or firm giving you this notice before making payment to your
contractor or (2) any other method or device which is appropriate under the circumstances."

California Civil Code, Section 3097(c).

7. The requirements for the preparation of the Preliminary Notice are strictly construed. For
example, a Preliminary Notice was invalidated, and lien rights were lost, because the "Notice to
Property Owner" was not in bold face type; James v. Five Points Ranch, (1984), 202 Cal.Rptr.
494.

8. The claimant need give only one Preliminary Notice to the owner and general contractor, even
though he/she may later furnish additional materials, services, labor, or equipment not within
the scope of those generally described in his/her notice. However, if the claimant furnishes
materials, services, etc. to more than one subcontractor, he/she must file a Preliminary Notice
as to each. California Civil Code, Section 3097 (g).

9. Many materialmen and subcontractors use printed forms available at builders supply stores for
preparing Preliminary Notices. These printed forms generally comply with the requirements
of California law (unless they are outdated forms -- many contractors retain a supply of
obsolete legal forms). However, the mere fact that the form is sufficient does not end the
inquiry. You must read the Preliminary Notice to make certain that the claimant has filled in
all of the required information.

10. The current Preliminary Notice form contains a declaration of service, which is designed to
simplify service of the form. Currently, a Preliminary Notice may be served in California by (1)
personal delivery at the place of address of the persons to be notified; or (2) by first class
registered or certified mail. This requirement is often ignored by suppliers, subcontractors,
and others. Ordinary mail, first class or otherwise, is not sufficient. Mail delivery must be
registered or certified, and the receipt of certification or registration must be attached to the
affidavit of service. California Civil Code Section 3097(f).

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 Appendix H-25

11. The contractor is required to permit any subcontractor or other claimant to view a copy of the
original contract between the owner or developer and prime contractor; this contract must
contain the owner's name and address and place of business. If the prime contractor gives the
subcontractor or his/her claimants incorrect information about the owner or construction
lender, his/her lien may be valid despite incorrectly identifying these parties. Brown v.
Superior Court, (1983), 148 Cal.App.3d 891.

12. Like the Preliminary Notice, the mechanic's lien itself must contain a number of required
elements. California Civil Code Section 3084 sets out the requirements as follows:

a. The lien must be signed and verified by the claimant. It need not be notarized,
however.

b. The lien must contain a statement of the demand, after deducting all just credits and
offsets.

c. The name of the owner or reputed owner, if known, must be stated.

d. There must be a general statement of the type of labor, services, equipment, or

materials furnished by the claimant.

e. The lien must show the name of the person or entity by whom the claimant was
employed or to whom he/she furnished the labor, services, etc.

f. There must be a description of the site to be liened sufficient for identification. The
lien need not contain a full legal description, including metes and bounds of the
property. If the description is completely inadequate, however, the lien may be
invalid.

13. A lien claimant need not wait until a project is completed before recording a mechanic's lien,
so long as his/her contribution to the work of improvement has been completed. However,
once the work of improvement is "completed" the time for recording a lien begins to run as to
all claimants as follows:

a. If a Notice of Completion was recorded, laborers, materialmen, and subcontractors

have only thirty days thereafter to record a mechanic's lien; the general contractor has
sixty days. California Civil Code Sections 3115 and 3116. Note that the Notice of
Completion must be filed within ten days after completion to be effective. California
Civil Code Section 3093.

b. If, after a cessation of work for a continuous period of thirty days or more, a Notice of
Cessation as defined by California Civil Code Section 3092 is recorded by the owner,
the lien times are limited to those discussed in the preceding paragraph.

c. If no Notice of Cessation or Notice of Completion has been recorded, all persons have
a period of ninety days after "completion" of the work of improvement in which to file
their claims of lien. California Civil Code Sections 3115 and 3116.

d. The time for recording the lien is computed by excluding the first day and including
the last, unless the last day is a holiday (including Saturdays and Sundays). When the
deadline falls on a Saturday, Sunday or holiday, the lien is timely recorded on the next
business day on which the County Recorder's Office is open.

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Appendix H-26

14. The "date of completion" of a project is a term of art and is often the subject of hot dispute.
California Civil Code Section 3086. The following events are considered to constitute
"completion" and will start the running of the ninety-day limitation period for recording liens:

a. Occupation or use of the work of improvement by the owner or his/her agent, when
accompanied by the cessation of labor;

b. Cessation of labor for a continuous period of sixty days;

c. Acceptance of the work by the owner or his/her agent.

15. If a work of improvement consists of two or more separate residential units, each unit is
ordinarily considered a separate "work of improvement" and the time for filing a lien against
each such unit commences upon the completion of each unit. California Civil Code, Section
3131. However, courts have held that this requirement is inapplicable to condominiums.

16. When a lien is placed upon an entire tract and/or where the claimant's work or materials were
supplied for more than one residential unit or other work of improvement, the lien will be
"postponed" to other liens unless the notice and claim designates the amount due on each of
the buildings or other improvements. The claimant may estimate the proportionate amount
due on each building.

17. No mechanic's lien binds property for a period longer than ninety days unless a lawsuit to
foreclose the lien is commenced in a proper court within that time. The sole exception is
when a "Notice of Credit" is recorded, which may extend the period for up to one year.
California Civil Code Section 3144.

18. The mechanic's lien remedy is not exclusive. A claimant may invoke any other remedies
he/she may have, including a suit against the subcontractor, the service of a stop notice, a
claim against any applicable bond, or any other available relief.

19. There is no relative priority among mechanic's liens, provided that the liens are all recorded
within the prescribed statutory time limit. However, all mechanic's liens enjoy priority over
any other type of lien encumbrance, deed of trust, or other claim to title which has attached
subsequent to the commencement of the work.

20. The function of a stop notice is slightly different than that of a mechanic's lien. A stop notice
is a device used to place a "hold" on undisbursed construction loan funds. Any person entitled
to a mechanic's lien other than a union trust fund may serve a stop notice. California Civil
Code Section 3158-3159.

21. The stop notice is ordinarily served on the owner and construction lender. It must be served
prior to the expiration of the claimant's time period to record a mechanic's lien against the
property as defined in California Civil Code Sections 3115-3117. California Civil Code Section
3160.

22. A stop notice claimant must furnish the same Preliminary Notice as a mechanic's lien claimant.
Otherwise, the stop notice is unenforceable. California Civil Code Section 3160(a).

23. California Civil Code Section 3103 provides that the stop notice must contain the following
information:

a. A general description of labor, materials, and/or services furnished;

b. The name of the person for whom the labor, materials and/or services was furnished;

c. The value of the work or material already furnished and the value of the entire amount of
work or material to be furnished;

d. A verification.
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 Appendix H-27

24. Unless a stop notice is accompanied by a bond issued by a recognized surety, it need not be
honored by a construction lender. California Civil Code Section 3083. However, some lenders
voluntarily honor unbonded stop notices.

25. To be valid, a stop notice must be served on the owner or construction lender within the time
permitted for recording mechanic's liens. California Civil Code Section 3160(b). The stop
notice must be served personally or by registered or certified mail. California Civil Code
Section 3103.

26. An action to enforce a stop notice may be filed no sooner than 10 days after the stop notice has
been served, and no later than 90 days after the expiration of the period during which
mechanic's liens may be recorded. California Civil Code Section 3172.

27. The Company should avoid dealing directly with materialmen and sub-subcontractors with
which they have no direct contractual relationship. If the Company begins dealing with these
parties directly, they may later claim a direct contractual agreement, which can confer lien
rights they would otherwise not enjoy.

D. Claims on Payment and Labor and Material Bonds.

1. In some cases, the Company may require its subcontractors to provide payment and labor and
material bonds to secure their performance on construction projects. The value of such bonds
depends, in large degree, on the timing of the steps taken to enforce the rights provided by the
bond.

2. The most critical thing to remember about bonds is the importance of notice to the surety.
Generally, bond rights arise from the contractor's failure to perform pursuant to the provisions
of his/her contract. Therefore, if it appears that the contractor is not going to be able to
perform his/her contractual obligations, notice should be given to the surety immediately.

3. The three defenses sureties typically raise are: (1) lack of timely notice; (2) lack of opportunity
to rectify the problem; and (3) a material change in the obligations imposed on the bonded
contractor, without notice to the surety. These defenses can be easily overcome when you can
show that the surety has been kept on full notice of the problems encountered with the
contractor's performance and has been given the opportunity to consult with you and/or
remedy any problem, consistent with timely performance of the job.

4. In some instances, it may be completely impractical to involve the surety in rectifying a jobsite
problem. For example, if the contractor simply quits the job, and work must be continued
through the immediate employment of another contractor, there may not be time to rectify the
situation. Nevertheless, you should build the best paper record possible to show that the
surety was (1) notified; and (2) was not willing to act in the limited time available.

VII. ADMINISTRATION OF CLAIMS

A. Right of Way Problems.

Frequently, the first "claims" experience of the Company on a project will be its
obtaining the right of access to various portions of the project. Section 2-8 of the Green Book provides:

"Rights of Way, Easements or Rights of Entry for the work will be provided by the
agency. Unless otherwise provided, the contractor shall make arrangements, pay for, and assume all
responsibility for requiring, using and disposing of additional work areas and facilities temporarily
required. The contractor shall indemnify and hold the agency.

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Appendix H-28

Appended hereto as Appendix "A" is a chart from a CEB publication setting forth the
relevant time limitation periods which govern the processing of construction lien and bond claims.

Appended hereto as Appendix "B" are various sample construction lien forms from the
same CEB publication. harmless from all claims for damages caused by such actions."

At Section 8-1.09 of the Standard Specifications of the Department of Transportation,

it is provided:

"If, through the failure of the state to acquire or clear right of way, the
contractor sustains loss which could not have been avoided by the judicious handling of forces,
equipment and plant, there shall be paid to the contractors such amount as the engineer may find to be
a fair and reasonable compensation for such part of the contractors actual loss, as, in the opinion of the
engineer was unavoidable.

***
"Actual loss shall be understood to include no item of expense other than idle
time of equipment and necessary payments for idle time of men, cost of extra moving of equipment,
and cost of longer hauls. Compensation for idle time of equipment will be determined as provided in
this section . . . and compensation for idle time of men, will be determined as provided in Section . . .
"labor", and no mark-up will be added in either case for overhead and profit. The cost of extra moving
of equipment and the cost of longer hauls will be paid for as extra work as provided in Section 4-1.03D.

If performance of the contractors work is delayed as the result of the failure

of the Department to require or clear right of way, an extension of time determined pursuant to the
provisions of Section 8-1.07 . . . will be granted . . .."

B. Documentation and Proof of Claim.

The Company will encounter events and increased costs which may be identifiable as
claims. Essential steps in the evaluation, preparation and proof of claims include:

1. Fact Finding, including investigations at the project site and elsewhere of the events of the
performance considering plans, specifications, drawings and other terms of the contract. This process
includes not only the reading of all documentation (job logs, quality control and field reports,
correspondence, contract and modification documents, etc.) but also the interviewing of persons
familiar with the project conditions. Timeliness of inquiry is obviously essential, including the taking
of photographs, preservation of soils data and other physical evidence, and the need to coordinate with
subcontractors, consultants and others. The investigation should include not only the technical tasks
of the performance, but also the costs associated with the potential claims.

2. Analysis of the events and costs, with consideration to the sequence of the work as originally
scheduled, changes in the sequencing caused by delays, the source of the delay, changes directed or
necessitated by deficient design, comparison of original contract work with work actually being
performed, the use of scheduling techniques, such as the critical task method, and the need for timely
notice of claims (in writing to the appropriate agency representative), the evaluation of estimates used
in the bidding with the cost being incurred in performance, including an estimate of costs to complete,
etc.

3. Identification of Contract and Legal Bases Upon Which a Claim May Be Presented. The
various contract clauses, specifications and other provisions such as the changes, different site
conditions (changed conditions) suspension of work, time extension and other provisions, including
the need for conferring timely written notice to representatives of the agency, have to be implemented.

4. The Preparation of a Draft of the Claims Narrative and exhibits for review by persons
knowledgeable on events and costs followed by a finalization of the draft to a well documented claims
package. This is an important step in the entire claims recovery process. It is a significant tool in the
evaluation of the claim by Company personnel and frequently is the basis for a successful or
unsuccessful resolution of claims.

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 Appendix H-29

5. Establishment of a Timetable for the Pursuit of the Claim allowing adequate time for
preparation, presentation, audit, fact finding discussions, settlement negotiations and the disputes or
litigation procedures.

To optimize the recovery of claims, the Company, having conducted actual investigations and
study of the terms and legal principals, has to use care in the documentation and presentation of the
claim to establish credibility. This process begins with realistic assessments of the "good and bad" and
a willingness to present fairly the data to the agency for evaluation. Not only must there be a factual
presentation of events but also of costs dependent upon the use of estimates, projections and/or
incurred costs.

C. Anticipate Claims and Claim Avoidance.

The Company is most frequently benefitted by its representatives in anticipating the

potential for claims. If you observe circumstances which tend to indicate that there may be a dispute
later on, involving cost, time extensions or some other important factor, than it is probably appropriate
to actively consider the potential of the claim situation, and prepare for it. Likewise, if at all possible,
the potential claim situation should be avoided by taking whatever appropriate action, if that action is
no more than simply giving oral or written communications.

D. Communicate to Solve Problems.

A constant theme of these materials is the need to communicate with the agency or
owner representatives and with your subcontractors. Likewise the need to communicate internally at
the Company, is clear, particularly with reference to efforts to identify and avoid potential claim
situations. In addition to anticipating problems, communication of information to resolve or avoid the
problems is critical.

E. Identify Problem Representatives of the Owner or Agency And React Accordingly.

As early as the first job meeting, you can make an evaluation as to whether a
particular job is a candidate for a claims situation. Is the agency's outside engineer or inside engineer a
person who seems to like to engage in debates or is somehow not cooperative? If there is anything
wrong in your initial impression of agency representatives, or engineers, than perhaps you should
anticipate the need to carefully document the companies position and to frequently communicate with
the agency in question, in order to avoid claims situations. The same is true of your initial encounters
with subcontractors on any given job. The efforts should be to identify particular problems as soon as
possible, whether they be with representatives of the agency or subcontractors or some other
circumstances and provide an appropriate Company response even if that is no more than a written
communication to preserve the record.

F. Examples of Constructive Change Orders Resulting In Claim Situations.

In addition to the entitlement to a constructive change order for the deficiencies in

design for which the owner is responsible, the Company may be entitled to the application of the
constructive change order doctrine if:

1. There is an increase in the level of inspection over that which was originally required under
the contract.

2. There is a limitation on the Company's work method which precludes the Company from
options otherwise available under the contract with regard to sequencing and other aspects of
the work.

3. There is an impossibility or impracticability of performance for which the owner has

undertaken the risk.

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Appendix H-30

4. There is an acceleration or delay in the work for which the owner is responsible.

5. There is an erroneous interpretation of the design or specifications for which the owner is
responsible and an owner's directive causes extra work.

6. There is an erroneous rejection of the work by the government.

G. Dealing With Unforeseen Conditions On the Job.

The "Changed Conditions clause" typically provides that in the event the physical
conditions at the site of the project varying materially from those represented or reasonably anticipated
and in a manner which increases the time or the cost of performance, the Company is entitled to
additional compensation or an extension of time.

One purpose of the clause is to secure a lower contract price by inducing bidders to
refrain from including in their bids contingencies for such things as unknown subservice conditions.
Some clauses may provide for an increase in the contract price in the event the conditions differ in
some manner as to reduce the cost of performance.

Most contracts contain a provision requiring bidders to examine the site of the work prior to
submitting a bid. The contractor is charged in such a case with knowledge of all conditions which
would have been discovered in the course of a reasonable site investigation. In the absence of such a
clause, bidders generally are not required to conduct an investigation of the site and are not charged
with knowledge of conditions which could have been discovered only by inspecting the site.

The knowledge charged to a contractor under these circumstances is that which would have
been discovered only by a reasonable site investigation and an intelligent contractor. Thus, the
contractor is not charged with knowledge of conditions which could not have been discovered without
the assistance of an expert in some field of science such as geology.

Notwithstanding his/her duty to investigate, the contractor is entitled to rely on any specific
representations by the owner respecting the condition of the site. Such representations may be
construed as warranties which are breached if the conditions are materially different. A contractors
right to recover on this theory may require proof of reliance by the contractor.

The contractor is required to furnish notice of any changed condition. The giving of such
notice within a specified period is a condition precedent to the right of any relief which might be due.
Failure to give notice within the required time may not operate as a waiver of rights if the existence of
the changed condition is known to the contracting agency.

H. Time Extensions.

As soon as you become aware of time problems with reference to completing a project, those
time problems should be documented in an appropriate request for a time extension under the
contractor and directed to the awarding authority. A standard clause in contracts for construction
provides for an extension of time in the event completion is delayed by certain kinds of events beyond
the control of the contractor. Such clauses frequently provide also that the contractor's sole remedy for
certain delays is an extension of time of performance, thus precluding any right to recover additional
costs occasioned by the delay. Typically, delays which permit an extension of time are those caused by
such things as acts of God, weather, action by government, and delays by failure to act attributable to
other contractors.

I. Identify and Communicate Extra Work Requests Before They Are Needed.

If at all possible, it is a good idea to identify and communicate to the awarding authority the
needs for extra compensation, e.g. change orders, before they are needed. In short, if you anticipate
that extra work is going to be required that situation should be communicated to the awarding
authority and appropriate change order requested, or at least a written communication of direction
from the agency requested.
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 Appendix H-31

J. Where The Project is Reduced In Scope As to Certain Work Items Below Which Is
Economically Feasible.

There may be circumstances where the amount of work in question is less than originally
anticipated, so much so that the unit price put in the bid is no longer realistic. The Green Book has a
25% rule where if a unit of work is reduced by change order more than 25% of the work, than the
pricing schedule for the work is changed to a time and materials basis. The Company should identify
as soon as possible the need to rely on such provisions where the work is reduced, and takes steps to
document a request for such compensation before undertaking the work if at all possible.

K. Set Up and Document Claim Book.

The claims documentation as the central basis for settlement of claims requires organization
and substance. The essential questions of entitlement to recovery, the legal basis therefore, the
amount of monies claimed and/or the time for which the claimant asserts a right have to be addressed,
including the use of suitable exhibits. The narrative should include a brief beginning summary of the
nature of the claim. It should also include a complete statement of the facts, a detailed chronology of
events, and references to applicable legal rules including contract provisions, specifications and other
terms. The narrative should also include a presentation of costs which are directly related to the claims
and time associated. For example, a narrative may seek the recovery of extended overhead and
adverse effects to the project as a whole due to a multiplicity of changes and other events for which the
awarding authorities is responsible.

Such claim documentation has to be correlated to include computation of labor inefficiencies,

extended overhead and other costs as applicable. Also, the Company should consider suggesting to the
awarding authority the Company's willingness to have its costs audited.

L. Consult With A Lawyer.

In many instances, Company management will probably want to consult with its counsel,
particularly as to major claims, in order to coordinate preparation of a persuasive claims presentation,
to prepare an appropriate negotiation strategy, and for pursuit of the claim in litigation.

M. Define Goals of Claim Administration.

Very early on, Company representatives should ascertain what their goals are based upon a full
evaluation of all the facts and circumstances. In short, how much money do you want from the claim,
how much of a time extension, and how much are you prepared to settle for? Once you have
determined the answer to these questions, then the Company can ascertain an appropriate claims
strategy, which can be implemented.

N. Prepare Claim Chronology and Documentation.

It is essential to prepare as a part of the claim documentation, a detailed chronology of the

events, concerning the claim, backed up by a chronological set of documents, including correspondence
on the subject claim. This helps document the Company's position, aids communication with the
agency, and assists the Company and its lawyers in presenting the Company's position in litigation.

O. Bite the Bullet and Settle.

In general, it is quite appropriate for a Company to identify its goals, document its position
and arrive at a strategy for obtaining the best possible result under the circumstances in the claim.
Once the Company has ascertained the awarding authority attitude, the Company should determine
the best amount that it is able to obtain through settlement and agree to settle if that appears to be the
most appropriate way to proceed.

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Appendix H-32

P. Use Arbitration Rights.

Wherever the Company has given rights to litigate its claims expeditiously, it should initiate
those rights, generally arbitrate as soon as possible, and be prepared to move the arbitration
proceeding along as quickly as possible. The Company should form an appropriate negotiation team,
including its attorneys for pursuit of the claim, formulate and implement an appropriate strategy for
settling the claim expeditiously.

Q. No Damages For Delay Clauses.

One of the most common express contractual limitations on remedies used in construction
contracts, particularly those with governments, is a provision which purports to deny the contractor the
right to recover damages for delay against the owner. Normally such provisions are quite broad, and
are, as a general rule, upheld by the courts. No damages for delay clauses are considered to be in the
public interest when used as a means of protecting public agencies against inappropriate claims. Some
clauses have at times been read literally so as to preclude recovery for any delay. But there are several
exceptions to the general rule that the clause is a legitimate vehicle. The courts will first look to the
language of the clause and to other relevant circumstances to see if it is appropriate to enforce the
clause.

R. Pursuit of Third Parties.

If the outside engineers retained by an awarding authority or other third parties are
inappropriately interfering with the Company's handling of the contract, appropriate communications
could be addressed to those parties informing them that their conduct could be actionable. In short,
the Company can pursue claims against those third parties because of their interference. It is
appropriate to communicate with those third parties, diplomatically, to inform them of their erroneous
position, and to inform them that they face of their erroneous position, and to inform them that they
face liability exposure. The goal should be to work harmoniously with such parties at all times, but if
necessary, they should be placed on notice of their liability exposure.

***

Seismic Retrofit Training

 Appendix I-1

WHAT DID YOU LEARN?

1. Prescriptive standards are:

a) just what the doctor ordered

b) rules of thumb that are better than engineering
c) legal standards that have passed the test of time
d) construction provisions that do not require an engineer or architect

2. Seismic retrofit construction requires an engineer or architect when:

a) homes are built over slopes steeper than 3:1

b) foundation walls are constructed with unreinforced masonry
c) there are more than four dwelling units in a structure
d) balloon framing exists
e) all of the above

3. The following statement is false:

a) the closer you are to an earthquake source, the greater force you will feel
b) soil and rock formations under a structure can amplify earthquake forces to a building
c) the more the ground accelerates, the greater forces the building will encounter
d) buildings that survived past earthquakes do not need to be retrofitted

4. The following statement is false:

a) the more a building weighs, the greater earthquake forces it will experience
b) the taller a building is, the more the roofline will move during an earthquake
c) reroofing can not change the seismic performance of a building
d) parts of buildings that are not tied together can vibrate apart during an earthquake

5. The following statement is false:

a) the greatest earthquake force occurs at the base of the structure

b) the cripple wall is usually the weakest part of the structure
c) more earthquake forces exist in first story walls than in second story walls
d) the length of plywood determines the length of a shear wall

6. Shear walls:

a) provide strength and stiffness like wood I-beams to resist uplift and shear
b) require holdowns when their weight cannot resist uplift
c) work best with continuous footings underneath them
d) are only one part of a complete horizontal force-resisting system
e) all of the above

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Appendix I-2

7. Retrofit work requires:

a) evaluation of the condition and species of the existing framing lumber

b) marking location of studs for sheathing nailing
c) pre-drilling hard dense lumber
d) providing underfloor ventilation when missing or insufficient
e) all of the above

8. The following statement is false:

a) oriented strand board expands more than plywood when wet

b) all 15/32 and ½ inch Structural 1 plywood is five-ply
c) Structural 1 panels are stronger and stiffer grades of wood structural panels
d) you cannot substitute oriented strand board for plywood without approval
e) plywood and OSB can be installed vertically or horizontally

9. The recommended fastener for shear wall sheathing is:

a) full headed common nails

b) gun nails
c) 8d or 10d
d) cooler, box, or sinker nails
e) wood screws

10. The following is false:

a) sheathing nails with larger edge distances in framing members produce stronger shear
walls
b) sheathing nails with larger shank diameters and head sizes produce stronger shear walls
c) sheathing nails with ¾-inch edge distance on the sheathing makes stronger shear walls
than shear walls with 3/8-inch edge distances
d) sinking the nail head below the surface of the sheathing does not reduce the strength of
the shear wall

11. The following locations on shear walls require nails at the closer edge distance spacing:

a) uppermost top plate

b) sill or sole plate
c) all holdown studs
d) all panel edges and around all reinforced openings
e) all of the above

12. The following are good holdown installation practices:

a) countersinking nuts and washers in end posts

b) drilling ¾-inch holes for 5/8-inch bolts
c) installing drilled-in-anchors for holdowns the same depth as for sill plate anchoring
d) following both the plans and the manufacturer’s installation instructions
e) allowing small kinks in metal straps

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 Appendix I-3

13. Shear connections are:

a) connections from the top plate to the shear wall

b) connections from the shear wall to the floor framing below
c) connections from the sill plate to the top of the foundation wall
d) connections that prevent any two parts of the building from sliding past each other

14. The following statement is false:

a) expansion and adhesive anchors must be located a minimum distance from any edge of
the concrete
b) adhesive anchors require clean holes and threaded rods
c) plate washers increase the strength of the sill plate connection
d) the depth of the all-thread rod and adhesive in the concrete determines the strength of a
retrofit holdown
e) lag screws do not have to be pre-drilled if they do not split the wood

15. To be an effective part of the horizontal force-resisting system, foundations should:

a) be free of excessive cracking or deterioration

b) be continuous around the perimeter of the building
c) have enough strength, depth and weight to resist shear and uplift forces
d) be evaluated by an architect or engineer
e) a&c

16. The following statement is false:

a) porches and patio covers should be well-connected to the rest of the house
b) unstrapped electric and gas water heaters can cause fires
c) masonry chimneys can be retrofitted by simply adding a brace to the roof
d) 50% of all earthquake damage costs are non-structural in nature

17. The length of time for liability for personal injury following completion of construction is:

a) three years for construction defects

b) fours years for patent defects
c) 10 years for latent defects
d) until death do you part

18. A good contract should contain many things, such as:

a) clear scope of work, completion date and how to handle changes in the work
b) be prepared under specific legal counsel
c) exculpatory provisions, price and payment schedule, & termination provisions
d) a loose definition of the work to allow for money-making extras
e) a, b & c

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Appendix I-4

ANSWERS: 1-d, 2-e, 3-d, 4-c, 5-d, 6-e, 7-e, 8-b, 9-a, 10-d, 11-e, 12-d, 13-d, 14-e, 15-e, 16-c, 17-d, 18-e

***

Seismic Retrofit Training