ANSI A300 Part 3 - Supplemental Support Systems_2013_v2_Layout 1 8/13/2013 3:19 PM Page 1

ANSI A300 (Part 3)-2013

Revision of ANSI A300 (Part 3)-2006

for Tree Care Operations –

Tree, Shrub, and Other Woody Plant
Management –Standard Practices
(Supplemental Support Systems)
ANSI A300 (Part 3)-2013 Supplemental Support Systems
Revison of ANSI A300 (Part 3)-2006
ANSI A300 Part 3 - Supplemental Support Systems_2013_v2_Layout 1 8/13/2013 3:19 PM Page 2
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ANSI®
A300 (Part 3)-2013

American National Standard

for Tree Care Operations –

Tree, Shrub, and Other Woody Plant Management –

Standard Practices (Supplemental Support Systems)

Secretariat
Tree Care Industry Association, Inc.

Published by
Tree Care Industry Association, Inc.
136 Harvey Road – Ste 101
Londonderry, NH 03053
800-733-2622
603-314-5380
Fax: 603-314-5386
Email: rrouse@tcia.org
Web: www.tcia.org

Copyright © 2013 by the Tree Care Industry Association, Inc.

All rights reserved.
No part of this publication may be reproduced in any form, in an electronic retrieval system or
otherwise, without prior written permission of the publisher.

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ANSI A300 Part 3 - Supplemental Support Systems_2013_v2_Layout 1 8/13/2013 3:19 PM Page 4

ANSI®
A300 (Part 3)-2013

Approval of an American National Standard requires review by ANSI that the require-
American ments for due process, consensus, and other criteria for approval have been met by the
National standards developer.

Standard Consensus is established when, in the judgement of the ANSI Board of Standards
Review, substantial agreement has been reached by directly and materially affected
interests. Substantial agreement means much more than a simple majority, but not nec-
essarily unanimity. Consensus requires that all views and objections be considered, and
that a concerted effort be made toward their resolution.

The use of American National Standards is completely voluntary; their existence does
not in any respect preclude anyone, whether he has approved the standards or not, from
manufacturing, marketing, purchasing or using products, processes or procedures not
conforming to the standards.

The American National Standards Institute does not develop standards and will in no cir-
cumstances give an interpretation of any American National Standard. Moreover, no per-
son shall have the right or authority to issue an interpretation of an American National
Standard in the name of the American National Standards Institute. Requests for inter-
pretations should be addressed to the secretariat or sponsor whose name appears on
the title page of this standard.

CAUTION NOTICE: This American National Standard may be revised or withdrawn at

any time. The procedures of the American National Standards Institute require that action
be taken periodically to reaffirm, revise, or withdraw this standard. Purchasers of
American National Standards may receive current information on all standards by call-
ing or writing the American National Standards Institute.

American National Standards Institute, Inc.

Headquarters:
1899 L Street, NW
11th Floor
Washington, DC 20036
New York Office:
25 West 43rd Street
4th Floor
New York, NY 10036

www.ansi.org

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ANSI®
A300 (Part 3)-2013

Contents

Foreword .......................................................................................................................... 6
1 ANSI A300 standards scope, purpose, and application........................................ 8
30 Part 3 – Supplemental Support Systems standards ............................................. 8
31 Normative references............................................................................................. 8
32 Definitions.............................................................................................................. 9
33 Supplemental support system practices ............................................................. 11
34 Cabling ................................................................................................................ 13
35 Bracing .................................................................................................................15
36 Propping ...............................................................................................................16
37 Guying established trees......................................................................................17
38 Guying newly installed landscape plants .............................................................18
39 Supplemental support system inspection and maintenance................................19

Annex A Additional hardware information ............................................................. 20

Annex B Supplemental support systems specification flow chart ........................ 21
Annex C Supplemental support system inspection process ................................. 22
Annex D Applicable ANSI A300 interpretations .................................................... 23
Annex E Sample specifications ............................................................................ 24

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ANSI®
A300 (Part 3)-2013

Foreword This foreword is not part of American National Standard A300 (Part 3)-2013 Supplemental
Support Systems.

ANSI A300 Standards are divided into multiple parts, each focusing on a specific aspect of woody
plant management (e.g. Pruning, Soil Management, Supplemental Support Systems, etc.)

These standards are used to develop written specifications for work assignments. They are not
intended to be used as specifications in and of themselves. Management objectives may differ
considerably and therefore must be specifically defined by the user. Specifications are then writ-
ten to meet the established objectives and must include measurable criteria.

ANSI A300 standards apply to professionals who provide for, or supervise the management of,
trees, shrubs, and other woody landscape plants. Intended users include businesses, govern-
ment agencies, property owners, property managers, and utilities. The standard does not apply
to agriculture, horticultural production, or silviculture, except where explicitly noted otherwise.

This standard has been developed by the Tree Care Industry Association (TCIA), an ANSI-
accredited Standards Developing Organization (SDO). TCIA is secretariat of the ANSI A300 stan-
dards, and develops standards using procedures accredited by the American National Standards
Institute (ANSI).

Consensus for standards writing was developed by the Accredited Standards Committee on Tree,
Shrub, and Other Woody Plant Management Operations – Standard Practices, A300 (ASC
A300).

Prior to 1991, various industry associations and practitioners developed their own standards and
recommendations for tree care practices. Recognizing the need for a standardized, scientific
approach, green industry associations, government agencies and tree care companies agreed to
develop consensus for an official American National Standard.

The result – ANSI A300 standards – unify and take authoritative precedence over all previously
existing tree care industry standards. ANSI requires that approved standards be developed
according to accepted principles, and that they be reviewed and, if necessary, revised every five
years.

TCIA was accredited as a standards developing organization with ASC A300 as the consensus
body on June 28, 1991. ASC A300 meets regularly to write new, and review and revise existing,
ANSI A300 standards. The committee includes industry representatives with broad knowledge
and technical expertise from residential and commercial tree care, utility, municipal and federal
sectors, landscape and nursery industries, and other interested organizations.

Suggestions for improvement of this standard should be forwarded to: ANSI A300 Secretary, c/o
Tree Care Industry Association, Inc., 136 Harvey Road - Suite 101, Londonderry, NH 03053.

ANSI A300 (Part 3)-2013 Supplemental Support Systems was approved as an American National
Standard by ANSI on May 6, 2013. ANSI approval does not require unanimous approval by ASC
A300.

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ANSI®
A300 (Part 3)-2013

The ASC A300 had the following members as of May 6, 2013:

Dane Buell, Chair Bob Rouse, Secretary

(SavATree, Inc.) (Tree Care Industry Association, Inc.)

Organizations Represented Name of Representative

Alliance for Community Trees Carrie Gallagher
American Nursery and Landscape Association Warren Quinn
Craig J. Regelbrugge (Alt.)
American Society of Consulting Arborists Donald Godi
Stephen Miller (Alt.)
American Society of Landscape Architects Ron Leighton
Asplundh Tree Expert Company Geoff Kempter
Bartlett Tree Expert Company Peter Becker
Dr. Thomas Smiley (Alt.)
Davey Tree Expert Company Chris Klimas
Grant Jones (Alt.)
International Society of Arboriculture Dr. Richard Hauer
Sharon Lilly (Alt.)
Professional Grounds Management Society Gene Pouly
Michael Bova (Alt.)
Professional Land Care Network Alice Carter
Tom Delaney (Alt.)
Society of Municipal Arborists Gordon Mann
Nolan Rundquist (Alt.)
Tree Care Industry Association Mark Stennes
Steve Mays Jr. (Alt.)
USDA Forest Service Keith Cline
Ed Macie (Alt.)
Utility Arborist Association Bill Rees
Matthew Simons (Alt.)

Additional organizations and individuals:

Michael Galvin (Observer)

Peter Gerstenberger (Observer)
Andy Hillman (Observer)
Tim Johnson (Observer)
Myron Laible (Observer)
Guy Meilleur (Observer)
Beth Palys (Observer)
Dr. Richard Rathjens (Observer)
Mary Reynolds (Observer)
Richard Roux (NFPA-780 Liaison)

ASC A300 Mission: To develop consensus performance standards based on current research and sound
practice for writing specifications to manage trees, shrubs, and other woody plants.

ASC A300 Vision: ANSI A300 standards will be the foundation for work specifications, training materials,
quality protocols, and regulations for the management of trees, shrubs, palms, and other woody plants.

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ANSI®
A300 (Part 3)-2013

American National Standard 30.4 Safety

for Tree Care Operations –
30.4.1 This performance standard shall not take
Part 3 Supplemental precedence over applicable industry safe work
practices.
support systems
30.4.2 Tree management shall be performed only
Subclause 1.1 to 1.3 excerpted from ANSI by arborists or arborist trainees who, through related
A300 (Part 1) – Pruning training or on-the-job experience, or both, are familiar
with the standards, practices and hazards of arbori-
1 ANSI A300 standards culture related to supplemental support systems and
equipment used to install and maintain them.
1.1 Scope
30.4.2.1 Arborists shall follow appropriate safe
ANSI A300 standards present performance stan- work practices.
dards for the care and management of trees,
shrubs, and other woody plants. 30.4.3 Performance shall comply with applicable
Federal and State Occupational Safety and Health
1.2 Purpose Administration (OSHA) standards, ANSI Z133, and
other federal, state, and local regulations.
ANSI A300 performance standards are intended for
use by federal, state, municipal and private entities 30.4.4 The sites shall be inspected for visible
including arborists, property owners, property man- above ground hazards prior to beginning any tree
agers, and utilities for developing written specifica- management procedure.
tions.
30.4.5 The location and type of utilities and other
1.3 Application obstructions both below and above ground shall be
considered prior to tree management operations.
ANSI A300 performance standards shall apply to
any person or entity engaged in the management of 30.4.6 Job briefings shall be performed as outlined
trees, shrubs, or other woody plants. in ANSI Z133.

30 Part 3 – Supplement support

system standards 31 Normative references

30.1 Purpose The following standards contain provisions which,

through reference in this text, constitute provisions
The purpose of this standard is to provide industry of this American National Standard. All standards
consensus guidelines for supplemental support sys- are subject to revision, and parties to agreements
tems and standards for writing specifications. based on this American National Standard shall
apply the most recent edition of the standards indi-
30.2 Reason cated below.

Supplemental support systems are used to provide ANSI A300 for Tree Care Operations – Tree, Shrub,
additional support or limit movement of a tree or and Other Woody Plant Management – Standard
tree part. Practices, all Parts

30.3 Implementation ANSI B18.12, Glossary of Terms for Mechanical

Specifications for tree management should be writ- Fasteners
ten and administered by an arborist or arborist
trainee who is under the supervision of an arborist. ANSI Z60, Nursery stock

30.3.1 Specifications shall be adhered to. ANSI Z133 for Arboricultural Operations – Safety
Requirements

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ANSI®
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ASTM A-475, Standard Specification for Zinc- lightning protection system that is intended to signif-
Coated Steel Wire Strand icantly reduce potential differences created by light-
ning currents.
Federal Standard: FF-T-276b, Thimbles, Rope
32.7 bracing: The installation of lag-thread
29 CFR 1910, Occupational Safety and Health screw or machine-thread steel rods in branches,
Standards (General Industry)1 leaders, or trunks to provide supplemental support.

29 CFR 1910.268, Telecommunications1) 32.8 cable: 1) Zinc coated strand per ASTM A-475
for dead-end grip applications. 2) Wire rope or strand
29 CFR 1910.269, Electric power generation, trans- for general applications. 3) Synthetic-fiber rope or
mission and distribution1) synthetic-fiber webbing for general applications.

29 CFR 1910.331 - 335, Electrical safety-related 32.9 cable-end termination: Hardware designed
work practices1) to anchor cables installed through a branch or stem.

29 CFR 1910, Subpart S – Electrical, §§ 1910.331 - 32.10 cable grip: A mechanical device that tem-
335, Safety-related work practices1) porarily grasps and holds a wire rope or strand
1) cable during installation.
Available from U.S. Department of Labor, 200
Constitution Ave. NW, Washington, D.C. 20210, or
32.11 cabling: The installation of a steel wire
www.osha.gov.
rope, steel strand, or synthetic-fiber system within a
32 Definitions (Definitions are considered tree between branches or leaders to provide sup-
plemental support.
part of the ANSI A300 Part 3 standard.)
32.12 compartmentalization: Physiological
32.1 amon-eye nut: Drop-forged eye nut, used
process that creates the chemical and physical
to fashion through-hardware
boundaries that act to limit the spread of disease
anchor(s).
and decay organisms.
32.2 anchor: Hardware
32.13 connector clamp: A multi-purpose bolt clamp
installed to affix and/or terminate
that is used to bond conductors, or bond a conductor
a cable or guy to the tree, ground,
to a ground terminal or tree supplemental support sys-
or other device.
tem, and meets the specifications of ANSI/UL-96.
Figure 32.1:
32.3 anchor-tree: A tree used amon-eye nut 32.14 dead-end brace: A brace formed by
to provide supplemental support
threading a lag-thread screw rod directly into the
in a guying installation.
limb, leader, or trunk, but not through the side oppo-
site the installation.
32.4 arborist: An individual engaged in the pro-
fession of arboriculture who, through experience,
32.15 dead-end grip: A manufactured wire wrap
education and related training, possesses the com-
designed to form a termination in the end of 1 X 7,
petence to provide for, or supervise the manage-
left-hand lay cable that meets the specifications of
ment of, trees and other woody plants.
ASTM A-475 for zinc coated strand.
32.5 arborist trainee: An individual undergoing
on-the-job training to obtain the experience and the
competence required to provide for, or supervise
the management of, trees and woody plants. Such
trainees shall be under the direct supervision of an
arborist. Figure 32.15: dead-end grip

32.6 bond: An electrical connection between an

electrically conductive object and a component of a

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ANSI®
A300 (Part 3)-2013

32.16 dead-end hardware: Anchors or braces 32.24 lag-thread screw rod: Lag-thread, steel rod,
that are threaded directly into the tree but not used for dead-end and through-brace installations.
through the side opposite the installation. Dead-end
hardware includes but is not limited to: lag hooks;
lag eyes; and, lag-thread screw rod.

32.17 eye bolt: A drop-forged, closed-eye bolt. Figure 32.24: lag-thread screw rod

32.25 loop anchor: A synthetic fiber termination

that serves as an anchor.
Figure 32.17: eye bolt
32.26 machine thread: A fine screw thread
32.18 eye splice: A closed-eye termination designed for fittings (such as hardware nuts).
formed into common grade cable by bending it back
on itself and winding each wire around the cable a 32.27 machine-thread rod: A machine-thread
minimum of two complete turns. steel rod used for through bracing installation.

32.28 peen: The act of bending, rounding or flat-

tening the fastening end(s) of through-hardware for
the purpose of preventing a nut from “backing-off.”
Figure 32.18: eye splice
32.29 prop: The installation of a rigid support
placed between a trunk and/or branch and another
32.19 guying: The installation of a steel cable or supporting sturcture.
synthetic-fiber cable system between a tree and an
external anchor to provide supplemental support. 32.30 shall: As used in this standard, denotes a
mandatory requirement.
32.20 lag eye: Lag-thread, drop-forged, closed-
eye anchor. 32.31 should: As used in this standard, denotes
an advisory recommendation.

32.32 specifications: A detailed, measurable

plan or proposal for performing a work activity or
Figure 32.20: lag eye providing a product, usually a written document.

32.33 stabilize: To support a tree in a new loca-

32.21 lag hook (J-hook): Lag-thread, J-shaped tion or after root or soil failure.
anchor.
32.34 standard, ANSI A300: The performance
parameters established by industry consensus as a
rule for the measure of extent, quality, quantity,
value, or weight used to write specifications.

Figure 32.21: lag hook 32.35 supplemental support system: A system

designed to provide additional support or limit
32.22 lag thread: A coarse screw thread movement of a tree or tree part.
designed for securing into wood.
32.36 swage stop: A sleeve-type fitting used to
32.23 lag-thread hardware: Anchors or braces terminate a wire rope or cable.
with lag-threads. Lag-thread hardware includes, but
is not limited to: lag eyes, lag hooks, and lag-thread 32.37 taut: Tightened to the point of eliminating
screw rod. visible slack.

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ANSI®
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32.38 termination: A device or configuration that 33 Supplemental support systems

secures the end of a cable to the anchor in a cabling practices
or guying installation.
33.1 Objectives
32.39 termination hardware: Hardware used to
form a termination. Termination hardware includes Objectives for supplemental support systems shall
but is not limited to: dead-end grips; thimbles used be defined prior to design, installation, or mainte-
in eye-splice configurations; cable-end termina- nance of the system.
tions; and, swage-stop terminations.
33.1.1 Objectives should be based on the reasons
32.40 thimble: An oblong galvanized or stainless for installing or maintaining the supplemental sup-
steel fitting with flared margins and an open-ended port system.
base.
33.1.2 Supplemental support system design shall
be specified. Specifications should include support
method (cabling, bracing, guying, etc), system type
(direct, triangular, hub and spoke, etc.), system
Figure 32.40: location, and materials, including number, sizes,
Thimble and types of components.

Heavy- Heavy- Extra 33.2 Tree inspection

duty, duty, heavy-
closed open duty 33.2.1 An arborist or arborist trainee shall visually
inspect each tree before beginning work.
32.41 threaded-steel rod: A machine-thread,
steel rod used for through-brace installations. 33.2.2 Structural integrity and potential changes in
tree movement and loading (dynamics) shall be
32.42 through-brace: A brace formed by considered prior to installing a tree supplemental
installing hardware completely through a branch, support system.
leader, or trunk.
33.2.3 If a condition is observed requiring attention
32.43 through-hardware: Anchors, cables, or beyond the original scope of work, the condition
braces that pass completely through the branch, shall be reported to an immediate supervisor, the
leader, or trunk, secured with nuts and heavy-duty owner, or the person responsible for authorizing the
washers or cable-end termination. Through-hard- work.
ware includes but is not limited to: cables; eyebolts;
lag-thread screw rods; and, threaded-steel rods. 33.3 Tools and equipment

32.44 turnbuckle: A drop-forged, closed-eye 33.3.1 Climbing spurs shall not be used when
device for adjusting tension. climbing trees to install supplemetal support sys-
tems, except in the case of emergencies.

33.3.2 Equipment and work practices that damage

bark, cambium, live palm tissue, or any combination
Figure 32.44: turnbuckle of these, beyond the scope of the work, should be
avoided.

33.3.3 Cable grips used to tension the cable shall

32.45 wire rope Figure be designed for use with the type of cable being
clamp: A clamp 32.45: installed.
consisting of a “U” wire rope
bolt, bracing plate, clamp
and fastening
nuts.

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ANSI®
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33.4 General 33.4.4 Steel cables or guys in trees with existing

lightning protection conductors, shall be bonded to
33.4.1 All necessary pruning should be performed the lightning protection system. A connector clamp,
prior to installing a tree supplemental support sys- designed for use in lightning protection systems,
tem. Pruning shall be in accordance with ANSI A300 shall be used to bond steel cables or guys to the
Part 1 – Pruning. lightning protection system [see ANSI A300 (Part 4)
— Lightning Protection Systems standard].
33.4.2 Prior to installation, the owner or owner’s
agent shall be notified of the need for periodic 33.4.5 Supplemental support systems shall be
inspection by an arborist of the supplemental sup- installed in compliance with minimum distance
port system’s condition; position; cable tension; and Table 1 in ANSI Z133 for overhead, energized con-
the tree’s structural integrity, see Annex C. ductors.
Scheduling inspections shall be the responsibility of
the tree owner. 33.4.6 Steel hardware shall be corrosion resistant
(e.g. galvanized or stainless steel). Synthetic fiber
33.4.3 Anchors and braces shall not be installed cable systems shall be ultra-violet (UV) light resist-
into decayed areas where sound wood is less than ant.
30% of the trunk or branch diameter, see Figure
33.4.3. 33.4.7 Wire rope clamps shall not be used to form
terminations in cables larger than 1/8 inch (3 mm).

33.4.8 Treatment of cavities by filling, shall not be

considered to provide support.

33.5 Installation practices

33.5.1 Holes should

not be drilled closer
together than the diame-
ter of the branch or trunk
being drilled. The diam-
eter of the hole shall not
be greater than 1/6 the
diameter of the limb,
Figure 33.4.3: Equations for finding the per- trunk, or branch at the
centage of sound wood. Symbol Key for point of installation.
Equations:
X = sound wood depth, working side.
Y = sound wood depth, opposite side.
Z = total trunk/branch diameter, bark diame-
ter not included.
Figure 33.5.1: Brace
Equation for percentage of sound wood for
positioning
through-bolt applications:

[(X + Y) ÷ Z] x 100 = % of sound wood for

through-bolt applications.

Equation for percentage of sound wood for

dead-end applications: 33.5.2 Longitudinal alignment of anchors and/or
braces should be avoided.
(X ÷ Z) x 100 = % of sound wood for dead-end
applications.

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33.5.3 Anchor(s) shall be installed in alignment 33.5.10 Washers shall not be countersunk into the
with the cable and termination hardware, and not be wood.
subjected to side loading.
33.5.11 Fasteners for threaded hardware, such as
nuts, amon eyes, and turnbuckles, shall be secured
to prevent loosening.

33.5.12 Excess portion of the through-hardware

shall be removed.

33.5.13 Terminations shall be specified in the sys-

tem design specifications.

33.5.14 Termination hardware shall be the appropri-

ate size and type for the cable to be installed.

33.5.15 Terminations formed by eye-splice configu-

rations shall incorporate thimbles.

Figure 33.5.3: 33.5.16 Dead-end grip terminations shall only be

Cable and used on cable that meets the specifications of
hardware ASTM A-475.
alignment
33.5.17 Dead-end grip terminations shall incorpo-
rate extra heavy-duty wire rope thimbles – Type III,
33.5.4 Only one termination shall be attached to that meet the performance specifications of federal
an anchor. standard FF-T276b.

33.5.5 Lag-thread hardware shall only be installed 33.5.18 All hardware within a system shall meet or
in sound wood. The hole for the lag-thread exceed the minimum strength required to achieve
hardware shall be 1⁄16" to 1⁄8" (1.5-3 mm) smaller than the objective, see Annex A.
the diameter of the lag.
33.5.19 Installations shall follow manufacturers’ rec-
33.5.6 Holes for through-hardware should be no ommendations.
greater than 1⁄8" (3 mm) of the diameter of the hard-
ware being installed. 34 Cabling

33.5.7 Lag hooks shall only be used when they 34.1 Cabling objectives
can be seated to the full length of the threads. If it is
not possible to seat the full length of lag hook Objectives for cabling shall be defined prior to
threads other hardware shall be selected. design, installation, or maintenance of the system.

33.5.8 Lag hooks shall be installed to prevent the 34.1.1 Objectives should include, but are not limit-
cable termination from coming loose. Bark should ed to, one or more of the following:
not be damaged beyond the scope of the work dur-
Limit the movement of codominant stems or
ing installation of the lag hook.
branches;
Limit the movement of weakly attached branches;
33.5.9 When installing through-hardware, heavy-
Provide supplemental support for overextended
duty or heat-treated, heavy-duty round steel wash-
branches; and,
ers shall be installed between the nut(s) and the
Provide supplemental support for branches that
wood or according to manufacturer’s recommenda-
may be exposed to extra loading.
tions.

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34.2 Cabling types 34.2.2.1 Location of hardware shall be specified.

Cabling system specifications should include one or 34.2.3 Box: Box cabling consists of connecting
more of the following types. four or more tree parts in a closed series. This sys-
tem should be used only when minimal direct sup-
34.2.1 Direct: Direct cabling consists of a single port is needed.
cable between two tree parts, e.g., two branches, two
stems, or a trunk and a limb (three direct cables
shown).

Figure 34.2.3: Box system

Figure 34.2.1:
Direct system with 34.2.3.1 Location of hardware shall be specified.
one cable (above),
and direct system 34.2.4 Hub and Spoke: Hub and Spoke cabling
with two cables consists of a center attachment (hub) with spans
(spokes) of cable radiating to three or more leaders.

34.2.4.1 Location of hardware shall be specified.

34.2.1.1 Location of hardware shall be specified.

Figure 34.2.2: Figure 34.2.4: Hub and spoke system

One triangular
system, and two 34.3 Cabling installation
triangular sys-
tems 34.3.1 Support cables should be taut following
installation.

34.2.2 Triangular: Triangular cabling consists of

connecting tree parts in combination of threes. This
method should be preferred, when maximum sup-
port is required (two triangular systems shown).

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34.3.2 Anchor(s) should be installed at or near a 34.3.4 If existing cables are to be replaced, they
point two-thirds (2/3) of the length/height of the shall not be removed until the new system is
branch or leader to be supported, measured from installed.
the junction to be supported, see Figure 34.3.2.
35 Bracing

35.1 Bracing objectives

Objectives for bracing shall be defined prior to

design, installation, or maintenance of the system.

35.1.1 Objectives should include, but are not limit-

ed to, one or more of the following:
Limit the movement of codominant stems
or branches;
Figure 34.3.2: Reinforce and/or close cracks in stems or
Cable branches; and,
positioning Restrict movement of rubbing branches.
35.2 Bracing types

Bracing system specifications should include one or

34.3.3 The angle of cable installation should be more of the following types.
perpendicular to an imaginary line bisecting the
angle between the tree parts being cabled, see 35.2.1 Single: Single bracing consists of one
Figure 34.3.3. installed rod, see Figure 35.2.1.

35.2.2 Parallel: Parallel bracing consists of two or

more rods installed in vertical and directional align-
ment, see Figure 35.2.2.

35.2.3 Alternating: Alternating bracing consists of

two or more rods installed in directional alignment
Figure 34.3.3: but not vertical alignment, see Figure 35.2.3.
Cable
angle

Figure 35.2.1: Figure 35.2.2: Figure 35.2.3:

single brace Parallel brace Alternating brace
system system system

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35.3.6.2 Through-braces shall be terminated

with heavy duty washers and nuts.

35.3.7 Dead-end bracing

35.3.7.1 Dead-end bracing shall be performed

with lag-thread screw rod.

35.3.7.2 The brace shall be installed completely

through the smaller or equal portion and at least
halfway into the other portion.
Figure 35.2.4:
Crossing brace
system

35.2.4 Crossing: Crossing bracing consists of two

or more rods installed in a non-aligned pattern.
Figure 35.3.7.2: Dead-
35.3 Bracing installation end brace installation

35.3.1 When bracing installation is specified, sup-

plement support should be installed in the crotch,
before bracing installation occurs.

35.3.2 The preferred location for a single rod for a 35.3.7.3 The end of the lag-thread screw rod
non-split crotch, should be approximately the branch shall be inside the bark or shall be fastened with a
diameter of the largest branch above the crotch. heavy duty or heat-treated washer and a nut.

35.3.2.1 Variables such as wood quality, 36 Propping

species, form, and branch structure, should be con-
sidered when determining the distance above the 36.1 Propping objectives
crotch.
Objectives for propping shall be defined prior to
35.3.3 Bracing systems using multiple rods should design, installation, or maintenance of the system.
have at least one rod installed above the crotch.
36.1.1 Objectives should include, but are not limit-
35.3.4 Braces shall be installed in either a through- ed to, one or more of the following:
brace or dead-end brace configuration. Support long, lateral branches;
Keep branches or leaning stems off the
35.3.5 The minimum hardware requirements for ground; and,
braces should be in accordance with Table 1 Support branches or leaning stems to pro-
Minimum hardware requirements for bracing trees. vide clearance.

35.3.6 Through-bracing 36.2 Propping installation

35.3.6.1 Through-braces shall be used when 36.2.1 Props shall be of sufficient strength to hold
bracing through decayed area/wood or in trees that the intended load.
are poor compartmentalizers or have weak wood
characteristics.

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Table 1: Minimum hardware requirements for bracing trees, English and metric equivalent

36.2.2 Props shall be fastened to the branch in a 37.2 Guying established trees – types
manner that minimizes damage and prevents the
branch from falling off the prop. Specifications for guying established trees should
include one or more of the following types.
36.2.3 Props shall be designed and installed in a
manner that minimizes restriction of plant growth. 37.2.1 T r e e - t o -
ground: Tree-to-
36.2.4 Props shall be anchored so that movement ground guying con-
does not damage the tree branch, limb, or trunk. sists of installing at
least one cable
37 Guying established trees between a ground
anchor and the tree
37.1 Objectives for guying established trees to be guyed.

Objectives for guying shall be defined prior to

design, installation, or maintenance of the system.

37.1.1 Objectives should include, but are not limit-

ed to, one or more of the following: Figure 37.2.1:
Stabilize an existing tree or shrub; Tree-to-ground
Reduce risk of windthrow; and, system
Reduce other specified risks.

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37.2.2 Tree-to-tree: Tree-to-tree guying consists 37.4.4.3 Ground-anchor(s) should be placed no

of installing at least one cable between an anchor- closer to the trunk than two-thirds the distance from
tree and the tree to be guyed. the ground to the height of the lowest point of
attachment in the tree, adjusted for slope and site
conditions.

Figure 37.2.2: Tree-to-tree system

Figure 37.4.4.3: Guy location

37.3 Safety in tree-to-ground systems

Public safety shall be considered when guying trees

including, but not limited to: 37.4.5 Tree-to-tree guying
Pedestrian and vehicular traffic; and,
Site and recreational use. 37.4.5.1 Anchor-tree(s) shall be inspected for
structural integrity.
37.4 Guying installation
37.4.5.2 Anchor-tree(s) shall have the ability to
37.4.1 Hardware should be installed so that it is in meet the objective.
alignment with the angle of pull from the guy.
37.4.5.3 Anchors should be attached in the
37.4.2 Permanent guys shall be attached to the upper half of the tree to be supported and in the
tree with dead-end hardware or through-hardware. lower half of the anchor-tree(s).

37.4.3 A temporary guy should be considered 38 Guying newly installed landscape

when there is an immediate need for supplemental plants
support.
38.1 Objectives
37.4.4 Tree-to-ground guying
Objectives for guying shall be defined prior to
37.4.4.1 Guys shall be secured to a ground- design, installation, or maintenance of the system.
anchor(s) sufficient to achieve the objective.
38.1.1 Objectives should include, but are not limit-
37.4.4.2 Guys should be attached to the tree at ed to, one or more of the following:
or above a point not less than one-half the height of Stabilize a larger transplanted tree or shrub;
the tree. Reduce risk of windthrow; and,
Protect a new transplant from damage,
including from maintenance or
vandalism.

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38.1.2 Guys or other supplemental support sys- 39 Supplemental support system

tems should not be installed unless necessary. inspection and maintenance

38.2 Guys shall be attached using a method that 39.1 Systems should be inspected periodically
minimizes damage to the tree. for wear, corrosion, degradation of hardware, and
damage to the tree. The inspection should include
38.3 A minimum of two guys should be installed the system’s condition, position, cable tension, and
at an angle sufficient to support the landscape plant. the tree’s structural integrity, see Annex C.

38.4 For trees over 10-inch diameter, guys 39.2 If problems are detected they should be
should be installed in accordance with subclause corrected or the system should be repaired,
37.2 Guying established tree-types. replaced, or modified.

38.5 Guys shall be secured to (a) ground

anchor(s) sufficient to achieve the objective.

38.6 Guys or other supplemental support sys-

tems shall be maintained and be removed when
they are no longer needed.

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Annex A – Additional hardware information (This annex is not part of the ANSI A300 Part 3
standard.)

Table A-1 Minimum hardware size for cabling trees

* N/A indicates not an acceptable application.

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Annex B – Supplemental support systems specification flow chart (This annex is not part of
the ANSI A300 Part 3 standard.)

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Annex C – Supplemental support system inspection process (This annex is not part of the
ANSI A300 Part 3 standard.)

C-1 Supplemental support systems may be inspected by an arborist or arborist trainee by

ground and/or aerial inspection methods on a periodic basis.

C-2 Appropriate timeframes for periodic inspections are based on the species and condition
of the tree, weather events, the supplemental support system method and type, and the type
and materials of components used.

C-3 Inspection checklist criteria may include, but is not limited to the:
System’s current condition and position in the tree;
Integrity of system components;
Bonding to lightning protection systems, as appropriate;
Growth of the tree;
Tension in the system;
Effect of the system on the tree; and,
Structural condition of the tree.

C-4 Inspection of supplemental support systems may be considered when other maintene-
nace tasks are being performed in the tree.

C-5 Suggested tools and equipment may include, but is not limited to:
Inspection checklist;
System tag;
Sounding hammer;
Binoculars;
Clinometer; and,
Aerial lift.

C-6 Suggested written record data may include, but is not limited to:
Inspection date;
Methods; and,
Findings.

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Annex D – Applicable ANSI A300 interpretations (This annex is not part of the ANSI A300 Part
3 standard.)

The following interpretations apply to the ANSI A300 Part 3 Supplemental Support Systems stan-
dard.

D-1 Interpretation of “should” and “shall” in ANSI A300 standards

“An advisory recommendation” is the common definition of “should” used in the standards devel-
opment community and the common definition of “should” used in ANSI standards. An advisory
notice is not a mandatory requirement. Advisory recommendations might not be followed when
defensible reasons for non-compliance exist.

D-2 Revised interpretation for compliant lag hooks, orignal version from ANSI A300
(Part 3)-2000)

The intent of this interpretation remains the same as the 2000 and 2006 versions.

Excerpts:

33.5.5 Lag-thread hardware shall only be installed in sound wood. The hole for the lag-thread
hardware shall be 1⁄16" to 1⁄8" (1.5-3 mm) smaller than the diameter of the lag.

33.5.7 Lag hooks shall only be used when they can be seated to the full length of the threads. If
it is not possible to seat the full length of lag hook threads other hardware shall be selected.

33.5.8 Lag hooks shall be installed to prevent the cable termination from coming loose. Bark
should not be damaged beyond the scope of the work during installation of the lag hook.

Interpretation: In normal circumstances, lag hooks that have a thread depth variance greater
than 1⁄16 inch make determination of correct hole size impossible and cannot be installed in a man-
ner compliant with the ANSI A300 Part 3 standard. Lag hooks with threads cut beyond the bent
portion of the hook cannot be installed in a manner that allows the full length of the threads to be
seated without damaging the bark beyond the scope of the work and cannot be installed in a
manner compliant with the ANSI A300 Part 3 standard.

D-3 Interpretation for cable selection when using dead-end grip terminations, update
for ANSI A300 (Part 3)-2013 standard

The intent of this interpretation remains the same as the 2006 version.

The user of ANSI A300 standards is instructed to cross-reference defintion subclauses 32.8
cable and 32.15 dead-end grip and subclause 33.5.16.

Interpretation: In normal circiumstances, dead-end cable grips that meets the ANSI ASTM A475
standard specification for zinc coated steel wire strand can be used with common grade and
extra high strength grade cable that also meets the ANSI ASTM A475 standard as long as they
are installed correctly and according to manufacturer’s instructions.

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Annex E – Sample specifications (This annex is not part of the ANSI A300 Part 3 standard.)

E-1 Sample specification for tree over historic cemetery.

Cite: “All work to be done according to ANSI A300 Part 3 Supplemental Support Systems stan-
dard” or, “All tree care management to be done according to ANSI A300 standards.”

Objective: Maximum, direct support of limb

Type of cabling to meet objective: Triangular system

Specification:

(6) 3⁄8 inch heat-treated, galvanized eyebolts shall be installed and secured with heat-treated, gal-
vanized nuts and washers in a through-anchor configuration.

The anchor on the subject limb should be installed at a location approximately two-thirds (2⁄3) the
height of that limb.
1
⁄4 inch EHS cable shall be secured to eyebolts with dead-end grips and thimbles, sized and
matched according to manufacturers’ instructions and ASTM A475. The EHS cables shall be
installed between anchors to form a triangular system.

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