AS 4440-2004 Installation of nailplated timber roof trusses.pdf

AS 4440—2004

Australian Standard™

Installation of nailplated timber roof trusses

AS

4440

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This Australian Standard was prepared by Committee TM-002, Timber Framing. It was approved on behalf of the Council of Standards Australia on 7 April 2004 and published on 1 June 2004.

The following are represented on Committee TM-002:

Association of Consulting Engineers, Australia

Australian Building Codes Board

Australian Institute of Building

Building Research Association of New Zealand

CSIRO Manufacturing and infrastructures Technology

Engineers Australia

Forest Industries Federation (WA)

Housing Industry Association

Master Builders, Australia

New Zealand Forest Industries Council

New Zealand Forest Research Institute

New Zealand Timber Industry Federation

Plantation Timber Association Australia

Plywood Association of Australasia

South Australian Housing Trust

Structural Engineered Timber Manufactures Association, New Zealand

Timber and Building Materials Association, NSW

Timber Development Association, NSW

Timber Development Association of South Australia

Timber Merchants Association of Victoria

Timber Promotion Council

Timber Queensland

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This Standard was issued in draft form for comment as DR 02024.

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AS 4440—2004

Australian Standard™


Originated as AS 4440—1997. Second edition 2004.

COPYRIGHT

© Standards Australia International

All rights are reserved. No part of this work may be reproduced or copied in any form or by any means, electronic or mechanical, including photocopying, without the written permission of the publisher.

Published by Standards Australia International Ltd GPO Box 5420, Sydney, NSW 2001, Australia

ISBN 0 7337 6041 4

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AS 4440—2004 2

PREFACE

This Standard was prepared by the Joint Standards Australia/Standards New Zealand

Committee TM/2, Timber Framing, to supersede AS 4440—1997, Installation of nailplated

timber trusses.

The Standard is the result of a consensus among Australian and New Zealand

representatives on the Joint Committee to produce it as an Australian Standard.

The objective of this Standard is to provide basic performance requirements and

specifications for the bracing, connection and installation of nailplated timber trusses.

The objective of this revision is to incorporate latest technical information and performance

criteria, which resulted from the continued development of timber framing systems in

Australia and overseas. Reflected in this Standard, the following have been included in this

revision:

(a) Provision for limit state design methods.

(b) Requirement for fixing to non-loadbearing external walls (Clause 2.2.3(d)).

(c) Amendment to the definitions of bow (Clause 3.4.2) and plumb (Clause 3.4.3).

(d) Provision for intermediate ceiling joists (Clause 3.6 and Appendix D).

(e) Provision for internal top chord ties for north-light trusses (Clause 4.2.2.2) and top-

hat trusses (Clause 4.2.2.3).

(f) Deletion of the informative Appendix for the permanent bottom chord ties (the

original Appendix G).

This Standard is intended to promote an agreement across different industries, and to

replace the various installation manuals and inconsistent bracing details currently in use. It

provides a unique method of bracing, connection and installation yet does not preclude the

use of other methods that are approved and authorized.

Statements expressed in mandatory terms in notes to tables and figures are deemed to be

requirements of this Standard.

The term ‘informative’ has been used in this Standard to define the application of the

appendix to which it applies. An ‘informative’ appendix is only for information and

guidance.

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3 AS 4440—2004

CONTENTS

Page

SECTION 1 SCOPE AND GENERAL

1.1 SCOPE ........................................................................................................................ 5

1.2 APPLICATION ........................................................................................................... 5

1.3 REFERENCED DOCUMENTS .................................................................................. 6

1.4 USE OF ALTERNATIVE MATERIALS OR METHODS .......................................... 6

1.5 DEFINITIONS ............................................................................................................ 6

1.6 LOADS...................................................................................................................... 11

1.7 DOCUMENTATION AT APPROVAL STAGE AND DELIVERY.......................... 11

1.8 NAILS ....................................................................................................................... 11

SECTION 2 SUPPORTING STRUCTURES

2.1 GENERAL ................................................................................................................ 12

2.2 WALLS ..................................................................................................................... 12

SECTION 3 TRUSS INSTALLATION

3.1 TRUSS LAYOUT...................................................................................................... 15

3.2 STABILITY DURING INSTALLATION ................................................................. 15

3.3 TEMPORARY BRACING ........................................................................................ 15

3.4 INSTALLATION TOLERANCES ............................................................................ 16

3.5 PLASTERBOARD FIXED DIRECTLY TO BOTTOM CHORDS ........................... 17

3.6 INTERMEDIATE CEILING JOISTS........................................................................ 17

3.7 TIE-DOWN REQUIREMENTS ................................................................................ 17

3.8 MULTIPLE (MULTI-PLY) TRUSS.......................................................................... 17

3.9 TRUSS MODIFICATION ......................................................................................... 17

3.10 REJECTION CRITERIA........................................................................................... 18

3.11 TRANSPORT, STORAGE, LIFTING AND HANDLING ........................................ 18

SECTION 4 ROOF BRACING

4.1 GENERAL ................................................................................................................ 19

4.2 ROOF BATTENS...................................................................................................... 19

4.3 TOP CHORD BRACING .......................................................................................... 22

4.4 BOTTOM CHORD BRACING ................................................................................. 37

4.5 WEB BRACING ....................................................................................................... 38

SECTION 5 TRUSS CONNECTION

5.1 GENERAL ................................................................................................................ 39

5.2 HIP ENDS ................................................................................................................. 39

5.3 GIRDER TRUSSES .................................................................................................. 45

5.4 VALLEY (SADDLE) TRUSSES............................................................................... 47

SECTION 6 TRUSS OVERHANGS

6.1 STANDARD TRUSS-OVERHANGS ....................................................................... 49

6.2 GABLE VERGE........................................................................................................ 50

6.3 BOXED GABLE ENDS ............................................................................................ 53

6.4 VERANDAHS........................................................................................................... 53

6.5 PERGOLAS .............................................................................................................. 53

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AS 4440—2004 4

Page

APPENDICES

A DOCUMENTATION AT APPROVAL STAGE AND ON DELIVERY ................... 54

B RECOMMENDED PRACTICE FOR TRUSS INSTALLATION.............................. 56

C RECOMMENDATIONS FOR TEMPORARY BRACING ....................................... 57

D INTERMEDIATE CEILING JOISTS AND HANGERS ........................................... 60

E TRANSPORT, STORAGE, LIFTING AND HANDLING OF TRUSSES................. 61

F TYPICAL SPECIFICATION FOR, AND EXAMPLE OF, A STEELBRACE .......... 63

G FIXING DETAILS FOR TYPICAL GIRDER BRACKETS (TRUSS BOOTS) ........ 64

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5 AS 4440—2004

www.standards.com.au Standards Australia

STANDARDS AUSTRALIA

Australian Standard


S E C T I O N 1 S C O P E A N D G E N E R A L

1.1 SCOPE

This Standard specifies requirements for the bracing, connection and installation of

nailplated timber trusses in roof structures for typical application.

1.2 APPLICATION

This Standard is intended to apply to nailplated timber roof trusses within the following

general limitations:

(a) Residential structures (BCA Classes 1, 2, 3 and 10) and light commercial structures.

(b) Maximum roof pitch of 45° (100:100).

NOTE: For roof pitch greater than 35°, supporting structure may need special consideration.

(c) Shape in plan view to be rectangular or near rectangular, or a series or combination of

rectangular shapes or near-rectangular shapes, including splayed-end and boomerang-

shaped buildings and the like, and projections such as bay windows.

(d) Maximum truss span of 16 m.

(e) Maximum truss spacing of —

(i) 900 mm; or

(ii) 1200 mm, for lightweight roofs (e.g., metal sheet roofs) in wind classification

N3 or lower.

(f) Maximum design gust wind speed of 74 m/s (wind classification C3) for ultimate

limit state method in accordance with either AS/NZS 1170.2 or AS 4055.

This Standard may also be applicable to the design and construction of other classes of

buildings where the design criteria, loadings and other parameters applicable to those

classes of building are within the limitations of this Standard.

NOTES:

1 Additional limitations are also included in the relevant Clauses of this Standard.

2 Subject to approval, this Standard may be used for other structures similar to those specified

herein.

3 AS 1720.1 provides for the design of timber elements within nailplated timber trusses, which

is not covered by this Standard.

4 Roof bracing and truss connection specified in this Standard does not cover nailplated timber

truss subjected to snow load.

5 Specifications in this Standard are applicable for use in conjunction with non-trussed hip-end

components.

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AS 4440—2004 6

Standards Australia www.standards.com.au

1.3 REFERENCED DOCUMENTS

The following documents are referred to in this Standard:

AS

1170 Minimum design loads on structures

1170.4 Part 4: Earthquake loads

1397 Steel sheet and strip — Hot-dipped zinc-coated or aluminium/zinc-coated

1684 Residential timber-framed construction (all parts)

1720 Timber structures

1720.1 Part 1: Design methods

4055 Wind loads for housing

AS/NZS

1170 Structural design action

1170.0 Part 0: General principles

1170.1 Part 1: Permanent, imposed and other actions

1170.2 Part 2: Wind actions

4491 Timber — Glossary of terms in timber related Standards

ABCB

BCA Building Code of Australia

1.4 USE OF ALTERNATIVE MATERIALS OR METHODS

This Standard does not preclude the use of materials or methods of bracing, fixing and

installation other than those specified in this Standard, provided it can be shown that these

satisfy the performance requirements met by the materials and methods described herein.

1.5 DEFINITIONS

For the purpose of this Standard, the definitions given in AS/NZS 4491, AS 1684 series,

and those below apply.

NOTES:

1 The names of the various timber truss members used in this Standard are given in Figures 1.1

to 1.7.

2 The following abbreviations are used in this Standard:

(a) BC — bottom chord.

(b) HTC — horizontal top chord.

(c) TC — top chord.

(d) TG — truncated girder (truss).

(e) TS — truncated standard (truss).

1.5.1 Approved

As approved by the regulatory authority.

1.5.2 Approved specification

Documentation approved by regulatory authority.

1.5.3 Boxed eaves

Eaves that form a horizontal plane below the rafter or truss overhang; also called flat eaves.

1.5.4 Camber

A curvature built into a truss intended to compensate for the long-term deflection due to

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7 AS 4440—2004


1.5.5 Eaves

The portion of main building outside the external wall line. Generally, it includes the truss

overhang and also cantilevered portions if present.

1.5.6 Gable-end truss

The first truss at a gable end.

1.5.7 Galvanized steel

Steel having a minimum corrosion protection of Grade Z275 in accordance with AS 1397.

1.5.8 Girder truss

A truss that supports other trusses or beams (see Figure 1.6 and Figure 3.1).

1.5.9 Nailplates

Metal plate connectors manufactured predominantly from light gauge galvanized steel with

teeth spaced and formed within the parent metal. Nailplates are normally pressed into

opposite faces of the timber members to form a spliced or gusseted type of joint.

1.5.10 Truss overhang

The portion of top chord extending beyond the body of the truss to provide eaves.

1.5.11 Pitching point

The intersection of underside of top chord and underside of bottom chord (see Figures 1.1,

1.2 and 1.7).

1.5.12 Raking eaves

Eaves line that follows the line of the roof, also called flush eaves.

1.5.13 Raking truss

A gable-end truss, which has the top chord lowered to accommodate outriggers; also known

as set-down or cut-down truss.

1.5.14 Regulatory authority

The authority that is authorized by legal statute as having jurisdiction to approve the design

and construction of a building, or any part of the building design and construction process.

NOTE: In the context of this Standard, the regulatory authority may include local council

building surveyors, private building surveyors or other persons nominated by the appropriate state

or territory building legislation as having the legal responsibility for approving the use of timber

trusses.

1.5.15 Reinforced-head nails

Nails with either an enlarged shank beneath the nail head or specially tapered head with

enough thickness to eliminate the possibility of the head becoming brittle during driving or

under load, and breaking off.

1.5.16 Spacing

The centre-to-centre distance apart of structural timber members or trusses.

1.5.17 Truss span

See Figures 1.1 and 1.2.

1.5.18 Station

The position of a truncated truss, a truncated girder truss, or a Dutch-hip girder truss,

measured from the pitching point to the near face of the truss (see Figure 1.7).

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AS 4440—2004 8


1.5.19 Steelbrace

A steel-bracing member with properties as specified in Clause 4.3.2.

1.5.20 Structural fascia

A fascia that is capable of distributing truss-overhang loads to adjacent trusses.

NOTES:

1 The common timber fascia is taken as a structural fascia when fixed directly to the end of the

truss overhang (see Figures 1.3 to 1.5). Other fascia or combination of members with similar

stiffness may be used.

2 Light gauge steel fascia is not generally capable of carrying out this function.

1.5.21 Timber truss

Framework constructed with timber of uniform thickness and fastened together in one plane

by connectors such as metal nailplates, bolts, plywood gussets, or other similar devices.

NOTE: Timber framework fastened by other connectors similar to nailplates, e.g., bolts, plywood

gussets, and the like, is not covered by this Standard.

1.5.22 Truss engineer

A professional engineer, as specified in BCA, experienced in the design of nailplated timber

truss systems.

1.5.23 Valley (saddle) truss

Frames that are supported on trusses and used to form the roof between roof segments

(see Figures 1.6, 3.1 and 4.2).

1.5.24 Verge overhang

Truss overhang at a gable end (see Figure 1.3).

1.5.25 Waling plate

Timber member normally fixed to the face of a truss to support intersecting rafters or

trusses.

Cantilever

Cei lingCantileverweb

Ceiling batten

Trussoverhang

Trussoverhang

Fascia

Pitching point

Web t ie(web bracing)

Battens

Top chord Nai lplate

Web

Roofing

Pitch

Pi tching point

Bottom chordBottom chord tie

Truss span

Overall length

FIGURE 1.1 TERMS APPYLING TO TIMBER TRUSSES

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9 AS 4440—2004


Top chord panel point

Pitching point

Apex

Top chord panel points

Pitching point

Bottom chord panel points

Heel

Truss overhang

Truss span

Cut-off

Truss overhang

FIGURE 1.2 TERMS APPLYING TO CUT-OFF TRUSS AND PANEL POINTS

Raking truss

Barge rafter

Standard trusses

Bargeboard

End wall

Outr iggers

Gable-end studs

Structuralfascia

FIGURE 1.3 TERMS APPLYING TO ROOF TRUSS SYSTEM — GABLE END

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AS 4440—2004 10


Structural Fascia

Jack trusses

Creeper trusses

Creeper trusses

Creeperrafter

Creeper rafter

Hip truss

Truncated girder truss

Truncated standard truss

Standard truss

FIGURE 1.4 TERMS APPLYING TO ROOF TRUSS SYSTEM — HIP END

Structural Fascia

Jack trusses

Creeper trusses

Creeper trusses

Creeper rafter

Creeper rafter

Hip truss

Dutch-hip girder truss

Standard truss

Waling plate

FIGURE 1.5 TERMS APPLYING TO ROOF TRUSS SYSTEM — DUTCH-HIP END

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11 AS 4440—2004


Saddle trusses

Girder truss

Saddle truss

Trusses

Intermediate top chordt ies as specified inClause 5.4.1

Trusses

Wall plate

Wall plate

FIGURE 1.6 TERMS APPLYING TO GIRDER TRUSS AND SADDLE TRUSS

Top chord extension

Jack or hip truss

Station(of truncated girder)

Truncatedstandard truss

Truncated girder

Near face oftruncated girder

Pitchingpoint

FIGURE 1.7 TERMS APPLYING TO STATION AND PITCHING POINT

1.6 LOADS

The standard loads, i.e., dead load, live load, wind load, and earthquake load, imposed on

trusses shall be in accordance with AS/NZS 1170.0, AS/NZS 1170.1, AS/NZS 1170.2, and

AS 1170.4, as appropriate.

Loads other than the standard loads shall not be imposed on the trusses without being

approved. Typical fittings, which may induce special loads, are hot-water services,

airconditioning, solar systems, protective handrails, and fall-resistant systems. Loads shall

not differ, nor be located at positions other than those taken in design.

1.7 DOCUMENTATION AT APPROVAL STAGE AND DELIVERY

NOTE: Documentation that should be available at the approval stage and at the time of delivery is

set out in Appendix A.

1.8 NAILS

Where 65 mm nails for connecting timber to timber are referred to in this Standard, they

shall be a minimum of 2.5 × 65 mm nails.

NOTE: Nailing details in this Standard may be substituted by screws of equivalent capacity.

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AS 4440—2004 12


S E C T I O N 2 S U P P O R T I N G S T R U C T U R E S

2.1 GENERAL

The correct information regarding location and dimensions of the supporting structures

shall be provided prior to the manufacture of timber trusses. Due consideration shall be

given to the reactions from any girder trusses.

CAUTION: THE SUPPORTING STRUCTURE SHALL BE STABLE AT THE TIME

OF TRUSS INSTALLATION.

NOTES:

1 The stability of supporting structures may be achieved by temporary bracing in cases where

the trusses will provide stability. When the trusses are in place and fixed correctly the

temporary wall bracing may be removed.

2 Lintels should be designed to carry the load applied by the trusses. The location of point loads

from any girder truss should be checked. Lintels may be chosen from relevant truss-span

charts providing the correct specification of load magnitude and supported truss-spans are

used.

3 Appendix B gives some recommended practices for the installation and fixing of nailplated

timber trusses.

2.2 WALLS

2.2.1 Loadbearing walls

Loadbearing walls shall comply with the requirements specified in the relevant Standards,

as appropriate to the material, and shall not be lower than the non-loadbearing walls when

trusses are supporting a level ceiling.

If any internal walls are required for support, the truss itself and the layout shall be marked

accordingly.

2.2.2 Non-loadbearing walls

Non-loadbearing walls shall comply with the requirements specified in the relevant

Standards, as appropriate to the material. Non-loadbearing walls, as designated, shall not

carry any truss loading and shall not be packed to touch the underside of trusses

(see Figure 2.1).

NOTE: One way to ensure non-loadbearing is to set the non-loadbearing walls at a lower level

than the loadbearing walls. The recommended difference in level is the ceiling batten depth, if

any, plus 10 mm min..

Timber trussCeiling batten depth,if any, plus 10 mm min.(recommended)

Loadbearing wall

Loadbearingwall

FIGURE 2.1 LOADBEARING AND NON-LOADBEARING WALLS Acc

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13 AS 4440—2004


2.2.3 Fixing to top plates of non-loadbearing walls

The requirements for fixing of timber trusses to the top plates of non-loadbearing walls

shall be in accordance with the following wall designations:

(a) Non-bracing wall Where a non-loadbearing wall is stable in its own right, no

stabilizing fixing is required.

(b) Bracing wall Where a freestanding non-loadbearing wall is designated as a bracing

unit in accordance with AS 1684.2 or AS 1684.3, the timber trusses shall be fixed to

the top plate of the wall in such a way that the bottom chord of the truss is restrained

horizontally but allows for deflection when the truss is loaded. Figure 2.2 gives an

example of the fixing details.

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(a) Truss parallel to wall (b) Truss perpendicular to wall

FIGURE 2.2 FIXING OF TRUSSES TO FREESTANDING NON-LOADBEARING WALL

THAT IS A BRACING WALL

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AS 4440—2004 14


(c) Non-bracing wall For an internal non-loadbearing wall not designated as a bracing

unit, stability of the wall shall be required to resist normal applied force, e.g., when

closing doors. The top plate of the wall shall be stabilized at maximum 1800 mm

centres. Where trusses are parallel to the wall, nogging shall be used in between the

bottom chords and fixed to the bracket. Figure 2.3 gives an example of fixing details.

Truss paral lel to wal l

Nogging

Truss parallel to wal l

Internal wall bracket nailed at top of slot. Do not dr ive nails fully home to allow for vertical movement of truss on loading

Truss at r ightangle to wal l

Wall topplate Wall top

plate

Two end nails to t imber

(a) Truss parallel to wall (b) Truss perpendicular to wall

FIGURE 2.3 FIXING OF TRUSSES TO FREESTANDING NON-LOADBEARING WALL

THAT IS NOT A BRACING WALL

(d) Non-loadbearing external wall For a non-loadbearing external wall, such as

verandah wall where trusses are pitched off verandah beams or other beams, the top

plate of the wall shall be stabilized at maximum 3000 mm centres. Figure 2.4 gives an

example of fixing details.

Truss bottom chord

Wall top plate

Block pieces

Gap between top plate and truss

Fixing of block pieces to wall top plate in accordance with AS 1684 series

FIGURE 2.4 FIXING OF TRUSSES TO NON-LOADBEARING EXTERNAL WALL

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15 AS 4440—2004


S E C T I O N 3 T R U S S I N S T A L L A T I O N

3.1 TRUSS LAYOUT

A layout with sufficient information to correctly locate the timber trusses shall be available

prior to the installation. If the information provided is unclear, guidance shall be sought

before proceeding with the truss erection.

NOTE: A typical roof truss layout, in part, is given in Figure 3.1 with a particular emphasis on

the girder truss location.

Ridge l ine

Valley (saddle)trusses Top

plate

Eaves l ine

Girder truss

Girder trussJack trussesHip truss

Truncatedstandard

Truncatedgirder

Standardtrusses

Girder trussflush w iththis l ine

Valley line

FIGURE 3.1 TYPICAL TRUSS LAYOUT

3.2 STABILITY DURING INSTALLATION

All trusses shall be braced (temporarily and/or permanently) and stabilized throughout the

installation of the roof truss system. Any nailplated truss shall not be loaded, including

stood on, until all temporary bracing for that truss is fixed in place and stabilized in

accordance with this Standard. All relevant workplace safety practices shall be followed.

NOTE: As truss installation invariably involves working at heights, a risk assessment should be

undertaken with any construction site.

3.3 TEMPORARY BRACING

Trusses shall be temporarily braced during installation to ensure they are held straight and

plumb to the installation tolerances, as specified in Clause 3.3, prior to fixing the permanent

bracing.

NOTES:

1 Recommended temporary bracing details are given in Appendix C.

2 If trusses are installed without adequate temporary bracing, the following problems may

occur:

(a) Collapse of trusses during installation.

(b) Exceeding tolerances may cause overloading, buckling and possible permanent damage

to the trusses.

3 It is recommended that the first truss be erected correctly, straight and vertical, and

temporarily braced in position; the remaining trusses are then set in line with the first one.

The temporary bracing shall not be removed until the permanent bracing has been installed.

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3.4 INSTALLATION TOLERANCES

3.4.1 General

Trusses shall be installed straight and vertical and in their correct position as specified in

Clauses 3.4.2 to 3.4.4.

NOTE: The best method for ensuring correct truss positioning is to mark the locations on the top

plate or other supporting elements in accordance with the truss layout prior to truss installation.

3.4.2 Bow

Trusses shall be erected with minimal bow, in the truss and in any chord, with a tolerance

not exceeding the lesser of L/200 and 50 mm, where L is as defined in Figure 3.2(a) or

Figure 3.2(b).

BowTruss

L

(a) Case 1

BowTruss

L

(b) Case 2

FIGURE 3.2 BOW

3.4.3 Plumb

Trusses shall be so erected that no part of the truss is out of plumb with a tolerance

exceeding the lesser of height/50 and 50 mm (see Figure 3.3).

Height o f any section

Out o f p lumb

Truss

FIGURE 3.3 PLUMB

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3.4.4 Spacing

Trusses shall be erected at a spacing not exceeding that specified in the design

specifications or truss layout.

3.5 PLASTERBOARD FIXED DIRECTLY TO BOTTOM CHORDS

Where plasterboard is fixed directly to the bottom chord of trusses, supplementary noggings

shall be supplied with the roof trusses. The supplementary noggings shall be not less than

70 mm × 35 mm F4 on edge, and shall be fitted as follows:

(a) At hip ends The supplementary noggings shall be fitted where the bottom chords of

the hip-end system do not continue to run parallel to the main run of trusses. They

shall be fixed at a spacing required by the plasterboard.

(b) Elsewhere The supplementary noggings shall be fitted between trusses where

internal walls run parallel to the common trusses. They shall be fixed at a spacing not

exceeding that for the common trusses.

3.6 INTERMEDIATE CEILING JOISTS

NOTE: Recommendations for the fixing of intermediate ceiling joists are given in Appendix D.

3.7 TIE-DOWN REQUIREMENTS

The requirements for fixing trusses to supporting structures shall be in accordance with the

approved specifications. In the absence of any tie-down documentation, the provisions for

tie-down set out in the AS 1684 series shall be used.

3.8 MULTIPLE (MULTI-PLY) TRUSS

A truss that is designated as double- triple- or multi-ply shall be nailed or bolted, or both, in

accordance with the truss details before the truss is loaded.

NOTES:

1 The laminating of a multiple (multi-ply) truss should be done at the time of manufacture.

2 If a multi-ply truss is to be laminated on site, the truss components should be labelled

appropriately.

3.9 TRUSS MODIFICATION

Under no circumstances shall a truss be modified by cutting, drilling, or by any other

method that may interfere with its structural integrity, without being approved.

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3.10 REJECTION CRITERIA

Trusses designed and manufactured for criteria other than those being used on site shall not

be used without being approved.

NOTE: Design criteria for trusses should be checked when they are delivered to site to ensure that

they are the correct trusses. If any truss has been cut, drilled, damaged, or manufactured in such a

way as to impair performance, notification should be given to the truss engineer in order to

provide adequate rectification to the truss.

Trusses with severely degraded timbers or nailplates due to poor storage shall not be loaded

prior to rectification or replacement.

NOTES:

1 Manufacturing error or damage deemed severe enough to warrant attention should include but

not be limited to the following:

(a) Broken or split timbers.

(b) Missing nailplates on one or both sides of a joint.

(c) Nailplates obviously misplaced, for example, missing a member at a joint or nailplate

not properly embedded.

(d) Any nailplate showing evidence of flattening of the teeth, or excessive splitting of the

timber under the nailplate.

2 A truss supported away from the design location may be rejected.

3 If a fault is discovered after the truss has been loaded, the load should be supported to

alleviate the load on the truss until rectified.

3.11 TRANSPORT, STORAGE, LIFTING AND HANDLING

NOTE: Recommended practices for the transport, storage, lifting and handling of timber trusses

are described in Appendix E.

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S E C T I O N 4 R O O F B R A C I N G

4.1 GENERAL

This Section specifies the permanent bracing requirements for roof trusses. These

requirements are suitable for restraining loads imposed by the direct action of wind on the

roof structure and do not make any allowance for wind loads on walls.

Before being loaded, roof trusses shall be permanently braced to a building element such as

supporting walls, which in turn can transfer these bracing loads to the structure, to prevent

rotation or buckling of trusses under the weight of roofing and ceiling materials or under

wind uplift.

Roof bracing shall comply with the following Clauses:

(a) Lateral restraints to truss top chords, i.e., roof battens or purlins .............. Clause 4.2.

(b) Diagonal bracing to truss top chords using steelbrace .............................. Clause 4.3.

NOTE: Typical specification for and examples of steelbraces are given in Appendix F.

(c) Bottom chord bracing ............................................................................. Clause 4.4.

(d) Web ties ................................................................................................. Clause 4.5.

4.2 ROOF BATTENS

4.2.1 General

The size, spacing and fixing of roof battens or purlins shall be in accordance with the

approved specifications. Battens shall be fixed to every truss, including each ply of the

multiple-truss.

In areas where battens or purlins are not bound at each end by diagonal bracing, battens

shall be continuous (see Figure 4.1).

Roof battens continuousin this area

Roof battens continuousin this areaSteelbrace

Ridge

Bracing angle

between 30

to 45 , to top plate when viewed on plan

°

°

See Note

See Note

Top plate

No two splices shall be adjacent on anytruss top chord

NOTE: Not more than 1 in 3 battens are spliced on any truss top chord.

FIGURE 4.1 TYPICAL BRACING LAYOUT

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In addition to providing support to the roof cladding, roof battens or purlins prevent truss

top chords from buckling. The buckling action is due to the compressive force in the top

chord of the roof truss. This buckling action is resisted by the roof battens or purlins, which

in turn transfer it to the steel roof bracing and down to the supporting structure. Each

element and fixing along this sequence is essential for the stability of the roof structure.

Where required, splices in battens or purlins shall be arranged such that in any top chord no

more than one-third of battens or purlins are spliced and no two splices are adjacent. There

shall be no splices in battens or purlins over girder trusses.

4.2.2 Intermediate and internal top chord ties

4.2.2.1 Intermediate top chord ties for valley intersection

Due consideration shall be given to the restraint requirement for the supporting truss top

chords where the valley trusses are located. Where the spacing of valley trusses is greater

than the restraint spacing in design, either the roof battens shall be continued at the design

spacing or intermediate top chord ties shall be fixed to the supporting trusses as shown in

Figure 4.2(a) (see also Clause 5.4).

4.2.2.2 Internal top chord ties for north-light or similar trusses

With north-light or similar trusses fabricated typically as shown in Figure 4.2(b), the

internal top chord shall be restrained with top chord ties as specified. The ties shall also be

restrained with diagonal timber, or cross steelbraces (see Clause 4.3).

4.2.2.3 Internal top chord ties for top-hat trusses

Some extremely deep trusses are fabricated in two segments, with a smaller upper truss

sitting piggyback on a lower truncated truss (see Figure 4.2(c)). The horizontal top chord of

the lower truss shall be restrained with top chord ties as specified. The ties shall also be

restrained with diagonally crossed steelbraces (see Clause 4.3).

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Valley truss Valley truss

See Clause 5.4 forconnection details

Top chord of support ing truss Intermediate

top chord tiesas required

(a) Intermediate top chord tie to supporting truss for valley intersection

Roof battens

Internal topchord segment

Top chord t iesas required

(b) Internal top chord ties for north-light and similar trusses

Roof bat tens

Upper t russ segment

Lower t russ segment

Hor izontal top chord

Top chord t iesas spec i f ied

(c) Internal top chord ties for top-hat trusses

FIGURE 4.2 INTERMEDIATE TOP CHORD TIES Acc

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4.3 TOP CHORD BRACING

4.3.1 General

The requirement for a top chord bracing system is to transfer forces generated in the top

chord restraints (usually roof battens or purlins) back to the supporting structure. The forces

are generated by resisting buckling of the top chord members, and by wind loading

perpendicular to the span of the trusses.

Bracing systems other than steelbrace, as specified in Clauses 4.3.2 to 4.3.8, such as timber

brace or tension strapping, may be used, provided that they can be shown to transfer the

necessary forces and limit movement of the top chords in an out-of-plane direction. The

material and methods described in Clauses 4.3.2 to 4.3.8 are deemed to satisfy the

requirements.

For complicated truss layouts not covered in this Standard, approved specification shall be

obtained.

4.3.2 Steelbrace

The steelbrace shall be manufactured from structural grade steel and, when installed, shall

not sag more than (distance between support points)/500.

The steelbrace shall be in accordance with the following specifications:

(a) Minimum tension capacity of 8.4 kN.

(b) Minimum corrosion protection equivalent to Z 275 galvanized steel.

(c) End fixing that provides a minimum tension capacity of 8.4 kN.

(d) Brace to intermediate truss fixing of minimum tension capacity of 0.70 kN.

(e) Minimum tension capacity at splice of 7.2 kN. For lap splice (see Figure 4.20(a)), the

splice shall be located not less than 2.5 m from the anchorage point measured along

the steelbrace. (See Figures 4.22 to 4.24 for the definition of anchorage point.)

NOTE: See Appendix F for a typical example of a steelbrace that is deemed to satisfy the

requirements specified in this Clause.

Where tension devices are used to pre-tension the steelbrace, the design of the tension

device shall be such that it does not contribute more than 3.8 mm to the extension of the

bracing system when a 8.4 kN load is applied.

NOTE: Care should be taken when using tension devices, i.e., the steelbrace should not be over-

tensioned. Flat brace should only be tensioned enough to remove any noticeable sag between

braced members. Where tensioners are used, additional temporary bracing may be required to

prevent the distortion of trusses.

4.3.3 Steelbrace for gable roof

4.3.3.1 General

The type and layout of the top chord steelbrace are related to the truss span, shape and

loading of the roof. The angle from steelbrace to wall frame shall be between 30° and 45°.

Bracing bays shall extend from the end trusses of the roof, unless otherwise specified in this

Standard.

The area of the standard truss-overhangs (see Clause 6.1) is not required to be braced.

In Figure 4.3 to Figure 4.18, length (L) and half truss-span (h) are defined as follows:

(a) Length (L) The length of run of similar trusses with similar support positions.

However, where adjoining sections of the roof have trusses running parallel to the

trusses in the section being considered and where the top chords are in the same

plane, length (L) may be extended into the adjoining section, provided that the trusses

have common support positions (see Figure 4.3). Acc

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(b) Half-span (h) The horizontal distance from the pitching point to the point at which

the top pitch changes (see Figure 4.3).

L

h

L�

L�

h�

h�

Steelbrace

Bracing angle between 30 and 45to top plate when viewed on plan

° °

Ridge

Vertical bracingsee Figure 4.26

FIGURE 4.3 LENGTH (L) AND HALF-SPAN (h)

4.3.3.2 Truss spans up to 8 m

For truss spans up to 8 m, the single steelbrace shall be arranged in a V-shape

configuration. Each truss in the brace section shall be crossed with at least two braces.

The top chord steelbrace shall be arranged according to the following roof lengths:

(a) Roof length (L) less than half truss-span (h) See Figure 4.4(a).

NOTE: Approved specification is required for freestanding roofs where roof length L < h/2.

(b) Very short roof Where the roof length (L) is 1 to 1.5 times the half truss-span (h) of

the roof truss, the steelbrace shall be arranged as shown in Figure 4.4(b).

h h

L L

SteelbraceSteelbrace

Ridge≤8 m ≤8 m

Ridge

(a) (b)

FIGURE 4.4 STEELBRACE LAYOUT FOR VERY SHORT ROOF —

TRUSS SPANS UP TO 8 m

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(c) Short roof Where the roof length (L) is 1.5 to 3.5 times the half truss-span (h) of the

roof truss, the steelbrace shall be arranged as shown in Figure 4.5.

L

h

Ridge

≤8

m

Steelbrace

FIGURE 4.5 STEELBRACE LAYOUT FOR SHORT ROOF — TRUSS SPANS UP TO 8 m

(d) Long roof Where the roof length (L) is 3.5 to 4 times the halfpan (h) of the roof

truss, the steelbrace shall be arranged as shown in Figure 4.6.

L

h

Steelbrace

Ridge

≤8

m

FIGURE 4.6 STEELBRACE LAYOUT FOR LONG ROOF — TRUSS SPANS UP TO 8 m

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(e) Very long roof Where the roof length (L) is more than 4 times the half truss-span (h)

of the roof truss, the steelbrace shall be arranged as shown in Figure 4.7.

h

L

Steelbrace

Ridge≤8 m

FIGURE 4.7 STEELBRACE LAYOUT FOR VERY LONG ROOF —

TRUSS SPANS UP TO 8 m

4.3.3.3 Truss spans of 8 m to 13 m

For truss spans of 8 m to 13 m, a steelbrace in an X-shape configuration shall be used. A

single steelbrace shall be used with the limitation in the overall length, i.e., truss span plus

truss overhangs, of roof trusses as specified in Table 4.1. Each truss in the brace section

shall be crossed with at least four braces.

TABLE 4.1

MAXIMUM TRUSS SPAN (m) FOR SINGLE OR DOUBLE STEELBRACE

Single steelbrace Wind

classification Roof pitch

<15°

Roof pitch

15° to 20°

Roof pitch

20°+ to 30°

Roof pitch

30°+ to 35°

Roof pitch

35°+ to 45°

Double

steelbrace

Up to N3, C1

Up to N4, C2

C3

13.0

13.0

12.0

13.0

13.0

11.0

12.5

10.5

8.5

11.5

9.5

Not suitable

9.5

8.0

Not suitable

13.0

13.0

13.0

For a roof with overall truss length greater than the maximum values specified in Table 4.1

but less than 13.0 m, a double steelbrace shall be used, as shown in Figure 4.8.

Double steelbrace

FIGURE 4.8 DOUBLE STEELBRACE

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The top chord steelbrace for truss spans of 8 m to 13 m shall be arranged according to the

following roof lengths:

(a) Very short roof Where the roof length (L) is very short compared to the half truss-

span (h) of the roof truss such that it would result in a brace angle greater than 45°, a

diagonal steelbrace arrangement shall be required each side of the ridge line as shown

in Figure 4.9. Bracing bays shall be spaced across the roof such that the brace angle is

always between 30° and 45°.

h

L

Steelbrace

Ridge

Brac ing angle

8 t

o 1

3 m

FIGURE 4.9 STEELBRACE LAYOUT FOR VERY SHORT ROOF — TRUSS SPANS 8 m

TO 13 m

(b) Short roof Where the roof length (L) is 1.5 to 3.5 times the half truss-span (h) of the

roof truss, the steelbrace shall be arranged as shown in Figure 4.10.

h

L

Ridge

Steelbrace

8 t

o 1

3 m

FIGURE 4.10 STEELBRACE LAYOUT FOR SHORT ROOF —

TRUSS SPANS 8 m TO 13 m Acc

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(c) Long roof Where the roof length (L) is long compared to the half truss-span (h) of

the roof truss such that it would result in a brace angle less than 30°, two or more

crossed bracing bays shall be required each side of the ridgeline to ensure the brace

angle is between 30° and 45° (see Figure 4.11).

h

L

Ridge

Steelbrace

8 to 1

3 m

FIGURE 4.11 STEELBRACE LAYOUT FOR LONG ROOF — TRUSS SPANS 8 m TO 13 m

(d) Very long roof For a very long roof, the steelbrace shall be continued for the length

of building such that each truss is crossed with at least four braces (see Figure 4.12).

h

L

Ridge

Steelbrace

8 to

13 m

FIGURE 4.12 STEELBRACE LAYOUT FOR VERY LONG ROOF —

TRUSS SPANS 8 m TO 13 m

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4.3.3.4 Truss spans 13 m to 16 m

For truss spans of 13 m to 16 m, the steelbrace shall be in an X-shape configuration over

the whole roof with an additional braced bay at each end and intermediate braced bays at

maximum 13 000 mm centres, as shown in Figure 4.13.

FIGURE 4.13 STEELBRACE LAYOUT FOR TRUSS SPANS 13 m TO 16 m

Either single or double steelbrace shall be used in accordance with Table 4.2 and

Figure 4.8.

TABLE 4.2

MAXIMUM TRUSS SPAN FOR SINGLE OR DOUBLE STEELBRACE

metres

Single brace Double brace

Roof pitch Roof pitch Wind

classification

<15° 15° to 20° <15° 15° to 20° 20°+ to 30° 30°+ to 35° 35°+ to 45°

Up to N3, C1

Up to N4, C2

C3

16.0

15.5

N/S

16.0

13.0

N/S

16.0

16.0

16.0

16.0

16.0

15.5

16.0

14.5

N/S

16.0

13.5

N/S

13.5

N/S

N/S

LEGEND:

N/S = not suitable

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4.3.4 Steelbrace for hip roof

4.3.4.1 Bracing requirement for standard trusses

For roofs on buildings of rectangular plan with trussed hip ends or Dutch-hip ends, the

steelbrace for standard trusses shall be required between the apex of hip ends only. In such

cases the roof length (L) shall be taken as being the distance between the two intersections

of hip and ridgeline, at each end of the building. One of the criteria from Clauses 4.3.3.2

to 4.3.3.4 shall then be applied as shown in Figure 4.14(a) except where the roof length (L)

of standard trusses is less than the half truss-span (h) of the roof truss, in which case

steelbrace shall be arranged as shown in Figure 4.14(b).

Steelbrace

h

L

Ridge

(a) Roof length L ≥ half-span of the roof truss, h

h

Ridge

Steelbrace

L

(b) Roof length L < half-span of the roof truss, h

FIGURE 4.14 STEELBRACE LAYOUT FOR STANDARD TRUSSES OF HIP ROOF

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4.3.4.2 Bracing requirement for jack trusses

For standard truss spans of 13 m to 16 m, the single steelbrace for jack trusses shall be

arranged in an X-shape configuration. The angle from steelbrace to end wall shall be

between 30° and 45°. The top chord steelbrace for jack trusses shall be arranged in

accordance with the following:

(a) Where the horizontal top chord length (HTL) is less than the truncated girder station

(TGS), the steelbrace shall be arranged as shown in Figure 4.15.

Steelbrace

13 m to 16 m

HTL

��

FIGURE 4.15 STEELBRACE LAYOUT FOR JACK TRUSS — HTL < TGS

(b) Where the horizontal top chord length (HTL) is 1 to 1.5 times the truncated girder

station (TGS), the steelbrace shall be arranged as shown in Figure 4.16.

SteelbraceHTL

TGS

13 m to 16 m

FIGURE 4.16 STEELBRACE LAYOUT FOR JACK TRUSS — HTL = 1 TO 1.5 × TGS Acc

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(c) Where the horizontal top chord length (HTL) is longer than 1.5 times the truncated

girder station (TGS), the steelbrace shall be arranged as shown in Figure 4.17.

TGS

SteelbraceHTL

13 m to 16 m

FIGURE 4.17 STEELBRACE LAYOUT FOR JACK TRUSS — HTL > 1.5 × TGS

4.3.5 Steelbrace for dual-pitched roof

On dual-pitched or cut-off roofs where the ridgeline is not central on the building, each side

of the ridge shall be considered as a separate case. A steelbrace layout resulting from a

combination of the criteria specified in Clauses 4.3.3.2 to 4.3.3.4 shall apply. Figure 4.18

gives a typical example of a layout.

L

h2

h1

Ridge

Steelbrace

FIGURE 4.18 TYPICAL STEELBRACE LAYOUT FOR DUAL-PITCHED OR CUT-OFF

ROOF

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4.3.6 Steelbrace for bell roof

Bell trusses shall be braced as shown in Figure 4.19. The steelbrace shall be spliced at bell

breaks.

Ridge

Hip trussor rafter

Bell truncated girder

Jack truss or rafter (bracing requirement for jack trusses in accordance with Clause 4.3.4.2, not shown for clar ity)

Refer to Figure 4.20(b)for spl ice detai l at break

Standardbell t russ

Steelbrace

FIGURE 4.19 STEELBRACE LAYOUT FOR BELL ROOF

4.3.7 Steelbrace for mono-pitched roof

Where the roof consists of half trusses (mono-pitched roof), the truss span of the half truss

shall be taken as the half truss-span (h), and one of the criteria from Clauses 4.3.3.2

to 4.3.3.4 shall be applied. The apex of the half truss shall be braced to the supporting

structure with diagonal bracing in the vertical plane as specified for half truss fixing for

apex bracing in Clause 4.3.8(g).

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4.3.8 Fixing

The steelbrace shall be arranged in a V-shape or X-shape configuration over the top of the

top chords as specified in the bracing layouts in Clauses 4.3.3 to 4.3.6. Steelbrace shall be

fixed to each truss in the brace section and to the supports, using a minimum of

Ø2.8 mm × 30 mm reinforced-head nails in accordance with the following details:

(a) Typical spliced detail See Figure 4.20.

SteelbraceSteelbrace

Top chord Top chord

Bend both brace ends over top chord and fix with three nai ls to each face of top chord

Three nai ls through common holes in overlapped ends

Two nails to top chord through each brace

(a) Lap splice (b) Wraparound splice

FIGURE 4.20 TYPICAL SPLICE DETAILS

(b) End fixing details (at apex) See Figure 4.21.

End-truss ofbraced bay

Bend brace over end-truss top chord and fix with three nails to the face of top chord

Two nails to top chord


Steelbrace

FIGURE 4.21 END FIXING DETAILS AT APEX

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AS 4440—2004 34


(c) End fixing details (at heel, to top plate) See Figures 4.22 and 4.23.

For fix ing to masonry-wall plate, use similar details as specified in Figure 4.27

Bend steelbrace to side of top plate and under plate; fix w ith two nai ls to side and three nails under top plate. Nai ls shal l be not closer than 10 mm to the edge of the t imber

<45°

FIGURE 4.22 END FIXING DETAILS AT HEEL — TO TOP PLATE

Timber block of similar size to truss top chord fit ted tightly between trusses using two nai ls to truss and three nai ls to top plate

SteelbraceTwo nails to each top chord

Two nails to each top chord

Framing anchor, one to each side of truss

Framing anchor, oneto each side of truss

Bend steelbrace over and fix with three nails to face of top chord

Anchorage point

For fix ing to masonry-wall plate, use similar details as specified in Figure 4.27

FIGURE 4.23 END FIXING DETAILS AT HEEL — TO TOP PLATE (ALTERNATIVE)

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(d) End fixing details (at heel, to girder truss) See Figure 4.24.

Girder truss

Girder bracket

Standard trusses


Two nails to top of truss and three to the side

Anchoragepoint

FIGURE 4.24 END FIXING DETAILS AT HEEL — TO GIRDER TRUSS

(e) Fixing details for cantilevers See Figure 4.25.

Timber block of similar size to truss top chord, fit ted tight ly between trusses, using two nails to fix to each truss and three nails to fix to top late

Steelbrace continuousto truss heel


Refer to Figure 4.21for end-fix ing detai ls(to both ends)

90 mm x 35 mm F5 min. timber block fixed in line with bottom of bottom chord, fit ted tightly between trusses using framing anchors as shown

Steelbrace in plane of bottom chord shal l be extended over sufficient trusses so that the trusses are adequately t ied to the bottom plate

The angle between the steelbrace and

support ing top plate does not exceed 45°

For fix ing to masonry-wal l plate, use similar detai ls asspecified in F igure 4.27

FIGURE 4.25 FIXING DETAILS FOR CANTILEVERS Acc

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(f) Fixing details for cut-off or half trusses See Figure 4.26.

Bend steelbrace over t imber block and fix with five nails

Timber block of similar size to top chord fixed to truss at each end with two nai ls and one framing anchor

30 bracing angle 45° ≤ ≤ °

Bend steelbrace to side of top plate and under, if necessary, and fix w ith five nai ls to side or under top plate. Nai ls shall be not closer than 10 mm to the edge of the t imber

For fix ing to masonry-wal l plate, use similar detai ls asspecified in Figure 4.27

FIGURE 4.26 FIXING DETAILS FOR CUT-OFF OR HALF TRUSSES

(g) Fixing details for brick-wall plate See Figure 4.27.

Framing anchor each s ide

Masonry

Cut-off orha lf t russes

Steelbrace f ixed wi th two na ils

Min. 45 mm th ick t imber b lock f i t ted t ight ly between t russes and na iled down to top pla te

Min. 35 mm th ick wal l p la te ( re fer to AS 1684.2 or AS 1684.3 for f ix ing of wall p la te to br ickwork)

F ix with f ive na ils to s ide of wal l pla te and t imber b lock

FIGURE 4.27 FIXING DETAILS FOR BRICK-WALL PLATE Acc

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4.4 BOTTOM CHORD BRACING

4.4.1 General

Permanent bottom chord bracing shall be required to restrain truss bottom chords against

lateral buckling. Provisions in Clauses 4.4.2.1 to 4.4.2.3 are deemed to comply.

4.4.2 Bottom chord lateral restraints

4.4.2.1 Battened ceiling

Where battens are fixed directly to the bottom chords of the trusses with nails or screws,

these battens provide the required bottom chord lateral restraints. Metal furring channels

clipped to trusses, which allow horizontal movement, shall require additional bottom chord

lateral restraints as for suspended ceilings.

Batten sizes shall comply with the approved specifications. Batten spacing shall not exceed

that specified by the approved specifications for ceiling support and bottom chord restraint

centres.

4.4.2.2 Suspended or no ceilings

For suspended ceilings, or exposed bottom chords, or where ceiling battens do not provide

lateral restraint to bottom chords, for example, metal furring channels clipped to trusses that

allow horizontal movements, the size and spacing of separate bottom chord ties shall

comply with the approved specifications.

Where bottom chord ties are required, they shall be braced or fixed to a building element

such as supporting walls, which in turn can transfer these bracing loads to the structure.

Steelbrace shall be used for fixing top of truss bottom chords to brace lateral ties to

sidewalls. Steelbrace shall be at approximately 45° to wall top plates (see Figure 4.28), and

shall be fixed to each truss and to the wall in the same manner as for top chord brace

fixing.

NOTES:

1 Bottom chord ties are not intended to replace the binders required to support the end wall.

2 Bottom chord ties and bracing details are intended only to laterally restrain (i.e., to stop from

buckling) truss bottom chords and do not provide lateral stability to the building to resist

lateral wind loads.

Span/2 Span/2

Span

Bot tomchord t ies

Steelbrace

FIGURE 4.28 TYPICAL BOTTOM CHORD TIES BRACING LAYOUT

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AS 4440—2004 38


4.4.2.3 Bottom chord ties for construction

Where bottom chord ties are not required as specified in Clauses 4.4.2.1 and 4.4.2.2, for

example, where the ceiling is fixed directly to the bottom chord, for the purpose of

construction, the following bottom chord ties shall be installed, unless another tie

configuration is approved by the regulatory authority:

(a) Spacing ..................................................................................... 4000 mm maximum.

(b) Fixing .............. Fixed to each truss bottom chord with a minimum of one 65 mm nail.

NOTE: Bottom chord ties are neither intended to replace the binders required to support the end

wall, nor designed to be a trafficable platform. They are intended for the purposes of locating

trusses in their proper alignment (see Appendix C).

4.5 WEB BRACING

Where truss designs require bracing to be applied to webs, this can be achieved by the use

of longitudinal ties, T-stiffeners or other supplementary members. Where longitudinal ties

are used, they shall be a minimum of 70 mm × 35 mm F5, or as specified in the design

specifications. The web ties shall be fixed to the web of each truss at even spacing of the

web with two 65 mm long nails and braced to the truss with one bay of crossed steelbrace at

each end and an intermediate bay at 10 m centres. Web ties shall be continuous or, where

required, spliced by lapping over at least two adjacent trusses. Figure 4.29 shows typical

web tie bracing and fixing details.

Bend stee lbrace over chord and f ix w ith f ive na i ls to face of chord. Typica l both ends of brace

Braces to crossat mid-length tomatch t ie

Two nails to web of eachintersect ion and t russ

Angle of brace to web ties shall

be between 30

and 45

°

°

Web t ie , as spec i f ied, f ixed to each truss web at even spac ing wi th two 65 mm nai ls

FIGURE 4.29 TYPICAL WEB TIE BRACING AND FIXING DETAILS

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S E C T I O N 5 T R U S S C O N N E C T I O N

5.1 GENERAL

This Section specifies the minimum requirements for truss-to-truss connections. At least

two Ø2.5 mm nails, with a penetration of 10 times of nail diameter into supporting member,

shall be used to connect each member.

NOTES:

1 Connection details specified in this Section are also applicable for use in conjunction with

non-trussed hip-end components.

2 Nailing details in this Standard may be substituted by screws with equivalent capacity (see

Clause 1.8).

3 Where hip end is constructed in a manner other than that shown in this Section, maximum

truncated truss station may be read as maximum jack span.

5.2 HIP ENDS

5.2.1 Hip-end connection for low wind area (wind classification N1, N2, N3, OR C1)

Connection of jack, or creeper, and hip trusses at a hip-end roof for wind classification N1,

N2, N3, or C1 shall be in accordance with the details shown and described in Figures 5.1

and 5.2. These details are suitable for a maximum truncated girder station of 3600 mm.

The fixing requirements for hip ends in this Clause are based on the design criteria that are

governed by dead loads.

Deta il D1 or E1

Deta il A1 or B1

Deta il A1 or E1

Deta il C1

Deta il B1

NOTES:

1 For effective skew nailing, the nail shall be driven into one member not closer than 25 mm to, nor more than 38 mm

from, he arris in contact with the adjacent member. The nail shall be driven at an angle between 30° and 45° to the

face into which the nail is driven.

2 Where nails are smaller than the nominated size or other than plain shank nails, or machine driven, or both, their

performance shall not be inferior to the nail sizes given.

3 Roof battens or purlins and ceiling battens shall be fixed to trusses in accordance with the approved specification.

4 Hip-end connection for wind classification N4 is similar to that for C2 (see Clause 5.2.2)

FIGURE 5.1 TYPICAL FULLY TRUSSED HIP-END CONNECTION FOR

WIND CLASSIFICATION N1, N2, N3, OR C1

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AS 4440—2004 40


Detail Description Connection details

A1 Hip truss to truncated girder truss

Top chord — one framing anchor bent

to suit, with 4/Ø2.8 mm × 30 mm

reinforced-head nails into the side of

each top chord for truncated girder

Bottom chord — three effective flat-

head 65 mm nails

Hip TC TS or TG HTC

TG BC TG BC

Hip BCHip BC

Hip TC

B1 Jack truss to truncated girder

truss

Top chord — one framing anchor bent

to suit, with 4/Ø2.8 mm × 30 mm

reinforced-head nails into the side of

each top chord for truncated girder

NOTE: For wind classification up

to N2, tile roofs, truncated girder

with truss spans up to 8000 mm

and station up to 2400 mm,

detail C1 may be used.


head 65 mm nails each side of jack

truss

Jack TCTG HTC

TG BC

TG BC

TG BC

Jack BC

Jack BC

C1 Extended jack or hip truss top

chord to truncated standard

trusses

Two 65 mm skew nails into the side

of each top chord

TS HTC

Jack TC

FIGURE 5.2 (in part) CONNECTION DETAILS — HIP-END TRUSSES FOR

WIND CLASSIFICATION N1, N2, N3 OR C1

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D1 Creeper or jack truss to hip truss

(maximum creeper/jack station

1800 mm)

Top chord — three effective flat-head

65 mm nails through jack truss top

chord into hip truss top chord


head 65 mm nails through jack truss

bottom chord to hip truss bottom

chord

Creeper BC

Creeper BC

Creeper TC

Creeper TC

Hip TC

Hip BC

Web

E1 Creeper or jack truss to hip truss

(maximum creeper/jack station

3000 mm)

Top chord — fix as detail D1 plus one

mitre plate with 6/Ø2.8 mm × 30 mm

reinforced-head nails to each top

chord


head 65 mm nails through jack truss

bottom chord to hip truss bottom

chord

Creeper BC

Creeper BC

Creeper TC

Creeper TC

Hip TC

Hip BC

Web


WIND CLASSIFICATION N1, N2, N3 OR C1

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5.2.2 Hip-end connection for high wind area (wind classification N4, C2 or C3)

Connection of jack and hip trusses at a hip end roof for wind classification N4, C2 or C3

shall be in accordance with the details shown and described in Figures 5.3 and 5.4. These

details are suitable for a maximum truncated girder station of 3600 mm.

Deta il E2 or F2

Deta il A2 Deta il C2 Deta il D2

Deta il B2

NOTES:

1 For effective skew nailing, the nail shall be driven into one member not closer than 25 mm to, nor more than 38 mm

from, the arris in contact with the adjacent member. The nail shall be driven at an angle between 30° and 45° to the

face into which it is driven.

2 Where nails are smaller than the nominated size or other than plain shank nails, or machine driven, or both, their

performance shall not be inferior to the nail sizes given.

3 Roof battens or purlins and ceiling battens shall be fixed to trusses in accordance with the approved specification.

4 Where framing anchors or G.I. straps are specified, they shall be fixed in accordance with the approved

specifications.

5 Jack trusses are assumed to be supported on the horizontal top chord of the truncated girder.

6 Hip-end connection for wind classification C1 is similar to that for N3 (see Clause 5.2.1)

FIGURE 5.3 TYPICAL FULLY TRUSSED HIP-END CONNECTION FOR

WIND CLASSIFICATION N4, C2, OR C3

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A2 Hip truss to truncated girder truss

Top chord — 1/30 mm × 0.8 mm G.I. looped strap

with 4/Ø2.8 mm × 30 mm reinforced-head nails to

each leg

Bottom chord — use one mitre plate with

6/Ø2.8 mm nails into each face

Hip TC

TG HTC

Jack TC

TG BC

Hip BC

Jack BC(see detai l B2)

B2 Jack truss to truncated girder truss

Top chord —

(a) Station up to 2400 mm — one framing anchor

with 4/Ø2.8 mm × 30 mm reinforced-head

nails into the side of each top chord

(b) Station 2450 mm to 3600 mm —

1/30 mm × 0.8 mm G.I. looped strap bent

under the horizontal top chord, fixed with

4/Ø2.8 mm × 30 mm reinforced-head nails to

each leg

Bottom chord — one framing anchor with

4/Ø2.8 mm × 30 mm reinforced-head nails into the

side of each bottom chord

Jack TC

TG HTC

Jack TC

TG HTC

TG BC

Jack BC


WIND CLASSIFICATION N4, C2, OR C3

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C2 Intersection of jack and hip trusses to

truncated standard trusses

Jack top chord to hip top chord — one mitre plate

with 6/Ø2.8 mm × 30 mm reinforced-head nails

into each face

Jack top chord to truncated standard horizontal

top chord — one framing anchor with 4/Ø2.8 mm ×

30 mm reinforced-head nails into the side of each

top chord

Hip TC

Jack TCTS HTC

D2 Extended jack truss top chord to truncated

standard trusses

One framing anchor with 4/Ø2.8 mm × 30 mm

reinforced-head nails into the side of each top

chord

Jack TC

TS HTC

E2 Creeper truss to hip truss (maximum jack

station 2400 mm)

Top chord — one mitre plate with 6/Ø2.8 mm ×

30 mm reinforced-head nails into each face

Bottom chord — one mitre plate with 6/Ø2.8 mm ×


Hip TC

Creeper TC

Creeper BC

Hip BC

F2 Creeper truss to hip truss (maximum jack

station 3000 mm)

Top chord — 1/30 mm × 0.8 mm G.I. looped strap

with 4/Ø2.8 mm × 30 mm reinforced-head nails to

each leg and one mitre plate with 6/Ø2.8 mm ×


Bottom chord — see detail E2

Hip TC

Creeper TC

Creeper TC

Hip TC


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5.3 GIRDER TRUSSES

5.3.1 Girder brackets (truss boots)

5.3.1.1 General

Where girder brackets (also called truss boots) are used for the connection of a truss to a

girder truss or between the girder trusses, the appropriate girder brackets shall be indicated

on the truss layout.

The girder brackets shall be designated as follows:

(a) Framing bracket (joist hanger) .......................................................... Clause 5.3.1.2.

(b) Standard truss boot ........................................................................... Clause 5.3.1.3.

(c) Anti-twist truss boot ......................................................................... Clause 5.3.1.4.

(d) High-load truss boot ......................................................................... Clause 5.3.1.5.

To accommodate the bolts for the truss boot, the bottom chord size of the girder truss shall

be in accordance with the approved specifications.

The fixing of girder brackets to the trusses shall be in accordance with the approved

specifications. The specifications in Clauses 5.3.1.2 to 5.3.1.5 are also deemed satisfactory.

Special attention shall be given to the use of the correct bolts and washers in accordance

with the approved specifications.

NOTE: Care should be taken to minimize interference of the girder brackets with ceiling material.

5.3.1.2 Framing bracket (joist hanger)

The framing bracket (also known as joist hanger) may be used to support standard trusses

with a small truss span, such as half trusses, jack or creeper trusses. It shall be fixed to both

supporting and supported trusses with nailing in accordance with the approved

specifications.

NOTE: An example for fixing detail of framing bracket (joist hanger) is given in Appendix G.

5.3.1.3 Standard truss boot

A standard truss boot is designed to support standard and truncated standard trusses. The

fixing details shall be in accordance with the approved specifications.

To prevent long-term twist of the girder bottom chord and the distortion of the truss system,

an anti-twist bracing shall be used.

NOTE: A typical detail of a standard truss boot with anti-twist bracing is given in Appendix G.

5.3.1.4 Anti-twist truss boot

An anti-twist truss boot is designed to support standard and truncated standard trusses as

well as small girder trusses. It shall be connected to the girder truss and the supported truss

in accordance with the approved specifications.

NOTES:

1 Nails may also be required to locate the bracket on the girder truss prior to bolting.

2 An example of the fixing detail of an anti-twist truss boot is given in Appendix G.

No additional bracing is required for girder truss bottom chord with anti-twist truss boot.

5.3.1.5 High-load truss boot

A high-load truss boot is usually a welded bracket designed to support heavy loading from

large standard and truncated standard trusses, as well as girder and truncated girder trusses.

It shall be connected to both supporting and supported trusses in accordance with the

approved specifications.

NOTE: An example for fixing detail of high-load truss boot is given in Appendix G.

No anti-twist bracing is required for girder truss bottom chord with high-load truss boot.

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5.3.2 Waling plates for Dutch-hip girder

A waling plate shall be fixed to every intersection of top chords and webs of the supporting

truss. The fixing and connection details of supported trusses to the waling plate shall be in

accordance with the approved specifications (see Figure 5.5).

NOTES:

1 It may be necessary to increase the depth of the truss chord or web to accommodate nails or

bolts.

2 It is recommended that the waling plate is fixed to the Dutch-hip girder during truss

fabrication.

Refer to truss designer'sspecificat ions for fix ingdetails

Waling plate

FIGURE 5.5 DUTCH-HIP GIRDER FITTED WITH WALING PLATE

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5.4 VALLEY (SADDLE) TRUSSES

5.4.1 Valley truss connection for wind classification N1, N2, N3 or C1

Connection of valley trusses to the supporting truss for wind classification N1, N2, N3 or

C1 shall be in accordance with the details shown and described in Figure 5.6 (see also

Clause 4.2.2).

Description Connection details

Roof pitch ≤15° — one

effective 65 mm nail

driven through bottom

chord of valley truss into

top chord of supporting

truss at each intersection

of the trusses

Roof pitch >15° — one

effective 65 mm skew nail

driven through bottom

chord of valley truss into

top chord of supporting

truss at each intersection

of the trusses, plus

1/35 mm × 45 mm min.

timber ledger or block

nailed to supporting truss

top chord with one 65 mm

nail, or one framing

anchor without timber

ledger

Block infill (minimum of

70 mm × 35 mm) — to

where the valley truss is

cantilevered more than

450 mm or where the

valley truss is not

supported by two truss

top chords, fixed to the

valley truss bottom chord

with 2/65 mm nails, and

to each end to supporting

truss top chord with

2/65 mm nails

Supporting truss top chord

35 mm x 45 mmtimber ledge orblock fixed totop chord

Valley truss

Valley truss

One effect ive 65 mm skew nai ldr iven through valley truss BC into support ing truss TC

Alternatively, one framing anchor without t imber ledge


One effect ive65 mm skew nail dr iven through val ley truss BC into supportingtruss TC

Where truss spacing is greater than roof batten centres, intermediate TC steel-brace ties shal l be required to overlap the exist ing battens

Where truss spacing roof batten centres, intermediate TC steel-brace t ies shall be required to overlap the existing battens

is greater than

Val ley truss


65 mm nails

65 mm nai ls

>450 mm

Valley truss

Block infil l

FIGURE 5.6 VALLEY TRUSS CONNECTION FOR WIND CLASSIFICATION

N1, N2, N3 OR C1

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5.4.2 Valley truss connection for wind classification N4, C2, OR C3

Connection of valley trusses to the supporting truss for wind classification N4, C2, OR C3

shall be in accordance with the details shown and described in Figure 5.7 (see also

Clause 4.2.2).

Description Connection details

Supporting trusses with a

ceiling — one framing

anchor with

4/∅2.8 mm × 30 mm

reinforced-head nails to

each face

Supporting trusses

without a ceiling — two

framing anchors with

4/∅2.8 mm × 30 mm

reinforced-head nails to

each face

Block infill (minimum of

70 mm × 35 mm) — to

where the valley truss is

cantilevered more than

450 mm or where the

valley truss is not

supported by two truss

top chords, fixed to the

valley truss bottom chord

with 2/65 mm nails, and

to each end of supporting

truss top chord with

2/65 mm nails


Two framing anchors with

4/ 2.8 mm nai ls to each face∅

Valley truss

Val ley truss Val ley truss

Valley truss

Suppor ting t russ top chord

One framing anchor wi th

4 / 2 .8 mm nai ls to each face∅

Where truss spacing is greater than roof batten centres, intermediate TC ties shall be required to overlap the existing battens

Where truss spacing is greater than roof batten centres, intermediate TC ties shall be required to overlap the existing battens

Suppor ting t russtop chord

65 mm nails

65 mm nails

>450 mm

Val ley truss

Framing anchor

Block in f i l l

FIGURE 5.7 VALLEY TRUSS CONNECTION FOR WIND CLASSIFICATION

N4, C2, OR C3

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S E C T I O N 6 T R U S S O V E R H A N G S

6.1 STANDARD TRUSS-OVERHANGS

6.1.1 General

The conditions for the truss overhangs on the standard trusses shall be clearly shown on the

drawings and built in accordance with the engineering specifications. There are generally

two types of standard truss-overhangs, i.e., raking-eaves overhangs and boxed-eaves

overhangs (see Figure 6.1).

NOTE: Truss overhang should not support other structures, e.g., carport roof, pergola, protective

handrails, and the like, without prior approval.

Eaves ledger

Dropper

(a) Raking-eaves overhang (b) Boxed-eaves overhang

FIGURE 6.1 STANDARDS TRUSS-OVERHANGS — NON-PROPPED

6.1.2 Raking eaves in hip corner

The fascia running up to the corner of a hip-end roof shall be designed to carry the small

loads from the end creeper rafters or trusses. In such a case, a structural member or similar

member, i.e., the fascia itself or a combination of member and fascia, shall be used.

NOTE: The size and details of the structural fascia should be in accordance with the approved

specifications.

6.1.3 Boxed eaves

6.1.3.1 Propped boxed eaves

Where the eaves trimmer is attached to the end of each top chord and to either a stud or

ribbon plate at the wall, the truss overhang shall then be regarded as being propped, and a

structural fascia is not required (see Figure 6.2).

6.1.3.2 Non-propped boxed eaves

The truss overhang shall not be regarded as being propped where, for instance—

(a) the eaves trimmer, as specified in Figure 6.2(a), is omitted; or

(b) with brickwork, a dropper is used outside the brick to support the eaves trimmer

(see Figure 6.1(b)).

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Stiffener, i f required

Eaves tr immer

Ledger plateLedger plate

Propping effecton stud wallrequireschecking Eaves tr immer li fted to

prop overhang midway

Equal

Equal

(a) Truss pitch >18° (b) Truss pitch <18°

NOTE: The above details should be used in accordance with approved specification.

FIGURE 6.2 STANDARDS TRUSS-OVERHANGS — PROPPED

6.2 GABLE VERGE

6.2.1 Gable-end truss

6.2.1.1 General

A gable-end truss may either sit on the end wall (i.e., be supported in full length by the top

plate) or be free spanning. These two supporting conditions will significantly affect the

design of a gable-end truss, and thus the supporting condition shall be confirmed prior to

the design.

The arrangement and fixing of a gable-end truss shall be in accordance with one of the

methods described in Clauses 6.2.1.2 and 6.2.1.3, and shown in Figures 6.3 and 6.4.

NOTE: Gable-end studs should be of sufficient size and grade to resist all roof dead, live and

wind loads on gable end. The studs should be spaced at centres to provide adequate grid to fix

brickwork or cladding.

6.2.1.2 Gable-end truss sitting on or supported by the end wall

Where a gable-end truss is designed to be supported by the end wall, either the truss is

sitting on the end wall or is set flush with the inside of end wall, the fixing details shown in

Figure 6.3 shall be required, as appropriate.

NOTE: Where gable-end studs are designed to support the gable overhang, the fabricator should

advise the builder that the gable-end studs are required to be installed for this purpose.

Gable-end truss

Loadbearing end wall

Gable-end stud

Ribbon plate or blocks at panel points, fixed to truss in accordance with approved specificat ion

Gable-end truss

Loadbearing end wall

Gable-end stud

Ribbon plate or blocks at panel points, fixed to truss in accordance with approved specificat ion

(a) Gable-end truss sitting inside of end wall (b) Gable-end truss set flush with inside of end

wall, with supporting blocks

FIGURE 6.3 GABLE-END TRUSS — SUPPORTED BY END WALL

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6.2.1.3 Gable-end truss, free spanning

Where a gable-end truss is located at the end wall and is designed to be free spanning, the

truss shall be installed for one of the following design conditions:

(a) Where the verge outriggers or purlins are not propped from the end wall, the gable-

end truss shall be designed to carry the load of the verge overhangs as well as the

normal spacing load (see Figure 6.4(a)).

(b) Where the verge outriggers or purlins are supported by the gable-end studs, a standard

truss may be used as the gable-end truss (see Figure 6.4(b)).

Non- loadbear ing end w all

Gable-end truss( free spanning)

Gable-end s tud(support ing verge overhang)

Loadbear ing end wal l

Gable-end truss( free spanning)

(a) Verge overhang supported

by gable-end truss

(b) Verge overhang supported

by gable-end studs

FIGURE 6.4 GABLE-END TRUSS — FREE SPANNIG

To form the verge overhang, a gable-end truss shall be either a raking truss (also called set-

down or cut-down truss) having the top chords set-down to allow for outriggers or extended

purlins to cross over, or a truss of the normal height with Z-sprockets (see Clause 6.2.2 and

Figure 6.5).

6.2.2 Verge overhang

The size and grade of the verge overhang shall be in accordance with the approved

specifications. Typical verge overhang details are given in Figure 6.5.

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Non-structural blockfor fixing bargeboard

Roof battenGable-end truss

Standard truss

Gable-end stud ( if applicable)

Max. 300 mm

(a) Small verge overhang

Roof bat ten

Standard truss

Gable-end s tud ( if applicab le)

Raking truss so locatedthat gable-end s tud iss it t ing on s tud end wal l

Out-r igger

Barge ra fter

(b) Outrigger supported by raking truss

Roof batten

Standard trussGable-end stud ( if applicable)

End truss so locatedthat gable-end stud issit ting on stud end wal l

Z-sprocket

Barge rafter

Z-sprocket fixed totruss top chord withframing anchor

Nailplate

(c) Verge overhang formed with Z-sprockets

FIGURE 6.5 TYPICAL VERGE OVERHANG DETAILS

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6.3 BOXED GABLE ENDS

Boxed gable ends have a truss suspended at the end of the gable overhang to provide a

fixing framework for the gable-end lining. The last truss is either a standard truss or a

special truss with vertical webs only. In either case, it is not usually regarded as a true truss,

but is primarily just framework acting in the same way as valley trusses. The bottom chord

of this truss is commonly dropped to line up with the fascia of the common trusses.

The outriggers’ size and location, fixing details, and any additional requirements to install

supplementary bracing shall be in accordance with the approved specifications.

NOTES:

1 The outriggers may be substantial members located at the heel and apex only, or may be

smaller members regularly spaced along the truss chords.

2 The following alternative forms of support may be used:

(a) Lintels may be extended out from the main walls to support the boxed gable-end truss

at the heels.

(b) The lower outriggers may be formed by running approximately sized bottom chord ties

out to the boxed gable-end truss.

Typical installation details are shown in Figure 6.6.

Box gableend truss

Waling plate

Fixings, refer to approved specificat ion

Lower outrigger

Standard truss

Upper outrigger

Optional brace(s), refer to approved specificat ion

FIGURE 6.6 TYPICAL INSTALLATION OF BOXED GABLE END

6.4 VERANDAHS

Verandahs shall be formed either by extending the truss overhang or by the addition of

separate rafters. If the truss overhang is intended to be used to form the verandah, adequate

support shall be provided to the end of the truss overhang, as specified in the design.

6.5 PERGOLAS

Pergola rafters shall not be attached to the ends of truss overhangs without specific design,

unless the reaction load transmitted by the rafter is taken by some means such as proper

propping back to the wall (see Figure 6.2).

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APPENDIX A

DOCUMENTATION AT APPROVAL STAGE AND ON DELIVERY

(Informative)

A1 INTRODUCTION

This Appendix sets out the minimum information on nailplated timber trusses that should be

available at the building application approval stage, as described in Paragraph A2, and at

the time of delivery of trusses, as described in Paragraph A3. Paragraph A4 recommends a

check list at building application stage. It is also recommended as a check list for the

recipient to use when trusses are delivered on site.

A2 APPROVAL STAGE

The following minimum information should be available at the approval stage:

(a) Truss layout.

(b) Design criteria.

(c) Reactions and fixings.

(d) Special loads including, but not limited to, airconditioning units, cooling/heating

units, hot water units, special lighting, operable walls and lifting devices.

(e) Special conditions, e.g., corrosive environment such as exposure to swimming pool.

NOTE: For jack trusses with a span less than 3600 mm, creeper rafter and valley trusses,

Items (b) and (c) may be omitted.

A3 DELIVERY

The following information should be provided at the time of delivery:

(a) Truss layout, including bracing details.

(b) Design criteria.

(c) Support locations and fixings.

(d) Details of any special bracing requirements.

NOTE: For jack trusses with a span less than 3600 mm, creeper rafter and valley trusses,

Items (b) and (c) may be omitted.

Truss configuration and design member and nailplate details should be available on request

at the time of delivery.

A4 CHECK LIST

The following information should be provided in the check list for approval:

(a) Name and address of the truss supplier.

(b) Name and address of the client.

(c) Site address.

(d) Design criteria of the project.

(e) Roof or truss layout with reactions for typical trusses such as standard trusses,

truncated girder trusses, hip trusses and girder trusses.

(f) Date of submission (or delivery).

(g) Roof layout (with fixing details) received.

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A recommended check list is shown in Figure A1.

Check list for certifier to check at building application stage Check list for recipient to check at delivery on site

Truss supplier:

Client name:

Client address:

Site address:

Roof layout, with/without fixing details, received: Yes/No

Date:

Design criteria Unit Specified Accepted

Roofing or flooring Material or kg/m2

Top chord restraint spacing mm

Ceiling Material or kg/m2

Material or kg/m2

Ceiling batten or direct Batten or direct

Bottom chord design restraint spacing mm

Wind classification (N1 to N4, C1 to C3)

Internal pressure coefficient (Cpi) = 0.2 or 0.7

Truss spacing mm

Roof pitch degrees

degrees

Bottom chord pitch degrees

Truss overhang mm

Propped by eaves sprocket Yes/No

Structural fascia Yes/No

Special loads: Water tank Litres or kg

Solar system Litres or kg

Airconditioning kg

Others kg

Special conditions (e.g., exposure to swimming pool)

The above criteria for roof/floor trusses supplied/submitted for approval have been

checked and accepted by:

Name: Signature:

FIGURE A1 EXAMPLE OF CHECK LIST FOR APPROVAL

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APPENDIX B

RECOMMENDED PRACTICE FOR TRUSS INSTALLATION

(Informative)

B1 INTRODUCTION

This Appendix provides some recommended practices for the installation of nailplated

timber trusses.

B2 CAMBERS

Trusses are built with cambers to allow for the initial deflection at the take up of load and

some creep (i.e., long-term deflection) as the timber settles. Thus, packing to the underside

of a truss over a non-loadbearing wall may stop these deflections and in turn support the

truss in an incorrect position.

A truss carrying a large load, such as a girder truss, may require more camber than a

standard truss.

B3 FIXING OF CORNICE

Trusses settle in varying amounts during the period following full dead loading due to the

effect of creep. With seasoned timber this takes up to a year to be fully realized, but in most

instances settlement occurs within three to six months. To accommodate this settlement, the

best practice is to fix the cornice to the ceiling alone, and to leave it free at the walls.

Shadow-line cornices are suitable for this detail.

It is recognized that common practice is to fix the cornice to the walls as well as to the

ceiling. This practice is acceptable without further consideration, provided that the camber

at the location of the internal wall bracket is nominal, and seasoned timber is used in the

truss.

The most critical circumstance is where a girder truss crosses a wall. If the cornice is fixed

at this location and the truss camber is significant, then localized crushing and the attendant

deformation of the cornice can be expected.

B4 BEARING WIDTH

The minimum bearing width for timber trusses should be 70 mm. For bearing widths less

than 70 mm, confirmation from the truss engineer should be sought.

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APPENDIX C

RECOMMENDATIONS FOR TEMPORARY BRACING

(Informative)

C1 GENERAL

This Appendix provides temporary bracing details recommended for gable, hip and Dutch-

hip end roof trusses.

The first truss should be erected correctly, straight and vertical, and temporarily braced in

position as described in Paragraphs C2 or C3, as appropriate. Each successive truss should

then be spaced using a gauging rod (see Figure C1) and fixed back to the first truss with

temporary ties to top chord at a maximum spacing of 3000 mm, and to bottom chord at a

maximum spacing of 4000 mm.

Gauging rod(see Detail A)

Tie

��

Locate and space each truss using gauging rod

DETAIL A

Gauging rod

NailsTruss spacing

FIGURE C1 EXAMPLE OF GAUGING ROD

Temporary ties should be made in accordance with Table C1. Ties should be fixed to each

truss with a minimum of one 65 mm nail.

Steelbrace is not acceptable for temporary bracing.

TABLE C1

SIZE OF TEMPORARY TIES

Truss spacing To top chord To bottom chord

Up to 900 mm 25 × 50 F5 or 35 × 45 F5 35 × 70 F5

Over 900, up to 1200 mm 35 × 70 F5 35 × 70 F5

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C2 HIP OR DUTCH-HIP END ROOF

Temporary bracing for a hip or Dutch-hip end roof is achieved by erecting and fixing the

truncated girder, or Dutch-hip girder, truss in the correct position to the top plates, and

bracing the girder truss back to the corner of the building as shown in Figure C2.

Tie

Tie

Brace

Brace

Top plate Brace

FIGURE C2 TEMPORARY BRACING FOR HIP OR DUTCH-HIP END ROOF

C3 GABLE-END ROOF

Temporary bracing for a gable-end roof is achieved by erecting and fixing the first truss to

top plates at one end of the roof and bracing the truss to a rigid element, e.g., a wall or the

ground, as shown in Figures C3 and C4.

Temporary longitudinalt ies to the top of topchords at maximumspacing of 3000 mm

First t russ

Gable-end wall

Wal l frame

Trusses

FIGURE C3 TEMPORARY BRACING FOR GABLE-END ROOF

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Temporary longitudinal ties to the topof truss top chord at 3000 mm max.

First truss

Gable-end wal l

Sol id prop fixed to ground at tielocation

Wall frame

Trusses

FIGURE C4 TEMPORARY BRACING FOR GABLE-END ROOF

METHOD 2 — PROP TO GROUND

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APPENDIX D

INTERMEDIATE CEILING JOISTS AND HANGERS

(Informative)

D1 GENERAL

This Appendix provides detailed recommendations for the fixing of intermediate ceiling

joists and hangers as part of the roof truss system. Intermediate ceiling joists and hangers

may be required where the ceiling material is to be fixed directly to the truss bottom chord

(see Figure D1).

The hangers should be located within 300 mm from every bottom chord panel point of the

supporting trusses.

D2 SIZE

The size of intermediate ceiling joists and hangers should comply with the approved

specifications.

D3 CONNECTION

The connection of the hanger to the intermediate ceiling joist should be made with a metal

connector suitable for the purpose, or a timber block fixed with two 65 mm nails to each

member.

The hangers should be fixed to the truss bottom chord as follows:

(a) In wind classification lower than C3, use two 65 mm skew nails, or equivalent.

(b) In cyclonic areas, use one framing anchor or equivalent.

Truss bottom chord

Trussbottom chord Hanger

Intermediateceil ing joist

Connection see AS 1684

Connection see Paragraph D1

FIGURE D1 INTERMEDIATE CEILING JOISTS AND HANGERS

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APPENDIX E

TRANSPORT, STORAGE, LIFTING AND HANDLING OF TRUSSES

(Informative)

E1 GENERAL

This Appendix provides recommendations for the transport, storage, lifting and handling of

timber nailplated trusses.

E2 TRANSPORT

Trusses should be fully supported when being transported in either a horizontal or vertical

situation. No excess stress from the tie-down straps or bracing should be placed on any part

of the truss. Where necessary, right-angle protectors should be used to avoid damage.

E3 STORAGE

Trusses should be stored on relatively smooth ground. Care should be taken so as not to

allow excessive bending of trusses to occur.

When trusses are stored on site, they should be blocked above the ground to protect them

from ground water as follows:

(a) If the trusses are stored horizontally, the blocking should be at 2.0 m to 2.5 m centres,

or as required, to prevent bending of the trusses.

(b) If the trusses are stored vertically, they should be supported at the designed support

locations or bottom chord panel points, and in a manner that will prevent tipping or

toppling. This is an important precaution to take to prevent personal injury.

Stored trusses should be protected from the elements in a manner that provides adequate

ventilation of the trusses. If tarpaulins or other similar materials are used, the ends should

be left open for ventilation.

E4 LIFTING AND HANDLING

Throughout all phases of installation, care should be taken to avoid excessive sagging of

trusses, which can cause joint and timber damage.

Where possible, trusses shall be lifted in a vertical position. Spreader bars with attachments

to the panel points should be used where the truss span exceeds 9.0 m. Trusses should not

be lifted by the apex joint only.

In general, trusses should be slung from the top chord panel points as shown in Figures E1

and E2. Slings should be located at equal distances from the truss centre-line, and be

approximately one-third to one-half truss length apart.

The angle between sling legs should be less than 60°. Several typical examples are shown

in Figures E1 to E3.

Where a crane is not used for lifting, the trusses should be lifted by hand following the

guidelines for lifting points in Figures E1 to E3. Where trusses are too large to be lifted

vertically, skids should be used to slide the truss up to the top plate level and sufficient

skids should be used to stop undue truss deflections.

CAUTION: UNDER NO CIRCUMSTANCE SHOULD TRUSSES BE DRAGGED

HEEL UP FIRST OVER THE TOP PLATE.

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00 0 0

Crane Crane

<60°

<60°

1/3 to 1/2 span 1/3 to 1/2 span

FIGURE E1 VERTICAL LIFTING OF TRUSSES—TRUSS SPAN LESS THAN 9 m

00 0 0

Crane Cranechain for brace on lateral

movement of truss

Vertical chainor sling

1/3 to 1/2 span 1/3 to 1/2 span

FIGURE E2 VERTICAL LIFTING OF TRUSSES—TRUSS SPAN FROM 9 m TO 16 m

0

0

0

0

0

0

Crane

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APPENDIX F

TYPICAL SPECIFICATION FOR, AND EXAMPLE OF, A STEELBRACE

(Informative)

The following typical specification for steelbrace (see also Figure F1) is deemed to satisfy

the requirements specified in Clause 4.3.2:

(a) Steel :

(i) Grade................................................................................................... G 300.

(ii) Thickness ............................................................................................... 1 mm.

(iii) Galvanized coating ................................................................................ Z 275.

(iv) Pre-punched holes—in a pattern .....................................................................

to allow a minimum of three nails to be driven into the centre third of a 35 mm

width of timber when placed at an angle of 45°, at any position along the length

of the brace.

(b) Nails ..........................................minimum ∅2.8 mm × 30 mm with reinforced heads.

Countersunk

nail holes 120°

20

20

1616

DIMENSIONS IN MILLIMETRES

FIGURE F1 TYPICAL STEELBRACE

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APPENDIX G

FIXING DETAILS FOR TYPICAL GIRDER BRACKETS (TRUSS BOOTS)

(Informative)

This Appendix provides some typical girder bracket (truss boot) details for connection of

truss to truss as follows:

(a) Framing bracket (joist hanger) (see Figure G1).

Suppor ting t russ

Hal f truss,jack truss,or creeper

Framing bracket ( jo is t hanger)(For na il ing deta ils , re fer tomanufacturer 's speci f ications)

FIGURE G1 FRAMING BRACKET (JOIST HANGER)

(b) Standard truss boot with anti-twist bracing (see Figure G2).

Double or s ing leg irder t russ

For bo l t ing and/or na il ing deta i ls , re fer to manufacturer 'sspec if icat ions

Tension s trap to restra inbot tom chord tw is t or bu il t- in anti - ro ta tion f lange to be na i led to unders ide of g irder and carr ied t russ

Girder bracket

Standard truss

FIGURE G2 STANDARD TRUSS BOOT AND ANTI-TWIST BRACING

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65 AS 4440—2004


(c) Anti-twist truss boot (see Figure G3).

For connection details, refer tomanufacturer 's specificat ions

FIGURE G3 ANTI-TWIST TRUSS BOOT

(d) High-load truss boot (see Figure G4).

For connection details, refer tomanufacturer 's specificat ions

FIGURE G4 HIGH-LOAD TRUSS BOOT

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AS 4440-2004 Installation of nailplated timber roof trusses.pdf

Documents

council of standards

standards uptodate standards

timber framing

university of south

standards web shop

building materials association

global standard

current standard