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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
Keeping Standards up-to-date
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Alternatively, the printed Catalogue provides information current at 1 January each year, and the monthly magazine, The Global Standard, has a full listing of revisions and amendments published each month.
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We also welcome suggestions for improvement in our Standards, and especially encourage readers to notify us immediately of any apparent inaccuracies or ambiguities. Contact us via email at mail@standards.org.au, or write to the Chief Executive, Standards Australia International Ltd, GPO Box 5420, Sydney, NSW 2001.
This Standard was issued in draft form for comment as DR 02024.
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AS 4440—2004
Australian Standard™
Installation of nailplated timber roof trusses
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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STANDARDS AUSTRALIA
Australian Standard
Installation of nailplated timber roof trusses
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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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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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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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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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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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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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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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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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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(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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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 —
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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
Two nails to top chord
Steelbrace
FIGURE 4.21 END FIXING DETAILS AT APEX
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(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 chord
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
Two nails to top chord
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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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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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.
Bottom chord — three effective flat-
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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Detail Description Connection details
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
Bottom chord — three effective flat-
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
Bottom chord — three effective flat-
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
FIGURE 5.2 (in part) CONNECTION DETAILS — HIP-END TRUSSES FOR
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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Detail Description Connection details
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
FIGURE 5.4 (in part) CONNECTION DETAILS — HIP-END TRUSSES FOR
WIND CLASSIFICATION N4, C2, OR C3
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Detail Description Connection details
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 ×
30 mm reinforced-head nails into each face
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 ×
30 mm reinforced-head nails into each face
Bottom chord — see detail E2
Hip TC
Creeper TC
Creeper TC
Hip TC
FIGURE 5.4 (in part) CONNECTION DETAILS — HIP-END TRUSSES FOR
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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
Supporting truss top chord
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
Supporting truss top chord
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
Supporting truss top chord
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
FIGURE E3 HORIZONTAL LIFTING OF TRUSSES Acc
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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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(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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