As1684 Changes 2006 Handouts

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AS1684 RevisionResidential Timber Framed

Construction Standard 2006 Edition

Reason for Revision

A requirement by Standards Australia to review BCA primary reference standards every 5 years.

Reason for Revision

Its been 6 years since the last revisionThis standard was first published in 1999

With amendments dated:1. April 20002. October 20003. May 20014. May 2002

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Revision Objectives

Address issues and practices of some state building industry interests to reflect:

State needs&

Construction practices

Revision Objectives

Include:Editorial amendments

&Technical changes

Revision Objectives

Improve deemed to satisfy (DTS) usage&

Provide economical DTS details

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Changes to Section1Scope and General


Clause 1.2 (1999 Version)“Application”

has been deleted

this clause used to introduce the Standard in January 2000 (no longer necessary)

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Clause 1.3 (1999 Version)“Use of alternative materials or methods”

has been deletedthis is the role of the BCA (provide DTS solutions) however does not preclude the use of alternative systems


Clause 1.4 (1999 Version)“Companion Documents”

moved to Clause 1.2AS1684.1 Design criteria (unchanged)AS1684.3 Cyclonic wind areasAS1684.4 Simplified – Non-cyclonic areas

AS1684 Parts 3 & 4

The changes in Part 2 have been mirrored in Parts 3 & 4

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Clause 1.5 (1999 Version)“Referenced Documents”

has been deleted

Replaced with:


Clause 1.3 (2006 Version)“Normative References”

a new clauselists 36 other Standards & the BCAas indispensable documentsnominates Appendix A as a list of “informative” related documents (page 218)

Explanation from the Preface

“Normative”an integral part of the Standard

“Informative”for information and guidance only

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1.16 Interpolation1.18 Interpolation

1.15 Considerations for Design using this Standard

1.17 Guidelines for Design using this Standard

1.14 Alternative Timber Dimensions1.16 Alternative Timber Dimensions

1.13 Size Tolerances1.15 Size Tolerances

1.12 Engineered Timber Products1.14 Engineered Timber Products

1.11 Stress Grades1.13 Stress Grades

1.10 Bearing1.12 Bearing

1.9 Dimensions1.11 Dimensions

1.8 Durability1.10 Durability

1.7 Load Paths Offsets and Cantilevers1.9 Load Paths Offsets and Cantilevers

1.6 Forces on Buildings1.8 Forces on Buildings

1.5 Design Criteria1.7 Design Criteria

1.4 Limitations1.6 Limitations

AS1684.2 2006AS1684.2 1999


Clause 1.8 (2006 Version)“Durability”

a technical changeAbove-ground durability classes (now nominated)Reference to AS1720 parts 1 & 2 deletedNew reference to AS5604

(more detail in Appendix C)


Clause 1.11 (2006 Version)“Stress Grades”

a technical change (contained within the notes to Table 1.2)

span tables from the standard can now be used for F8 & F11 unseasoned softwood F8 & F11 unseasoned hardwood tables are recommended for use (no new table)

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Clause 1.15 (2006 Version)“Considerations for Design using this Standard”

a name change onlyhowever nominated Clause 1.6 has been changed to 1.4 to line up with the overall renumbering of the clauses

Section1Scope and General

Clause 1.15 “Considerations for Design using this Standard”Nominates procedures to be adopted

must first determineDesign gust wind speed

&Corresponding wind classification

Section1Scope and General

Clause 1.15 “Considerations for Design using this Standard”

basic considerationwind classification is the primary reference used throughout this Standard recommends flow chart in Figure 1.7 as guidance for design procedures (page 18)

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Changes to Section 5 Flooring and Decking

Clause 5.7 (1999 Version)

Decking has been removed

Table 5.3 upgraded


Clause 5.7 (2006 Version)refers only to maximum spacing of supports for T & G and sheet flooring

Table 5.3 – Strip Flooringall hardwoods considered on density and grading characteristics only, as per AS2796Softwoods (excluding cypress) are noted as per the detail of AS4785.1

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Clause 5.8 (2006 Version)a new clause

Decking – deals only with the spacing of floor joists for timber decking

Table 5.4, moved from Clause 5.7Table 5.5, Decking Board Fixing Requirements has been added



Table 5.5, Decking Board Fixing Requirements

Specifies hot-dip galv or stainless steel2 nails per board crossingDifferent thicknesses for machine or hand-driven nails

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Changes to Section 6 Wall Framing


Section 6.2.3 Openingsspecifies that jack studs must be the same orientation as the common studsallows the use of nail lamination in jack studs


Clause 6.2 (2006 Version) Section 6.2.3 Openings– Figure 6.9 Openings, Detail (a)

span has been increased from 900 mm to 1200 mmtitle has been amended to include (Non-loadingbearing walls)

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Clause 6.3 (2006 Version) Section 6.3.8 Posts supporting roof and/ or floor loadsAn allowance has been made for the use of undersized seasoned posts

New paragraph at bottom of page 79


Clause 6.3 (2006 Version) Section 6.3.8 Posts supporting roof and/ or floor loads

Industry normal is up to 3mm under size i.e. 90 X 90 are normally 88 x 88mmCalculate roof and/or floor area to be supported 10% bigger, then use nominal seasoned size from Span Table 53

Change to Section 7 Roof Framing

Clause 7.2 (2006 Version)Section 7.2.10.4 Support of underpurlins

This section has been completely rewrittenGreater clarification is given to underpurlins that support valley or hip rafters

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Clause 7.2 (2006 Version)Section 7.2.10.4 Support of underpurlinsThere are 2 new subsections

(a) Underpurlins supporting a hip or valley rafter



(a) Underpurlins supporting a hip or valley rafter(b) Underpurlins supported by a hip or valley rafter

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(a) Underpurlins supporting a hip or valley rafter(b) Underpurlins supported by a hip or valley rafterFigure 7.7 has been upgraded

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Changes to Section 8 Racking and Shear Forces

(Bracing)

Clause 8.1 (2006 Version)8.1 General

the inclusion of the words “shall be” preceding “distributed evenly throughout” in the 2nd paragraph


(Bracing)

Clause 8.1 (2006 Version)8.1 General

“even distribution” now becomes a requirement rather than a recommendationstill no guidance on what “even distribution” means.


(Bracing)

Table 8.18 (2006 Version)Structural Wall Bracing

extra fixing requirements included in some of the detailsexample detail (b)

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(Bracing)


extra fixing requirements included in some of the detailsexample detail (b)example detail (d)

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(Bracing)

Table 8.18 (2006 Version)Structural Wall Bracing/Errors

(advised by TDA Engineer Andrew Dunn)detail (d)

Net sectional area of alternative metal strap should be 24 mm² not 15 mm² as shownFixing of bottom plate requires specific fixing from Clause 8.3.6.10 – not nominal as shown


(Bracing)


additional details and Bracing types added to Hardboard

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(Bracing)

Table 8.18 (2006 Version)Structural Wall Bracing Detail (l) Hardboard Type A

Minimum thickness, 4.8 mm specifiedSpacing and length of nail fixing has been alteredFixing of bottom plate to floor frame or slab has been reduced to nominal fixing only

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(Bracing)

Table 8.18 (2006 Version)Structural Wall Bracing Detail (m) Hardboard Types B & C

Type C is new, a 9kN/m unitMinimum thickness, 4.8 mm specifiedSpacing of nail fixing has been alteredSpecific fixing details of bottom plate to floor frame or slab have been included for both Types B & C

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(Bracing)

Table 8.18 (2006 Version)Structural Wall Bracing Detail (n) Hardboard Types D & E

Type D is new Short Panel, 3.4kN/m unitMinimum thickness, 4.8 mm specifiedSpacing and type of fixings specifiedNominal fixing of bottom plate to floor frame or slab for Type D only

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(Bracing)

Table 8.18 (2006 Version)Structural Wall Bracing Detail (n) Hardboard Types D & E

Type E is new Short Panel, 6.0kN/m unitMinimum thickness, 4.8 mm specifiedSpacing and type of fixings specifiedSpecific fixing of bottom plate to floor frame or slab is required i.e. M12 rods each end

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(Bracing)

Table 8.18 (2006 Version)Structural Wall Bracing All Details Hardboard Types A B C D & E

A new note to all details, L M & N, which specifies that at least one side of the bracing wall shall be lined with gypsum plaster board or equivalent

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Changes to Section 9 Fixings and Tie-Down Design

Clause 9.2 (2006 Version) General Connection Requirements Section 9.2.2 Corrosion protection and steel grade – has been revised

minimum corrosion protection for strap or similar connections – shall be Z 275Minimum thickness of strap – shall be 0.8 mmMinimum steel grade for strap or similar connections – shall be G 300

Changes to Section 9 Fixings and Tie-Down Design

Table 9.15 (2006 Version) Joint Groups

Item 6 – Elsewhere has been clarifiedNow reads –Douglas fir (Oregon) from elsewhereunseasoned J5seasoned JD5

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Changes to Appendices

There are 9 separate appendices

Changes to Appendix A Informative and Related Documents

Renamed – formerly “List of Referenced and Related Documents”Reclassified as “Informative”

The “referenced Documents” have been placed into the body of the standard at Section 1 Clause 1.3 Normative References

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Changes to Appendix B Typical Construction Mass

Renamed – formerly “Mass of Roof”

Table B1.2 renamed as “Guide for Determination of Typical Building Construction Mass”No real change, only slight restructure of the table

Changes to Appendix C Durability

C 1 Durability – now includes the new above – ground durability recommendations

Figure C 1 has been updated to include above –ground durability selections

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Changes to Appendix C Durability

Table C 1 has been updated to include more detailed specifications, the new headings are:

ExposureSpecific service conditionsBiological hazardTypical use

Changes to Appendix H Timber Species and Properties

H 2.10 (2006 Version) : now reads as –Natural durability class of heartwood

upgraded to include the new above – ground durability recommendationsTable H2 has been added to define the probable life expectancy of above - ground

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Extract from Table H1

Changes to Appendix H Timber Species and Properties

H 2.11 (2006 Version) : now reads as –Lyctid susceptibility of sapwood

RS – Rarely susceptible (has been deleted) New note has been added to explain the case of Alpine Ash and to confirm if origin unknown it must be assumed to be susceptible

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Extract from Table H1

Timber Solution SoftwareThe computer program used to derive

the AS1684 span tables is now: “free to download”

www.timber.org.au or www.timber.net.au

AS1684 RevisionResidential Timber Framed

Construction Standard 2006 Edition

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