This Standard incorporates Amendments No. 1 (April 2000), No. 2 (October 2000), No. 3 (May 2001) and No. 4 (May 2002). The changes required by the Amendments are indicated in the text by a marginal bar and amendment number against the clause, note, table, figure, or part thereof affected.

This 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 the building industry with procedures that can be used to determine building practice, to design or check construction details, and to determine member sizes, and bracing and fixing requirements for timber-framed construction in cyclonic areas.

Prior to using this Standard, it is necessary to establish the design gust wind speed and wind classification (refer Clause 1.6).

The continued development of timber framing systems and the need to cater for a widening variety of materials and design conditions have led to a total revision of structural framing design. These developments include—

(a) provision for limit state design methods;
(b) revised/new structural grades for timber;
(c) provisions catering for open plan living—larger spans, wider openings and bigger rooms, which need more rational approach to bracing design;
(d) special ‘engineered’ and fabricated timber products;
(e) recognition of a wider range of high wind and cyclonic design.
(f) computer-aided design software for member sizes, bracing and tie-down.

The increased scope and application of this Standard to cater for these conditions has also led to the need to perform a more rigorous design check on a wider range of members and construction practices including windowsill trimmers and roof bracing.

This Standard is a companion publication to the following:

AS
1684 Residential timber-framed construction
1684.1 Part 1: Design criteria
1684.2 Part 2 Non-cyclonic areas
1684.4 Part 4 Simplified—Non-cyclonic areas

This Part of the AS 1684 series differs from AS 1684—1992 in a number of areas including—

(i) input values required to used the Span Tables in the Supplements are assessed as load width (e.g. roof load width (RLW), floor load width (FLW), etc.) in lieu of ‘EL’ or spacing;
(ii) wind speeds up to C3 (74 m/s) are catered for;
(iii) bracing design uses individually rated (kN/m) bracing system capacities; and
(iv) some building geometric limits have been removed.

It should be noted that Part 4 of the AS 1684 series also contains additional differences to Parts 2 and 3 and to the 1992 edition of AS 1684.

This Standard is based on the 1992 edition of AS 1684 and various timber-framing manuals in use in the States and Territory, which will be superseded after the industry has had time to adjust to the new edition of AS 1684 series. The timber-framing manuals include the following:

(A) Timber framing manual (Timber Promotion Council, Victoria).
(B) Timber framing manual—Supplementary tables (Timber Promotion Council, Victoria).
(C) Timber framing manual—W33N–W41N (Timber Research and Development Advisory Council, Queensland).
(D) New South Wales timber framing manual (State Forests of NSW).

The terms ‘normative’ and ‘informative’ have been used in this Standard to define the application of the appendix to which they apply. A ‘normative’ appendix is an integral part of a Standard, whereas an ‘informative’ appendix is only for information and guidance.

First published as AS 1684.3-1999.