Residential timber-framed construction - Part 4: Simplified

AS 1684.4-2010 provides the requirements for building practices and the selection, placement and fixing of structural elements used in timber framing for Class 1 (houses) and Class 10 (i.e. garages) for both new buildings and alterations for wind classifications up to N2.

This Australian Standard also provides procedures and practices to assist in determining correct timber sizes for given applications and bracing and connections requirements to ensure adequate structural performance of the buildings noted.

Part 4 is a more user-friendly version than Part 2 and is popular for its hard copy span tables and minimal information to calculate bracing requirements and determine timber spans using span tables.

As a simplified version though, Part 4 is conservative and may not provide as economical outcomes as Part 2 of the Standard and has tighter geometrical constraints than AS 1684 Part 2.

What's included

AS 1684.4-2010 contains nine sections: 

• Section 1: provides the scope as noted in the overview above and the general requirements of the Standard including other Standards referenced, the limitations on the use, durability requirements, the various forces on buildings, timber stress grades, size tolerances and other information that can relate to other parts of the Standard.
• Section 2: provides terminology and definitions relevant to timber members and construction methods including loading requirements and the span and spacing of timber members.
• Section 3: sets out the requirements for the preparation of sites in relation to site clearing and drainage, the requirements for sub-floor supports and how to determine pad footing sizes for stumps, posts and piers.
• Section 4: sets out the requirements for the construction of timber-framed floors including jointing and construction methods for timber framed floors which can, where applicable, be applied to decks and verandahs and similar construction.
• Section 5: provides the general requirements for the installation of both strip and structural plywood and particleboard flooring and also has provisions for the selection and installation of timber decking.
• Section 6: provides the building practice and details for conventionally framed timber walls to be used in conjunction with the Timber Span Tables in Appendix A of this Standard. It deals with all aspects of timber wall framing including lintels, ring beams, window trimmers and non-loadbearing timber walls.
• Section 7: sets out the requirements for the design, specification and building practice for conventionally framed roofs to be used in conjunction with the Timber Span Tables. It provides details of various types of conventionally pitched roofs, ceiling framing, roof supports and fixing. It also provides boxed eave details and roof components not provided in the Span Tables.
• Section 8: sets out the bracing requirements for sub-floors walls and roofs. It provides information on temporary bracing during construction, provides methods to calculate the required amount of permanent bracing and details bracing units and components used in bracing buildings.
• Section 9: specifies the fixing requirements between the various structural components and materials of a house. It details the various fixing and tie-down methods for typical load actions that a building may encounter from the sub-floor structure to the roof.

This standard also contains four appendices:

• Appendix A provides the member span tables for sub-floor through to roof members.
• Appendix B provides the recommended average moisture content at installation for timber flooring through various climatic zones.
• Appendix C provides diagrammatic information on how to evenly distribute bracing.
• Appendix D specifies typical fixing details for collar ties in conventionally pitched roofs when there are multiple rows of under purlins installed.

AS 1684.4-2010 is referenced in Volume Two of the National Construction Code (NCC).

Related Australian Standards

• AS 1684 Part 1 Design Criteria.