Residential timber-framed construction - Part 4: Simplified-Non-Cyclonic Areas

AS 1684.4: Residential timber-framed construction - Part 4: Simplified-Non-Cyclonic Areas

For engineers and designers working in Australia's construction sector, understanding the nuances of timber-framed construction is paramount. AS 1684.4 provides an essential, streamlined approach for designing residential timber structures in regions not subjected to extreme cyclonic wind events, ensuring both safety and structural integrity.

What is AS 1684.4?

AS 1684.4, published by Standards Australia, is a key component of the broader AS 1684 series on residential timber-framed construction. This particular part offers a simplified design methodology specifically tailored for non-cyclonic wind classifications. Its primary purpose is to provide proven, practical procedures for determining member sizes, bracing, and fixing requirements for timber-framed housing in lower wind-risk areas.

Scope & Purpose

This authoritative standard governs the design and construction of timber-framed residential buildings within defined non-cyclonic wind classifications (N1 and N2). It outlines simplified procedures for structural elements, including wall framing, floor framing, and roof framing, with specific attention to bracing and tie-down systems appropriate for these conditions. Notably, it is derived from AS 1684.2 but imposes more restricted geometric limits and simplified bracing designs to achieve its streamlined approach. It does not cover cyclonic regions or more complex wind classifications.

Who Must Comply?

• • Primary audience: Structural engineers, building designers, architects, builders, certifiers, and experienced carpenters involved in residential construction.
• • Industries affected: Construction, building design, architecture, timber manufacturing and supply, and local government building authorities.
• • Compliance nature: Compliance is generally mandatory when specified by the Building Code of Australia or relevant local planning schemes.
• • Enforcement: Compliance is typically checked by building surveyors, council inspectors, and regulatory bodies during building approvals and inspections.

Key Requirements Overview

The standard requires professionals to accurately determine the appropriate wind classification for the building's location. Key provisions include:

• • The standard necessitates adherence to simplified span tables for timber members, ensuring appropriate load-carrying capacity.
• • Professionals must ensure adequate bracing is incorporated to resist lateral loads, with simplified detailing compared to cyclonic standards.
• • Specific fixing and tie-down requirements are detailed to maintain structural integrity under expected wind pressures.
• • The design must consider the geometric limitations of the building, such as maximum width and roof pitch, as specified within the standard.
• • Durability considerations for timber elements in the building envelope are also addressed.

Related Standards & References

AS 1684.4 is an integral part of a suite of documents and works in conjunction with:

• • AS 1684.1: Residential timber-framed construction - Part 1: Design criteria: This standard provides the fundamental design principles and criteria that underpin the entire AS 1684 series.
• • AS 1684.2: Residential timber-framed construction - Part 2: Non-cyclonic areas: AS 1684.4 is a simplified version derived from this standard. For higher wind classifications (N3 and N4) in non-cyclonic areas, AS 1684