AS 1684:2010 (with current parts and amendments)
Residential Timber-Framed Construction
AS 1684 is the residential timber-framed construction standard, published in four parts: Part 1 (Design criteria), Part 2 (Non-cyclonic areas), Part 3 (Cyclonic areas), and Part 4 (Simplified — non-cyclonic areas). It provides span tables, member-size selections and connection details for timber-framed Class 1 (residential), Class 10 (non-habitable, e.g. garage, shed) and similar low-rise structures, designed within prescribed loading and geometry envelopes. The standard's loading basis is harmonised with AS 1170 series (with cyclonic-area provisions in Part 3 derived from AS 1170.2 Region C and D wind speeds), and timber capacity is harmonised with AS 1720.1 (the engineering timber design code). AS 1684 provides a deemed-to-satisfy pathway for residential timber-framed construction without requiring per-project engineering — the span tables and connection details have been engineer-developed to meet the relevant performance requirements. The standard is the controlling reference for residential timber-framed Class 1 and Class 10 structures under NCC Volume Two and is widely applied across the Queensland low-rise residential sector. Various amendments and Part-specific updates have been published since 2010, with the standard remaining current.
AS 1684 is rarely directly applied in TRSC's commercial-asset practice, but it becomes important in three categories of engagement: heritage residential adaptive-reuse (timber-framed pre-1940 housing being converted to commercial use), Class 1 to Class 9 reclassification (residential being converted to assembly or office), and post-disaster timber-framed assessment (cyclone, fire, flood damage to residential timber framing). Three application points matter when AS 1684 is relevant. First, the standard's deemed-to-satisfy span tables are tied to specific loading and geometry envelopes — Class 1 residential, single-storey or two-storey lightweight construction, prescribed wind-region speed values, prescribed roof and wall loading, and prescribed snow loading where applicable. Where the existing structure falls outside the AS 1684 envelope (e.g. converted to commercial occupancy with higher imposed action, or the wind region has changed under AS 1170.2:2021 mapping refinements), the deemed-to-satisfy pathway no longer covers the structure, and engineering assessment under AS 1720.1 is required for any continuing-life or change-of-use Form 15. Second, AS 1684 cyclonic-area provisions (Part 3) include connection-detailing requirements that pre-Part-3 timber-framed houses do not satisfy. Pre-1981 (pre-cyclonic-code) timber-framed residential in Queensland coastal regions frequently has roof-to-wall and wall-to-floor connections that fail current AS 1684 Part 3 requirements — particularly cyclone-tie installation rates and bracket-fixing capacities. Heritage adaptive-reuse projects in cyclone regions must address these connection deficiencies as part of the reclassification, and the cost of cyclonic-zone retrofit can be the decision-controlling input to the project commercial case. Third, AS 1684 timber-framing detail for floor systems (joist sizing, bearer sizing, post sizing) is calibrated to residential Q values (typically 1.5 kPa); converting a timber-framed residential floor to commercial use (typically 3.0 kPa office or 4.0 kPa retail) doubles or triples the imposed action, and the as-installed floor system rarely has adequate margin. TRSC's adaptive-reuse assessments for converted heritage residential structures include explicit AS 1720.1 capacity calculation for floor joists, bearers and supporting elements under the proposed commercial Q, and the resulting Form 15 documents the basis for either sufficiency or required strengthening (typically composite-deck overlay or supplementary steel sub-framing). The standard's roof framing provisions are similarly calibrated to residential snow and roof imposed loading; rooftop plant addition or vertical extension on heritage timber-framed residential always requires AS 1720.1 engineering assessment rather than AS 1684 deemed-to-satisfy table use.
Form 15 RPEQ certifications for adaptive-reuse and post-disaster assessment of timber-framed residential structures reference AS 1684 where the structure remains within the standard's deemed-to-satisfy envelope, and reference AS 1720.1 where engineering assessment is required (the typical case for change-of-use). The Form 15 file documents whether the structure falls within the AS 1684 envelope (and which Part — non-cyclonic or cyclonic), the verified loading basis under AS 1170 series, and the connection-condition assessment for cyclonic-zone retrofits. For pre-1981 cyclonic-zone residential, the Form 15 cannot be issued without explicit verification of cyclone-tie installation rates and bracket-fixing capacities meeting current AS 1684 Part 3 — pre-code timber-framed residential routinely fails these provisions and requires retrofit before continuing-life certification.