Structural design actions — Wind actions
Engineered wind load calculation for buildings outside AS 4055 scope.
Overview
AS/NZS 1170.2 is the engineering standard for calculating wind actions on buildings and structures. It defines wind regions across Australia (A–D), terrain categories, height multipliers and topographic factors, and is used wherever a structure falls outside the simplified housing pathway in AS 4055.
Key Requirements
- Determine wind region from the regional map (A, B, C or D).
- Apply terrain category multiplier (TC1 open water through TC4 dense urban).
- Apply topographic and shielding multipliers for hill, ridge or escarpment sites.
- Calculate site wind speed and design pressure coefficients.
- Output is a design wind pressure used by structural engineers for member design.
How it's used in the NCC
Referenced for engineered buildings or where AS 4055 does not apply — for example, larger or irregular houses, multi-storey, or unusual roof forms.
Practical Notes
- If your house is small and rectangular and meets the AS 4055 geometric limits, you almost certainly don't need AS 1170.2.
- Engineers will provide a wind classification (e.g. N3) for procurement and detailing.
Where to obtain
The full text of AS/NZS 1170.2 is published by Standards Australia and must be purchased — typical price A$150–400 per part. Always work from the current edition referenced in the NCC, not an older one.