Timber structures
Engineered design of timber — used when a project falls outside AS 1684.
Overview
AS 1720 is the engineering standard for timber. Part 1 covers design methods; Part 2 covers timber properties. It's used by structural engineers to design timber members and connections where the simplified AS 1684 approach doesn't apply — large openings, long spans, unusual loads.
Key Requirements
- Limit state design method for timber members.
- Strength group and stress grade classifications for timber.
- Connection design (bolts, screws, nail plates).
- Duration of load factors.
How it's used in the NCC
An alternative to AS 1684 for engineered timber design. Builders don't typically work from it directly — the engineer's drawings translate AS 1720 calculations into a buildable detail.
Practical Notes
- If your engineer's drawings call out an LVL beam with specific fixings, that came from AS 1720.
Where to obtain
The full text of AS 1720 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.