AS 3959:2018 — Construction of Buildings in Bushfire-Prone Areas — is the Australian Standard that specifies how buildings must be constructed to resist bushfire attack. The 2018 edition introduced significant changes from the previous 2009 edition, particularly around glazing requirements, cladding systems and documentation.
Background
AS 3959 was first published in 1988 and has been revised several times. The 2018 edition incorporates lessons from major bushfire events including the 2009 Black Saturday fires, which exposed significant weaknesses in the construction requirements of the 2009 edition, particularly for buildings at BAL-29 and above.
Key Changes in AS 3959:2018
- Glazing requirements strengthened at BAL-19 and above — minimum 6mm toughened now required at BAL-19 (was 4mm in 2009 edition)
- Window and door frame requirements clarified — exposed timber framing no longer acceptable at BAL-29 and above
- Wall cladding systems at BAL-29 and above must now be assessed as complete systems, not individual products
- Documentation requirements significantly expanded — test evidence must now be retained and available for inspection
- Deck and sub-floor requirements tightened — non-combustible decking required at BAL-29 and above
- Garage door requirements clarified for each BAL level
- New provisions for attached structures (pergolas, carports) at higher BAL levels
Changes by BAL Level
BAL-12.5 and BAL-19
Modest changes at these levels — primarily the toughened glazing upgrade at BAL-19 and clarification of vent cover requirements. Most standard construction methods remain acceptable with appropriate product selection.
BAL-29
The most significant changes were at BAL-29. Window and door assemblies must now be complete BAL-rated systems — not just toughened glass in a standard frame. Wall cladding must be a tested, assessed system. These changes substantially increased the cost and complexity of BAL-29 construction.
BAL-40 and BAL-FZ
Changes at these levels primarily clarified existing requirements rather than introducing new ones. The 2018 edition provides more prescriptive guidance on acceptable construction systems and documentation requirements.
Documentation Requirements Under AS 3959:2018
One of the most significant changes in AS 3959:2018 is the expanded documentation requirement. Test evidence for all BAL-rated products and systems must be retained and available for inspection by building certifiers and councils. This means product CodeMark certificates, test reports and installation evidence must be gathered and filed — not just specified and then forgotten.
Use a Structured Documentation Register
Our AS 3959 Construction Documentation Pack provides element-by-element checklists for BAL-12.5 through BAL-40, with product data fields, test evidence reference columns and a DA compliance summary — ensuring you capture all required documentation during construction.
Put This Into Practice
Our digital tools are built to complement exactly what you've just read — registers, checklists and documentation packs ready to download today.