Timber in bushfire-prone areas
Timber can be used safely in many bushfire-prone areas, with the right species and design.
If you're building or renovating in a bushfire-prone area, your site will need a bushfire assessment to set its Bushfire Attack Level (BAL). Construction must then meet AS 3959:2018 Construction of buildings in bushfire-prone areas and the National Construction Code. In NSW, Planning for Bush Fire Protection 2019 (NSW RFS) also applies. We can advise on the right timber species for your BAL.
Bushfire Attack Levels
AS 3959 sets six levels, based on the fire danger index, surrounding vegetation, distance to that vegetation and the slope of the land. As the level rises, so do the restrictions on building materials.
| Level | Main risk |
|---|---|
| BAL-LOW | Insufficient risk to warrant specific construction requirements |
| BAL-12.5 | Ember attack |
| BAL-19 | Increasing ember attack and burning debris, with radiant heat up to 19 kW/m² |
| BAL-29 | Increasing ember attack and burning debris, with radiant heat up to 29 kW/m² |
| BAL-40 | As above, with radiant heat up to 40 kW/m² and increasing likelihood of flame contact |
| BAL-FZ (Flame Zone) | Direct exposure to flames from the fire front, plus heat and ember attack |
Bushfire-resisting timber species
These species have been tested and are listed in AS 3959 as bushfire-resisting timber without fire-retardant treatment. They can be used for many elements up to BAL-29, such as decking, stair treads, posts and cladding, depending on the element and how it is built:
At BAL-12.5 and BAL-19, some elements need timber with a density of 750 kg/m³ or more (650 kg/m³ for some window and door joinery), as listed in AS 3959. Fire-retardant-treated timbers are also available for some uses. Ask us about treated options.
Current guidance
Requirements vary by element (subfloor, decking, walls, windows, roof) and by BAL, and NSW has its own variations. Use these current publications rather than older summaries:
- WoodSolutions Technical Design Guide 4: Building with Timber in Bushfire-prone Areas (opens in a new tab) ↗ (PDF, written for AS 3959:2018)
- NSW Rural Fire Service: Building in a bush fire area (opens in a new tab) ↗, including Planning for Bush Fire Protection 2019 and the Single Dwelling Application Kit
- AS 3959:2018 Construction of buildings in bushfire-prone areas, available from Standards Australia
A building professional or bushfire consultant should confirm the requirements for your site and design.
This information is general guidance only. See our disclaimer, and check current Australian Standards and the National Construction Code for your project. Questions? Ask our team.