BAL-FZ (Flame Zone): the highest BAL rating
BAL-FZ, the Flame Zone, is the highest Bushfire Attack Level. It means a building would be in direct contact with flames from the fire front, as well as radiant heat above 40 kilowatts per square metre and ember attack. Building here needs systems tested for flame contact, and some states restrict it.
What the Flame Zone means
At BAL-FZ the fire front is close enough that flames reach the building directly. Radiant heat is beyond what ordinary materials can survive. Protection relies on systems that have been tested against flame contact, rather than on choosing better materials.
What puts a site in the Flame Zone
Vegetation very close to the building, particularly forest, woodland or scrub, or bush on steep ground falling away from the house.
A BAL determines which construction requirements apply to the building. Your building surveyor or an accredited bushfire practitioner can tell you what they are.
State restrictions
Some states restrict new homes in the Flame Zone. In WA, planning policy generally doesn't support new development at BAL-40 or BAL-FZ unless it's minor or unavoidable, and a habitable building at these levels generally needs development approval. Check with your council before you buy or design. See the BAL calculator by state.
What BAL-FZ costs
The highest of any level. Tested windows, doors and shutters are specialist products, and design and approvals take longer. If the site allows a different position, moving out of the Flame Zone is usually the biggest saving available.
Getting out of the Flame Zone
Distance is the lever. BAL Buddy shows how far the building would need to move to reach BAL-40. See how to lower your BAL.
BAL Buddy gives an indicative Bushfire Attack Level (BAL) only. It isn't a determination under any Act, and no council or building surveyor has to accept it. For a BAL you can rely on, use an accredited bushfire practitioner.
Need a bushfire practitioner?
FPA Australia keeps a public register of BPAD-accredited practitioners, searchable by state and accreditation level: BPAD practitioner register. If you're not sure who to call, email me and I'll point you in the right direction. I don't take referral fees.
Questions people ask
What is BAL FZ?
The Flame Zone, the highest Bushfire Attack Level. The building would face direct flame contact as well as intense radiant heat and embers.
What are the BAL FZ requirements?
Windows, doors, walls and roof generally need to be tested for flame contact to AS 1530.8.2 or built to a stated fire-resistance level, often with bushfire shutters. It's specialist work.
Can you build in the Flame Zone?
Sometimes. It depends on your state and council. WA generally doesn't support new development at this level, and other states have their own controls.
Is BAL-FZ the same as BAL-40?
No. BAL-40 means flames may intermittently reach the building. BAL-FZ means direct flame contact.