All our readers who have had a Bushfire Attack Level (BAL) Assessment conducted are probably aware that it is an assessment of vegetation within a 100 m radius of their property and a Bushfire Attack Level (BAL) rating in accordance to that vegetation. All those readers that have been given a Bushfire Attack Level (BAL) rating of Flame Zone (FZ) for their property may be aware of the trouble that accompanies this. If you’ve been given a BAL-FZ, then your development is subjected to an extreme bushfire risk with chances of great damage to your property in the catastrophic case of a bushfire.
A Bushfire Attack Level (BAL) of BAL-FZ is the highest possible BAL rating and is primarily concerned with maintaining protection from ember attacks, radiant heat of more than 40kW/m2 and direct flame contact. Being such a high risk, most councils and the WAPC will most probably not grant developmental approval for such a development unless:
- It is an unavoidable development
- It is a minor development
- It is a non-habitable unattached structure that does not increase the risk the risk of bushfire for the existing development.
In any of the above scenarios, if approval is granted, the structure must uphold stringent safety construction standards as per the Building Code of Australia and AS3959. AS3959 lists the bushfire construction requirements for Bushfire Attack Level (BAL) FZ is summarised as the following:
- Subfloor supports, including support posts, columns, stumps, piers and poles shall be made from a non-combustible material, with a FRL of at least 30/-/-, or a system complying with AS 1530.8.1.
- Walls of a structure to achieve compliance with a Bushfire Attack Level (BAL) rating of BAL-FZ are to be of non-combustible material, or cladded with non-combustible materials or a combination of the materials specified by the AS3959.
- Roof covering shall be made of non-combustible or materials specified by the AS3959 and the underside of roofs are to be sealed to avoid any gaps and threat of ignition through ember attack.
- All unenclosed structures such as Verandas, Decks, Steps, Ramps and Landings must be made from a non-combustible material or a system which complies with the AS 1530.8.1.
- All doors and windows must be fully covered by bushfire shutters. The window/door system shall have an FRL of at least -/30/- or comply with AS 1530.8.2 when tested from the outside.
- Door and window frames and all assemblies are to be metal.
- All glazing shall be toughened Grade A safety glass which a minimum thickness of 6 mm.
- Ember guards and mesh screens are to protect all openings vents, weep holes etc.
- Joint openings in all joinery to be kept at a minimum size as specified by the AS3959.
- All water and gas supply pipelines to be made from metal.
If you are looking at a BAL-FZ rating as a result of your Bushfire Attack Level (BAL) assessment you should consider contacting your local BPAD accredited level 2 Bushfire Attack Level (BAL) Assessor, inquiring about a Bushfire Management Plan (BMP), which can potentially lower your rating. A Bushfire Management Plan (BMP) will also aid you to determine a scheme which will best equip you in the case of a bushfire emergency by ensuring safety to yourself and your property.