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Understanding the Bushfire Attack Level
| Bushfire Attack Level (BAL Rating) | Radiant heat exposure (AS 3959) and levels of exposure | Description |
|---|---|---|
| BAL-LOW | Insignificant | Standard construction materials and methods, including timber framing and cladding materials can be used. These sites have no special requirements as there is such a low risk of bushfire attack. |
| BAL-12.5 | 0 to 12.5 kW/m2 | Some possibility of ember attack has been identified from looking at the closeness of vegetation, the site itself and local conditions with construction elements expected to be exposed to a radiant heat flux not greater than 12.5 kilowatts per square metre (kW/m2). |
| BAL-19 | 12.5 to 19 kW/m2 | Sites identified as having an increasing level of predicted ember attack and burning debris ignited by wind-borne embers together with an increasing radiant heat flux, not greater than 19 kW/m2. |
| BAL-29 | 19 to 29 kW/m2 | Increasing level of chance of ember attack and burning debris ignited by wind-borne embers, together with an increasing radiant heat flux not greater than 29 kW/m2. |
| BAL-40 | 29 to 40 kW/m2 | Further possibility of ember attack and burning debris ignited by wind-borne embers; together with an increasing radiant heat flux, not greater than 40 kW/m2, and an increased likelihood of exposure to bushfire flames. |
| BAL-FZ | 40 kW/m2 + (flame contact) | Extremely bushfire-prone, probably in a picturesque bushland setting, a home with this BAL has a predicted direct exposure risk to flames from a fire front, ember attack and a radiant heat flux greater than 40 kW/m2u. |
Reduce the potential for bushfire attack and damage by following the Standard’s guidelines for building systems and materials and special timber choices. Following the Standard, ensuring common sense maintenance, as well as complying with Wildfire Management Overlays (WMO) and fire authority rules and instructions, are all important.
All information on this page is a guide only and assumed to be correct at time of publishing. Barwon Timber strongly advises readers check all information against current Australian Standards and guidelines.
