BAL stands for Bushfire Attack Level.
The bushfire industry has commonly used the terms Bushfire Attack Level certificates, bushfire risk assessments and bushfire attack level reports to describe the bushfire documentation required to obtain development consent from your local council.
To determine the Bushfire Attack Level (BAL), the slope and type of vegetation are determined. These site characteristics form some of the inputs into bushfire behaviour and the fire engineering calculation that determine the flame length and the potential radiant heat this flame length can emit.
The radiant heat from the flame will decrease as the distance between the vegetation and the proposed building increases. The separation between the vegetation and the proposed development is then used to determine the potential radiant heat experienced by the proposed building, which relates to the level of bushfire risk and type and quality of construction materials that can be used. Importantly there are two accepted methods to undertaking this process, which is further explained in my Bushfire assessment methodology.
There are six levels of bushfire construction provided in the below table. Refer to the BAL Construction level comparison table provided in another blog.
| BAL rating | Radiant heat exposure | |
|---|---|---|
| BAL-LOW | >100m from classifiable bushfire threat | There is insufficient risk to warrant any specific construction requirements but there is still some risk. |
| BAL-12.5 | < 12.5 kW/m2 | There is a risk of ember attack. Ignition of cotton fabric after a long time. |
| BAL-19 | 12.5-19 kW/m2 | There is a risk of ember attack and burning debris ignited by wind borne embers and a likelihood of exposure to radiant heat. |
| BAL-29 | 19-29 kW/m2 | There is an increased risk of ember attack and burning debris ignited by windborne embers and a likelihood of exposure to an increased level of radiant heat. Ignition of timber after a long time. |
| BAL- 40 | 29-40 kW/m2 | There is an increased risk of ember attack and burning debris ignited by windborne embers, a likelihood of exposure to a high level of radiant heat and some likelihood of direct exposure to flames from the fire front. |
| BAL – FZ | >40 kW/m2 | There is an increased risk of ember attack and burning debris ignited by windborne embers, a likelihood of exposure to a high level of radiant heat and some likelihood of direct exposure to flames from the fire front. |
| BAL – FZ | >40 kW/m2 | Flame contact with building through ground attachment and limited flame buoyancy Ignition of cotton fabric after 5 s Ignition of timber in 20 s |
The terminology of BAL certificate, BAL Assessment or BAL Report to obtain development consent for bushfire was developed in the early stages of the bushfire protection industry and is not entirely true under the current bushfire planning requirements. Importantly, development consent for bushfire is reached through meeting two elements, bushfire construction and bushfire planning. The BAL certificate, BAL Assessment or BAL Report only covers the bushfire construction. An assessment of Bushfire planning that covers water access, emergency management, electricity and gas services is also required to obtain consent.
A BAL certificate, BAL Assessment or BAL Report is not a document that council will accept as adequate bushfire documentation. The only documentation that is acceptable, that cover both bushfire construction and bushfire planning are:
• Bushfire Complying Development Certificate (CDC) for complying or exempt development, that is determined through the State Environmental Planning Policy (SEPP) Exempt and Complying development (2008); or
• Bushfire Assessment Report for development Applications that is determined through the Environmental Planning and Assessment Act (1979).
BEMC completed BAL certificate, BAL Assessment or BAL Report when the client only requires knowing the construction requirements and separation distances of proposed buildings. This can be at pre-purchase or within the initial planning stage.
