12.5 Bal Requirements
The BAL assessment is the Australian standard for measuring the risk of a home being exposed to ember attacks, radiant heat and direct contact with the flame. The BAL assessment determines the construction and construction requirements required to protect homes in areas prone to bushfires. There are six stages of the BAL assessment in accordance with the Australian standard – AS 3959:2018 Construction of buildings in areas vulnerable to bushfires. We have detailed each of the BAL assessments and what they mean in the table below. If your building is more than 100 m of classified vegetation, the BAL rating is most likely BAL-LOW and does not require any special construction requirements. If there is a risk or possibility that an ember attack could affect your home, we recommend using BAL – 12.5. BAL – Low There is not enough risk to justify certain design requirements. BAL – 12.5 ember attack and radiant heat up to 12.5kW/m2. BAL – 19 Increased attack of embers and combustion of debris ignited by embers carried by the wind, as well as increase in radiant heat from more than 12.5 kW/m2 to 19 kW/m2 inclusive. BAL – 29 Increase in ember attacks and burnt debris ignited by embers carried by the wind, as well as increased radiant heat from more than 19 kW/m2 to 29 kW/m2 inclusive. BAL – 40 Increase in ember attacks and burning debris ignited by embers carried by the wind, as well as increased radiant heat from more than 29 kW/m2 to 40 kW/m2 inclusive. BAL – FZ Direct flame exposure with ember attack and radiant heat of more than 40 kW/m2. Construction in BAL-FZ may require a reliance on measures other than construction.
The requirements for the construction of a BAL-FZ BUILDING may be regulated by the responsible building authorities in the states and territories of Australia. Planning a modular home is a deliberate process that takes into account both function and aesthetics as well as the environment. One of the most important aspects to consider is how the risk of a bushfire affects the construction requirements needed to keep your home and family safe. For the BAL (Bushfire Attack Level) index of BAL 12.5, there are specified design requirements listed in the AS3959 that prevent an orange attack. These structural requirements ensure that an ember attack is avoided and that the building can withstand a heat flow of approximately 12.5 kW/m2 in the event of a bushfire. These requirements are listed in AS3959 under the Bushfire Attack Level (BAL) Design Requirements BAL-12.5: In the case of a BAL 40 assessment, roofing materials must be made of non-combustible materials such as steel. If the BAL rating is 12.5 and above, the roofs must be completely barred and the connection between the roof and the walls must be completely sealed. If you have completed a Bushfire Attack Level Assessment (BAL) for your development and need guidance on bushfire construction requirements for your Bushfire Attack Level (BAL) assessment, contact your BPAD-accredited Bushfire Attack Level Assessor (BAL) today for a compliance report. A BAL (Bushfire Attack Level) rating expresses the heat flow to which a structure would be exposed in the event of a bushfire and is measured in kW/m2.
The lowest rating is LOW`s Bushfire Attack Level (BAL), which means that the development is not subject to any additional construction requirements. This means that it is either more than 100 m from classified vegetation (50 m for grasslands) or part of the other five exclusions specified in RO 3959 for low-threat vegetation. The next level in the Bushfire Attack Level is BAL-12.5. This level is a relatively low bushfire threat rate, but there is a risk of ember attack. This means the ignition of the fire from a wandering ember that can float on a combustible material or in wet vents/holes, thus igniting the building material and causing a fire that can spread quickly. A bushfire attack level of BAL-12.5 does not justify very comprehensive requirements for bushfire construction. Most of the requirements are something that a solid build will already follow. The key element for the bushfire attack level of the BAL-12.5 Bushfire construction is the avoidance of an ember attack, hence the requirement for ember/mesh protection devices and bushfire roller shutters at all openings. BAL – LowThe attack level of bushfires BAL – LOW is based on insufficient risk to justify specific requirements for the construction of bushfires. Our designers will work diligently to ensure that the design and construction of your home reflects the relevant BAL rating. To learn more about our construction process and design features, you can check out some of our recent projects or learn more about our custom homes.
Protection from bushfires should be a top priority given the prevalence of bushfires and climate change in our country, especially for Australians.