What is a Bushfire Attack Level (BAL) Report?

As of April 2016 it has become mandatory for all developments that are located within a bushfire prone region to have a Bushfire Attack Level (BAL) assessment conducted. A Bushfire Attack Level (BAL) Assessment consists of a certificate which is a declaration of the Bushfire Attack Level (BAL) rating for a particular site and a Bushfire Attack Level (BAL) report which is a detailed account of why you are that rating.

The Bushfire Attack Level (BAL) is a measure of the building’s exposure to direct flame contact, ember attack and radiant heat. It is measured as radiant heat in kilowatts per meter square. For convenience, these quantities are categorised as Bushfire Attack Level (BAL) ratings. As per the AS 3959, there are 6 levels of potential radiant heat impacts each with its own bushfire construction requirements:

• Bushfire Attack Level (BAL) – LOW: Low or insufficient risk and no construction requirements

• Bushfire Attack Level (BAL) – 12.5: This is considered to be a low threat with a risk of an ember attack and construction elements should be able to withstand a heat flux of 12.5 kW/m2

• Bushfire Attack Level (BAL) – 19: The risk is moderate with a risk of an ember attack, burning debris and potential exposure to radiant heat. The construction elements should be able to withstand a heat flux of 19 kW/m2

• Bushfire Attack Level (BAL) – 29: The risk is considered to be high. There is a risk of an ember attack, burning debris and potential exposure to increased level of radiant heat. The construction elements should be able to withstand a heat flux of 29 kW/m2

• Bushfire Attack Level (BAL) – 40: This is a very high risk rating. All the risks of an ember attack, burning debris and an exposure to radiant heat are heightened with even a threat of direct exposure to flames. The construction elements should be able to withstand a heat flux of 40 kW/m2

• Bushfire Attack Level (BAL) – Flame Zone (FZ): The risk is extreme with all the likelihood of flame contact, spread and an exposure to very high levels of radiant heat. The construction elements should be able to withstand a heat flux greater than 40 kW/m2

In order to determine the Bushfire Attack Level (BAL) rating, a site assessment is carried out by BPAD Accredited Level 1 Assessor to highlight the bushfire threat i.e. unmanaged vegetation within a 100 m radius of the site and classifying them as per AS3959. The second factor in determination of the Bushfire Attack Level (BAL) is the separation distance of the building (measured from the elevation excluding eaves/overhangs) from the edge of the vegetation. Then as per AS 3959, the Bushfire Attack Level (BAL) rating is determined using pre- determined classification and separation distance values. For instance, if your building is at a separation distance from Group B Woodland of 16 m, you fall between the ranges of Bushfire Attack Level (BAL) 29 which is between 14 – 20 m. However, one of the key factors is slope of the land under the vegetation. Since slope affects the rate of fire spread i.e. fire travels faster downslope, if a classified vegetation has a downslope underneath it, a greater separation has to be achieved from that plot of vegetation.

If you know your development is in a bushfire prone region, you will require a Bushfire Attack Level (BAL) assessment to be conducted by a BPAD Accredited Level 1 Assessor. However, if your Bushfire Attack Level (BAL) rating is above 29, you will require a more complex report like a Bushfire Management Plans (BMP) or a Bushfire Management Statement (BMS) to be written by a BPAD Accredited Level 2 Assessor.

Contact Green Start Consulting’s experienced team for expert advice on everything building industry related including Bushfire Attack Level (BAL) Reports, Bushfire Management Plans (BMP), Bushfire Management Statement (BMS) and Bushfire Attack Level (BAL) Contour Maps.

Due to constantly evolving legislation the information provided within this blog may no longer be valid. The advice given on this site is general in nature and does not take into account your specific circumstances. Please email one of our building surveyors to check what is right for you