What is a BAL - do I need one?

Fire truck.jpg

This is general advice and may not apply specifically to your property. For more detailed information on your personal circumstances please contact the Rebuilding Planning Team on 9294 6999.

Most of the Dandenong Ranges are bushfire prone and covered by a Bushfire Management Overlay.

Each property is individual and will have different circumstances. If you have a property which is to be partially rebuilt contact the dedicated Rebuilding Planning Team on 9294 6999 or/and your Building Surveyor, who should be able to provide you with further advice before you start. 

If you are completely rebuilding you will need to include a Bushfire Management Plan as part of your planning application.  Your Bushfire Attack Level (BAL) Assessment will be part of your Bushfire Management Plan, along with other requirements, and is usually undertaken by a specialist.

The CFA Bushfire Management Plan web pages provide more information, examples and templates of Bushfire Management Plans so you know what to expect from your specialist.

The BAL assessment also guides the minimum construction requirements needed to ensure your property is built to Australian Standard (AS) 3959-2018. 

The BAL is a nationwide approach to determine the severity of a building’s potential exposure to ember attack, radiant heat and direct flame contact.

Designing and building houses that are resistant to ember attack is fundamental to bushfire resilience. Our Planning Journey pages have more information on design and building

The BAL is measured using levels of radiant heat, expressed in kilowatts per square metre. To put it more simply: the higher the number, the more severe the potential exposure.

The BAL is based on:

  • Your location. This will include how many directions a bushfire may approach from as well as road access in and out of the property.
  • The type of vegetation on your property. There is no such thing as fireproof vegetation as it can all burn in extreme fire conditions. The denser the vegetation, the more intense the fire zone is. If there is a mixture of trees, shrubs, grasses and leaf litter, this can have a kindling effect allowing the fire to build.
  • How far your house is from vegetation. The closer the property is to vegetation, the higher the fire risk. Research into Australian bushfires has indicated that around 85 per cent of house destruction happens within 100 metres of bushland.
  • The slope of your property. The topography affects the speed and spread of a fire. Fires burn faster uphill. The steeper the slope, the quicker the fire. When moving upslope, the fire dries out the vegetation ahead making it easier to burn. This is often a challenge, as some with to site a home at the top of a slope to maximise views.

In addition to ember attack, each BAL is based on heat flux exposure thresholds. BAL-LOW is the lowest risk category and there are no additional construction requirements for this category; and BAL-FZ (Flame Zone) is the highest risk category. 

Attack Level    

 Radiant heat
 exposure (AS3959)

 Description of prediction bushfire attack and levels of 
 BAL Low  Insignificant  The risk is very low, radiant heat on the building is insignificant to warrant specific construction requirements, however ember attack may still occur.
 BAL 12.5  0 to 12.5kW/m2

 Primarily risk of ember attack; risk of radiant heat is considered low.

 BAL 19  12.5 to 19kW/m2 Risk is considered moderate with increasing levels of ember
attack and burning debris ignited by wind borne embers;
increasing likelihood of exposure to radiant heat.
 BAL 29  19 to 29k/W/m2  Risk is considered to be high with increasing levels of ember
 attack and burning debris ignited by wind borne embers;
 increasing likelihood of  exposure to radiant heat.
 BAL 40  29 to 40kW/m2  Risk is considered to be very high. Increasing levels of ember
 attack and burning debris ignited by wind borne embers;
 increasing likelihood of exposure to radiant heat and some
 direct exposure to flames possible.
 BAL FZ  40kW/m2 plus
 (Flame contact)
 Risk is considered to be extreme. Direct exposure to flames
 from fire front is likely in addition to high levels of radiant heat
 exposure and ember attack.

Ember attack BAL image.JPG

How do I find out the BAL for my property?

To find out the BAL for your property, or to complete a Bushfire Management Plan, you will need to have a bushfire hazard assessment undertaken.

Given the technical nature of a BAL assessment and Bushfire Management Plan, it is recommended that a suitably qualified person, with expertise in applying AS 3959-2018 undertake the assessment.

Fire Protection Association Australia (FPAA) is the national technical and educational fire safety organisation. FPAA provides training and accreditation and can provide you with a list of qualified people. 

Useful links

Rebuilding in a bushfire area can be complex with lots of information widely available. Here are some links to key websites and documents.

Building in bushfire prone areas - this link takes you to the Dept of Environment, Land, Water and Planning where there is information on building construction and planning controls for properties in designated bushfire prone areas.   

VBA Bushfire areas and overlays The Victorian Building Authority has details on standards for building in bushfire prone locations.

Domestic buildings constructed in Victoria must comply with the Australian Standard AS 3959-2018 – Construction of buildings in bushfire-prone areas or the NASH Standard 2014 – Steel Framed Construction in Bushfire Areas. This applies to all new domestic buildings, alterations and additions in Victoria, including associated garages and sheds. 

Bushfire Management Overlay Information for Landowners(PDF, 2MB) has details on planning matters, the 10/50 rule and more. 

If you need further advice contact Council's dedicated Rebuild Planning Team on 9294 6999. The Community Wellbeing pages has contact details if you require further support.