What is a BAL rating
The best way to think about a BAL rating is in terms of heat levels. When someone says “My home has a rating of BAL 12-5” what they really mean is my home has been built to withstand 12-5 kilowatts/m2 of radiant heat. To give a bit of meaning to this value, a typical firefighter will get 2.5 kilowatts of exposure to heat fighting a fire.
Once your home or land has been assessed, it will be given a BAL rating that fall into 6 categories ranging from BAL-LOW (meaning your home doesn’t require any upgrades to the construction) all the way unto BAL Flame Zone (Meaning your home will need to be constructed in such a way that it can withstand 80 kilowatts/m2 of radiant heat).
Can the BAL rating of my home change?
Yes – The best way to lower your BAL rating is very basic, move the proposed building away from the uncontrolled vegetation that has resulted in the BAL rating or with permission from your local shire you can remove some of the vegetation.
What is required for a BAL assessment?
To give a BAL rating we will require a plan that indicates the location of your proposed building, we will then need to travel to site and collect photos of the vegetation within 150m. All pockets of vegetation will then be classified into 5 main classes.
Class A Forest
Class B Woodland
Class C Shrubland
Class D Scrub
Class G Grassland
The slope of the land can have a huge impact on your BAL rating, If your home is placed on the top of a hill, the fire will not only tend to run towards your home. It will also increase in speed and intensity. Once the vegetation Class and slope of the land are known, the only element that needs to be confirmed is the distance from the vegetation to your building. As anyone who has stood next to a fire knows, you only need to move a few feet away for the heat to drastically drop off.
An example of how a BAL rating is calculated.
A very basic example would be a site that has Class B Woodland on flat land with a 14m clearing between the vegetation and the home, this would result in a rating of BAL-29. If this clearing can be increased to 20m, the BAL rating will drop to BAL-19. This not only represents a very large cost saving but a real increase in safety to the building.
What are the costs associated with different levels?
The associated costing to your building when it comes to complying with the new standard can differ significantly, even if you only receive a BAL rating one level higher can add $10,000s to the build cost. It is out advice that before placing any offer on land or even an existing building, particularly in a rural location, it’s essential you have an understanding of what your Bushfire attack level (BAL rating) might be and all the costs that are required to conform to AS3959-2009. Please contact us for FREE guidance before placing an offer.
BAL 12.5 - +$3,000 to $6,000
BAL 19 - +$6,000 to $11,000
BAL 29 - +$11,000 to $20,000
BAL 40 - +$20,000 to $30,000
BAL FZ - +$50,000 to $150,000
Once your bushfire attack level rating (BAL rating) is known, you will be able ask your builder/designer to give you a summary of the different costs related to your ratings. Your welcome to contact us with any information that you have been provided with, this will allow us to share the most up to date information on balrating.com.au.
Some information taken from nist.gov