Learn more about BAL
- BAL assessment - Do i need one ?
- The state government has come out with a Map of Bush Fire Prone Areas Map. It is a simple task to locate your land or development on the map. If any part of your land/development is covered in purple, then it is deemed bushfire prone. Please use the state governments map below to find out if your Perth home will need a BAL assessment.
Vast amounts of research have been done my local governments to determine if a given area warrants being classed as bushfire prone. In some cases, the map will show areas as been bushfire prone when in fact that area has been cleared of all vegetation. A bushfire attack level of BAL-LOW would be applied to the building in question and no special construction standards would be required.
If you are still having problems locating your building area on the map, you are welcome to contact us to establish if your site is considered bushfire prone and in need of a BAL Rating. We are happy to perform this task for free.
- What is a BAL assessment
- A BAL (Bushfire Attack Level) is a means of measuring a building's potential exposure to ember attack, radiant heat and direct flame contact, in a bushfire event. It is a basis for establishing the requirements for construction to improve protection of building elements from attack by bushfire.
Once the assessment has been completed you will know your BAL "bushfire attack level" and be able to construct your house to the correct standard.
BAL assessment - The Science of Wildfires
- How do we perform a BAL assessment?
- There are 6 main steps to performing a BAL.
1. Determine your Fire Danger Index (FDI)
2. Determine your site’s vegetation
3. Determine the distance from the site to the vegetation in question
4. Determine the slope of the land under the vegetation
5. Determine the BAL
6. Apply the construction requirements set out in Australian Standard AS 3959-2009
We achieve this by attending your property/vacant land to take a quantity of photographs and examine and classify the vegetation. We also determine the slope of the classified vegetation with an industry specific laser rangefinder. Once we have discovered and recorded the distances and size of classified vegetation we can apply AS3959-2009 to exclude any low threat vegetation to achieve the lowest possible BAL rating.
- What is included in the report.
- Click here to view a Demo bushfire report
- What do the different ratings mean?
- Any building situated in a bushfire prone area will need to meet the construction standard that are applicable to that rating, please see below
There are 6 different ratings that have their own construction requirements
The risk is VERY LOW. No special construction requirements would be needed (All vegetation is over 100m from the land been assessed)
The structure will begin to fail at a heat flux greater than 12.5kW/m2
The structure will begin to fail at a heat flux greater than 19kW/m2
The structure will begin to fail at a heat flux greater than 29kW/m2.
The structure will begin to fail at a heat flux greater than 40kW/m2
The structure is expected to be exposed to a heat flux greater than 40kW/m2.
- What is AS3959-2009
- AS3959 is an Australian Standard for construction of homes/building in bushfire prone areas. The latest version AS3959:2009 was speedy release after the destruction of "Black Saturday" bushfires, which killed 173 individuals and devastated over 2,000 homes.
This Standard is mainly concerned with improving the capacity of a structure in designated bushfire-prone areas to better withstand a bushfire. In the hope of allowing the fire front to pass with minimal damage to the building and allow the occupants to survive. AS3959 is the combination of lots of research into fire behaviour and its effects on structures.
- How to know if your building complys with AS3959-2009
- BAL assessments can make a reference to "Exclusions".
- 126.96.36.199 Exclusions
The BAL Rating will be classified BAL—LOW when the vegetation is any of the following .
(a) Vegetation over 100m from the site.
(b) Small areas of vegetation that are under 1 ha and are over 100 m from other areas of vegetation being classified.
(c) If you have a few areas of vegetation less than 0.25 ha and are more than 20m from each other, and the site.
(d) Strips of vegetation under 20m in width and more than 20m from the site.
(e) Non-vegetated areas.
(f) Low threat vegetation.
Often we can drastically lower your bushfire attack rating by applying the exclusions outlined in AS3959-2009
Some of the key features of building a BAL rated home are use of hardwood or steel for exposed structural parts of the house such as beams and posts, weep holes in brickworks having to have metal meshes installed, and no gaps greater than two millimetres in openings in the walls and the roof. Along with many more seemingly small requirements that all add up. With all these different regulations to comply with, what are some key ones that you, as a homeowner, can see?
One key area that is often overlooked with protecting your home from bushfire attack is the installation of Dektites on your roof. A Dektite is a rubber boot that is fitted around holes on your roof for pipes, chimneys, and cables.There are different types and offten some of them don't comply with BAL requirements and shouldnt be used for that rating? How can you spot if your Dektites are the right ones? Luckily it's pretty simple. If your Dektites are red then you can be very confident that it's compliant up to BAL 29. These are made from red silicone and the genuine ones can withstand temperatures of up to 250 degrees intermittently.
If your Dektites are black or grey you need to investigate a bit more closely to see if it's premium range or original and that it's manufactured by DEKS. If it's a premium version marked on the rubber then it's likely to be compliant up to BAL 12.5. These are made from a material called EPDM and can withstand temperatures up to 150 degrees. If they're either black or grey and don't have any markings then it's worth finding out where they came from and ringing the supplier to confirm. On top of this, check for gaps around windows and doors such as these. Often these gaps can let embers into your cavity such as wall cavitys, this could start a fire you might not see until it's too late. If you're planning to build in a bushfire prone area it's important to ask your builder what their experience is to make sure you're working with one that specialises in bushfire construction.
Follow this link to buy a copy