Building a deck in a bushfire-prone area. Bushfire Attack Levels (BAL) Explained.
If you’re building a deck in a bushfire-prone area, chances are you need a decking material that has a Bushfire Attack Level, or BAL-rating.
But what is a BAL-rating?
BAL stands for Bushfire Attack Level, and there are 6 different levels, all measured on the risk of a home’s exposure to ember attack, radiant heat and direct flame contact (measured in kW per square meter):
| Bushfire Attack Level | Radiant heat exposure | Description |
| BAL-LOW | 0 to 12.5 kW/m2 | The risk is very low and radiant heat on the building is not significant enough to warrant specific construction requirements; however ember attack may still occur. If you are in a designated BPA and your bushfire attack level is BAL – LOW, you must still construct to a minimum BAL 12.5. |
| BAL-12.5 | 0 to 12.5 kW/m2 | Primarily risk of ember attack; risk of radiant heat is considered low. |
| BAL-19 | 12.5 to 19 kW/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 29 kW/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 40 kW/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 | 40 kW/m2 & 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. |
If you’re building a deck in a bushfire-prone area, it is important to check whether you require fire-rated materials with the local council or fire authority.
For any building or construction work taking place in a bushfire-prone area, it is a good idea to have a copy of AS 3959:2018 Construction of buildings in bushfire-prone areas on hand, so that you can ensure that you’re building to the right specifications for your home to comply to the BAL-rating requirements.
According to AS 3959, several timber species are considered bushfire-resistant, whether they are naturally bushfire-resistant, or have been altered with a fire retardant material – a select number of timber species can be used in certain BAL zones (generally BAL-LOW to BAL-40).
The list of naturally bushfire-resistant timber species according to AS 3959 includes the following: silvertop ash, blackbutt, river red gum, spotted gum, red ironbark, merbau and turpentine.
Only non-combustible products can be used in areas with a BAL-FZ (Flame Zones); concrete, metal and bricks are some of the most common non-combustible construction materials.
For a composite decking material to be considered a certified BAL-rated product, it must be tested to AS 1530.8.1 Methods for fire tests on building materials, components and structures, as it is regarded as a non-standard building material in the National Construction Code (NCC).
In addition to the test method laid out in AS 1530.8.1, there are various other fire-related tests for building materials set out by the Australian Standards, however, these don’t actually determine a BAL-rating of a building material, rather they determine various burning or fire-related characteristics of the material.
One such test is AS ISO 9239.1-2003 Reaction to fire tests for floor coverings. This test determines the critical radiant flux and smoke development rate of a product, and the results can be used to determine if the product meets NCC 2016 BCA Vol. 1 Specification C1.10 ‘Fire Hazard Properties’ specifications.
Another fire-related test that may be mistakenly used to claim a BAL-rating, is AS 1530.3:1999 Simultaneous determination of ignitability, flame propagation, heat release and smoke release, which grades building materials on the basis of ignition tendency, flame spread, heat development and tendency to produce smoke.
Some suppliers of composite products have been known to use AS/NZS 3837:1998 Method of test for heat and smoke release rates for materials and products using an oxygen consumption calorimeter as evidence for a BAL-rating, but again, the only testing method that can provide a BAL-rating is AS 1530.8.1.
Whilst these tests provide important and useful information regarding the burning characteristics of a building or decking material, they cannot be used as evidence to support a BAL-rating for an outdoor composite decking material. Testing to AS 1530.8.1 is the sole method to certify that a composite decking material is adherent to the NCC.
It is important to ensure that whatever composite decking material you’ve chosen for your home or project has been tested to AS 1530.8.1 by a NATA-accredited testing authority, as this is the only approved testing method for a composite decking material to obtain a compliant BAL-rating in Australia.
But why is BAL compliance important?
BAL compliance is crucial because it ensures that buildings in bushfire-prone areas are designed and constructed to withstand potential bushfire threats.
This compliance is based on the assessed level of bushfire risk to the building and surrounds and dictates the specific construction requirements needed to minimise damage from a bushfire.
You can check out more information on Ekodeck and compliance here.
Ekodeck’s BAL-ratings
Our Flame Fighter decking range has been tested to AS 1530.8.1 and comes with a certified BAL-29 rating, meaning it can be used in the construction of a deck up to a BAL-29 zone, including BAL-LOW, BAL-12.5, BAL-19 and BAL-29 zones.
At Ekodeck, we test our Flame Fighter decking boards on a rigorous schedule to ensure that our boards are compliant – so that you can rest easy knowing that you have installed a compliant and bushfire-rated material.
Feel free to reach out to us at [email protected], or give us a call if you have any further questions about Ekodeck and BAL-ratings.
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