BAL-rated decking for bushfire prone areas
Northern Decking Co builds decks to the BAL construction requirements of AS 3959 across the City of Joondalup and the City of Wanneroo. If your lot is on the DFES Map of Bush Fire Prone Areas, the deck's materials, gaps and fixings have to match the lot's BAL rating. Tell us the rating and the contractor will quote it free.
What you get
Start with the map
The DFES Map of Bush Fire Prone Areas shows which lots in Western Australia are designated bushfire prone. If your lot is inside a mapped area, new building work including a deck attached to the house has to meet the bushfire construction requirements of AS 3959, and a BAL assessment sets the level for your lot. We never state on this site that a particular suburb is or is not bushfire prone, because the map runs through suburbs and changes over time. Check your own address on the map, and if you already have a BAL assessment, tell us the level when you enquire.
What the BAL levels mean for a deck
The Bushfire Attack Level runs from BAL-LOW, where the standard imposes no construction requirements, through BAL-12.5, BAL-19 and BAL-29, to BAL-40 and BAL-FZ (flame zone). Each step up tightens what a deck attached to the house can be made of and how it is detailed.
In broad terms, at the lower levels the standard controls the subfloor supports, the boards close to the house and what sits under the deck, and it allows timber decking if the timber is a listed bushfire-resisting species or the deck is detailed a particular way. At the higher levels the options narrow to non-combustible materials, and at BAL-40 and BAL-FZ timber decking against the house is largely off the table. The contractor designs to the assessed level for the lot, not to a guess.
Bushfire-resisting timbers
AS 3959 lists a small group of hardwoods as bushfire-resisting timbers on the strength of their density and fire performance. Merbau (kwila) and spotted gum are both on that list. Jarrah is not, which matters on a BAL-rated lot where the owner wanted jarrah boards. Blackbutt and a few eastern-states species make up the rest of the list.
Composite on a BAL lot
Composite boards are not automatically compliant or automatically excluded. Some products have been tested and rated for specific BAL levels, and the product’s own test report is what counts. The contractor confirms the report for the board you want before it goes in the quote.
Gaps, fixings and the space underneath
The details matter as much as the boards. The standard sets rules for the gaps between boards near the house, for whether the subfloor is enclosed, for what the supports are made of, and for the material of any skirt or screen. Stainless and galvanised fixings are used as they would be on any coastal deck. What sits under the deck matters too: a BAL-compliant deck over a pile of stored timber is not compliant in practice.
Approvals
A deck on a bushfire prone lot goes through the same council process as any other deck, with the BAL assessment and the bushfire construction details added to the building permit application. The panel below has the current position for each council.
How it goes in
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Joists
Joists go across the bearers at the centres the board maker specifies, typically 450 mm for hardwood and tighter for composite.
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Boards
Boards are laid from the house out with an even gap, fixed with screws or hidden clips.
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Finish
Fascia and trims go on and the deck is oiled, or a composite deck settles into its finished colour.
What changes the price
- Size
- More area is more boards, joists and fixings, but the rate per square metre usually falls as the deck gets bigger.
- Height
- A deck over 500 mm needs more structure, probably a balustrade, and may need planning approval and privacy screens.
- Material
- Composite costs more per board than most hardwood, and hidden clip systems add to that, but it is the last money you spend on the surface.
- Access
- A deck at the back of a narrow lot means carrying everything through by hand and takes longer.
- Approvals and engineering
- A building permit, drawings and any engineering for a raised deck are real costs that sit outside the build itself.
We do not publish prices, because two decks of the same size can be very different jobs. Read what affects the cost of a deck, then get a free quote from the contractor.
Approvals
City of Joondalup
- Building permit requirements depend on the deck. Confirm with the City of Joondalup on 9400 4000 before work starts.
- For a single house or grouped dwelling, development (planning) approval is not required for decking 500 mm or less above natural ground level.
- Decking over 500 mm can avoid planning approval if it meets the R-Code setbacks for the lot's density.
- A deck within 7.5 m of a side or rear boundary needs a privacy screen at least 1.6 m high.
City of Wanneroo
- All decking requires a building permit, regardless of height or floor area.
- Planning approval may be required for decking over 500 mm above natural ground level.
- Decking over 500 mm is treated like a balcony, with a 7.5 m setback to side and rear boundaries unless a reduced setback is approved.
Check the DFES Map of Bush Fire Prone Areas for your lot. Decks in a bushfire prone area have to meet the BAL construction requirements of AS 3959. DFES Map of Bush Fire Prone Areas.
Questions people ask
How do I find out my BAL rating?
Start with the DFES Map of Bush Fire Prone Areas. If your lot is inside a mapped area, a BAL assessment sets the rating for the lot, and the deck is designed to that rating.
Which decking timbers are allowed in a bushfire prone area?
AS 3959 lists bushfire-resisting timbers that can be used up to certain BAL levels, and it sets rules for the gaps between boards and the material of the subfloor. Which species and which detail apply depends on the rating.
Can composite decking be used in a BAL area?
Some composite products are tested and rated for specific BAL levels. The product's own test report is what counts, so the contractor confirms it before quoting.
Get a free quote
Send your details. The contractor calls you, looks at the site and quotes in writing. No obligation.