Bushfire safety: How to check the BAL rating on your build

Key overview: How to make your build more bushfire safe and check the BAL rating

• If you’re working in a bushfire-prone area, at the start of the project you’ll need to find out the BAL rating, which stands for Bushfire Attack Level.
• BAL is a measure of how much radiant heat and fire risk a home could be exposed to in a bushfire.
• There are six categories of BAL ratings (see below), ranging from low risk to extreme risk.
• Certain types of decking and cladding can be used with each BAL level.
• When installing decking and cladding in bushfire-prone areas, other factors to consider include spacing and gaps.

Tip: Always wear the appropriate safety equipment (safety glasses, gloves and a mask, for example) when required on the job. Always follow the instructions for the product or equipment.

Australia is one of the most bushfire-prone countries in the world and our warming planet is making fires more frequent and widespread. So, if you’re a builder who specialises in decking and cladding – aka the parts of the home at greater risk of fire damage – or you work in bushfire-prone areas more generally, it’s super important to understand the extra rules you need to follow, including how to check the BAL rating.

“The probability of bushfires is very, very low, but the outcome, if something does go wrong, can be very, very bad,” builder Scott Clancy from NSW outdoor renovation specialist Venom Construction, says. “It’s very important to do the right thing by yourself and, more importantly, by the homeowner.”

Scott and Steve Greenwood, technical advisor at the Housing Industry Association (HIA), share their top tips for installing decking and cladding in bushfire-prone areas.

What is BAL rating?

Bushfire attack level (BAL) rating is a measure of the intensity of radiant heat, embers attack and direct flames a home could be exposed to in a bushfire.

If there’s one thing to know about working in bushfire-prone areas, it’s the importance of building according to the property’s BAL rating. “At the very start of the project, you have to find out the BAL,” Scott explains.

There are six BAL ratings, from BAL low through to BAL flame zone. Steve says higher ratings indicate a greater bushfire threat and tougher building requirements. “In the lower BALs you have good materials choices for cladding and decking, but it becomes quite minimal in the higher BALs.”

How do you find the BAL rating of a property?

A property’s BAL rating is usually determined through an official bushfire assessment, not by a quick online search. In most cases, you’ll need an accredited bushfire consultant, building designer, surveyor or local council guidance to confirm it. They will take into account factors like location and slope, but also vegetation type near the dwelling site.

BAL ratings explained

• BAL-LOW: Low risk; no specific construction requirements.
• BAL-12.5: Some risk of ember attack; low radiant heat risk.
• BAL-19: Moderate risk of ember attack and burning debris.
• BAL-29: High risk of ember attack and burning debris.
• BAL-40: Very high risk of ember attack and burning debris; some direct exposure to flames possible.
• BAL-FZ: Extreme risk with direct exposure to flames from bushfire front likely.

Can you use timber decking in a bushfire-prone area?

You can use timber for decking in some bushfire-prone areas – if it aligns with the site’s BAL rating. For homes with the lowest BAL ratings (BAL 12.5, 19 and 29), Steve says there is a good variety of timber to choose from. In areas with higher bushfire risk, the options become limited to non-combustible materials only.

“A common timber used in the lower BAL areas is merbau,” Steve says. Composite decking products like Ekodeck Flame Fighter, which is suitable for areas rated up to BAL 29, can be a practical and durable alternative to timber.

What decking can you use in areas with a high BAL rating?

Only non-combustible products can be used for decking in areas with the highest BAL ratings. “For BAL 40 to BAL FZ products such as Ekodeck Flame Fighter series or James Hardie Hardie DeckTM can be used, also steel or fibre cement – something that’s not going to be able to catch on fire,” Scott says.

In flame zones, which carry extreme bushfire risk, concrete, metal and brick are good options. Cement-based decking products like James Hardie Hardie DeckTM are approved for areas with the highest BAL rating and deliver a stylish, durable finish.

What wall cladding should you use in bushfire-prone areas?

When it comes to wall cladding, certain timber, fibre cement sheet and metal can all be used on sites with lower BAL ratings, Steve explains. “The higher BALs restrict cladding to brick, concrete, fibre cement sheet and non-combustible materials such as metal cladding.”

Steve says James Hardie Hardie PlankTM is a good option, as is James Hardie HardieTM Groove Lining for eaves and soffits. “It’s important to observe the minimum thickness requirements for fibre cement sheet cladding as BALs increase,” he adds. For roofs, cladding must be non-combustible – look to concrete or terracotta tiles or metal cladding like Fielders Zincalume steel.

What else do you need to know about decking in bushfire-prone areas?

Pay attention to gaps. There’s more to installing decking and cladding in bushfire-prone areas than the choice of materials – spacing and gaps matter, too. Steve says the relevant Australian Standard only provides guidelines so it’s important to use good judgement. “If the gaps are too narrow in decking, for example, embers may lodge in there and cause a problem. If they're too wide, they can allow embers to pass through or blow away,” he says. “Gap sealing is also important – any gaps greater than 2mm need to be protected or screened, including wall or sub-floor vents.”

After irrigation solutions?

While summer can bring the fire, it’s also a time to protect your clients’ turf. Check out this guide to irrigation solutions.