Bushfire Safety for New Homes - What’s a BAL Rating?

With the terrible bushfires along Australia’s east coast a few years ago, many people are rethinking the durability and safety of their home. If you don’t have experience with bushfires, it is difficult to know whether your home is at risk and what you can do to keep your family safe and minimise the risk of bushfire damage. Thankfully, Australia has a system to measure bushfire risk, called a BAL rating, and an associated standard for construction in areas where bushfires are a risk, called AS3959.

BAL is an acronym for Bushfire Attack Level. BAL ratings are a way to measure the risk of a particular home being threatened or damaged by a bush fire. If your home is being built in a bushfire zone, the BAL rating will determine what extra measures are required to protect your home from fire.

Complying with BAL rating requirements will cost extra, and may limit the type and style of materials you can use in the construction of your home.

BAL Ratings

There are six different BAL ratings. They are measured in increments of radiant heat exposure, measured in kilowatts/m². In short, a higher BAL rating means that your home may be at greater risk in a bushfire.

BAL LOW – Very low risk
BAL 12.5 – Possible ember attack with heat exposure of up to 12.5kW/m²
BAL 19 – Increasing levels of ember attack with heat exposure of up to 19kW/m²
BAL 29 – Increasing levels of ember attack with heat exposure of up to 29kW/m²
BAL 40 – Increasing levels of ember attack with heat exposure of up to 40kW/m² with possible exposure to flames
BAL FZ – Direct exposure to flame from the fire front, plus heat exposure greater than 40kW/m²and ember attack

More information about BAL ratings is available from the NSW Rural Fire Service.

How are BAL Ratings Determined?

Australian Standard AS3959 covers the methodology used to determine BAL Ratings. The BAL Rating that applies to a particular dwelling depends on distance from a bushfire hazard, the type of hazard, whether the hazard is up or downhill from the dwelling, and the Fire Danger Index for your part of NSW. In general, a dwelling located more than 100m from a bushfire hazard will not have a BAL rating.

The Rural Fire Service has a comprehensive guide to determining the BAL Rating for your proposed property, which can be downloaded here.

Alternatively, a bush fire consultant can provide a report detailing the BAL rating for your property. You can find an accredited Bush Fire Consultant at www.fpaa.com.au.

Complying with BAL Rating requirements

The BAL rating on your new home will determine what extra measures must be used to reduce the risk of damage from bushfire attack. Australian Standard AS 3959 lists the requirements for construction in a bushfire zone.

Methods and materials used to comply with BAL rating requirements include:

Using non-combustible materials for external walls or using BAL-rated external cladding
Preventing any gaps in the external walls large enough for embers to collect
Using metal insect screens in a suitable metal frame
Using metal-framed windows
Using BAL rated external doors and door frames
Using thicker glass in windows and sliding doors
Sealing garage doors to deter ember attack
Using ember guards in roof openings and penetrations
Adding gutter guard to stop leaves building up in gutters and roof valleys

The above is not an exhaustive list. Depending on the applicable BAL rating and the design of a particularly home, we may have a very long list of requirements to comply with the Australian Standard and the National Construction Code.

In some cases, our normal construction methods and materials comply with the requirements for construction in a bushfire zone. In some cases, we need to use different materials or techniques.

How Much Does it Cost to Build in a Bushfire Zone?

Building in a bushfire zone does cost more than standard construction, but it may not be as expensive as you might think.

On an average size home, complying with BAL 12.5 or BAL 19 standards costs our clients approximately $3,000 to $5,000. If gutter guard is also required, add another $3,000-$4,000.

Complying with BAL 29 requirements is likely to cost $8,000 to $10,000 including gutter guard.

Building to BAL 40 standards may set you back $10,000 to $13,000 including gutter guard.

We encourage our clients to avoid building in a flame zone, as the requirements are very thorough and very expensive – in some cases well over $50,000.

Every home is different, and every site is different, so these figures are only intended to be a guide. Compliance with BAL rating requirements will generally cost less for a smaller home and more for a larger home. It is also possible to have different BAL ratings apply to different parts of a house (BAL 29 to the rear, and BAL 19 to the sides and front, from example). If you are thinking about building in a bushfire zone, call the friendly team at Balance Design and Construction to discuss your situation.

BAL Compliant Materials

Not all building materials are suitable for use in a bushfire zone, and some are only suitable for use in low BAL rating situations. As you move up through the BAL Ratings, the number of available building products decreases.

For example, Weathertex cladding is a fantastic Australian-made product, but it is only certified for use in BAL LOW, BAL 12.5, and BAL 19 zones.

Can I Improve the Bushfire Safety of an Existing Home?

Even if you aren’t building a brand new home, there are a range of steps you can take to better protect your home against bushfire risks. The NSW Rural Fire Service recommends you consider the following steps to prepare your property:

Clean your gutters of leaves and twigs
Install metal gutter guards
Repair damaged or missing tiles on the roof
Install fine metal mesh screens on windows and doors
Fit seals around doors and windows to eliminate gaps
Enclose the areas under the house
Repair or cover gaps in external walls
Attach a fire sprinkler system to gutters
Keep lawns short and gardens well maintained
Cut back trees and shrubs overhanging buildings
Clean up fallen leaves, twigs and debris around the property
Have hoses long enough to reach around your house
If you have a pool, tank or dam, put a Static Water Supply (SWS) sign on your property entrance, so firefighters know where they can get water
Check and maintain adequate levels of home and contents insurance. Ensure it is up to date

You may also wish to contact a bushfire consultant, who can help you draw up a specific and detailed plan to improve the bushfire safety of your existing home.

How about Asset Protection Zones?

BAL rated properties are often also protected by an Asset Protection Zone.

An Asset Protection Zone (APZ) is a fuel reduced area surrounding a home or other structure. An Asset Protection Zone will be located between the building and a bush fire hazard. An APZ may be registered on the title of a block of land as a positive covenant, which means it cannot just be ignored or removed without following a specific legal procedure.

An APZ provides:

a buffer zone between a bush fire hazard and an asset;
an area of reduced bush fire fuel that allows suppression of fire;
an area from which backburning may be conducted; and
an area which allows emergency services access and provides a relatively safe area for firefighters and home owners to defend their property.

Asset Protection Zones are significant, because we are not permitted to build a house (or other habitable dwelling) within that zone. If you are considering a block of land that is affected by an Asset Protection Zone, contact us to explore the potential of the land, and ask your solicitor to double check all the applicable sections in your land contract.

An Asset Protection Zone does not mean that a block is unusable. An APZ may be used as a yard or garden, and with approval, you may be able to construct a pool, barbeque shelter or pergola, shed, carport, or other non-combustible and non-habitable structure.