Building In Bushfire-Prone Areas: How A Builder In Forster Works With Your BAL Rating

Planning a new home near bushland involves more than choosing a floor plan. Your bushfire attack level, or BAL rating, can influence where the house sits, which materials you use and how much construction costs. Working with a builder in Forster early gives you time to understand these requirements and explore options that suit your block and budget.

What Is a BAL Rating?

A BAL rating describes the severity of a building’s potential exposure to embers, radiant heat and direct flame contact during a bushfire. It helps determine the construction measures needed for the proposed home. It does not predict when a fire will occur or guarantee that a building will survive one.

There are six BAL categories:

• BAL–LOW: Exposure is low enough that AS 3959 does not specify additional bushfire construction measures
• BAL–12.5: Ember protection is required, with radiant heat exposure up to 12.5 kilowatts per square metre
• BAL–19: Ember attack and increasing radiant heat exposure require additional protection
• BAL–29: Higher radiant heat exposure requires more demanding construction measures
• BAL–40: Very high radiant heat exposure and potential flame contact affect construction requirements
• BAL–FZ: Flame Zone involves extreme radiant heat exposure and a significantly greater likelihood of flame contact



The rating relates to the proposed building’s exposure. Homes on neighbouring blocks can have different ratings because their positions, surrounding vegetation and terrain differ.

How Is Your BAL Rating Assessed?

A site assessment examines the bushfire hazards around the proposed building. Bushfire-prone land mapping identifies land where bushfire planning requirements need consideration, but it does not establish the BAL for your house.

The assessment considers several factors:

• Vegetation classification: The type of surrounding vegetation, such as forest, woodland or grassland
• Separation distance: The distance between the proposed building and classified vegetation
• Effective slope: The slope beneath the vegetation that most influences potential fire behaviour
• Regional fire weather: The fire weather assumptions required for the location under the assessment framework

For bushfire-prone land on the MidCoast, Planning for Bush Fire Protection 2019 provides the NSW assessment framework. Its BAL tables replace those in AS 3959 for NSW assessments. AS 3959 sets out construction specifications, subject to NSW variations and additional requirements.

A suitably qualified bushfire consultant can assess the proposal and prepare the supporting report. Your designer and builder then use its findings alongside the approved plans and consent conditions. Access, firefighting water supplies and landscaping also need consideration.

Confirm your BAL rating in Forster while the proposed house position and layout remain flexible. Whether you are building locally or working with a builder in Harrington, the assessment needs to address your particular site and proposed home.

How Your BAL Rating Changes the Build

The assessed rating influences how the home’s external elements resist bushfire attack. Your builder needs to carry the required specifications through the drawings, product selections and installation details.

The main construction considerations include:

• Ember screening: Relevant vents, weepholes and other openings may need suitable metal mesh or other protection. Gaps, roof junctions and external door seals also need attention
• Glazing and window frames: Requirements can affect glass thickness and type, frame materials, screening and shutters. The complete window assembly must suit the applicable construction requirements
• External cladding: Wall materials and their installation must meet the relevant provisions. A product’s appearance or general description does not establish its suitability
• Roofing: Roof coverings, junctions, penetrations and associated sealing details need to address the required protection
• Decking and subfloors: Deck surfaces, supports, stairs and exposed subfloor areas need appropriate materials and detailing

NSW applies additional provisions to some construction elements, including at lower BAL categories. Flame Zone construction also requires a performance-based compliance approach rather than simply following the AS 3959 Flame Zone specifications.

Thoughtful architectural design can incorporate these requirements while considering daylight, ventilation and outdoor living. Reviewing the specifications during design helps you understand which options suit both the proposed home and its assessed exposure.

Can Siting and Design Lower Your BAL?

Moving a proposed home further from classified vegetation may reduce its assessed exposure. Whether that changes the BAL category depends on the site and the revised assessment. A smaller adjustment will not necessarily cross the threshold into a lower category.

Options to investigate before finalising plans include:

• Repositioning the home: Testing a location with greater separation from the vegetation
• Changing the footprint: Adjusting the layout so the building fits within a less exposed part of the block
• Reviewing attached outdoor areas: Checking deck and verandah positions as part of the overall proposal
• Planning an asset protection zone: Allowing for a managed buffer between the home and the bushfire hazard



For example, a proposed house on a Green Point block might initially sit near vegetation at the rear boundary. If setbacks and other constraints allow, the designer could test a position further forward. A bushfire consultant would then determine whether the revised separation reduces the assessed BAL.

These decisions must also account for access, slope, drainage and environmental controls. Do not assume you can clear vegetation or rely on neighbouring land for the required buffer. Any asset protection zone needs appropriate approval arrangements and ongoing maintenance.

The same early planning matters when comparing bush-fringe blocks in Tuncurry or Pacific Palms. Establish what the site can accommodate before committing to a particular floor plan.

How Much Does a Higher BAL Add to Building Costs?

A higher BAL can increase construction costs, but the additional amount depends on the house design and the specifications it requires. An itemised quote provides a more useful answer than applying a general percentage to the entire build.

Potential cost changes include:

• Windows and doors: Different glazing, frames, screens or shutters
• External materials: Changes to cladding, decking and exposed building components
• Protective details: Required mesh, seals and treatments at openings or junctions
• Installation: Labour associated with fitting and documenting the selected systems



Some materials in your preferred design may already satisfy the relevant requirements. Others may need replacing or additional protection. Large glazed areas and extensive decks deserve early review because their size and specifications can influence the budget.

Ask a builder in Forster to explain:

• Which selections need changing to meet the assessed requirements
• Whether the quote includes required screening, seals and installation details
• Whether alternative layouts or compliant products could reduce costs
• How required access, water supplies and site works affect the overall price

When comparing home builders in Forster, provide the same report, drawings and specifications. Check exclusions and confirm that any later design changes are reflected in the assessment and pricing.

Plan Your Forster Build Around Your BAL

Understanding your site’s bushfire requirements early gives you time to review house placement, materials and construction costs before finalising the design. An assessment, coordinated plans and detailed pricing help you make informed decisions before building begins.

At Mid North Coast Drafting & Construction, we offer new home design and construction, drafting and development application support. As a builder in Forster, we can help you plan a home around your block, lifestyle and budget.

Bring your site details and any existing bushfire report, then get in touch to discuss your new home.

Frequently Asked Questions