Bushfire Attack Level Ratings and Bushfire-Prone Land

A bushfire attack level is a rating that sets the construction standard a building has to meet on land mapped as bushfire-prone. It is not a warning label. It is a number that changes what the walls, windows, roof, subfloor and decking are made of, how much cleared ground has to sit between the building and the vegetation, and in several states whether the development can proceed at all in the form proposed. For a developer, the rating lands in three places at once: the cost plan, the developable area, and the approval pathway.

Before considering a site on bushfire-prone land, you’ll need professional advice from an accredited bushfire consultant and a town planner. The consultant determines the rating and prepares the assessment or management plan the consent authority relies on. The planner works out whether the resulting setbacks, access and water requirements still leave the scheme you priced. The consequences fall on you rather than on them: a site bought at a yield that assumed forty lots may only carry thirty once the buffers are drawn inside the boundary, and a product priced at one construction standard may be conditioned to a higher one. This guide is written to make that conversation sharper, and the questions worth putting to each adviser are set out near the end.

Figures, mapping and policy references here were current at the date of writing and they move. Bushfire-prone area maps in particular are revised on a cycle, and a site that sat outside the mapping last year can sit inside it this year. Each linked primary source is where to confirm the current position before relying on it.

What is a bushfire attack level, and what does the rating control?

A bushfire attack level measures how severely a building is likely to be exposed to a bushfire, and that measure drives the construction requirements in the National Construction Code. The NSW Rural Fire Service describes it as a measure of the severity of a building’s potential exposure to ember attack, radiant heat and direct flame contact, used to determine construction requirements for buildings in bush fire prone areas under the National Construction Code.

The rating comes from Australian Standard AS 3959, Construction of buildings in bushfire-prone areas, published by Standards Australia. The current edition is AS 3959:2018, incorporating Amendment Nos 1 and 2. It is referenced in both volumes of the National Construction Code as the deemed-to-satisfy pathway for building in a bushfire-prone area, which is the mechanism by which a Standard you have to buy becomes a rule you have to follow.

There are six levels. CSIRO’s published summary of the assessment sets out the radiant heat bands each one covers.

The NSW Rural Fire Service puts the same ladder in plainer terms: at BAL-12.5 the “risk is primarily from potential embers during a fire”, BAL-40 is “very high risk” and “likely to be impacted by embers, debris, heat and potentially flames”, and BAL-FZ is “extreme risk” and “directly exposed to the flames of a potential fire front”.

The levels are not evenly spaced in cost or in consequence, and that tends to matter more than the ladder itself. The step from BAL-LOW to BAL-12.5 is largely screening and sealing. The step from BAL-29 to BAL-40 introduces flame contact. At BAL-FZ the building is assumed to be engulfed, which is generally where a conventional residential product stops working and a performance-based fire engineering solution starts. That is a different consultant, a different programme and a different number.

How is a bushfire attack level determined?

The rating is calculated rather than assigned by inspection. AS 3959 sets out two routes, and the one used on most sites is the simplified procedure, often called Method 1. Geoscience Australia’s description of the method breaks it into five steps: establish the Fire Danger Index for the jurisdiction, classify the vegetation, measure the distance from the site to that vegetation, determine the effective slope of the land under the vegetation, and read the resulting level off the Standard’s tables.

Each input is worth understanding, because each is a lever or, in one case, conspicuously not one.

Fire Danger Index. Set by jurisdiction and region from a lookup table, and Geoscience Australia notes it ranges from 40 to 100 depending on location. It is fixed for the site. Nothing a designer does changes it.

Vegetation classification. AS 3959 works from major vegetation types including forest, woodland, shrubland, scrub, mallee or mulga, rainforest and grassland. Forest produces the harshest outcome and grassland the mildest. Classification is a judgement at the margins, and two competent assessors can reach different answers on the same patch of ground, which is one reason the assessment may be worth commissioning yourself rather than accepting a vendor’s version.

Separation distance. CSIRO notes the distance to the classified vegetation is measured in the horizontal plane. This tends to be the largest lever available to a designer, and it is the one that consumes land.

Effective slope. The slope under the vegetation relative to the building, not the slope of the building platform. Downslope increases exposure because fire runs uphill. Geoscience Australia notes the simplified method is not valid where the downslope exceeds 20 degrees, which is the point at which a site moves to the detailed procedure or to a performance solution.

The second route, the detailed procedure, calculates radiant heat flux directly rather than reading a table. It generally produces a more precise and more defensible answer on a difficult site and costs more to prepare. On a constrained site where the difference between BAL-29 and BAL-40 decides whether the product works, the extra fee may be small against what it could save.

Who may do the work is regulated in some states. In Western Australia, accreditation runs through the Fire Protection Association Australia Bushfire Planning and Design scheme, and the Western Australian Planning Commission publishes the qualifications for each level: a Level 1 assessor completes a five-day bushfire attack level short course, while Level 2 and Level 3 practitioners hold a diploma or a postgraduate qualification in bushfire protection or bushfire planning. Other states do not always mandate accreditation in the same way, but consent authorities tend to expect it.

What does each bushfire attack level require you to build?

Each step up the scale adds material substitution, sealing and screening, and the requirements compound rather than replace one another. The Shire of Denmark’s published summary of the BAL-29 requirements gives a workable picture of what a mid-range rating means on site:

• Subfloor. Where unenclosed, naturally fire-resistant timber or non-combustible bearers and joists where 400mm or closer to the ground.
• External walls. Non-combustible material such as masonry, brick veneer, mud brick, aerated concrete or concrete, or timber or steel framed walls sarked on the outside and clad with 6mm fibre cement sheeting.
• Windows. Completely screened with steel, bronze or aluminium mesh or 5mm toughened glass, metal or bushfire-resisting timber frames, and the portion within 400mm of ground level screened.
• Doors. 6mm toughened safety glass, metal or bushfire-resisting timber frames, weather strips at the base, and the lower 400mm non-combustible or bushfire-resisting timber.
• Roof. Non-combustible covering, roof and wall junction sealed, openings and penetrations fitted with non-combustible ember guards, fully sarked.
• Eaves, fascia and barge. Eaves lined in 4.5mm fibre cement sheeting, metal fascia and barge fixed at 450mm centres.
• Decking. Non-combustible or bushfire-resisting within 300mm horizontally and 400mm vertically of a glazed element.
• Services. Exposed water or gas pipes in metal.

That list reads as a procurement problem more than a design problem. Most of it is substitution: a cheaper cladding becomes a dearer one, standard glazing becomes toughened, timber decking within a zone becomes a non-combustible product, and every penetration needs an ember guard. Nothing there is exotic at BAL-29. At BAL-40 the glazing and shutter requirements tighten, and at BAL-FZ the assumption of flame contact generally pushes the solution towards fire-rated systems and bespoke engineering.

Some states add requirements that sit outside the building fabric altogether. In South Australia, Ministerial Building Standard 008, Additional requirements in designated bushfire prone areas, adds non-combustible water tanks in steel, metal or concrete, a firefighting water supply and equipment, vegetation clearance within 100 metres of the development, and access provisions for emergency vehicles, as the South Australian Government’s building guidance sets out. None of that shows up in a construction rate per square metre.

Where does the rating land in the cost plan?

It lands in the fabric trades first and the site works second, and the honest answer on quantum is that it depends on the product, the form and how much of the building is affected. There is no published government schedule of cost uplift by bushfire attack level, and the figures circulating online come from suppliers and builders rather than from anything worth resting a feasibility on. The quantity surveyor’s cost plan, priced against the actual rating and the actual specification, is where the number comes from. A rate carried across from a project that was not bushfire-affected is not a starting point, it is a source of error.

What can be said with more confidence is where the money goes and how the exposure behaves.

The uplift concentrates in the building envelope. Walls, glazing, roofing, eaves, subfloor, decking and every screened opening. A single-storey detached house with a large facade area and a lot of glass tends to carry proportionally more uplift than a compact two-storey form with the same floor area, because it is the envelope that gets treated. On an attached townhouse product, only the exposed faces attract it.

The rating is not uniform across a site. AS 3959 allows different elevations of the same building to be assessed at different levels where exposure differs. A row of lots backing onto a reserve can carry a high rating on the rear elevation and BAL-LOW on the street frontage. A cost plan that applies the worst-case rating to the whole building across the whole estate will be wrong, and wrong in the expensive direction. Getting elevation-by-elevation ratings into the cost plan early is one of the few places where a modest consultant fee tends to pay for itself.

The step changes are lumpy. Because the requirements compound, the marginal cost of moving from BAL-12.5 to BAL-19 is not the marginal cost of moving from BAL-29 to BAL-40. A site sitting on the boundary between two levels may be worth the detailed assessment method, because a single metre of extra separation can move the whole product down a level. Our guide to construction cost per square metre in Australia covers why a benchmark rate needs rebuilding rather than adjusting when the specification changes this much.

There is also a timing exposure worth carrying explicitly. Where the rating is determined at development application stage and confirmed again at construction certificate or building permit stage, vegetation can change in between, and so can the mapping. A rating assessed while a neighbouring block was cleared, on land that has since regrown, is the common version of this trap.

How much developable area does the buffer take?

Enough to change the yield, and on a subdivision the buffer is usually the binding constraint rather than the construction standard. An asset protection zone, called defendable space in Victoria, is a fuel-reduced buffer between the hazard and the building, and the width required is a function of vegetation type, slope and the applicable fire danger rating.

The critical rule for a developer is containment. Newcastle City Council’s development control plan states the position the way most consent authorities state it: bush fire protection measures, including an asset protection zone and fuel management zones, are to be placed wholly within the development site. You cannot borrow the neighbour’s paddock and you cannot assume a council reserve stays clear. That plan also records that fire trails cannot be placed on existing council-owned land, and that asset protection zones must not conflict with environmental protection areas, which is where bushfire and biodiversity constraints collide on the same strip of ground.

Containment is what turns a rating into a yield number. The buffer is measured from the building to the classified vegetation, so on a site with a vegetated boundary it eats the rear of every lot along that edge. Depending on vegetation and slope that can be a few metres or many tens of metres. On a rectangular site with vegetation on one boundary it removes a strip. On a site with vegetation on three sides it can remove the middle of the scheme.

The scale of that is worth putting in numbers. The figures below are illustrative and chosen to show the mechanism rather than to describe any site. Take a 2 hectare site, 20,000 square metres gross, with classified vegetation running along one 140 metre boundary. Assume roads, drainage and reserves take 30 per cent, leaving 14,000 square metres of net developable area, which at an average lot of 450 square metres is about 31 lots. Now contain a 30 metre asset protection zone inside the title along that boundary. The strip is 140 by 30 metres, or 4,200 square metres, so net developable area falls to 9,800 square metres and the yield to about 21 lots.

Ten lots, roughly a third of the scheme, from a buffer that does not appear on a title plan and does not change the construction standard for a single dwelling. Two qualifications matter on a real site. Some of the strip may be recoverable where it coincides with a road reserve, a drainage reserve or deep soil that was coming out of the developable area anyway, so the loss is the buffer area net of what the layout was already giving up. And the width is a function of vegetation class, slope and fire danger rating rather than a standard figure, so 30 metres is an input to test with the consultant rather than a default.

The interactions worth testing before pricing the land include:

• Net developable area. The buffer reduces it, and unlike a drainage reserve it does not always produce a public asset to hand over. The land is still yours, still rated, and still not saleable as a lot.
• Lot depth and product fit. A buffer that takes eight metres off the rear of a lot may leave a lot too shallow for the product you priced, which is a redesign rather than a discount.
• Staging. Newcastle’s plan notes that staged subdivisions have to demonstrate how temporary protection measures are managed and released as future stages proceed. A stage relying on a future stage’s cleared land for its buffer creates a sequencing dependency, and sequencing dependencies cost money.
• Ongoing management. The buffer has to stay fuel-reduced. On a community title or owners corporation product that becomes a continuing obligation someone has to fund, and it belongs in the disclosure material rather than in a surprise later.

Where the buffer materially reduces yield, whether the scheme is still the highest and best use of the site becomes a real question rather than a rhetorical one.

Which rules apply in each state and territory?

The construction Standard is national. Almost everything around it is not. The mapping, the planning trigger, the referral authority and the point at which a rating has to be locked down all vary.

New South Wales

Bush fire prone land maps are prepared by local councils and certified by the Commissioner of the NSW Rural Fire Service under section 10.3 of the Environmental Planning and Assessment Act 1979. The NSW Rural Fire Service states the designation should also be noted on the section 10.7 planning certificate for the property, which makes that certificate the first place a purchaser is likely to see it. Our guide to section 10.7 certificates covers what else the document does and does not disclose at acquisition.

The mapping works from three vegetation categories. The NSW Government’s published dataset description sets out Category 1 as forest, woodlands, heaths, forested wetlands and timber plantations; Category 2 as rainforests and lower-risk vegetation parcels; and Category 3 as grasslands, freshwater wetlands, semi-arid woodlands, alpine complex and arid shrublands. Buffers of 100 metres apply to Category 1 vegetation and 30 metres to Categories 2 and 3. The buffer is itself part of the mapped land, which is why a site carrying no vegetation of its own can still be caught.

The assessment standard is Planning for Bush Fire Protection 2019, which the NSW Department of Planning records as having replaced the 2006 edition from 1 March 2020. A bush fire safety authority under section 100B of the Rural Fires Act 1997 must be obtained from the NSW Rural Fire Service for subdivision and for special fire protection purpose development, which captures schools, hospitals, aged care and similar uses. The Development Coordination Authority is now the single point of contact for state agency referrals in development assessment, though the NSW Rural Fire Service notes that the bush fire safety authority remains a function of the Commissioner under section 100B.

The hardest edge in New South Wales is the complying development restriction. Clause 1.19A(1)(a) of the State Environmental Planning Policy (Exempt and Complying Development Codes) 2008 (NSW) provides that “the development must not be carried out on land in bush fire attack level-40 (BAL-40) or the flame zone (BAL-FZ)”. The restriction applies across the codes other than the Housing Alterations Code, with carve-outs in clause 1.19A(2) covering matters such as non-habitable detached structures more than six metres from a dwelling, landscaped areas, non-combustible fences and swimming pools. If a fast-track pathway is load-bearing in the programme, a BAL-40 rating does not slow that pathway down, it removes it.

Victoria

Victoria runs two layers and they are easy to conflate. The designated bushfire prone area is a building control. The Minister designates it under section 192A of the Building Act 1993, and Planning Victoria confirms that where part of a building footprint falls within the area, the whole building must meet the requirements. CSIRO’s summary of the Victorian regulations records that the minimum standard you can build to inside a designated bushfire prone area is BAL-12.5, so there is a floor even on a site with modest exposure.

The Bushfire Management Overlay is the planning control, and Planning Victoria describes it as applying to bushfire-prone areas with very high and extreme bushfire hazard. Land in the overlay is automatically within the designated bushfire prone area, but not the reverse. The Country Fire Authority is a referral authority under section 55 of the Planning and Environment Act 1987 for development and subdivision in the overlay.

Within the overlay the pathway depends on the proposal. Planning Victoria’s guidance describes single dwellings in existing settlements being assessed under clause 53.02-3, non-habitable outbuildings under clause 53.02-5, and other development and subdivision under clause 53.02-4, with clause 44.06 as the overlay itself. Most applications call for a bushfire hazard site assessment covering 150 metres from the site, a bushfire hazard landscape assessment considering a much wider area, a bushfire management statement and a bushfire management plan.

The developer-specific lever in Victoria is the mapping review. Planning Victoria runs the designated bushfire prone area review twice a year, each cycle taking around six months, and states that developers and councils identify areas for review where development is happening and the bushfire hazard has been removed. Individual property owners cannot request a review. Each cycle runs an open review period, then site visits, then consultation to conclusion, with the resulting mapping changes taking effect across a batch of councils at the end. On a large estate where earlier stages have removed the hazard, getting later stages out of the mapping could be a real saving, and it runs on a calendar the delivery programme has to accommodate. That timing interacts with the staging and titling sequence covered in our guide to subdivision in Victoria.

Queensland

Queensland has adopted AS 3959:2018 for construction in bushfire-prone areas, according to the Queensland Government’s published guidance, which records that position as updated on 26 February 2024. Designation works differently from the southern states: the same guidance describes a designated bushfire prone area as land declared by local governments as likely to be subjected to bushfires, so the mapping sits in the local planning scheme rather than in a single state layer, and the bushfire hazard overlay code in the relevant scheme carries the planning requirements.

The published state guidance applies the construction requirements to new homes, outbuildings of any construction type, rebuilding, repairs to sections of a building, and additions within six metres of a dwelling. That six metre rule catches a good deal of minor work on established sites and is worth checking on refurbishment or staged delivery.

South Australia

South Australia’s Planning and Design Code currently carries four bushfire overlays: Hazards (bushfire, general risk), Hazards (bushfire, medium risk), Hazards (bushfire, high risk), and Hazards (bushfire, urban interface), which the state guidance describes as applying within 500 metres of high-risk areas. Construction requirements sit in Ministerial Building Standard 008, and the Country Fire Service acts as a statutory referral body with a published response timeframe of 30 business days for residential development under Schedule 9 of the Planning Regulations. Thirty business days is roughly six weeks, and on a tight programme it is a real path item rather than a formality.

South Australia is also the jurisdiction most likely to change under a developer’s feet. The State-wide Bushfire Hazards Overlay Code Amendment proposes removing the Hazards (Bushfire, Regional) Overlay and replacing the existing high, medium and general risk overlays with a single Hazards (Bushfire) Overlay carrying three hazard levels, using updated vegetation mapping and grassfire fuel modelling in place of the 2012 mapping. PlanSA’s record of the amendment shows it was initiated on 4 February 2021 and consulted from 23 November 2023 to 5 April 2024, with determination and implementation still awaiting completion of the previous stage. On a South Australian site with a long option period or a multi-year delivery programme, the overlay applying at development application may not be the one on the map when the land is priced.

Western Australia

Western Australia rewrote its policy recently, and an assumption carried over from the previous version is likely to be wrong. State Planning Policy 3.7 Bushfire was published on 24 September 2024 and became operational on 18 November 2024. The Western Australian Planning Commission describes the new framework as outcomes-based rather than performance-principle based, allowing flexibility where the acceptable solutions cannot be achieved but the policy outcomes can still be demonstrated, and introducing a broader landscape assessment that looks past the immediate 150 metre assessment area.

Designation of bushfire prone areas sits with the Fire and Emergency Services Commissioner under section 18P of the Fire and Emergency Services Act 1998, with the Office of Bushfire Risk Management maintaining the map. The Department of Fire and Emergency Services records the current version as coming into effect on 13 December 2025, with a four month transition period applying to newly designated areas. On a site that has just been mapped in, that transition period is a genuine planning window.

On whether BAL-40 and BAL-FZ development is possible at all, the Commission’s published material indicates the policy does not impose a universal BAL-29 ceiling, and provides pathways in higher-risk areas where lots were created before the 2015 policy, where environmental or site constraints exist, or in exceptional circumstances, with up to three residential lots able to be created within BAL-40 and above areas in lower-risk urban zones. That is a narrow door, and it is one that requires a Level 3 practitioner. Where vegetation modification can bring a site to BAL-29 or lower within the lot boundaries, a Level 2 practitioner may prepare the assessment instead.

Published council guidance in Western Australia also sets out currency periods that catch long programmes. The City of Busselton’s information sheet states that a bushfire attack level assessment is valid for 12 months from the date of issue and a bushfire management plan for 24 months. Where the development application, subdivision approval and building permit are separated by more than that, the assessment gets redone, and the vegetation may have moved in the interval.

Tasmania

Tasmania splits the work between the planning and building systems, and the split is unusual enough to catch out interstate developers. The Tasmanian planning guidance states that most building work is not considered under the Bushfire-Prone Areas Code, with impacts on building work mainly considered through the building system, and that the Code manages only defined hazardous and vulnerable uses and subdivision. Code C13.0 of the Tasmanian Planning Scheme is the relevant provision, and bushfire planning hazard maps accompany the building system under the Building Act 2016. Construction requirements sit with Consumer Building and Occupational Services through the Director’s Determination for building in bushfire-prone areas.

The practical consequence is that a subdivision in Tasmania attracts the full planning treatment while an individual dwelling largely does not, so the burden sits at the front of the project rather than spread across it.

Australian Capital Territory and Northern Territory

Both territories designate bushfire-prone land and apply AS 3959 through the National Construction Code in broadly the same way as the states, so the shape of the exercise holds: mapping check, then rating, then construction standard, then buffer. The detail sits with the territory authorities, and the mapping status and applicable construction requirements for a specific site are worth confirming with them directly, because neither territory’s requirements are set out in the national material.

New Zealand

New Zealand has no direct equivalent to the bushfire attack level system. There is no national wildfire construction standard sitting in the Building Code the way AS 3959 sits in the National Construction Code, and no statutory bushfire-prone area mapping layer of the kind the Australian states maintain. Wildfire risk at the rural and urban interface tends to be handled, where it is handled at all, through district plan provisions and the consenting process rather than through a construction rating. A New Zealand project on a vegetated interface site should expect the question to arrive as a district plan and consenting matter, council by council, rather than as a building standard. The broader framework is covered in our guide to resource consent in New Zealand.

Can a rating be improved, and what are the levers?

It can, and the levers are geometric before they are anything else. A bushfire attack level is a function of what is growing near the building, how far away it is and which way the ground falls. Each of those can sometimes be changed, and each change carries its own approval and its own cost.

Separation distance. Moving the building further from the classified vegetation is the most direct lever and the most expensive in land terms. On a subdivision it is the buffer, and the buffer is yield.

Vegetation modification. Removing or managing vegetation within the lot changes the classification or the distance. Western Australia contemplates this explicitly in the split between Level 2 and Level 3 practitioners. The constraint is that vegetation removal usually needs its own approval, and where the vegetation is protected the two approvals point in opposite directions. This is the collision Newcastle City Council’s plan anticipates when it requires that asset protection zones not conflict with environmental protection areas.

Siting and orientation. Because AS 3959 allows different elevations to be assessed separately, turning the building or shifting the footprint can reduce the area of expensive facade. Across a detached estate, a handful of plan types oriented to the hazard may be materially cheaper to deliver than one type rotated arbitrarily.

Assessment method. Moving from the simplified procedure to the detailed procedure can produce a lower rating where the table-based method is conservative. Geoscience Australia notes the simplified method is not valid where the effective downslope exceeds 20 degrees, so on steep ground the detailed method is not an optimisation, it is the only route.

Mapping review. Where development has itself removed the hazard, the mapping can catch up. Victoria’s twice-yearly review is the clearest published example, and it is open to developers and councils rather than to individual owners.

Performance solution. Where the deemed-to-satisfy pathway through AS 3959 cannot deliver the scheme, a performance solution under the National Construction Code, prepared by a fire engineer, is the alternative. It is slower, it costs more, and it depends on the consent authority and the certifier accepting it, so it belongs in the programme as a risk rather than as a plan.

What does this mean at due diligence?

Treat the rating as an acquisition question rather than a design question. The mapping is public and an indicative assessment is cheap relative to the site. Three things are worth resolving before an option lapses or a contract goes unconditional: whether the land is mapped, what rating the intended product would attract, and how much area the buffer takes.

A workable sequence on any site with a vegetated interface:

1. Check the mapping. In New South Wales, the section 10.7 certificate and the council’s bush fire prone land map. In Victoria, the designated bushfire prone area and whether the Bushfire Management Overlay applies. In Western Australia, the Office of Bushfire Risk Management map. In Queensland and South Australia, the relevant planning scheme or Code overlay. Remember the buffers: in New South Wales the 100 metres from Category 1 vegetation and 30 metres from Categories 2 and 3 are part of the mapped land, so an unvegetated site next to a reserve is still in.
2. Get an indicative rating early. A desktop assessment from an accredited practitioner before exchange is cheap against the risk of discovering the product does not work. Ask for it elevation by elevation, not as one site-wide number.
3. Draw the buffer on the plan. Inside the boundary, with environmental constraints overlaid. This is where a yield assumption survives or dies.
4. Check the approval pathway. In New South Wales, whether clause 1.19A takes complying development off the table and whether a bush fire safety authority is required. In Victoria, whether the overlay triggers a Country Fire Authority referral. In South Australia, whether the Country Fire Service referral timeframe sits inside the programme.
5. Price it properly. Not a rate per square metre with an allowance, but a cost plan against the actual specification for the actual rating on the actual elevations.
6. Check currency. Assessment validity periods, mapping review cycles and pending policy changes such as the South Australian overlay amendment all mean a rating obtained early may need refreshing before it is relied on.

The town planner’s scope should name the bushfire pathway explicitly rather than leave it to implication, and our guide to town planner fees covers how that scope is usually structured and where the gaps appear.

What to ask your bushfire consultant

These are the questions that decide the number on a specific site, and they are the ones this guide deliberately does not answer.

• What rating does each elevation attract under the current mapping, and what would each attract under the detailed procedure rather than the simplified one?
• What vegetation classification have you applied, and is there a defensible alternative classification that produces a different result?
• What effective slope have you used, and where did the levels come from?
• How wide is the asset protection zone or defendable space required, and does it fit entirely within the site boundary at the proposed density?
• Which parts of the buffer depend on vegetation removal that needs its own approval, and what is the status of that pathway?
• If the neighbouring vegetation regrows or the adjoining land changes use, does the rating change, and at what point is it locked in for approval purposes?
• How long is this assessment current, and what triggers a reassessment before building approval?
• Is a performance solution likely to be needed, and if so what is the realistic programme and what is the acceptance risk with this consent authority?

What to ask your town planner

• Does the mapping or overlay status remove any fast-track or code assessment pathway for this product?
• Which referrals are triggered, what are their statutory timeframes, and do those timeframes sit inside the programme we have priced?
• Is the site eligible for a mapping review, and if so when is the next cycle and what evidence would it need?
• Where do the bushfire buffer and any biodiversity, riparian or heritage constraint overlap, and which one prevails?
• On a staged subdivision, how do the protection measures for early stages get released as later stages proceed, and what does that do to the titling sequence?
• What ongoing vegetation management obligation will be imposed on the completed development, who carries it, and how is it documented?

What to ask your quantity surveyor

• What is the cost uplift for this specification at this rating, built up from the actual elements rather than adjusted from a benchmark rate?
• How much of the uplift sits in the envelope, and how would it change under an alternative building form or orientation?
• What does the buffer cost to establish and to maintain through the delivery period, and where does that sit in the cash flow?
• What allowance is appropriate for a rating that moves up one level between development application and construction certificate or building permit?

The short version

A bushfire attack level is one of the few site constraints that hits cost, yield and approval pathway simultaneously, and it is one of the cheapest to test before you are committed. The mapping is free to check, an indicative rating costs a fraction of a due diligence budget, and the buffer can be drawn on a concept plan in an afternoon. Sites get bought on yields that the buffer was never subtracted from, and that is a modelling failure rather than a bushfire one.