Building on bushfire prone land in Wollondilly: BAL, PBP 2019, AS 3959

If your Wollondilly block at Wilton, Picton, Tahmoor, Thirlmere, Bargo or Buxton is mapped as bush fire prone land, a house DA must be assessed against Planning for Bush Fire Protection 2019 under section 4.14 of the Environmental Planning and Assessment Act 1979, the house must be built to the Bushfire Attack Level (BAL) set by that assessment using AS 3959:2018 as called up by the National Construction Code, and the DA is assessed by Wollondilly Shire Council under Wollondilly Local Environmental Plan 2011 and Wollondilly Development Control Plan 2016. For an owner builder the sequence matters: the bush fire assessment report fixes the asset protection zone, the BAL and often the position of the house before the plans are drawn, and the BAL then drives the construction specification, the window and door schedule and the cost. Complying development is only available up to BAL-29; at BAL-40 and BAL-FZ a DA is required.

Who this is for: owner builders with an owner-builder permit, or planning to obtain one, who are building a house on a bush fire prone lot in Wollondilly and need to understand the assessment, the BAL and the order in which the reports, the DA and the construction certificate come together.

How do I know if my Wollondilly block is bush fire prone?

Bush fire prone land is defined by the map, not by what you can see from the driveway. Under section 10.3 of the EP&A Act each council prepares a Bush Fire Prone Land Map in consultation with the NSW Rural Fire Service, the Commissioner certifies it and it is reviewed on a five year cycle. Wollondilly Shire Council’s fact sheet explains that the map records vegetation hazard, including most vegetated areas and the buffer land around them, and that a new development or an alteration or addition that needs a DA on mapped land must consider bush fire and meet the requirements of Planning for Bush Fire Protection and AS 3959. The council’s map was recertified by the RFS Commissioner in 2023, so lots that were not mapped under the earlier map may now be.

Three ways to check: the bush fire prone land item on a section 10.7(2) planning certificate, the RFS online bush fire prone land tool, and the Hazard layers on the NSW Planning Portal Spatial Viewer. The 10.7 certificate is the document council relies on. The common mistake is to assume a block in a newer Wilton estate is clear because the vegetation was cleared for the subdivision; the buffer around the retained bushland corridors often still catches the rear lots.

What does Planning for Bush Fire Protection 2019 require for a single house?

Section 4.14 of the EP&A Act states that before granting consent for development on bush fire prone land the consent authority must consider the relevant bush fire protection planning guide, which is PBP 2019, adopted under the EP&A Regulation from 1 March 2020. PBP 2019 is a performance based document: Chapter 5 deals with subdivision, Chapter 7 with residential infill, which covers a single dwelling on an existing lot, and Chapters 6 and 8 with other development. Each chapter sets performance criteria and acceptable solutions for the bush fire protection measures: asset protection zones, construction standard, access, water supply, landscaping and, for larger developments, emergency management.

For a house in Wollondilly the four measures translate as follows. The asset protection zone is the managed, low fuel area between the house and the hazard, sized from the tables in Appendix 1 of PBP 2019 for the vegetation formation, the effective slope and the fire danger index that applies to the Wollondilly area; it must sit within the lot or on land that will be managed, and in a new subdivision Volume 3 of the Wollondilly DCP requires it to be outside environmentally sensitive land. The construction standard is the BAL, which sets the AS 3959:2018 construction requirements. Access requires the driveway and the road to allow firefighting vehicles to reach the house and residents to leave, and in rural areas PBP 2019 section 3.4.3 notes the difficulties with long property access roads. Water supply for a house without reticulated mains requires a dedicated static water supply and fittings to the PBP 2019 tables, which is common on the larger lots at Bargo, Buxton and Yanderra.

PBP 2019 also draws the line on the approval pathway: complying development is not permitted on higher risk bush fire prone land at BAL-40 or BAL-FZ, and a DA is required in those cases. At BAL-29 and below a complying development certificate under the Housing Code may be available if every other standard is met and the certifier is satisfied on the bush fire requirements.

How is the BAL assessed?

The BAL is a measure of the severity of the house’s potential exposure to ember attack, radiant heat and direct flame contact. There are six levels: BAL-LOW, BAL-12.5, BAL-19, BAL-29, BAL-40 and BAL-FZ (flame zone). The number is the radiant heat in kilowatts per square metre that the construction is designed to resist. The assessment uses four inputs: the vegetation formation within 100 metres of the house (forest, woodland, heath, grassland and so on, classified using the Keith vegetation formations), the effective slope of the land under that vegetation (upslope and flat, or downslope in degree bands), the distance from the building to the vegetation across the asset protection zone, and the fire danger index applying to the region. PBP 2019 and the RFS Single Dwelling Application Kit provide tables that read off the BAL from vegetation, slope and distance; AS 3959:2018 contains the equivalent method and the construction requirements for each level.

The RFS Single Dwelling Application Kit is written for exactly the situation most Wollondilly owner builders are in: a new house, or an alteration or addition, on existing land with a dwelling entitlement where no new roads or hydrants are needed. The kit steps through the bush fire assessment report that must accompany the DA and applies up to BAL-29. Where the assessment returns BAL-40 or BAL-FZ, where the proposal increases density (a dual occupancy or secondary dwelling), or where the site is complicated by steep downslopes or multiple vegetation types, a consultant bush fire assessment report is needed. Not every council accepts the self-assessed kit, so confirm with Wollondilly before relying on it.

What do Wollondilly LEP 2011 and DCP 2016 add?

Wollondilly LEP 2011 controls permissibility and the local provisions. Dwelling houses are permitted with consent in the residential zones and, subject to clause 4.2A, on rural and conservation land; clause 4.2A (erection of dwelling houses on land in certain residential, rural and conservation zones) sets out when a dwelling can be approved on RU1, RU2, RU4, R5, C3 and C4 land, and a lot that fails it cannot carry a house regardless of bush fire. Clause 7.1 (essential services) prevents consent unless water, electricity and sewage disposal are available or arranged, which on unsewered lots means an on-site wastewater system whose land application area cannot overlap the asset protection zone. Clause 7.5 (earthworks) requires consent for earthworks that are not exempt or ancillary and lists the matters council considers, which matters on the sloping lots around Picton and Thirlmere where the APZ and the house pad both involve cut. Clause 4.1(5) sets a 975 square metre minimum for subdivision of unsewered R2 and R3 land, and clause 4.1C sets 800 square metres for an attached dual occupancy and 975 square metres for a detached one (each with a 1,400 square metre maximum) in R2, R3 and MU1.

Wollondilly DCP 2016 is published in eight volumes. Volume 1 General carries the definitions and general requirements, Volume 3 Subdivision of Land requires bushfire management plans in named release areas and locates asset protection zones outside environmentally sensitive land, and Volume 4 Residential Development carries the house controls: a 4.5 metre ground floor front setback on lots under 450 square metres and 6 metres on lots of 450 square metres or more, side and rear setbacks by lot type, and a site coverage scale from 60 per cent on small lots to 50 per cent on standard residential lots of 700 to 1,500 square metres and 40 per cent on large residential lots. Volume 4 also requires two storey houses to read as single storey or with a recessive upper level under its Option A and Option B tests. Confirm the current volume on council’s website, as the DCP has been amended since the 2020 consolidation and a comprehensive review has been exhibited.

Wilton is the exception to note. The Wilton growth area is governed by State precinct provisions and its own DCP requirements rather than the general Wollondilly DCP volumes, and the bush fire mapping and APZ arrangements were set at subdivision stage; a house DA there still needs a BAL assessment, but the APZ is usually already fixed by the estate’s bush fire management plan.

What does the BAL mean for the National Construction Code and the build?

NCC 2022 Volume Two applies to a Class 1a house and its Class 10a garage. Part H7 (ancillary provisions and additional construction requirements) contains the bush fire provisions for houses in designated bush fire prone areas, and the deemed-to-satisfy solution is compliance with AS 3959:2018 (with the NASH standard for steel framed construction as an alternative), as varied in NSW. In other words, once the DA fixes the BAL, the construction certificate drawings and specification must demonstrate AS 3959:2018 compliance for that BAL, element by element: subfloor, external walls, windows, doors, roof, gutters, verandahs and decks, and water and gas services. The certifier will check this at the construction certificate stage, not at the DA.

For an owner builder the practical points are these. The BAL changes the window and door schedule (toughened glass and screens at BAL-29, shutters or fire rated assemblies at BAL-40 and FZ), the cladding (non-combustible above BAL-19 in many elements), the roof (sarking, sealed ridges, ember guards) and the decks (non-combustible or bush fire resisting timber). The NCC’s Housing Provisions Part 3 (site preparation) and the drainage and footing parts still apply, and a consent condition will require the APZ to be established before occupation and maintained thereafter.

The owner builder sequence on a Wollondilly bush fire lot

1. Check the bush fire prone land status on a section 10.7 certificate and the RFS tool, and check clause 4.2A dwelling entitlement if the lot is rural or conservation zoned.
2. Commission or prepare the bush fire assessment report: vegetation classification, effective slope, APZ distances from PBP 2019 Appendix 1 and the resulting BAL. Use the Single Dwelling Application Kit only if the outcome is BAL-29 or below and council accepts it.
3. Site the house so the APZ, the on-site wastewater land application area (clause 7.1) and the driveway all fit inside the lot without clearing protected vegetation, and keep cut and fill within what clause 7.5 and the DCP allow.
4. Design to Wollondilly DCP 2016 Volume 4 setbacks, site coverage and two storey tests, and check the water supply and access acceptable solutions in PBP 2019 Chapter 7 for lots without mains water.
5. Decide the pathway: a DA to council for BAL-40 or FZ, for any variation or for rural land; a CDC under the Housing Code only where BAL-29 or below and every other standard is met.
6. Lodge the DA with the bush fire assessment report, the Statement of Environmental Effects, the site analysis and the wastewater report where relevant; expect council to condition the BAL, the APZ and the water supply.
7. Obtain the owner-builder permit for the construction certificate, have the plans and specification detailed to AS 3959:2018 for the conditioned BAL, and establish the APZ before the occupation certificate inspection.

Definitions

Bush fire prone land

Land recorded on a Bush Fire Prone Land Map certified by the Commissioner of the NSW Rural Fire Service under section 10.3 of the EP&A Act.

Bushfire Attack Level (BAL)

A measure of a building’s potential exposure to ember attack, radiant heat and flame contact, in six levels from BAL-LOW to BAL-FZ, used to select construction under AS 3959:2018.

Asset protection zone (APZ)

A managed, fuel reduced buffer between a building and the bush fire hazard, sized from the PBP 2019 tables by vegetation, slope and fire danger index.

Planning for Bush Fire Protection 2019 (PBP 2019)

The NSW RFS guide that the consent authority must consider under section 4.14 of the EP&A Act, setting performance criteria and acceptable solutions for development on bush fire prone land.

AS 3959:2018

The Australian Standard for construction of buildings in bushfire prone areas, referenced by the National Construction Code as a deemed-to-satisfy solution and setting the construction requirements for each BAL.

Bush fire safety authority

The authority issued by the NSW RFS under section 100B of the Rural Fires Act 1997 for subdivision of bush fire prone land and special fire protection purpose developments; not required for a single dwelling on an existing lot.

URBA prepares Statements of Environmental Effects for owner builders on bush fire prone land across Wollondilly and the Southern Highlands, coordinating the bush fire assessment, the wastewater report and the site analysis so that PBP 2019, clause 7.1 and the DCP are addressed together. See our Statement of Environmental Effects service and our Wollondilly town planning page, or request a fee proposal for your lot.