Site Assessment Methodology
The following methodology is to be followed when determining the required Asset Protection Zones (APZ) and construction standards for a development on bush fire prone land. This methodology is also outlined in Planning for Bush Fire Protection 2006 (PBP). Alternatively, the assessment tools can be used.
For the purposes of complying development, the level of Bush Fire Risk (or BAL) is derived using the methodology for determining the construction standard.
Determining Asset Protection Zones (APZ)
The following procedure is to be adopted when assessing a development to determine the appropriate APZ width:
Step 1: Determine vegetation formations, as follows:
- Identify all vegetation in all directions from the site for a distance of 140 metres:
- Consult Table A2.1 of PBP to determine the predominant vegetation type; and
- Select the predominant vegetation formation as described in Table A2.1 of PBP.
Step 2: Determine the effective slope of the land under the predominant vegetation class and the site (slope classes are detailed on page 56 of PBP).
Step 3: Determine the appropriate fire (weather) area in Table A2.3 of PBP and note the relevant FDI.
Step 4: Consult Tables A2.4–2.7 of PBP and determine the appropriate APZ for the assessed land use, vegetation group and slope range.
Determining Construction Standards
The following procedure is to be adopted when assessing a development to determine the level of bush fire attack and corresponding construction standard. This methodology is also used to determine the bush fire risk for the purposes of complying development:
Step 1: Determine vegetation formation types and sub-formations around the building (see Appendix 2), as follows:
- Identify all the vegetation types within 140 metres of the site using Keith (2004);
- Classify the vegetation formations as set out in Table A2.1 in Appendix 2 of PBP:
- Select the predominant vegetation formation as described in Table A2.1 of PBP; and
- Convert vegetation classification (Keith) to Specht classifications using Table A3.5.1 in Addendum Appendix 3
Step 2: Determine the distance between each vegetation formation identified (from the edge of the foliage cover) and the building.
Step 3: Determine the effective slope of the ground for each vegetation group (see Appendix 2 of PBP) using the classes provided below. Slopes are classified as follows:
- Upslopes are considered to be 0º.
- From 0º but not greater than 5º.
- Greater than 5º but not greater than 10º.
- Greater than 10º but not greater than 15º.
- Greater than 15º but not greater than 20º.
Step 4: Determine the relevant FDI for the council area in which the development is to take place from Table A2.3 in Appendix 2. For Alpine Resorts see Step 5 below.
Step 5: Match the relevant FDI, appropriate vegetation, distance and effective slope classes to determine the bush fire attack levels using the relevant tables of AS3959-2009 as indicated below:
- FDI 100 – Table 2.4.2
- FDI 80 – Table 2.4.3
- FDI 50 – Table 2.4.4
Apply the relevant attack category to each facade.
|A development can not be considered 'complying development' where the Bush Fire Risk is certified as being BAL-40 or BAL-FZ.|
|An Alternative Solution will be required if the building exceeds the specification of BAL-40 of AS3959-2009 (i.e>40kW/m2) in which case it is considered to be within the 'Flame Zone'. NSW has made a State based variation to the BCA. This variation excludes BAL-FZ as a deemed-to-satisfy solution.|
Note: A building with any facade identified as requiring a construction level must build all facades to at least BAL-12.5. Where more than one facade is exposed to a hazard, then the facade with the highest construction requirement is used to determine the appropriate level of construction. All other facades may be reduced by one level of construction unless that facade is also subject to the same bush fire attack level.