I was asked recently about issues relating to building in bush fire prone areas. Although I have written about this previously, given the time of the year, and as this is a subject that is related to recent posts relating to planning matters, it seemed quite an appropriate subject for further discussion.
At first glance it can seem quite extraordinary that it is only in the last 10–20 years that serious consideration of bush fire protection has been included in planning legislation. But if we recall from our earlier discussion that legislation specifically directed at environmental aspects of planning was only introduced in NSW with the Environmental Planning and Assessment Act (EP&A Act) in 1979, it’s a little less so. The expansion of urban areas into bushland, and ‘tree change’ migration to life style blocks in rural areas such as ours, of course, has brought the issue into focus, as needs exceed those that can be satisfied with generally available fire fighting resources.
The best place to start for anyone interested in the relevant building requirements is the NSW Rural Fire Service (RFS) document Planning for Bush Fire Protection (PBP). At this point it should be noted that, while the 2006 version (PBP 2006) is the legally referenced document at this time, it is expected that PBP 2018, which is currently available for reference, will come into force in mid-2019 with the enactment of the updated Building Code of Australia (BCA) (part of the National Construction Code (NCC 2019)).
For building purposes, bushfire risk in any location is identified in terms of a Bush fire Attack Level (BAL), given as a measurement of the associated radiant heat flux in kW/m2. BAL ratings are identified in steps, from BAL-LOW (no specific building requirements) through BAL-12.5, BAL-19, BAL-29 and BAL-40, identifying measures that must be undertaken to protect from the associated radiant heat flux of 12.5, 19, 29 or 40 kW/m2 respectively, to BAL-FZ, for structures in a ‘Flame Zone’. As might be expected, protection measures increase with increasing BAL.
PBP provides the necessary background information relating to these requirements (PBP 2018 has been extensively expanded in this regard and as such is a much better reference than PBP 2006) and a comprehensive, step-by-step guide to assist in assessing the BAL at a given site. It also includes details for the establishment of an Asset Protection Zone (APZ) with reference to clearing practices identified under the 10/50 Vegetation Clearing Scheme.
The actual building requirements under a particular BAL, as noted in the BCA, are articulated in Australian Standard AS3959 – 2018, for timber framed dwellings, or the National Association for Steel Framed Housing NASH Standard for Steel Framed Construction in Bushfire Areas (2014).
Most of the documents referenced above are free, and while Standards documents are typically quite expensive, free copies are out there (just Google “AS3959”, but note that at this time there have been three Amendments to the 2009 document). NASH documents must also generally be purchased.
There’s a lot of information to assimilate in there, and it can be a challenge to bring existing, and particularly older structures into compliance (although there is no regulatory requirement to do so). Solutions are, nonetheless, available and it is really a case of informed management of the risks associated with any given situation.
Pete Harrison ~ The QPR Blog cross-reference
28 January 2019 @ 17:58
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