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BAL ratings for planning to change

May 12, 2019

Assessments completed under bushfire planning policies in WA must be assessed in accordance with AS3939 – Construction of Buildings in Bushfire Prone Areas as referenced in the current version of the National Construction Code (NCC).

From 1 May 2019, the current NCC references AS3959:2018. Therefore all BAL assessments completed for planning purposes must be carried out in accordance with the 2018 version of the standard.

Limited exceptions exist under State Planning Policy 3.7 where the site assessment and development of the BAL assessment/contour map occurred prior to 1 May, 2019. No exemptions exist under the Planning and Development (Local Planning Schemes) Regulations 2015 and assessments may need to be repeated.

The difference in assessment processes include:

  • The removal of low trees and shrubs from the Woodland classification – see comparison of image B – 05 from the various standards to GROUP G Grass land. See ‘Fig 2.4(A) Classification of Vegetation – Summary’
  • Clarification that, “In assessing vegetation classes for forests, woodlands and rainforests, the classified vegetation will be determined by the unmanaged understorey rather than either the canopy (drip line) or the trunk of any trees.” See 'Figure 2.2 example of varying slope ranges for assessment’ in AS3959-2018 for additional details.
  • The notes to figure 2.1 relating to the measuring distance between fuel and house has been amended. The 2018 version has removed the reference to small decks and landing under 1m as an exemption to the measurement distance. Therefore a small concrete pad or landing on the side of the house is now the point to measure from.

A summary of the changes to AS3959 can be found in HIA’s information sheet.

Due to the transition period available for the NCC requirements for a building approval, members should take care in using the BAL rating completed for planning. If NCC2016 is used for the building approval, a performance solution supporting the use of AS3959:2018 for purposes of the BAL assessment will need to be developed.

Contact wa_technical@hia.com.au if you have any queries.