Appendix F - bushfire attack level assessment report · MCU25/0022

7.2      Asset Protection Zones and Landscaping




Figure 11. Components of an Asset Protection Zone (APZ)

Asset protection zones provide the most strategically valuable defense against radiant heat and flame, and to
a lesser extent embers. The relationship between radiant heat level and distance is not linear, as shown in
Figure 9. The function of the Inner Protection Area (IPA) is to distance the Asset from Flame and Radiant
Heat. The Outer Protection Area (OPA) separates ground fuels from canopy fuels, causing canopy fires to
collapse and become ground fires.

A minimum of 25m downslope of the dwelling shall be constructed and maintained as IPA.

The IPA should be maintained as free as possible of available fuel, through short mowing of grass and
removal of fine flammable debris. Plants retained in or introduced into the IPA should be selected based on
low combustibility, by virtue of high moisture content, low volatile oil content, high leaf mineral levels, large
fleshy leaves, absence of shedding bark. Plant arrangement is just as important as low combustibility. Plants
should be placed so as to not provide either vertical or horizontal connectedness of plant material. Appendix
1 provides examples of less hazardous plant species. Combustible vegetation shall not be allowed to come
into contact with combustible parts of buildings. Trees shall not be allowed to directly overhang roof lines.

The OPA should be maintained with low and minimal ground fuels, free of understorey or mid storey, and
with separation of around 2 - 5m between tree canopies.

In this instance the APZ for the structures shall be maintained as IPA.




Report compiled by Bushfire Risk Reducers for Mr A. Wittaker, February 2023                  Page 18