The use of appropriate timber in residential construction is an important consideration in bushfire prone areas, according to Archicentre Australia.
With various bushfire risk categories and many species of timber from which to choose, it is a complex area for design consideration whether constructing a new residence or making additions to an existing home, the national architect’s advisory service says, which makes it important to seek professional advice.
For medium, high and extreme categories of bushfire attack, the National Constriction Code (NCC) and Australian Standard 3959 set out levels of acceptable construction.
Archicentre Australia director Peter Georgiev says, “Non-combustible materials are generally acceptable, with the use of timber restricted to certain fire tested species, which is testing for architects let alone for home renovators or para-professionals.”
For floors timber is acceptable in most categories, however if the floor is not enclosed, or for homes in the extreme category, it must be sheeted underneath with non-flammable material or constructed using fire-retardant treated timber. Species of timber that generally accord with the criteria include Blackbutt, Spotted Gum, Merbau (imported rainforest timber), Turpentine, Red Ironbark, Red River Gum and Silver Top Ash.
Peter Georgiev warns that ‘treated timber’ does not have any fire-retardant value and, in fact, fumes from burnt treated timber could be toxic.
External doors must have weather strips or draught excluders and tight fitting metal flyscreens. In the high risk category, aluminium mesh cannot be used and leadlight windows must be protected by non-combustible shutters or toughened glass. In the extreme category, timber doors must be fire-retardant treated, have a non-combustible covering, be protected by non-combustible shutters or be solid core doors at least 35mm thick.
For the medium risk category fascias may be timber but for the high risk category, fire-retardant treated must be used.
There must be a separation between decking timbers and the rest of the house to prevent the spread of fire into the building.
Archicentre Australia has prepared a Bushfire Design Guide, which can be viewed here.
For more information go to www.archicentreaustralia.com.au
This media release has been written and distributed by:
Peter Georgiev, Director
Level 1, 9 Strathalbyn Street,
Kew East, VICTORIA, 3102
Phone: 1300 13 45 13 | 03 9859 9950