Bushfire Screening
What is Bush Fire Protection? Bush fire Protection is the protection of buildings, as specified in the Australian Standard AS3959-2009 “Construction of buildings in bushfire-prone areas“, against burning embers, radiant heat or flame generated by a bushfire. The 2009 edition of AS 3959 explains Bushfire Attack Levels (BALs) as follows.
SCREENING REQUIREMENTS
BAL
DESCRIPTION
Screens for windows and doors shall
12.5
have a mesh or perforated sheet with a maximum
Aperture of 2mm made of corrosionresistant steel, bronze or aluminum. Gaps between
The perimeter of the screen assembly and the building element to which it is
SUITABLE MESH
Aluminum, Bronze or Stainless steel
BAL
DESCRIPTION
SUITABLE MESH
fitted shall not
Exceed 3mm.The frame supporting the mesh or perforated sheet shall be made from metal
or bushfire resistant timber.
BAL 19
Same as Above
BAL 29
Same as Above
Screens for windows and doors shall
BAL 40
have a mesh or perforated sheet with a maximum
Aperture of 2mm made of corrosionresistant steel or bronze. Gaps between
Aluminum, Bronze or Stainless steel
Aluminum, Bronze or Stainless steel
BAL
DESCRIPTION
The perimeter of the screen assembly and the building element to which it is fitted shall not
Exceed 3mm.The frame supporting the mesh or perforated sheet shall be made from metal.
BAL FZ
Same as Above
SUITABLE MESH
Bronze or Stainless steel
Bronze or Stainless steel
Bronze or Stainless steel
Explaining the numbers:
BAL – Low The risk is considered to be Very Low BAL – 12.5 (protection from ember attack and radiant heat up to and including 12.5kW/m²) there is a risk of ember attack. The risk is considered to be Low. BAL – 19 (protection from ember attack and radiant heat greater than 12.5kW/m² up to and including 19 kW/m²) There is a risk of ember attack and burning debris ignited by wind borne embers and a likelihood of exposure to radiant heat. The risk is considered to be Moderate.
BAL – 29 (protection from ember attack and radiant heat greater than 19 kW/m² up to and including 29 kW/m²) There is an increased risk of ember attack and burning debris ignited by windbourne embers and a likelihood of exposure to an increased level of radiant heat. The risk is considered to be High. BAL – 40 (protection from ember attack, increased likelihood of flame contact and radiant heat greater than 29kW/m² up to and including 40 kW/m²) There is a much increased risk of ember attack and burning debris ignited by windbourne embers, a likelihood of exposure to a high level of radiant heat and some likelihood of direct exposure to flames from the fire front. The risk is considered to be Very High. BAL – FZ (protection from flame contact, together with ember attack and radiant heat of more than 40 kW/m²) There is an extremely high risk of ember attack and burning debris ignited by windborne embers, and a likelihood of exposure to an extreme level of radiant heat and direct exposure to flames from the fire front. The risk is considered to be Extreme.
Source: http://ehiaustralia.com.au/bushfire-screening-2/