Australia has different climate zones due to its vast geographical size. During the warmer months of the year, residents located in the northern part of the country experience a tropical climate. During these humid and dry seasons, bushfire incidents highly occur which causes property damage and even loss of human life at its worst.
Because of these tragic incidents, the government issued Australian Standard 3959 for construction of homes in bushfire prone zones. However, a later version of AS3959:2009 has been released last April 8, 2016. Under this new standard all projected buildings require the builder or landowner to undergo a BAL Assessment.
What is BAL?
A Bushfire Attack Level (BAL) is a means of measuring the severity of a building’s potential exposure to ember attack, radiant heat and direct flame contact. It’s measured in increments of radiant heat (expressed in kilowatts/m2).
BAL is also the basis for establishing the requirements for construction (under the Australian Standard 3959-2009 Construction of Buildings in Bushfire Prone Areas).
BAL Rating is used to identify measures to improve performance of buildings when subjected to bushfire attack.
6 Bushfire Attack Levels
BAL – Low: The risk is considered to be low. There is insufficient risk to warrant specific construction requirements.
BAL – 12.5: The risk is considered to be low but there is a risk of ember attack.
BAL – 19: The risk is moderate. There is a risk of ember attack and burning debris ignited by wind-borne embers and a likelihood of exposure to radiant heat.
BAL – 29: The risk is considered to be high. The construction elements are expected to be exposed to a heat flux not greater than 29kW/m2.
BAL – 40: The risk is very high. Increasing levels of ember attack and burning debris ignited by wind-borne embers, together with increasing heat flux and with the increased likelihood of exposure to flames. The construction elements are expected to be exposed to a heat flux not greater than 40kW/m2.
BAL – Flame Zone: The risk is considered extreme. Direct exposure to flames from fire, in addition to heat flux and ember attack.
Who can assess Bushfire Attack Levels?
There are ways you can follow to assess your own BAL, but keep in mind that the result will be an indication only and will still require approval from a building surveyor. Take appropriate steps needed to ensure your project is 100% compliant. Make sure you’ve got the experts at conducting BAL Assessment Reports and fully recognised by national accrediting bodies.