If you live in Victoria, or are planning to move to and build in Victoria the Black Saturday fires of February 7th 2009 aren’t far from your thoughts. Historically Victoria has been extremely prone to wildfire and bushfire having the highest Fire Danger Index rating of all the Australian states. Most of Victoria has a Fire Index Rating of 100 while the alpine regions have a rating of 50, in contrast, the Fire Index Rating of Queensland and the Northern Territory is only 50. There are many “Black Days” that mar the history of Victoria, as such special precautions must be taken to live in this environment.
To understand the danger of a bushfire you can compare the amount of energy released during the recent 2009 fires was equivalent to 1,500 Hiroshima sized nuclear devices. Over 2,000 homes were destroyed, around half a million hectares of earth scorched, and over 170 human lives claimed by the fast moving flames. (of these 113 died in their homes, 6 died in a garage, and one poor bloke in a shed) All of this damage (not including medical services provided to burn injuries and other injuries resultant of the flames) equates to $4.4 billion. The lesson of all this is don’t become a victim
Due to the fires, building codes in Victoria have become stricter to protect people and properties being developed in the wildfire prone areas. AS 3959-2009 was endorsed by the Australian Building Codes Board (ABCB) and enacted in response to the result of the black Saturday fires, this code provides guidelines for building homes and other structures in brushfire prone areas.
An easier to follow guideline that will help people wishing to build new homes or structures, and those retrofitting their homes to comply, have the Bushfire Attack Level (BAL) system to use. These range from BAL-LOW which has almost no risk of brushfire, to BAL-FZ which will have direct contact by the flames of a brushfire.
As a rule of thumb when building a structure (a medium sized home) in accordance to the BAL, expect to spend $1,000 for every BAL unit; for a BAL-29 expect to spend roughly an extra $29,000 to protect your home. BAL is a calculated risk assessment depending on the surrounding environment around your home. This includes the kind of vegetation around the home and the slope of the ground around it. This is done by a trained surveyor or contractor, who must be consulted before putting up any major construction in a new site.
- BAL-LOW – Virtually no risk to brushfire
- BAL-12.5 – Slight risk of Ember Attack
- BAL-19 – Moderate risk of ember attack and windswept burning debris with a heat flux between 12.5 and 19 kWm2
- BAL-29 – Elevated Risk of ember attack and burning debris together with a heat flux between 19 and 29 kWm2
- BAL-40 Extremely high risk of ember attack and prone to contact with flames with a heat flux between 29 and 40 kWm2
- BAL-FZ Direct exposure to flames is highly likely to eminent.
Homes will need to be designed and built with materials designed and tested to withstand the conditions that may be placed on it according to the BAL level. These are considered the lowest acceptable values by the government and therefore it may be a good idea to build your home to a higher BAL rating than necessary, just to make sure.
When Building a home in a BAL-FZ area there are many design requirements that you will need to follow as you are in an extremely high risk area to direct contact with brushfires. The following should be considered essential additions to any structure to be built in a BAL-FZ rated area.
- Dedicated fire fighting water supply and necessary equipment with at least 22,000 litres of water.
- Gaps between the interior floor and the ground are sealed so that embers and burning debris cannot set the structure alight.
- The structures must be situated at least 20 metres away from any vegetation.
- You must also supply the property with proper entry and exit roads that are designed to handle emergency vehicles such as fire trucks.
- The whole exterior of the structure must be built to BAL-FZ standards, from the foundation to the roof.
Any questions at all please call David on the Flashings Hotline
0422 590 552
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