Bushfire zone windows and doors

A recent community workshop helped demystify window requirements in bushfire prone areas, writes Anna Cumming. Listen to the full workshop at www.ata.org.au/bushfire.

Its communities hit by Victoria’s Black Saturday bushfires in 2009, the Strathewen & St Andrews Sustainable Rebuilding Project recently held the first in a series of workshops designed to help those rebuilding homes and businesses to do it as energy efficiently as possible.

On the topic of windows and glazed doors, the workshop covered design considerations that can have a big impact on the passive thermal performance and energy efficiency of the house, including size, orientation, frame and glazing type and shading. It also addressed the extra issues that need to be considered when building in a bushfire prone area and looked at some windows, frames and shutters rated for use in the higher Bushfire Attack Level (BAL) zones.

Here’s an overview of the workshop’s main points on glazing in high BAL zones below. Listen to the full, highly informative presentations on the ATA website at www.ata.org.au/bushfire.

BAL zones
A home site’s Bushfire Attack Level (BAL) is determined by a number of factors including the area’s Fire Danger Index (a measure of the probability of a fire starting), the type of vegetation and its distance from the house, and the slope of the land. The recently introduced new building regulations impose more stringent requirements on design and materials as the site’s BAL increases; for the top two levels, BAL-40 and BAL-FZ (Flame Zone), these are aimed at protecting the house from ember attack, a fairly to very high likelihood of direct flame contact and radiant heat up to 40 kilowatts per square metre (for BAL-40) or even hotter.

Requirements for windows in high BAL zones
The requirements for lower BAL zones specify various combinations of frame material, toughened glass or double glazing, and steel or bronze mesh screens to openable windows to prevent ember attack. In BAL-40 and BAL-FZ zones, however, the requirements are stricter.

Read the full article in ReNew 118

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