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Following several cases where replacement roofs have dangerously lifted off in WA, the State’s building regulator is warning that suitable supports and expertise are essential when changing a roof cover to a different material.
Building and Energy has published a handy guide for home owners on re-roofing after an investigation report found that replacement roofs, often made of a different material to the original, were over-represented in damage from storms and cyclones.
As part of its monitoring of building standards, Building and Energy worked with James Cook University’s Cyclone Testing Station to consider cases of wind damage to re-roofed buildings in cyclonic and non-cyclonic regions in WA over the past 15 years.
Building and Energy Executive Director Saj Abdoolakhan said the General Inspection Report revealed common patterns among the damaged properties, including re-roofing work without the required building permits or licences and inadequate tie-downs to secure the replacement roof to the house.
“The loss of a roof could cause serious injury or death to people sheltering inside or hit by wind-borne debris,” Mr Abdoolakhan said.
“There have been many close calls in WA, including metal sheets and large steel or timber beams propelled up to 100 metres over houses, power lines and trees before becoming embedded into the ground, fences or other buildings.
“Events like Tropical Cyclone Seroja highlight why changing a roof covering from one material to another requires careful planning and expert knowledge to ensure a lighter roof doesn’t lift off during a wind event.
“Even if a like-for-like material is being used, the roof supports may have sagged or deteriorated over time.
“Replacing a roof covering with a different shape or weight will usually require a building permit and the work will need to be carried out by a registered builder, but our report found this was lacking.”
When considering houses and other buildings that lost roofs during storms in the Perth metropolitan area, the report found about half of them involved lightweight metal sheet cladding that had replaced the original heavy tile or asbestos cladding on the roof.
In all regions, the study found that modified roofs were damaged even when winds did not exceed speeds that building standards require them to withstand.
“This shows the importance of having the existing roof structure and design upgrades checked by a structural engineer or registered builder, which had not been done in many of these cases,” Mr Abdoolakhan said.
Building and Energy has used the report as a springboard for increasing awareness about re-roofing for the building industry, local government permit authorities and the community. Key advice for home owners includes:
Media contact: BEmedia@dmirs.wa.gov.au
Link to guide – Changing your roof cover: things you need to know https://www.commerce.wa.gov.au/publications/changing-your-roof-cover-things-you-need-know
Link to report – General Inspection (Investigation) Report Five: Investigation into the re-roofing of buildings: https://www.commerce.wa.gov.au/publications/general-inspection-report-five-investigation-re-roofing-buildings
Photo caption: Building and Energy Senior Technical Officer Justin McAullay inspects damage to a South Perth home after the roof lifted off.
Additional high-resolution images are available.