- Replacement roofs are over-represented regarding wind damage
- Investigation reveals inadequate tie-downs and absent building permits
- Building and Energy has published a re-roofing guide for home owners
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:
- Ensure a building permit is in place (unless an exemption applies) and the plans and supporting structures are documented in detail.
- Use competent and suitably qualified and experienced people, such as a structural engineer and/or a registered builder, who can check the existing roof structure and any proposed upgrades as well as drainage and water protection. The roof covering should be installed in accordance with the manufacturer's instructions and applicable building standards.
- Check the company has appropriate insurances and positive impartial reviews.
- Get a written quote that details all the work (for example, if the price includes straightening out the roof members before replacing the cover) and remember that a maximum 6.5 per cent deposit applies to building contracts of $7,500 or more.
- See the Building and Energy website (dmirs.wa.gov.au) for further advice on engaging a roof restorer or roofing contractor.
