Months after a tornado destroyed homes and businesses in Western Australia's biggest regional city, researchers say some of the houses worst affected were not built well enough to withstand tornado-level winds.
The finding has prompted calls for long-awaited state government reforms to be fast-tracked to make WA houses safer.
Lots of roofs were lost during wild weather in Bunbury in 2024. (ABC South West WA: Jacqueline Lynch)
Two major storms, including a tornado, swept through Bunbury earlier in the year, tearing roofs off houses and sending debris flying across the city.
Some residents are still repairing the damage.
A study from James Cook University's Cyclone Testing Station found some of hit by winds of up to 180 kilometres per hour had previously had their tile roofs replaced with sheet metal and that not enough had been done to secure the roofs in place.
Steve Wallace has had his roof replaced with extra tie-downs to help it withstand stronger winds. (ABC South West WA: Jacqueline Lynch)
It was a lesson Steve Wallace learnt the hard way.
He was inside his home in southern Bunbury during the tornado when there was "a hell of a roar" and the roof lifted off.
"We've had … mini-tornadoes go through and just rip up the middle of the street, but they didn't affect any houses and we never ever thought about it," Mr Wallace said.
"But this one was just a little bit bigger and different."
Steve Wallace was inside his Bunbury house when a tornado ripped the roof off in May. (ABC South West WA: Jacqueline Lynch)
Mr Wallace, a carpenter, added tin to his roof during a home extension in 2008.
He said he carried out the work in accordance with the standards at the time but ultimately the structure was not enough to withstand the unexpected wind.
"I think it was because there was some pine timbers that were put in to marry the house into the new garage," he said.
"I think that it wasn't quite strong enough — it would have needed a lot more tie-downs on it to hold it down."
The National Construction Code outlines the necessity for tie-downs – used to secure a roof – in all homes in WA, but the requirements are stricter in cyclone-prone northern coastal areas such as the Pilbara and Kimberley.
Mr Wallace said he had builders install extra tie-downs after the storm. (ABC South West WA: Jacqueline Lynch)
A common problem
The Cyclone Testing Station research in the wake of the recent wild weather in Bunbury found evidence of "inadequate" tie-downs in at least four houses impacted by the storms.
Structural engineer and researcher Geoff Boughton said it was an issue that kept cropping up after major storms in Western Australia.
"We investigated lots of different storm events," he said.
"We have investigated others in Bunbury, some in Mandurah, some in Perth, and each case we see roofs with tiles that have been replaced by sheet roofs without strengthening the tie-down system, and the roof disappears."
Mr Boughton said because sheet roofs were lighter than tile roofs they were more likely to fly off unless they were tied down correctly.
Geoff Boughton says he frequently sees roofs not build to standard in WA cities affected by extreme weather. (ABC News: Tyne Logan)
A WA Department of Mines, Industry, Regulation and Safety (DMIRS) study in 2021 reported about half of lost roofs investigated after storms in the Perth area had been re-roofed.
Mr Boughton urged people to get building approval from their local councils ahead of making any structural changes to their house, including re-roofing.
The City of Bunbury said for building permits to be approved, the work needed to comply with the National Construction Code and be signed off by a structural engineer.
It said it was providing building information and support to residents impacted by the storms.
An investigation into buildings that lost roofs in Perth found about half of them had been re-roofed in the years leading up to the storm. (Supplied: WA Department of Mines, Industry, Regulation and Safety)
What's the solution?
The state government has been working to bring in changes outlined in the 2018 Building Confidence Report to crack down on builders doing the wrong thing and improve safety in WA homes.
It is set to roll out mandatory inspections for apartment builds from 2026.
The inspections are likely to become a requirement for all residential building in years to come but no timeline has been set.
The WA government is set to implement mandatory building inspections for apartments from 2026. (ABC News)
South West builder Rob Maratea said he would like to see mandatory inspections for all new homes and renovations brought in as soon as possible.
"I don't think any of us intentionally would tie a roof down incorrectly but having a second eye over or an inspection at a key point would definitely help," he said
"Tie-downs are missed or not even thought about a lot of the time … so if we do have an inspection at that point, that's great.
"The sooner this can be implemented the better not just for builders but consumers who are building new homes so they can sleep when a storm comes through."
The tornado in May devastated some prorties in Bunbury. (ABC South West WA: Anthony Pancia)
WA Master Builders Association director of housing and construction Jason Robertson also backed a wider rollout of inspections.
He said he would also like to see compulsory and regular training for builders fast-tracked.
Mr Robertson said mandatory inspections were "not the sole answer".
"The Building Confidence Report recommended that every jurisdiction requires registered building practitioners to undertake some form of continuing professional development on the National Construction Code," he said.
"What that will do is allow practitioners and contractors to better interpret and apply all the requirements of the construction code."
The state government has vowed to bring in compulsory personal development for building surveyors next year and says it will consider extending the initiative to builders following the rollout.