Insurers warn building flaws will leave homes at risk of cyclone damage

Insurers are demanding stronger regulations to protect homes against cyclones, as engineers warn the tin-and-timber houses popular in southeast Queensland and northern NSW are at high risk from Cyclone Alfred.

Janet Roussounis in her home destroyed by flooding in Ipswich in 2011. Picture: Adam Smith

You can now listen to The Australian's articles. Give us your feedback.

You can now listen to The Australian's articles.

Insurers are demanding stronger building regulations to protect homes against cyclones, as engineers warn the tin-and-timber houses popular in southeast Queensland and northern NSW are at high risk from Cyclone Alfred.

The Insurance Council of Australia called on federal, state and territory governments to mandate “resilience’’ in the national construction code so that houses are “built to last a lifetime’’.

“Currently, minimum building standards in Australia are designed to preserve life in catastrophic event, but they are not designed with the goal of also preserving the property itself,’’ an ICA spokesman said. “Currently (houses) cannot withstand the worsening extreme weather events of today, let alone the future.

“As cyclones increase in intensity, and possibly track further southward, the concept of resilience needs to be embedded in our building codes and standards to ensure a home can maintain its function following a severe ­weather event.’’

Modern design trends of open-plan and indoor-outdoor living with large windows and floor-to-ceiling glass, combined with lightweight construction materials such as polystyrene bricks, make homes more vulnerable to storm damage.

Brisbane City Council prohibits the demolition of houses built ­before World War II, so many inner suburbs are dominated by tin-and-timber homes with fragile casement windows.

Engineers Australia spokesman Geoff Boughton, who heads its cyclone working group, said that houses built since the mid-1980s should withstand the wind speeds of Cyclone Alfred.

“Older homes weren’t necessarily built to resist those wind loads,’’ he said.

Associate Professor Broughton said houses in Queensland’s southeast were more vulnerable to damage from flying debris than homes built in northern Australia.

“The problem is the cyclone picks up things like garden furniture, toys, trampolines, garden sheds and tree branches, and they become cyclone debris that can break glass and damage cladding,’’ he said. “In southeast Queensland, buildings haven’t been designed to survive debris attack.’’

Once wind enters through smashed windows or cracks in a house, Associate Professor Boughton said, “the wind forces tend to tug away at the building and rip the roof off’’.

Residents survey the damage at Helensvale caused by wild weather on Christmas night in 2023.

The ICA made similar warnings in 2013, when it warned that Australia’s housing was “exposed to high levels of risk due to poor land-use planning, inappropriate construction standards and development controls’’.

In 2021, it warned that older homes may need to be retrofitted to withstand wild weather.

Homes in northern Australia must include stronger window glass, cyclone screens over windows, stronger walls and door hinges, stronger roof fastenings and garage doors with wind locks so they don’t blow in. The chief ­engineer at the cyclone testing station at James Cook University, David Henderson, said buildings in Queensland’s south were designed for a lower wind speed than those in the north.

He said buildings in the south were designated “wind region B” in the national construction code, which was less than “wind ­region C” for the cyclonic region further north.

Although wind region B buildings were designed to withstand a category 3 cyclone with winds of between 180km and 200km/h, Dr Henderson said there were other issues that made them more ­vulnerable.

“If a window blows in or the door breaks, that positive pressure enters the building space, greatly increasing the load on that structure,” he said.

“Whereas wind region C buildings are designed to withstand that pressure, a sudden increase in internal pressure (in wind region B buildings) can push the strength of our buildings a bit closer to their limits.”

He said residents could help protect their homes by keeping doors, windows, screens and shutters closed, and removing anything in outdoor areas that could be picked up by strong winds.

Smaller rooms such as bathrooms or hallways tended to be the safest place to seek shelter, and Dr Henderson advised keeping blankets and mattresses close by.

He said buildings “with a view” would have a lot more wind coming at them, because gales could potentially speed up through hills.

“If you’re in a built-up area, you might be a bit more shielded, but there could perhaps be more debris flying at you as well as trees and other bits of stuff from houses that are falling apart,” Dr Henderson said. “It’s really important to seek shelter in your home, and not just stand in front of a window filming the world go by.”