Wind-driven rain entering homes around windows and doors is a major source of cyclone damage, even when building exteriors are mostly unharmed, new insurance research shows.

James Cook University’s Cyclone Testing Station found 70% of strata property claims include damage caused by wind-driven rain, while the percentage of claims costs for which this accounted varied from 2-60%.

The study was commissioned by IAG and Suncorp.

“Water can wreak havoc in a cyclone,” Suncorp CEO Insurance Gary Dransfield said. “Past events have found that buildings appearing visibly fine disguised significant interior damage caused by wind-driven rain throughout the home.”

The study analysed strata and house claims from cyclones Marcia and Debbie, to investigate potential mitigation measures for north Queensland homes.

Videos taken by residents during Debbie showed “considerable volumes” of water coming through windows and sliding glass doors, under swing doors and through light fittings.

“The rain caused damage to vulnerable elements such as plasterboard wall linings and ceilings, floor coverings and personal belongings,” James Cook’s report says.

“In multistorey buildings the rain percolated down through the building for a number of storeys below the original point of entry.”

A wind-driven rain simulator found homeowners can keep water at bay using a strip of plastic sheet taped inside windows or sliding doors. The report calls for increased awareness of the issue in the design and construction industry, and among residents.

The insurance and window and door industries should work together to promote weather-resistant openings for cyclonic regions, it says.