From the Sydney Morning Herald news website...
October 27, 2008 - 6:23PM
Many of Sydney's roofs are inadequate to cope with major hailstorms, such as the devastating downpour in the city's west last summer, a study shows.
Professor Alan Jeary from the University of Western Sydney said Australian building codes did not acknowledge the terrible impact of hail, despite Sydney suffering six severe storms in the past 20 years.
The storms have cost billions of dollars in damages, including about $2 billion in a 1999 storm which pummelled parts of Sydney.
Damage of more than $400 million was recorded in the Blacktown area after a violent storm last summer, which led to 58,000 insurance claims.
"The current wind codes in Australia require buildings to withstand a one in 1,000 year wind storm, yet preliminary data analysis suggests the devastating hailstorm in Blacktown last December could happen as often as every 10 to 15 years," said Prof Jeary, from the university's school of engineering.
The study found hail was a recurrent problem in Sydney, with stones between 30-40mm in diameter falling every five years.
Hailstones of 40-50mm, which can crack old slate and other tiles, happen every 10 years.
Hail of 60-75mm, which can break new concrete and terracotta tiles, was recorded every 20 years, the study found.
Prof Jeary said there had not been sufficient historical data kept on hail storms to properly assess the risk of hail damage.
He said new building standards should be drawn up to ensure tiling was more resilient to hail.
"It is extraordinary to contemplate replacing a roof potentially every 10 years because of hail damage," he said.
