Dry spell causes subsidence

Houses across the country are cracking up because of this summer's heatwave, surveyors warned today.

Prolonged high temperatures and a lack of rain are causing subsidence in houses around London and the South-East, says the Royal Institution of Chartered Surveyors.

Holidaymakers are returning home to find fissures in the plaster and brickwork that were not there when they left.

RICS spokesman John Sparkes said houses built before 1970 - particularly Edwardian and Victorian homes - have shallower foundations than more modern buildings and are most at risk of cracks.

Average temperatures in the South-East hit a peak in August of 100.6F (38.1C) with only 1.2mm of rain recorded at Heathrow airport in the past four weeks. Weather experts say it could be the second warmest August in 100 years.

"We, like the insurance companies, are expecting to see a rise in subsidence because of the heatwave," Mr Sparkes said.

"The sustained hot weather causes loss of water from the subsoil and it shrinks, which can lead to subsidence. It can also arise when the hot spell breaks and rain makes the soil expand, which makes buildings move and crack."

Surveyors warn that cracks of 3mm and over are serious, particularly if they pass through brickwork or stone, and need immediate attention.

However, Richard Driscoll, technical director of the Building Research Establishment, urged people not to panic. He said the heatwave may have caused cracks but we should not be too concerned.

"I do not believe there is enough evidence to show that we have had a serious problem with subsidence this summer," he said. "It would be a different story if we had had two dry summers with a dry winter between them, but we started from a position where the ground was fully saturated.