Early predictions of the effects of climate change in Britain suggested that severe droughts would cause houses built on clay soils to subside and walls to crack, especially those that were built before the 1960s without proper foundations.
With fissures in clay soils in the south of Britain currently large enough to swallow tennis balls, insurance companies will be braced for a host of expensive claims.
Most of London’s older housing stock is built on heavy clay and is particularly vulnerable to the heave that will be caused when the rain returns after the heatwave.
It is the uneven nature of the expansion of the clay that causes stresses on the building above and the cracks in the brickwork that follow. They may take months to develop. A slow-motion calamity unfolds as the cracks get wider, longer and more worrying.
Most insurance companies are slow to act, waiting for months to see if the house has stopped moving.
Some insurers already won’t offer cover in vulnerable areas but most policies stipulate that the householder should pay the first £1,000 of any work to remedy the situation. This will generally only be a minor part of the overall cost of an extensive and disruptive underpinning operation.