Claims set to go through the roof as the ground shifts beneath us

As the sun blazed last week, the odds against a blistering summer with temperatures topping 2003's UK record of 101.3F (38.5C) were chopped from 5-1 to 4-1.

As the sun blazed last week, the odds against a blistering summer with temperatures topping 2003's UK record of 101.3F (38.5C) were chopped from 5-1 to 4-1.

But that news might not go down as well with homeowners as it does with sun worshippers, for sizzling heat can quickly dry out the soil beneath bricks and mortar.

This isn't usually too much of a problem if plenty of rain has fallen during the previous winter and spring. But without enough moisture in the ground, hot temperatures increase the risk of subsidence as soil crumbles and weakens foundations. Meanwhile, tree and plant roots lengthen in search of water and destabilise the ground further.

And ominously, rainfall last winter was at its lowest since 1975, says the Met Office.

Homeowners may remember the long hot summer of 2003, when 54,100 subsidence claims were made for damage worth £390m. Although last year's figure fell back to 37,200 claims - much closer to the long-term industry average - there are now fears that the dry months since January could lead to higher numbers again this year.

Some 3.7 million homeowners live in areas susceptible to subsidence, reports insurer More Th>n, which uses a risk- mapping system to price premiums for properties according to their location.

"All homeowners should check that their building insurance provides adequate cover in case of subsidence," warns Neil Curling of Halifax Home Insurance. "If you're concerned about newly sticking doors or windows with cracks developing, then contact [your] insurer immediately.

"The sooner the problem can be investigated, the sooner it can be resolved."

Not all cracks indicate a problem; they are common, in particular, in new homes and extensions.

But if the cracks are thicker than the edge of a 10p coin and wider at the top, or appear around doors and windows, then get them checked out.

To protect your home, don't plant trees and shrubs less than eight metres away and prune existing ones regularly. Trees are implicated in 70 per cent of reports of subsidence on clay soil, as a mature deciduous tree can draw up to 50,000 litres of water a year from surrounding soil.

"It's vital that homeowners take this risk seriously and do their research either before they plant trees near their home, or before they buy a property. If in doubt, seek the advice of a landscape gardener," says Mark Winlow, a spokesman for Zurich Insurance.

Subsidence isn't caused just by hot weather. It can also be brought on by leaky drains, excess ground water, mining and coastal erosion. In particular, damaged drains can cause the ground to soften, so clear gutters regularly.

Most incidents of subsidence can be addressed - for instance, by cutting down the trees that caused the damage, and repairing cracks - with minimal disruption. But in rare and more severe cases, your home could need underpinning with cement poured into the foundations to stop further movement.

Most buildings insurance policies include standard subsidence cover with an excess of £1,000 per claim. In high-risk areas, however, homeowners might be faced with an excess of £2,500. So if you're thinking of moving to one of these locations, you might need to save up the cash.

Make sure you check for exclusions, though. Damage to gardens, patios and driveways is normally covered only if they are damaged at the same time - and by the same cause - as the house.

You should also check for warning signs before you buy a new home, though only a full structural survey will reveal details of any subsidence, says Mike Taylor-West, the head of Savills Insurance Services. A standard buyer's survey may suggest a further study.

Where there is an extreme risk of subsidence, an insurer could refuse to offer cover - and getting a mortgage for the property could also be tricky, he warns.

However, if the subsidence is being monitored and steps are being taken to reduce its impact, mortgage companies will usually agree to lend the money to buy the property.

AFTER THE SHOCK, A CALL FOR REINFORCEMENTS

Ted Nash's bungalow in Gainsborough, Lincolnshire, suffered from subsidence last Christmas.

"My son's bedroom door was sticking. To find out the cause, I put a spirit level across the door and found it had moved.

"We then looked under the carpet in the hall and found a crack about half an inch wide all the way across. When we noticed one or two other cracks around the place, we began to get quite worried."

Mr Nash rang his insurer, Halifax, which sent a surveyor round. He found that a burst pipe in the kitchen, the subject of an earlier claim, had caused the subsidence.

It took some structural reinforcing, and repairing of the cracks, to get his property back to normal.

Normally, a Halifax policyholder would have to pay the standard £1,000 excess on such a claim. But since Mr Nash had alerted the insurer after the earlier problem, he only had to pay £50.

In most cases, however, insurers do insist on the £1,000 excess.