Crack down on creeping willows

The unusually hot summer made some trees dig deep for water - and insurers' budgets are feeling the strain, says Christopher Browne

Phew, what a scorcher! Five months of almost constant sunshine - and in the cloudy old UK at that. No sooner have we come back from a fortnight in Greece or the Maldives than we are topping up our tans with yet another spell of sun in the last rays of the Indian summer.

Phew, what a scorcher! Five months of almost constant sunshine - and in the cloudy old UK at that. No sooner have we come back from a fortnight in Greece or the Maldives than we are topping up our tans with yet another spell of sun in the last rays of the Indian summer.

Suddenly life's become a bed of hoses as we spray, sprinkle and soak those drooping plants, flower-beds and borders to help them survive and then look on excitedly as a second bloom of azaleas, peonies and petunias bursts forth like an unexpected lawn chorus. Not to mention all those barbecues, al fresco breakfasts and weekend trips to Devon, Cornwall, the Lake District and Brittany. You name it, we've done it, as we gratefully soak up the last remnants of the hottest UK summer on record.

But, beneath our sky-blue enjoyment, some unseen forces have crept in to spoil the party. Soaring temperatures have dried out the subsoils around our homes and, in extreme cases, left underground gaps and crevices causing houses to move and jagged cracks to appear in the walls and plaster.

In the past month, the major insurance companies have reported a marked rise in subsidence claims and inquiries because of the arid summer. Norwich Union, which insures one in five UK homes, says reports have doubled from 250 to 500-a-week, while Direct Line, another of the big five, reports a threefold increase and "four extremely busy weeks of cracks and slippage in UK homes".

Most claims have been in London and the South-east, due to its large tracts of soft clay soil which shrinks and swells during parched spells. In the North and Scotland, where most foundations are rock-solid, there have been fewer reports. Axa says the roots of large trees such as willows, oaks, elms, ashes and poplars have caused many of the movement problems.

Like all fauna and flora, trees need water to sustain them, and during dry spells their root hairs burrow farther afield, sometimes snaking under a neighbouring house's foundations, causing it to move or slip. The same can happen when a mature tree is removed, which leads to a patch of previously dry soil to swell up with moisture causing both ground and house foundations to heave.

These are the main causes. But what are the answers? A leaflet produced by Direct Line advises you to put all shrubs in containers or plant smaller trees such as cypresses and hollies when planning a garden around your house. Any tree should be the same distance from the house as its full-grown height to prevent its roots, which grow around the same length, disturbing it.

Though summer claims will continue long into the autumn, your policy is unlikely to meet them. "Insurance companies have seasonal budgets. We know a long, dry summer - or a particularly wet one for that matter - is going to mean increased claims, so we always have money set aside for these periods," says Royal and SunAlliance spokesman John McClennan.

If, however, you think you have a problem, you should report it to your insurers immediately. The tell-tale signs are diagonal cracks in the walls or plaster around the doors or window-frames. The company will then send a structural surveyor to investigate. It could mean several visits or weeks of monitoring before he makes a decision. Should remedial work be needed you, the homeowner, pay a £1,000 excess - the set sum for all subsidence claims.

At best, it could mean a day's crack-filling. At worst, it could involve major underpinning while you and your family spend several months in a hotel or B&B. Accountant Johnnie Hampton whose terraced home in Norwich was damaged by subsidence, had his kitchen and dining-room removed while contractors injected resin into cavities under the foundations. "It was a painful experience and I had to get the next-door neighbours' permission, as their houses adjoin mine," he says. "My partner and I lived in a B&B for six months while the ground movement was tested. It's all back to normal now and we have seen no more cracks. It's a great feeling - just like living in a new house."

Many insurance queries never turn into claims. If you've moved into a new house or added an extension, for instance, you shouldn't worry if hairline cracks appear in the plaster after a few months. It's known as general settlement and merely shows it's getting used to the foundations. If, however, you've got your eye on an old property, your best safeguard is to get a structural survey first. It'll certainly help avoid a nasty sinking feeling later.

To order 'Cracking the Problem of Subsidence' call 01473 824447