Despite the rainy weather many of us have had over the past week, this has been one of the driest summers in the past 50 years, and homeowners are warned this means the threat of subsidence – which could cause hundreds of thousands of pounds of damage to their properties – has increased.
Halifax, which saw a 22 per cent increase in insurance claims for subsidence last year, says that with hotter weather subsidence is a danger in many parts of Britain. About 70 per cent of this damage is down to shrinking clay soil, commonly found in the South-east, says the insurer. Trees and hedges planted too near to buildings take moisture from the soil, extending their roots and causing the ground to shift and the building's foundations to crack. Other contributing factors are blocked or damaged drains which may leak water and wash away soil.
The cost of repairs can easily spiral and claims for this type of restoration take a sizeable chunk out of the insurers' pockets. In 2009, insurers paid out £175m against subsidence claims, says the Association of British Insurers (ABI). Some homes can even be completely destroyed so it's vital for homeowners to have appropriate cover and to keep an eye out for the tell-tale signs. Many cracks are innocent and can often close during the wetter winter months, but if they don't, or grow beyond 5mm in width, it's time to call the insurance company.
"Signs of subsidence include cracks that begin at the corners of windows and doors, can be seen from both sides of the wall, and get wider from one end to the other. Windows and doors that are no longer easy to open or close can also be a sign that something is amiss," says Neil Curling, a senior claims manager at Halifax.
If your property has no history of previous subsidence, all standard building insurance policies will provide cover. Most expect policyholders to pay an excess of £1,000, and if you live in a high-risk area, determined by soil maps, you are already paying more for your insurance than those in lower-risk areas.
"Pretty much every underwriter in the UK uses sophisticated geological modelling to assess the risk of subsidence in individual post codes. So if you have never made a claim for subsidence you can be sure your insurance provider is hedging its bets and is loading your premium with the appropriate risk level," says Darren Black from comparison site Confused.com.
There will also be exclusions and limits, so review your policy to see exactly what you're covered for and by how much. Some insurers may exclude damage to external walls and patios hit by subsidence, for example, while others may refuse to cover for flooring and peripheral features so always check the small print.
Another thing to look out for is providers dropping subsidence and flood cover from some of their standard policies. "With the recent trend of building new housing developments on brownfield sites (which generally have higher subsidence risk), this is something that first-time buyers should really be aware of when they are purchasing their first policy," says Mr Black.
If you do have to make a claim, don't expect your insurer to act quickly. Many claims can drag on as insurers will want to monitor the situation to assess the best course of action. Subsidence as well as heave claims (when the property rises rather than falls) require a lot of investigative work and insurers will use specialist structural engineers to take measurements and monitor the situation over a period before the repairs start.
In the worst-case scenario, your home will need to be underpinned by digging out and replacing the foundations. It is a costly affair, potentially tens of thousands, so you can expect a steep increase in premiums. Your insurer may also include a clause in your policy that makes you liable for a certain proportion of any subsidence-related claim. Mr Black says that this can vary from as little as £50 to tens of thousands of pounds depending on the insurance provider's assessment of how likely you are to make a claim.
The big problem is that the stigma of subsidence stays with any property, and most insurers will steer clear of a house that has faced subsidence problems in the past. If you want to buy a property that has had subsidence issues, you may find that you're left with little choice but to stick with the current insurer.
"It does make sense for the existing insurer to continue to cover and there is an agreement in place that says they will do that, but you will need to have a new policy," says Steve Foulsham from the British Insurance Brokers' Association (Biba).
There does come a point, however, once a property has been corrected and stabilised for two or three years, that you may be better off looking elsewhere for your insurance.
"Once a property becomes a normal risk you could argue that it's not fair for a policyholder to suffer increased premiums. Consumers should shop around and try to achieve more competitive terms," says Mr Foulsham.
Specialist brokers such as Bureau Insurance Services, for example, are designed to help homeowners with high-risk properties, and after inspecting your property may be able to offer a cheaper policy. Biba say that Bureau can help homeowners struggling to arrange appropriate insurance for such a property in about 90 per cent of cases, but be warned that this may require you to agree to a higher excess than the industry standard of £1,000.
Above all, the message is to stay calm and remember that prevention is better than cure so take steps now to avoid subsidence issues later. Find out what type of soil your home is built on – if you can roll the soil into a ball easily it has high clay content and is at higher risk of subsidence. You should also think twice before planting trees or large shrubs near the house or any outbuildings.
The ABI says that trees more likely to cause problems include poplars, willows, elms and oaks. It's also wise to keep your drains free of leaves and check your pipes for any splits which could lead to flooding. Finally, if you're buying a property, it's important to check for any past subsidence and have a thorough structural survey to identify any potential problems. You should also ask your surveyor to investigate potential underground mining excavations, which account for about 15 per cent of subsidence claims.
Darren Black, Confused.com
For most, subsidence isn't a problem, but if your property has a history of movement, it's a different story. You will be classed as a non-standard risk and as such you will find it difficult to get a quote from any of the mainstream building-insurance providers. This will likely force you down the route of dealing with specialist underwriters which have experience in dealing with properties in subsidence hotspots.