The following has been provided by the ABI

It is the sight every homeowner dreads - cracks appearing in the walls of their home. But don’t fear the worst - while there has been an increase in subsidence claims in recent years, most buildings suffer minor cracking at some time so it doesn't mean that there is a subsidence problem.

Subsidence is the downward movement of the ground supporting the building. Particular problems arise when the movement varies from one part of the building to another.

It can be caused by:

Certain soils. Clay soils are particularly vulnerable since they shrink and swell depending on their moisture content.

Vegetation. Trees and shrubs take moisture from clay soils particularly causing them to shrink, especially during long periods of dry weather as roots extend in search of water.

Leaking Drains. Damaged drains can soften or wash away the ground beneath the foundations.

Less commonly, problems may occur where properties are built over, or close to, mine workings.

Other types of ground movement, which although less common can still result in cracking and structural damage, are:

Heave - the upward movement of the ground supporting the building.

Landslip - movement of ground down a slope.

The first obvious sign is the appearance of cracks. However, not all cracks indicate that there is a problem. Most buildings experience cracking at some time. There is no need to be alarmed by every crack which appears.

Cracks are not uncommon in new properties and newly built extensions. They are likely to be the result of the building settling under its own weight. These usually are nothing to worry about, nor are fine cracks which often appear in newly plastered walls as the water content dries out. And buildings shrink and swell naturally due to changes in temperature and humidity, which can lead to minor cracks where walls and ceilings meet. These too should not normally be anything to worry about.

What should be looked out for are small, usually diagonal, cracks which suddenly appear in plaster work inside and outside bricks at weak points, such as around doors and windows, especially after long periods of dry weather. These may, but not necessarily, indicate movement in the building's foundations. The cracks will normally be wider than the thickness of a 10p coin, and usually wider at the top. Doors and windows may also 'stick' due to the distortion of the building.

Yes. Taking a few simple precautions can help reduce the risk of structural damage.

Trees and shrubs planted too close to a property are a common cause of problems, so they should not be planted near to houses, garages or outbuildings. They should be kept away from any underground drains and buildings belonging to neighbours.

Ensure that trees and shrubs are pruned regularly. Expert advice should be sought from an arborist to make sure they are pruned correctly. Regular general maintenance checks should be carried out around a property. Checks should be made for blocked or leaking drains, dirt and leaves cleared from gutters and pipes checked to make sure there are no splits.

A buildings insurance policy will normally cover damage caused to a property by subsidence, heave or landslip. Damage to walls, gates, fences, patios, drives and swimming pools will not usually be covered unless a home is damaged at the same time and by the same cause. The policy should set out what is and what is not covered but if any clarification is required, an agent or the insurer will be happy to help.

Policyholders will normally have to pay the first part of any claim - the excess. For most policies this will be £1,000.

If the damage is so serious that a home cannot be lived in, most buildings, and even contents, policies will pay for the cost of comparable alternative accommodation, while the damage is being investigated and the repair work is carried out. This will be subject to a limit which is usually a percentage of the sum insured.

As soon as it is believed that there may be a problem, contact should be made with the buildings insurer. A policy will normally require the insurer to be advised of any potential claim as soon as possible and, in any event, it is sensible because the sooner the problem is investigated, the less inconvenience will be caused and the quicker everything can be put right.

It will first be necessary to identify the cause of the damage and what needs to be done to stop it. Once any movement has been stabilised the necessary repairs can be carried out.

Insurers really do understand and appreciate policyholders' concerns and will do all they can to minimise the worry and inconvenience. Insurers will also keep policyholders informed of developments at every stage.

Once they are aware of the damage, the insurer may arrange for a structural engineer and other specialists to carry out detailed investigations to decide the best course of action. These experts will report back to the insurer with their recommendations and then supervise any work which needs to be done.

Alternatively, the insurer may advise the policyholder to contact a structural engineer (it may be able to provide a list of recommended firms) so that the problem can be investigated. Once again, the insurer should then know the cause of the problem and how best to deal with it.

Investigations may include digging holes to find out the type of soil, the depth and condition of the foundation and whether roots are causing a problem - this is quite normal.

It may also be necessary to monitor the width of cracks or other signs of movements over a period of time, usually for at least twelve months, so that the extent of the problem can be accurately established. Once all the information has been collected and analysed, then a plan of action can be drawn up to cure the problem.

Today, very few cases of subsidence are likely to require under-pinning - the strengthening or deepening of building foundations. Generally, further damage can be prevented by the professional removal or pruning of trees, repairing drains, or by localised repairs to brickwork. Then internal decorations will be renewed to complete the job.

If a property has suffered coal mining subsidence damage, the Coal Authority or mine owner mining in the area will be responsible for dealing with any claim. If a problem arises contact should be made with the Coal Authority as they will be able to provide information regarding the procedure involved. At the same time, the buildings insurer should also be informed.

If a policyholder changes their buildings insurer and then discovers problems, the way a claim may be dealt with will be set out in the Association of British Insurers' Domestic Subsidence Claim Handling Agreement. The majority of household insurers subscribe to it and it sets out which insurers will be responsible for handling any claim. If a claim is made within the first eight weeks of the changeover, the previous insurer will deal with it. Claims between 8 weeks and 1 year will be handled by the new insurer with the cost of settlement shared equally between the two insurers.

Any claims made a year after the changeover means that the new insurer alone will deal with the claim.

If cracks suddenly appear, it does not necessarily mean there is a major problem.

Careful attention should be paid to the type, size and distance of any trees from a property.

While buildings insurance covers damage caused by subsidence, heave or landslip, there will normally be an excess which the policyholder will have to pay - currently about £1,000.

Contact should be made with the buildings insurer as soon as the policyholder believes there is a problem. They are there to give help and guidance.

If the policyholder changes insurer and a problem arises, there is an ABI Agreement which sets out which insurer will deal with the claim.