Other than the odd sink hole, subsidence rarely hits the headlines, but the difficulties of obtaining cover is of equal concern to those in affected areas, particularly if the property has suffered damage in the past and in fact, subsidence affects as many properties as flood in the UK, with one in five homes in England and Wales at risk of damage.

Subsidence is the downward movement of a buildings foundations caused by the loss of support of the ground beneath, with structural damage occurring if the movement is uneven. Upward movement is called heave, although is less common.

Soil conditions cause 75% of subsidence, with clay being the main culprit as it is prone to shrinkage and swelling and is a problem in Sussex, with pockets of clay across the county YOURURL.com. Other causes include building on landfill sites and mining is an issue in parts of the UK.

An outside influence is usually required to trigger damage, with trees causing approximately 60% of claims by removing moisture from the soil. Drains are the second biggest problem, either causing the ground to soften or erode and other triggers include vibration from traffic and nearby excavations.

Building regulations for foundations were changed as a result of the number of properties damaged in the 1976 drought, so subsidence should be less of a problem for properties built since then, although in any area of risk a maintenance programme for trees in a zone of influence is advisable, as are periodic checks on drainage systems.

Policies cover subsidence, heave and landslip and whilst wordings differ, they generally exclude coastal and river erosion, damage to patios, drives and walls (unless the main building is also damaged), general settlement and structural faults such as roof spread or wall tie failure, as well as any reduction in value of the property.

With claims, the initial difficulty can be whether the crack is general settlement or subsidence and with at least a £1000 excess it can be a gamble whether to engage a qualified specialist, however, you will need to show that damage is due to ‘subsidence’ as defined in the policy. The cracks may also need monitoring for a period before any remedial work is undertaken and as insurers are only responsible for the damage that has occurred and not the cost of stopping future damage, (although this is obviously in their interest), the whole claim process can be complicated and take many months or even years to resolve.

There can also be issues if some of the damage is historic and there has been a change of insurer since the damage started, although most insurers have signed up to an agreement as to who deals with the claim in these circumstances.

There is also an agreement for Association of British Insurer members to maintain cover on properties that have suffered subsidence, although it is not a cast iron guarantee and will likely involve higher premiums and excesses. In many cases, once a claim occurs, you are stuck with the same insurer.

Most household policies automatically provide subsidence cover, but it is usually an optional extension on commercial policies and surprisingly many property owners choose not to insure, although this is partly because many older rental and lease agreements do not make subsidence cover a requirement. Not only does this leave the building uninsured, but it has a knock on effect to the Business Interruption cover, which usually has a ‘material damage’ proviso, meaning that unless cover is in place for physical damage, the business interruption policy will not respond. Subsidence cover for contents is also often overlooked and is usually very inexpensive as claims rarely occur.

It is certainly worth checking whether you are fully covered, especially when they start fracking!