What is subsidence?


What is subsidence?

Spotting the signs of subsidence

If you’ve noticed cracks on the inside and outside of your home, there’s a chance you have subsidence. Subsidence is caused when the ground beneath your home starts to sink. This movement affects the foundations of the building and the loss of support from the foundations beneath the ground results in cracking and property damage.

The main cause of subsidence

You may be surprised to read that 60% of cases of subsidence in the UK are caused by trees and their roots. As the UK has a wet climate, it means trees absorb lots of water, especially in spring and summer. This difference between clay soil being very wet and then very dry (known as shrinkage) can cause the ground movement that results in subsidence.

Leaking drains and water mains

The second highest cause of subsidence, leaking drains and pipes are responsible for around 15% to 20% cases. Other causes include the weakening of the ground around the foundations of your home. Building extensions, weakened foundations, nearby site excavation and digging can all cause a sideways collapse of the ground. Ground vibrations created by heavy traffic close to your home can add to the problem.

Dealing with subsidence

Since the 1970s, subsidence has been taken into consideration when building a property. And you should keep in mind that most houses move and settle with time, causing small hairline cracks but no further issues. So, in most cases, the problem may not be as bad as you think. However, having a professional take a look at the cracks in your home can give you a clearer picture of what you’re dealing with.

Insurance and subsidence

Buildings insurers should cover any damage to property caused by subsidence. It is important, as with any potential insurance claim, to notify your insurer as soon as you notice cracks in your home. An insurer will normally arrange for a structural engineer to monitor your property, often over a 12-month period.

Repairing subsidence

In rare circumstances, severe subsidence will mean your property needs to be underpinned. Underpinning is a slow process, where short sections are dug out around existing foundations and filled with concrete. Cracks can be repaired and filled before being painted over.

When leaking drains, water mains or broken downpipes cause subsidence, simply repairing them should solve the problem without the need for underpinning.

You may need to move out of your home while repairs are carried out, and while this can be inconvenient, your policy should cover you for the cost of suitable alternative accommodation.

Your insurance excess

Subsidence insurance claims can be expensive. This means the excess you’ll be asked to pay may be high, so always check the details of your policy carefully. Excess for subsidence claims could cost anywhere from £1,000 up to £5,000 in high-risk areas. It is also worth noting that most policies will not cover you for damage to garden walls, fences or gates. When you apply for subsidence insurance, you may be asked about the number of trees around your house, what type they are and how close they are to your property.

Buying and selling homes with subsidence

If your home has suffered subsidence, or you’re interested in buying a home with subsidence, read on.

Homes that have been underpinned due to subsidence will only be covered by specialised insurers. Many insurers won’t cover a house if it has been the subject of a subsidence claim, unless it was a policy they issued. This means that if you are the new owner of an underpinned property, you can insure it only with the insurer that paid out the original claim. 

So, if you are looking at a home with a history of subsidence, the cost of the insurance is likely to be high, so you may want to make an offer that reflects this. It is always best to have a full structural survey if you are interested in a property with subsidence.

Risk reduction

You can help to avoid subsidence by planting trees and shrubs a good distance from your home or any outbuildings. If you are concerned that trees are too close to the property, they should be removed if they were planted after the house was built. Some trees can have preservation orders, and may need local authority permission to be removed.

For more helpful information and updates on home insurance and mortgages, please check out our blog and take a look at our previous articles.