Subsidence means your house, or part of it, is sinking into the ground.
The damage it causes can be incredibly expensive to put right, so you need to make sure your home insurance covers subsidence.
Subsidence puts stress on the structure of your home which can result in cracks, depending on the severity. Here are a few common causes of subsidence:
The soil your home is built on shrinks in dry weather, so your home could sink slightly, making it lopsided and causing major cracks in wallls
Homes built on clay soil will be affected more than those that aren’t, as clay soil shrinks a lot when the weather is warm
Tree roots and leaking drains dislodging the soil beneath your home can cause subsidence
Homes built in an area that used to be mined can have unstable foundations, which can lead to subsidence too
What’s heave?
Ground heave is the opposite of subsidence. It’s the upward movement of the ground when soil gets wet and expands
Your buildings insurance will cover subsidence, but only if your home's never suffered from the problem in the past.
Look out for larger compulsory excesses if you need to claim - £1,000 in some cases. If there is an increased excess for subsidence, it’ll be listed in your policy documents.
Also, be aware that although your insurer will cover first instances of subsidence, it usually won’t include the cost of preventing it from happening again. There’s usually a large excess to pay too.
To work out whether subsidence has been an issue for your house, check the subsidence history of the property. You could ask your neighbours about the area.
Properties with a history of subsidence are difficult to insure and you might end up paying higher premiums with a specialist insurer - shop around to find a policy that works for you.
When subsidence is caused by coastal or river bank erosion, insurers might reject a claim if they exclude these causes.
And, if there’s a solitary occurrence of loss or damage to swimming pools, hot tubs, tennis courts, drives, patios, walls, fences and gates, because of subsidence they probably won’t be covered.
However, if the subsidence happens simultaneously to your house and outdoor areas, you can probably make a claim.
Speak to your insurer about the specifics of your policy.
Most homes will get a crack or two, but cracks from subsidence look slightly different.
Subsidence cracks can appear and spread quickly, be thinner at one end, run diagonally, be found on the inside and outside of the building and around windows and doors.
Other signs of subsidence include:
Here are a few ways you can avoid and prevent subsidence:
Buildings with shallow foundations are at risk of subsidence caused by trees and roots. If your house was built before 1950s, it will be particularly susceptible.
Tree roots seek water and grow towards drains which aren’t watertight. However, they’re unlikely to break through solid foundations.
If you're planting new trees and shrubs, don’t put them too close to your home, and prune bushes and trees regularly. Have large, older trees surveyed every few years to see if they pose any immediate danger to your property.
If a pipe leaks or a drain overflows under your home, it will make the earth damp and weak, potentially causing heave and moving the foundations of your home.
You must maintain the pipes and drains under your home, even if they are difficult to access. If you suspect water’s escaped underneath your house, contact your insurer - It might put you in touch with a CCTV drainage surveyor.
If you’re buying a house, look out for large diagonal cracks, inside and out, and check that the doors and windows shut properly.
If you can’t see any cosmetic concerns, read your homebuyers or RICS Building survey.
The latter is best for older properties because it breaks down structural issues into a traffic light, colour coded (red, amber, green) rating system, alerting you to any hidden structural red flags, not just subsidence, and how serious the issue is.
The Homebuyer report doesn’t consider damage under floorboards or behind walls.