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Subsidence – what is it and what to do about it

Subsidence can be one of the most serious problems a property can suffer, and could affect not only your home’s safety, but also its resale value and future insurance premiums.

Here, we’ll explore what subsidence is, what causes it and what you can do about it.

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What is subsidence?

Subsidence is a very specific issue and occurs when the ground under your house falls away, taking with it some of your home’s foundations. When this happens, it puts strain on your home’s structure as part of it sinks. This is what causes the cracks to appear. (The opposite of this is called heave, when the ground under your home expands and rises)

Not all cracks you see on the inside or outside of your home are signs of subsidence. If you see some suspicious cracks, you’ll need to take a proper look before assuming the worst. Cracks are much more likely to be caused simply by natural shrinkage or swelling caused by changes in temperature or humidity.

If a crack is caused by subsidence it is likely to:

  • Be thicker than a 10p coin
  • Be diagonal running down you wall
  • Be wider at the top than at the bottom
  • Be visible inside and outside the property
  • Be close to windows, doors or extensions

Other signs that subsidence is at work could be:

  • Wallpaper crinkling with no sign of damp
  • Doors and windows sticking or frames warping

What causes subsidence?

Not all homes have the same risk of subsidence. There are a number of reasons that subsidence occurs, some of them might be through the work of nature and others simply by seasonal changes.

  • Your soil type may have an impact. Clay soils in particular expand when they get wet, and contract as they dry out. This means if there is a period of hot dry weather, the soil below your house could shrink, crack and move, making the ground unstable and possibly leading to your foundations moving.
  • If your area is prone to droughts, this makes the chances of your soil drying out more likely.
  • Trees can also be a cause, particularly if they’re close to your home. Some species, such as willows can absorb a lot of water, drying the soil and making subsidence more likely.
  • Older homes, such as Victorian properties were built with shallower foundations than houses today which in theory, may make them more susceptible.
  • Leaking water from drains, water mains or gutters could soften or even wash away soil from around your foundations leading to movement.
  • Less likely perhaps, but a possibility depending on where in the country you live, old mining activity may cause instability.

What can I do to prevent subsidence?

Preventing subsidence or, catching it early is always best. If you think your property might be at risk of subsidence, the first thing to do is try and reduce the risk as much as possible.

While there’s not a lot you can do to change your soil structure dramatically, you can avoid planting trees or shrubs close to your house. If you already have some there, keep them well pruned so that they need to draw less moisture to support themselves.

Don’t just dig out any trees that you think might be too close though, you might do more harm than good if it leads to the ground becoming waterlogged. A tree surgeon could be consulted to get some good advice.

Keep your external guttering, drain pipes and your plumbing well maintained and without leaks. Catch any surplus rainwater in water butts to prevent it just running into the foundations.

A house

What do I do if I think my property is affected by subsidence?

If you think you’ve spotted some signs of subsidence either inside or outside your home don’t panic. Spotting them means that you can take some action to remedy the situation.

Contact your insurance provider at the earliest opportunity. They can arrange for a full survey if necessary to confirm whether or not it’s a genuine case of subsidence. Building insurance policies usually cover you against the costs of subsidence, though subsidence claims will usually have a higher excess than your standard policy excess, so check your policy documents.

Unfortunately, if subsidence is confirmed and even if the issue is resolved, you could still face higher insurance costs going forward.

Always check the terms and conditions in your policy when taking out a home insurance policy and read what subsidence cover you have. If you’re not sure what it means, or you want more information on it, give your insurance provider a call to discuss.

Use our home insurance comparison service to find the right policy for you.