What is subsidence and what causes it?

If you’re in the market for a buy-to-let property or are already a landlord with an extensive portfolio, one of the things you need to be aware of is subsidence.

Subsidence can have a serious effect on the structural integrity of your property, affecting your ability to rent it as well as its resale value.

Definition of subsidence

So what is subsidence? Well, subsidence is where all or part of your house starts sinking into the ground, putting strain on the building and causing cracks to form.

It’s a different but similar issue to heave, where the land beneath the property rises, but will usually have the same results, namely a rupture of the house’s foundation and damage to its structure.

What causes subsidence?

There are quite a few causes of subsidence, both geological and man-made. Here are some of the main risk factors:

  • Clay soil is more likely to shift during weather changes than other types of soil.
  • Drought prone areas tend to be at higher risk because the soil is likely to dry out and shift.
  • Trees and large shrubs with expansive root networks can be a problem if they are too close to your property as they may suck too much water from the soil.
  • Older properties may have shallower, less sturdy foundations - however, depending on their building material, they may also be more flexible and less likely to subside.
  • Nearby mining activity, both past and present, can cause subsidence. Take a look on the Coal Authority’s website too see if your area is likely to be affected.
  • Leaking water pipes can wash away soil below your house.

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How to spot subsidence

It’s important to know and be able to recognise the signs of subsidence as there are steps you can take to fix the problem before it progresses.

One of the most common signs is subsidence cracks. Cracks in your house may have been caused by subsidence if they’re:

  • More than 3mm wide.
  • Diagonal.
  • Wider at the top than they are the bottom.
  • Visible from the outside and the inside.
  • Close to doors and windows.

Other signs of subsidence are:

  • Wallpaper crinkling where it meets the ceiling.
  • Doors and windows sticking because of warped frames.
  • Cracks where an extension joins the property.

It’s important that you keep these in mind when inspecting your property or buying a new one, as knowing how to check for subsidence will ensure that you can take appropriate measures moving forward.

Preventing and fixing subsidence

If you suspect your house might be likely to subside, there are steps you can take to limit this likelihood. Those include:

  • Not planting shrubs or trees too close to your property, lest they dry out the soil
  • Not removing shrubs or trees that are already planted there as this can cause water logging or instability
  • Regular pruning of any trees near your property
  • Maintaining any external guttering, pipes and plumbing to avoid leaks

Should you suspect your property may be subsiding, make sure you contact your insurer as they could be able to help with conducting a survey to establish the cause of the problem.

If you have buildings insurance, this may help cover the costs of fixing the subsidence, although there are a number of exclusions so make sure you check your policy documents.

Once the extent of the problem has been established you can then move on to working out the best way to solve it, though in some cases subsidence cannot be fixed.

Buying a house with subsidence

If you’re looking at buying a house that may have subsidence then it’s best to have a survey carried out. There are sometimes ways of fixing subsidence so you may decide to go ahead with buying the property if the benefits such as location and rentability exceed the downside of having to fix the subsidence.

However, when it comes to insurance you will have to disclose that the property has subsidence. This could mean a higher premium or you may find that the particular issue will not be covered in your policy.

Please note this article should only be used as a guide. Buyers should always conduct their own research, or seek the help of a professional before making any decision.

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