What is subsidence – and how do you spot 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.

Subsidence meaning – explained

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:

1. clay soil – clay is more likely to shift (expand and shrink) during weather changes than other types of soil
2. hot weather – drought and hot weather can dry out soil and cause the ground to shift
3. tree roots – 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
4. nearby mining activity – past and present mining activity can cause subsidence. Take a look on the Coal Authority’s website too see if your area is likely to be affected
5. leaking water pipes – problems with drainage and leaks can cause subsidence as the ground becomes saturated and shift beneath the foundations

Another thing to be aware of is that 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.

Common subsidence signs to look for

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, either inside or in the external brickwork.

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 at 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
• external doors not closing easily

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 make sure that you can take appropriate measures moving forward.

Hot weather and record high subsidence claims

Hot weather is putting greater risk of subsidence on UK properties and insurance claims are at a record high.

New data from Simply Business reveals a rise in subsidence claims during the summer months. Claims doubled in 2022 and peaked in August and September, so it’s even more important to spot the signs as temperatures soar.

We saw 430 subsidence claims last year, with 73 and 79 in August and September respectively.

Alan Thomas, our UK CEO, says: “Subsidence occurs when the ground sinks around the foundations of a house – and it can happen when the ground becomes dry and shrinks. So inevitably as the weather gets warmer, and there is less rainfall, the causes of subsidence become more common.”

How to fix subsidence (and prevent it in the first place)

If you suspect your house might be likely to subside, there are steps you can take to limit the chances, including:

• 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

How long do you have to declare subsidence?

If 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 can’t be fixed.

To fix subsidence you might need a tree surgeon, surveyor, and building contractor. And if underpinning of the foundations is needed then you’ll need to notify building control through your local authority.

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 on the property. 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.

Issues with subsidence can seriously affect the selling price of a property though, so it’s worth keeping a close eye on any potential issues.

For more information, Geobear has subsidence area maps, while full data from the British Geological Survey includes a subsidence risk postcode checker for England and Wales.

Is subsidence covered by insurance?

When it comes to insurance you’ll have to disclose that the property has subsidence and existing structural issues with your property when you take out your cover. If you fail to do so, your insurer can refuse to pay out if you later try to make a claim.

Insurance premiums can be more expensive if you have a property with a risk (or previous claim) relating to subsidence.

Your buildings insurance should cover the risk of subsidence, so any costs to fix it will be paid by your insurer.

Severe cases of subsidence can damage items within the property, from fixtures and fittings to contents, and even less severe cases may require the building to be empty while repairs are made, which can cause loss of income.

What does subsidence insurance cover?

Insurance that covers subsidence will usually pay the cost of repairing the damages caused by subsidence. So, buildings insurance can pay for the cost of repairing the subsidence itself, while contents insurance could pay for the cost of repairing or replacing the contents if it were damaged by the subsidence. The exact coverage will depend on the type of insurance you have in place.

Building work to fix subsidence could include things like underpinning to support the ground, removing trees, or repairing leaky pipework.

It’s important to check your documents carefully when you buy your insurance so that you’re clear about what is and isn’t covered. There will also be certain conditions that you need to meet to make sure you’re covered.

Subsidence insurance for landlords

As a landlord it’s important that you’re protecting your property and your livelihood. Covers to protect you in case of subsidence include:

• landlord fixtures and fitting insurance – in case things like the kitchen or bathroom are covered by subsidence
• landlord contents insurance – if you let your property furnished (either fully or just with white goods)
• loss of rent cover – this can cover you if your tenants have to move out while repair work is done following a case of subsidence

All of these covers can be combined into a single landlord insurance policy through Simply Business.

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.

More landlord guides and resources

• How often should landlords redecorate a rental property?
• How to build a property portfolio in the UK
• Best buy-to-let areas in the UK
• What does landlord insurance cover?

Have you ever had to manage subsidence with your rental property? Let us know your experience in the comments.

Photograph: Parilov/stock.adobe.com