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Subsidence: insurance, causes and cures

If your home suffers from subsidence, you could find yourself facing a costly repair bill or having to claim on your home insurance policy.

But with a little preparation and knowledge, you might be able to stop the problem before it starts. Here’s what you need to know.

A model house sinks into sand  
 

What is subsidence?

Subsidence is when the ground beneath your house starts to sink. This causes parts of your house to sink, too, creating misaligned walls, cracks, and damage to the building.

 

What causes subsidence?

The two main causes of subsidence are either too much or too little moisture in the soil beneath your home’s foundations. 

There are many different risk factors that can increase the chance of subsidence in a home. They include the following: 

Nearby trees and shrubs

If there are trees and shrubs close to your home, their roots can suck up any moisture in the soil. This could cause the soil to dry up, crack, and sink. 

Leaking drains and burst pipes 

Too much water in the soil around your home, from leaks or burst pipes, can cause it to wash away and sink.

Mining

If your house is built over an old mine or near an old quarry, the ground beneath could be structurally unsound.

Periods of intense weather 

Flash flooding or summer droughts might change the moisture levels in soil. Clay soil is particularly vulnerable to subsidence, as it’s sensitive to moisture. This makes it expand when wet and contract when dry – not ideal with unpredictable British weather.

The age of your property

Subsidence is more common in Victorian and Edwardian houses as their foundations are shallower than the UK minimum (1 metre). As such, they’re more at risk of damage.

Clay

Subsidence is more common in areas with clay-rich soil, like much of south-east Britain. The Subsidence Support website has a useful map of areas at risk of subsidence

You can check current subsidence claims on the Coal Authority’s website.

 

What does subsidence insurance cover?

Most home insurance policies should have some cover for subsidence. There could be exclusions, though, especially if your property has fallen victim to subsidence in the past.

Policies with subsidence insurance might cover:

As with any home insurance claim, you’d likely have an excess to pay before you’d get any payout.

Although insurance companies offer cover for subsidence-related damage, the scale of the repairs can often leave you facing an excess of up to £1,000.

Compare home insurance quotes

 

How long do you have to declare that subsidence exists in your property?

There’s no limit on how long you have to declare subsidence in your property. No matter the time frame, If it’s been affected by subsidence in the past, you have to tell an estate agent or buyer about it. This is especially true if you've made an insurance claim for subsidence.

 

How much does subsidence devalue a property?

It depends on a few factors:

  • The level of subsidence
  • When it happened
  • What action was taken
  • The state of the property.

However, the subsidence factor risks knocking off 10- 20% off the asking price, on average. 

 

What does subsidence look like?

Subsidence comes in many forms and there are lots of different signs to show it’s happening in your home. If you’re concerned about dealing with subsidence, the first thing to do is check you have it and the extent of the damage.

Cracks in a wall are one of the most common signs of subsidence. But they could also be the natural swelling/shrinking of your home’s walls in response to temperature. 

A cracked wall caused by subsidence

Exterior or interior subsidence cracks could also be the house settling into its foundations and naturally sinking down a little - this is more common in new build houses under 10 years old. 

You can also often find settlement cracks after extension work has been completed.

Other common examples of subsidence include the following:

  • Sudden cracks along your walls
  • Cracks that are visible on the outside and inside of your home
  • Doors and windows sticking for no apparent reason
  • Rippling wallpaper that isn’t caused by damp or moisture
  • Cracks around a particular weak point e.g, where an extension meets the main property

If you spot any of these problems it’s worth getting in touch with your home insurance company. 

You could also have a qualified surveyor look at the problem to limit the damage.

 

 

How can you prevent subsidence in your home?

There are a few steps you can take to minimise the risk of damage caused by subsidence.

Plant trees away from your home

According to the Royal Horticultural Society (RHS), tree roots can extend up to three times the height of the tree.

So, even if you think your trees are far enough away, they could still pose a risk. This is particularly true if you live in an area with clay-rich soil.

The Association for British Insurers (ABI), gives this guidance on how far from your home to plant certain kinds of tree:

Species Normal Mature Height (m) Safe distance (m)
Apple / pear
12
10
Ash
23
21
Beech
20
15
Birch
14
10
Cypress
25
20
Cherry
17
11
Damson
12
11
Elm
25
30
Hawthorn
10
12
Holly
14
6
Horse Chestnut
20
23
Laburnum
12
9
Laurel
8
6
Lime
24
20
Magnolia
9
5
Maple
21
20
Oak
24
30
Pine
29
8
Plane
30
22
Plum
12
11
Poplar
28
35
Sycamore
24
17
Spruce
18
7
Walnut
18
14
White Beam / rowan
12
11
Willow
24
40
Yew
12
5

So, you’re looking at a minimum distance of five metres to plant your tree, but the further away you go, the lower the risk.

Clean your gutters and drains

Regular maintenance on your home is generally a good idea, especially as you go into the colder, wetter months.

But it becomes especially important if your home is at risk of subsidence.

Make sure your gutters are free from debris so water doesn’t overflow into the soil. It’s also your responsibility to make sure that your drains are in good shape.

If you’re worried about drainage being a problem, you could get a CCTV drainage survey to make sure your waterworks are in good condition.

If your drains are watertight, there should also be less risk of tree roots getting in and causing further damage.

Check surveyor’s reports

Before you buy a house, you’ve got the option of having a building survey done of the property.

This report should tell you if there are any red flags for subsidence. You can then make an informed decision as to whether you want to buy a house that has this risk.

Always follow building regulations

Before you carry out any work on your home, you must check if you need approval first. This comes under the Building Regulations 2010. If you use someone registered with a competent person scheme you should not need this.

 

Can you fix subsidence?

The potential fixes for subsidence depend on what the cause was.

If moisture-sucking trees are the culprit, you could have them removed. Then you’d monitor the property to see if taking the trees out has stabilised the soil enough to fix the issue.

If your drains are to blame, then fixing any broken pipework could be enough to sort out the problem without a ton of cost. Again, you’d need to monitor the property to make sure the subsidence stops and doesn’t get worse.

The most common ‘big fix’ for subsidence is underpinning your foundations.

This involves installing support beams, or a second concrete layer, to strengthen your foundations.

Having an underpinned home might be an indicator to insurers that your home is at risk of subsidence again, which may lead to higher prices.

That's why it's a good idea to compare buildings insurance quotes to find the best deals.

 

What is heave?

Heave is a separate problem which is often covered under the same insurance guidelines as subsidence.

Heave has the opposite effect to subsidence. It happens when the ground beneath a building becomes saturated with water and begins to swell, moving upwards and often sideways.

An example of heave on a path

This can have similar symptoms, and cause similar damage to subsidence.

Sometimes, if you take out a tree to lessen the risks of subsidence, you could then experience heave.

This is because the previously dry soil suddenly has no tree roots to absorb it, causing waterlogged soil that swells and pushes the foundations.