What is subsidence and its signs?

Find out how to spot the signs of subsidence and ways to prevent it in our handy guide.

Home maintenance

14 July 2022

Subsidence is one of the most serious issues for homeowners as its consequences can jeopardise the safety of your home and lead to expensive damage costs.

Knowing the signs of house subsidence will help you to feel safe in your home as you can spot damage and act early. So find out everything you need to know about subsidence, including signs of subsidence, the risks involved and how to prevent and fix the problem.

What is subsidence

Subsidence is a severe problem caused by the ground under your property sinking. This means the foundations of your home can become unbalanced, moving the walls and floors of the house from their original groundwork, and leading to cracks and destabilisation of your house. 

Other issues such as a landslip, heave or settlement also cause the property's foundation to shift and are often mistaken for a subsidence issue. Make sure you know when to act and take appropriate preventative measures:

What is heave?

Heave causes the ground below the property to shift upwards, resulting in the walls, floor and foundation of the property shifting upwards too.

What is landslip?

For houses that are built on a slope or near a slope, a landslip occurs as a sideways movement from underneath the house.

What is settlement?

Settlement is the downward movement of a property due to the excessive weight of the building forcing compression of the soil underneath it. If you’ve heard of a similar issue and wondered what is compaction, this is another name for a settlement issue.

Illustration of house on subsided earth

Signs of subsidence

There are many visible signs of subsidence to look out for inside and outside the house, which may indicate the severity of the problem. Common indicators such as cracks in the home are often mistaken as early signs of subsidence. Whilst cracks are indeed among the typical signs of subsidence, they can usually be caused by natural shrinkage and swelling according to the changes in weather and humidity levels.

You will know whether a crack is caused by subsidence if you notice the following:

  • The crack is more than 3mm thick (thicker than a 10p coin)
  • A diagonally positioned crack that is wider at the top and slimmer at the bottom 
  • You can see the crack both internally and externally
  • The crack is visible near doors and windows
  • You may notice the crack spread under the damp-proof course (a layer of waterproof material in the wall of a building near the ground, used to prevent rising damp).

Other signs of subsidence may include:

  • Wallpaper creasing at the joins where the wall meets the ceiling 
  • Doors and windows sticking as frames warp
  • Cracks where an extension joins the house

If you do notice some of these subsidence signs, then it is essential to seek advice to tackle the issue as soon as possible.

A ten pence piece alongside a gap between two bricks of a house with signs of subsidence

What causes subsidence

There are many potential causes of subsidence that one should be aware of. Some of the main reasons are:

  • Roots from trees and other shrubs can often cause disturbance to the foundations of the ground beneath the home, causing it to become unstable. However, trees causing subsidence isn’t always the case; not all conditions where a tree grows near a house will trigger a subsistence issue. 
  • Clay soil is also another potential cause of subsidence. The consistency of clay soil changes depending on the weather, which means in dry weather, it will crack and shift, whilst in wet weather, the soil will swell. Clay shrinkage can cause subsidence as it can result in the foundations of the house becoming unstable and potentially sinking.
  • Subsidence caused by drains can happen when leaking drains soften and moisten the ground surrounding the property, causing it to destabilise and sink because the ground under may not be able to hold its weight of it due to the ground becoming unstable.

Subsidence risks

Depending on an array of factors like how old the property is and surrounding conditions, there are types of houses and buildings that are more at risk of subsidence than others. To know whether your home is at risk, it’s good to investigate the factors that contribute to what makes a higher subsidence risk property:

  • How old the property is: In older properties the foundations may be shallower due to the weight of the property being on the same ground for an extended period and increase subsidence risk.
  • Property built on clay soil: Clay soil can change drastically depending on the weather, this fluctuation can cause the property ground to become unstable and potentially sink lower.
  • If the area you live in is prone to drought: dried-out soil can increase your subsidence risk. This is due to dry soil potentially cracking and shifting, causing the ground to destabilise.

How to treat and prevent subsidence

Now that you are aware of what subsidence is, you may be wondering how to prevent subsidence or how to treat subsidence.

  • Before planting a tree around your property, ensure that you have checked what type of root system the tree has. It is not recommended to plant any trees or scrubs in close proximity to your house and this useful table from The Association of British Insurers (ABI) shows how far away each tree type should be.
  • You can prevent existing trees on your property from absorbing less water by regularly pruning them, however, if it seems to be a deeply rooted issue, it is best to get it checked by a tree surgeon.
  • Ensure your property is regularly getting maintenance checks to avoid any internal and external leakage.

Distances away from a house: apple tree 10 metres, plane tree 22 metres, and a willow tree 40 metres

How to fix subsidence

Whether you’re a homeowner or looking to buy a property with a suspected subsidence issue, you need to find a long-term subsidence repair solution. Fixing a subsidence issue for good is expensive but it can be done by a professional for each type of subsidence issue:

  • Underpinning
  • Tree removal
  • Pipework

Contact your insurer as soon as possible to arrange a survey if you suspect subsidence and find the right solution. If you’re looking for subsidence insurance, you’ll be pleased to know that with AXA buildings insurance, you will be fully covered against cases of subsidence and heave, subject to terms, conditions & exclusions, for more details, take a look at your policy wording.

While finding a fix for subsidence isn’t quick and easy, we’re here to help with any questions on home subsidence insurance. At AXA, we’re ready to guide you in understanding the process of making a subsidence insurance claim:

How much does subsidence devalue a property?

Unfortunately, a property’s subsidence problem can decrease its value by around 20%. So, if you’re looking to buy or sell, the risks of ignoring the issue outweigh the money saved.

Does building insurance cover subsidence?

AXA building insurance covers damage from subsidence with some exclusions. If the issue is a result of construction, demolition, or flaws in the building process you may not be covered.  To find out more about insurance for a property with subsidence, look at AXA insurance policy details.

How long do you have to declare subsidence?

Although there is no given timeline or limit on how long you must declare subsidence, you must inform estate agents and buyers.

Making a subsidence claim

If the claim in an emergency, then you should call our emergency helpline on 0330 024 8086.

If the claim isn’t urgent, you can register the claim online. Just fill out a quick form, and we will aim to be in touch within 24 working hours to discuss the next steps.

If you register your claim on a weekend, you'll receive a follow-up call on Monday.

What are the claiming guidelines

AXA is committed to ensuring making a claim is stress-free. Registering your claim online with AXA home insurance is a quick and easy process.

Whilst some preventative measures may help to reduce your risk of subsidence, it is best to seek structural support from a professional to ensure the issue is dealt with from the ground up.