Subsidence: Definition, Signs, Fixes & Insurance

a house experiencing subsidence

Subsidence sounds pretty dramatic (after all, it means your home is sinking into the ground!), but it is actually nothing to get too stressed about. Most cases are treated successful, covered by your home insurance policy and don’t cost too much to put right. Spotting subsidence as early as you can is the best course of action, so let’s break down all the tell-tale signs of subsidence, what causes it, how you can fix it and how you can help to prevent it, as well as how a subsidence claim could affect your home insurance.

Subsidence definition: what is it?

This probably isn’t the first time you have heard of subsidence, especially if you have been looking for home insurance policies, but do you know what is actually meant by the term? Let’s make everything clear with an easy to understand subsidence definition.

Subsidence happens when the ground underneath a building sinks or collapses. When this occurs, it causes the foundations of a building to move or shift, which puts strain on the structure of the building.

Quite simply, a house that is suffering from subsidence is sinking into the ground. This makes the house itself unstable and can affect its long term structural integrity.

Is subsidence the same as settlement? No, while both involve a building moving downwards, settlement and subsidence are not the same. Settlement is simply the act of a building sinking slightly in the first ten years of its construction as the soil underneath it compresses. It is a normal process that happens to all new buildings as they ‘settle’ after being built.

What causes subsidence?

Subsidence can be both man-made and naturally occuring, which means that some homes are more at risk than others of experiencing it. The main causes and risk factors associated with subsidence are:

  1. Tree roots - the roots of big trees close to your home can grow under your home and cause big problems to the foundations. As the roots drain the moisture from the soil, the soil can dry and sink down, causing subsidence. This is one of the most common causes of subsidence in homes, with studies estimating that around 70% of all home insurance subsidence claims are caused by tree roots.

  2. Type of soil - clay soil is particularly vulnerable to changes in the weather. When it is hot and dry, clay soil is known to dry out, crack and shrink, possibly causing your home’s foundations to move.

  3. Leaky drains - a leaky drain or water pipe can wash away soil under your home, or cause it to become so wet that it gives way, causing the foundations to shift.

  4. Drought - in areas that are particularly prone to drought, the soil can become very dry. This increases the risk of it cracking and affecting your house’s foundations.

  5. Older homes - older homes typically have much shallower foundations than new builds, which means the structural integrity of the house is more likely to be impacted by shifts in the ground underneath. However, on a positive note, older homes tend to be made with brick and soft lime mortar, which are quite flexible and so less likely to be damaged by ground movement.

  6. Mining activity - the foundations of homes built next to or close to a former quarry or mine have a greater risk of being unstable as the material used to fill in the site will move as it decomposes. As the material decomposes, it will cause the surrounding ground to shift, increasing the chance of your home experiencing subsidence.
infographic showing subsidence on a house

Take a look at a map of the UK’s most at risk subsidence areas to see if your home is more at risk or not.

Signs of subsidence: what to look out for

Subsidence is not like an earthquake: you are not going to suddenly feel you house move when it occurs. In fact, the signs of subsidence are not dramatic or sudden. They typically occur over a long period of time as your house very slowly sinks. Here are four tell tale signs to look out for:

  1. Doors and windows sticking out of their frames and/or being hard to close as they are not properly aligned.

  2. Rippling/crinkling of wallpaper both on walls and where it meets the ceiling.

  3. Cracks in the walls where an extension has been added to the house.

  4. Cracks in general.

Cracks are one of the most obvious signs of subsidence, but that doesn’t mean all cracks equal subsidence. Cracks in homes are normal. They can occur when a house first settles onto its foundations, and as walls and ceilings swell due to warm temperature. Newly plastered homes will often also form cracks as the plaster dries. These types of cracks are nothing to worry about. So how do you know when a crack is a sign of subsidence?

What do subsidence cracks look like?

Cracks caused by subsidence have some key features that let you know they are likely caused by the ground under your home shifting: they may as well have subsidence written all over them! A subsidence crack will usually:

  • Be wider than 3mm (this is basically the width of a 10p coin so use one to measure a suspicious wall crack).

  • Be visible on the inside and outside of your house.

  • Be diagonal.

  • Be wider at the top than the bottom.

  • Appear and spread quite quickly.

  • Be close to windows and doors.

House subsidence: action, treatment and prevention

What should you do if you spot signs of subsidence? Can it be fixed? Are there ways to help prevent it? Let’s take a look.

What to do if you spot signs of subsidence

a microscope

In most cases, subsidence can be fixed quite easily so spotting signs of it does not need to instill full blown panic. The best thing to do is act quickly as the sooner subsidence is identified, the easier and cheaper it is to sort out.

If you think your house is experiencing subsidence, call your home insurance provider. Your insurer will send a professional house surveyor to assess your house and confirm if it is experiencing subsidence or not. In most cases, this is not done overnight. There is a high chance that they will monitor your home for a period of 12 months before determining if subsidence has occurred and is still occurring.

How can you fix subsidence?

The good news is that subsidence is usually treated successfully. The exact treatment for fixing it depends on what has caused it in the first place and what damage has occurred.

  1. Tree roots - if subsidence has occurred due to tree roots growing into your house’s foundations, the obvious and most likely cause of action will be to remove the tree in question. However, do not remove the tree yourself! If not done correctly you could cause further damage. You will need to consult a chartered property surveyor and tree surgeon before cutting down any trees.

  2. Leaky drains - if it’s caused by leaking drains or pipes, you will need to get these repaired.

  3. Minor cracks - if cracks don’t affect the structural integrity of your home, they can just be filled in or painted over.

  4. Major cracks - if the wall cracks do affect your home’s safety, they may need to be repaired with metal fixings.

In the worst case scenario, your home might need to be underpinned in order to fix the effects of subsidence and stop it occurring in the future. Underpinning is the process of strengthening the existing foundations of a house by making them deeper or wider so that they rest on more stable ground. This can be very expensive (up to £50,000), but luckily it is always a last resort. According to the Royal Institution of Royal Surveyors, only 10% of subsidence cases result in underpinning.

Ways to prevent subsidence

As mentioned earlier, the process for identifying subsidence and what has caused it can be lengthy, and, in the worst case scenario, it can be very expensive to put right. Preventing it would therefore be the ultimate goal. Obviously you cannot stop subsidence from happening in all cases, but there are steps you can follow to reduce the risks:

  • Make sure all external guttering, pipes and plumbing are well maintained to avoid leaks and blockages.

  • Catch any excess water by placing buckets in your garden or water butts in the soil.

  • Regularly prune all trees and shrubs close to your house so they don’t become overgrown.

  • If you have any trees or shrubs close to your house, do not remove them yourself. If not done correctly, removing them can cause more damage than simply letting them be.

  • If you do want to plant trees in your garden, make sure they are a safe distance from your house. The Association of British Insurers (ABI) has put together a useful guide detailing the appropriate distance from your home different types of trees should be planted.

Type of Tree Safe Distance (in meters)
Apple/Pear 10
Ash 21
Beech 15
Birch 10
Cypress 20
Cherry 11
Damson 11
Elm 30
Hawthorn 12
Holly 6
Horse Chestnut 23
Laburnum 9
Laurel 6
Lime 20
Magnolia 5
Maple 20
Oak 30
Pine 8
Plane 22
Plum 11
Poplar 35
Sycamore 17
Spruce 7
Walnut 14
White Beam/Rowan 11
Willow 40
Yew 5

Source ABI

Subsidence insurance

Subsidence insurance is usually included in most combined home insurance and buildings insurance policies, which means you can make a subsidence claim to your provider and get compensation.

However, policies typically include a lot of exclusions, meaning events and/or items that they will not cover subsidence for, such as subsidence caused by faulty workmanship, materials and design.

a house with an insurance document

Insurers will not usually pay out for your outbuildings or surrounding structures, such as your garden wall, fence, gate, patios and driveway, if they have been damaged by subsidence that has not also affected your actual house. In other words, in most cases you cannot make a stand alone subsidence claim for a part of your property that is not your physical house.

As we have mentioned, subsidence is not quickly identified, which means that most subsidence claims are not processed quickly. The Financial Ombudsman warns that you should not expect any subsidence claim to be resolved quickly: your provider will need to identify the nature of the damage and how it started, which can take up to 12 months. So, if you make a subsidence claim, be prepared to be patient.

All subsidence claims related to subsidence caused by coal mines are dealt with by the Coal Authority, not your home insurance provider.

If you discover subsidence damage shortly after you have switched insurance providers and need to make a claim, it will not necessarily be your current provider who deals with the claim. Under an agreement issued by the Association of British Insurers, the following conditions apply:

  • If the claim is within eight weeks of your switch, your previous home insurance provider will handle it.

  • If the claim is between eight weeks and one year after you switch, your current and previous provider will share the costs of the claim.

  • If the claim is after one year of your switch, your current provider will deal with it.

Is there a subsidence excess on claims?

As with all insurance claims, claims for subsidence are subjected to excess. In most cases you will find that insurers actually charge a higher excess rate for subsidence claims than other claims. A typical home insurance policy will have an excess of around £1,000 for a subsidence claim.

Home insurance for a property with subsidence history

Is it hard to get insurance for a property that has a history of subsidence? While there are insurance providers that will still insure your property if it has a history of subsidence, unfortunately you will find that it is harder to find a good deal and your premium will be more expensive.

It is a good idea to shop around and compare home insurance policies to try and find an attractive deal. If you are having problems finding a price and policy that suits you, an insurance broker could be very helpful (but remember you will have to pay them commission).

If you are looking to switch providers after making a subsidence claim, you must declare the claimto your new provider when you purchase the policy. If you do not and need to make a subsidence claim with them in the future, the claim will likely be refused.

Should you buy a house with subsidence?

If you find your dream house but it shows signs of, or has a history of, subsidence, it doesn’t mean you need to write the house off. But it does mean you need to make sure the house is safe and you have the necessary paperwork before you buy it.

If you think a house is showing signs of subsidence, ask the owner if it has experienced subsidence before (they should be honest with you) and get a professional building’s survey done. This should confirm if there is subsidence and how severe it is. The decision whether to buy the house is then up to you.

If you know a house has experienced subsidence before, ensure you get two types of legal documents when you purchase it:

  1. A Completion Certificate (if the home has been underpinned)

  2. A Certificate of Structural Adequacy (if any repairs made were part of a subsidence insurance claim)

As previously mentioned, home insurance for houses with a history of subsidence is more expensive, and you will have to declare its subsidence history when purchasing a policy. So, if your dream house has subsidence, be prepared to pay a bit more for your policy and spend time comparing home insurance providers.

Data and information correct as of September 2019.

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