House subsidence repair costs: signs, causes, and what to do next

Spotting a crack in your home can be unsettling, especially if it appears suddenly, seems to be getting bigger, or sits near a door or window. The good news is that not every crack means subsidence. The important thing is knowing when to take it seriously and who to speak to next.

House subsidence happens when the ground beneath part of a property sinks, causing the building above it to move. In some cases, the issue is minor, historic, or linked to a one-off problem such as a leaking drain. In more serious cases, it can lead to structural damage, expensive repairs, insurance complications and a reduction in property value.

How much does house subsidence cost?

The cost of repairing subsidence depends on the cause, severity, and extent of the damage. A small area of historic movement may only need investigation, monitoring, and cosmetic repairs. A more serious case may need drainage repairs, ground stabilisation, structural repairs, or underpinning.

As a rough guide, you may need to budget for the following:

These figures are only a guide. Costs can be much higher for larger homes, period properties, difficult access, complex foundations, serious structural movement, or cases affecting several parts of the building.

It’s important not to spend money on cosmetic repairs until the cause has been properly investigated. Filling cracks or redecorating before the movement has stopped can hide the symptoms without solving the problem.

What is house subsidence?

House subsidence is the downward movement of the ground beneath a property. As the ground sinks, the foundations can move with it, causing cracks, distortion, or structural damage.

Subsidence is different from normal settlement. Settlement can happen when a new building naturally settles after construction, and can cause hairline cracks of up to 2mm wide. Subsidence usually means something has changed in the ground beneath the property, such as soil drying out, ground being washed away, or foundations not being properly supported.

It is also different from heave, where the ground moves upwards, and landslip, where the ground moves down a slope. These problems can look similar to a homeowner, so it is important not to self-diagnose. A professional inspection is the safest next step.

What are the signs of subsidence?

Cracking is the sign most people notice first, but not all cracks are a cause for panic. Hairline cracks are common in many homes and can be caused by plaster drying, seasonal movement, temperature changes, or normal settlement.

Subsidence cracks tend to have certain features, which include:

• Cracks wider than around 3mm
• Diagonal cracks, especially around doors and windows
• Cracks that are wider at the top than at the bottom
• Cracks that are visible both inside and outside the property
• Cracks that appear where an extension joins the main house
• Existing cracks getting longer, wider or deeper
• Doors or windows starting to stick
• Sloping or uneven floors
• Wallpaper rippling or tearing where there is no sign of damp

One sign alone does not always indicate subsidence. But if you notice several signs together, or the problem seems to be getting worse, it is worth getting professional advice.

What does subsidence inside a house look like?

Subsidence inside a house can appear as cracks in plaster, gaps around fixtures, sticking doors or uneven floors.

You may notice cracks:

• Above doors
• Around window frames
• Where walls meet ceilings
• Near staircases
• Around chimney breasts
• In corners of rooms
• Around skirting boards or door frames

Internal cracks are worth taking more seriously if they align with external cracks, widen, or appear alongside other signs of movement in the property. Taking photos and noting the date can help you see whether anything is changing, but it is still best to get concerning cracks checked by a professional.

What causes house subsidence?

There are several possible causes of house subsidence. The right repair will depend on finding the cause, not just treating the visible cracks.

Clay soil

Clay soil expands and shrinks depending on moisture levels. During hot, dry weather, clay can shrink and crack, causing the ground to move. Homes built on clay soil can therefore be more vulnerable to subsidence, especially during long dry periods.

Trees and large shrubs

Around 70% of subsidence insurance claims are tree-related. Trees and large shrubs can draw moisture from the ground, which can cause problems in clay soil, where changes in moisture can lead to shrinkage and movement.

This does not mean every nearby tree is a problem. Trees should not be removed without proper advice from a structural engineer, arboriculturist, insurer or tree specialist. Removing a tree in the wrong situation can sometimes worsen ground movement.

Leaking drains or water mains

Leaks can soften the ground or wash soil away from beneath the property. In some cases, fixing the leak may allow the building to stabilise without more invasive foundation work. Subsidence insurance claims list drainage problems in 10%-15% of cases.

Poor foundations or groundworks

If foundations were not properly designed or built, or if the ground was not correctly prepared, movement can occur later.

Mining or previous ground disturbance

Homes built near former mines, quarries, or filled ground may be at greater risk of movement. In some areas, coal mining damage may need to be handled through the Coal Authority rather than a standard home insurance claim.

Extensions with different foundations

Cracks can sometimes appear where an extension meets the original house, especially if the two parts of the building have different foundations and move at different rates.

Who should you call if you think you have subsidence?

If you think your home has subsidence, do not ignore it, but do not rush into repairs either. The right first step is to get the problem assessed.

Depending on your situation, you may need to contact:

Your buildings insurance

If the damage appears serious, active, or structural, your building's insurer may be the first call to make. Subsidence is often covered by building insurance, although policies vary, and subsidence claims usually have a higher excess.

Your insurer may arrange for a loss adjuster, surveyor, or structural engineer to inspect the property.

A structural engineer

A structural engineer can take a closer look at the cracks, check for signs of movement, and help identify what may be causing the problem. They can also advise whether you need further checks, such as monitoring cracks over time, inspecting drains, or assessing the foundations.

You may choose to speak to a structural engineer before contacting your insurer, especially if you are not sure whether the damage is subsidence. This can help clarify whether there is a serious issue, although you should check your insurance policy and not delay reporting damage if it may affect a claim.

A chartered surveyor

A surveyor can assess the property's condition and may recommend further investigation by a structural engineer. This is especially common if subsidence is flagged during a house purchase.

A builder

A builder can help carry out repair work once the cause has been properly identified. For suspected structural movement, a builder should not simply fill the cracks and move on. The repair should follow the recommendations of a structural engineer, surveyor, or insurer-appointed specialist.

Drainage or tree specialists

If leaking drains, pipework or trees may be involved, additional specialist advice may be needed before choosing the repair method.

How is subsidence diagnosed?

Diagnosing subsidence usually starts with a visual inspection. A structural engineer or surveyor will assess the type of cracking, the pattern of movement, the property's age and construction, nearby trees, drainage, soil conditions, and any previous building work.

They may recommend:

• Measuring and recording cracks
• Monitoring cracks over time
• Checking whether cracks change seasonally
• Drain surveys
• Soil investigations
• Trial pits to inspect foundations
• Tree or root assessments
• Reviewing previous extensions or alterations

In some cases, monitoring may be needed for several months to see whether the movement is active. This can be frustrating, but it helps avoid spending money on the wrong repair.

Active subsidence vs historic movement

Not all movement is active.

Historic movement means the property has moved in the past but is no longer moving. It may have been repaired, stabilised, or stopped once the original cause was addressed.

Active subsidence means the property is still moving. This is usually more serious because damage may continue to worsen until the cause is found and addressed.

The difference matters. Historic movement may only need evidence, monitoring records or cosmetic repairs. Active subsidence needs investigation and an appropriate repair plan.

How do you repair subsidence?

There is no single way to repair subsidence. The right method depends on what is causing the movement and whether the property is still moving.

Fixing leaks or drainage problems

If leaking drains or water mains are affecting the ground, the first step is usually to repair the leak. The property may then be monitored to see whether the movement stops.

Managing trees or vegetation

If trees or large shrubs are contributing to soil shrinkage, options may include pruning, root management, root barriers, or removal. This should only be done with specialist advice, especially if the tree is protected or close to neighbouring property.

Crack repairs and making good

Once the movement has stopped, visible damage can usually be repaired. This may include repointing external brickwork, repairing plaster, redecorating, or replacing damaged finishes.

Underpinning

Underpinning strengthens or deepens foundations. It is usually reserved for more serious cases where other options are not suitable. It can be expensive and disruptive, but it may be needed if the building needs additional support.

Resin injection or ground stabilisation

Some properties may be suitable for specialist ground stabilisation methods, such as resin injection. This can be less disruptive than underpinning, but it is not suitable for every property or every type of ground movement. A structural engineer or insurer-appointed specialist should advise.

Does every house with subsidence need underpinning?

Underpinning is often the repair people worry about most, but many subsidence cases do not need it.

In many cases, the first step is to deal with the cause, such as a leaking drain or vegetation-related movement, and then monitor the property. If the building stabilises, major foundation work may not be needed.

Underpinning should only be considered after proper investigation and professional advice.

What happens if you ignore subsidence?

Ignoring possible subsidence can make the problem more expensive and harder to resolve later.

Possible consequences include:

• More extensive structural damage
• Higher repair costs
• Difficulty getting building insurance
• Difficulty getting a mortgage
• Reduced property value
• Problems selling the property
• Delays during conveyancing

Subsidence can also make buyers nervous, even if repairs have been completed. If your home has had confirmed subsidence, you will usually need to disclose this when selling.

Acting early does not mean assuming the worst. It means getting the right advice before the problem has a chance to develop.

Will insurance cover subsidence repair costs?

Buildings insurance often covers subsidence damage to the main structure of your home, but this depends on your policy. Subsidence claims also usually come with a higher excess than many other types of claims.

Your insurer may cover investigation, monitoring, repair work, and making good, depending on the terms of your policy and the cause of the damage.

Before arranging major repairs yourself, check your policy and speak to your insurer. Carrying out unauthorised work could affect a claim.

Can subsidence affect selling your house?

Yes. Subsidence can affect your home’s value, saleability and insurance position.

If the issue has been properly investigated and repaired, and you have evidence that the property is stable, it may still be possible to sell. But buyers, lenders and insurers will usually want clear documentation.

Useful records may include:

• Structural engineer reports
• Survey reports
• Insurance claim documents
• Repair records
• Guarantees or warranties
• Monitoring records
• Evidence that the cause has been addressed

Being upfront is important. Trying to hide a history of subsidence can cause legal problems later.

How to reduce the risk of subsidence

You cannot prevent every cause of subsidence, but good home maintenance can reduce some risks.

Helpful steps include:

• Keep gutters and drains clear
• Repair leaks promptly
• Check the pipework and drainage if you suspect a problem
• Avoid planting large trees too close to the house
• Manage existing trees and shrubs responsibly
• Get advice before removing trees
• Watch for cracks around extensions
• Keep photos and dates if cracks appear to be changing
• Ask a professional to inspect worrying cracks early

If you live in an area with clay soil, large nearby trees, or a known history of subsidence, it is especially important to stay alert to changes.

Why choose an FMB builder for subsidence repairs?

Subsidence repairs can involve more than filling cracks. Depending on the cause and severity, work may involve drainage, brickwork, foundations, plastering, flooring, structural repairs, and making good.

An FMB builder can help carry out the repair work properly once the cause has been diagnosed. Every member must pass a vetting and independent inspection process before joining, showing their commitment to high standards and quality work.

This offers extra reassurance when choosing a builder for important work on your home.

Frequently asked questions about house subsidence