Subsidence Repair Cost

Is your house subsiding? Is there evidence of subsidence cracks and you need to know the costs to repair it?

Subsidence is a word that's dreaded by homeowners all over. It can be an absolute tragedy and can affect the structural safety of your house as well as its value.

But how much will it cost to fix?

The cost of repairing subsidence on average can range from a few hundred pounds up to £50,000 or even more.

We've created this price guide so you can calculate exactly how much subsidence repair will cost you.

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How Much Does it Cost to Fix Subsidence?

In the worst-case scenarios of subsidence, your house may need to have some serious underpinning installed. This is not only very costly, but it is also somewhat disruptive.

What concerns you most regarding subsidence repair?

The overall cost of the repairs

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Ensuring the right repair method

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Whether insurance will cover the costs

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How long the work will take and any disruption to my home

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The impact on my property’s value

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The prices for this work can reach highs of around £50,000 in severe cases. This is quite rare, however. Most subsidence repair costs are less than this, and the average cost you can expect to pay is around £5,000-£15,000.

Fixing subsidence is never a quick or easy job. You must follow a process that includes spotting the signs of subsidence, getting a diagnosis, and then moving on to fix the problem depending on how severe it is.

Subsidence Repair Prices

Below are the average costs for hiring a tradesperson to underpin single walls in different sized rooms.

Subsidence Repair Cost per m²

The table below shows average material costs per m² for each repair method, excluding labour. In practice, most contractors quote an all-in price, so these figures are most useful as a reference when comparing quotes.

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Labour Cost of Fixing Subsidence & Timescales

The cost you can expect to spend on labour for fixing subsidence will depend a lot on the severity of the job and the methods used to fix it.

As an example, the average cost for a mass concrete underpinning is around £12,000-£14,000 for labour, and the job will take approximately 4-5 weeks.

The prices will vary a lot, however, depending on many factors, including your location and how much work needs to be done. You may also sometimes have to hire additional labourers in some cases.

For example, if you need to remove or add a floor in your property, a structural engineer will likely need to perform inspections for this type of work.

Subsidence repairs are typically completed within 4 to 5 weeks, although this can vary on the size of the property and extent of the issue. The concrete used may take longer to cure than expected, this can sometimes be a result of the weather conditions, both of which can potentially delay the work being completed.

Additional Subsidence Repair Costs

On top of the main repair work, there are several additional costs you may need to budget for. Not all of these will apply to every job.

• Structural engineer — £300 to £1,500+ (survey) or £75 to £125 per hour. A structural engineer is required for all underpinning work. They assess the cause of the subsidence, confirm the repair method, submit documentation to Building Control, and issue a Certificate of Structural Adequacy on completion.
• Party Wall Agreement — up to £1,000 per neighbour. If the affected wall is shared with a neighbouring property, the Party Wall Act applies. Written consent must be obtained before work begins, and where a neighbour does not agree, a formal Party Wall Agreement with legal documentation is required.
• Drain survey — £150 to £400. If leaking pipes are suspected as a contributing cause, a drain survey may be recommended before or after the repair work to identify and resolve the source of the problem.
• Tree root removal — £150 to £1,000. Where tree roots are the cause of clay shrinkage beneath the foundations, removal or pruning may be necessary. The cost varies depending on the size of the tree and whether full removal or root barrier installation is required.
• Removing and replacing individual bricks — £110 to £130 per m². Cracked or damaged brickwork uncovered during the repair process will need to be removed and replaced.
• Scaffolding hire — £150 to £400. Required where the affected area is difficult to access safely without it.
• Skip hire — £150 to £300. Excavated material and debris will need to be cleared from site. Confirm with your contractor whether waste removal is included in their quote.
• Painters and decorators — £50 to £100 per hour. Once structural work is complete, internal walls and ceilings affected by cracking or damp may need redecorating.
• Treating rising damp — around £1,250. Where water ingress has caused damp damage alongside the structural movement, damp proofing treatment may be needed as a separate remediation step.

Factors That Impact Subsidence Repair Costs

There are a number of things that may affect the overall cost of the job. Below is a list of the things that could affect the cost of fixing subsidence:

Type of Subsidence Repair Method

The type of subsidence repair method that is used can affect the overall cost of the job. For example, the cost of the mass concrete method of underpinning on a 2-bedroom terraced house is around £5,000-£7,000 on average, whereas the cost for the mini piling method on the same size property is around £20,000-£22,000 on average.

Size of Property

The size of your property can also affect the overall cost of the job by a significant amount. For example, the price for Resin injector underpinning on a 2-bedroom terraced house is around £4,000-£5,000 on average.

In contrast, the same type of subsidence fix on a four-bedroom detached house is around £15,000-£17,000 on average.

Extent of Damage

The cost of the job can vary depending on the extent of the damage. The more damage there is to the property, the more difficult the job will be to fix, and the job will also take much longer.

Properties that have more damage than others can expect to pay more for the overall cost of the job. Those with extensive damage can expect to pay anywhere up to around £50,000.

Location of Property

The location of your property can affect the cost of the job. Those based in London can expect to pay anywhere from £1,000-£10,000 more for the total cost of the job than those based in the North or other parts of the UK.

What Are the Warning Signs to Look Out For?

There are a number of signs you can look out for that could suggest there's an issue with subsidence in your property:

• Loose bay windows.
• Doors and windows sticking or not opening/closing properly.
• Wallpaper ripples.
• Diagonal cracks that appear wider at the top than the bottom.
• Signs that a new extension may be moving away from the rest of the property.
• Cracks or splits in the walls.
• Walls leaning inwards or outwards.
• Uneven floors.
• If your neighbours have had underpinning.

Should you be concerned or need a second opinion, then a qualified structural engineer or your local building control department should be able to help.

Causes of Subsidence

There are several potential causes of subsidence. It is usually caused by one of the following:

Clay Shrinkage

This is the most common cause of subsidence. Clay contains a lot of water, and so soil that contains a lot of clay can dry out if nearby vegetation takes up a lot of the water content. The volume of the soil then decreases, and this causes the foundations to subside.

Trees

Trees can sometimes cause structural problems to a property because of the shrinkage of clay subsoil underneath the foundations. Tree roots can dry clay soils (causing shrinkage/subsidence). After major tree removal, clay can re-swell (heave), so anti-heave measures may be needed.

Water Escaping

If water is escaping from the pipes beneath your home, this can wash away some of the particles of the soil underneath your home. When this happens, you will have less soil under the house, and this can result in the foundations subsiding.

Mining

Buildings can sometimes subside due to mines underneath collapsing. This can even happen in old unused mines.

Poor Ground Quality

After a home is built, it can take some time for it to fully settle on the ground below. If the ground is poor, the house may subside more than it should, and this can be dangerous and damaging to the home.

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What's Involved in Repairing Subsidence?

Repairing subsidence is not a DIY job. Most cases take 4 to 5 weeks to complete, depending on the size of the property and the method used. Here's what to expect at each stage.

Before the Work

• Spotting the signs — Keep a lookout for warning signs such as diagonal cracks, sticking doors or windows, and uneven floors. If you notice any of these, contact a contractor or structural engineer as soon as possible.
• Professional assessment — A structural engineer will inspect the property, carry out soil tests, and confirm the cause and extent of the subsidence. This must happen before any physical repair work begins.
• Building Control notification — Underpinning is notifiable work under Building Regulations. Your contractor or structural engineer will submit the necessary application before work starts.
• Party Wall Agreement (if applicable) — If the affected wall is shared with a neighbour, written consent or a formal Party Wall Agreement must be in place before work begins.

During the Work

• Excavation — Trenches are dug where concrete will be poured, or holes are drilled for resin injection, depending on the method used.
• Reinforcement — Concrete is poured and left to cure in stages (mass concrete method), piles are driven to depth (mini-piling), or resin is injected and left to expand and harden (resin injection).
• Infilling — Any excavated soil is replaced once the repair material has set.
• Defective brickwork — Cracked or damaged bricks are removed and replaced, and wall cavity ties are renewed where needed.

After the Work

• Make good — Any defective materials are removed and the property is left in a presentable condition.
• Building Control sign-off — A Certificate of Structural Adequacy is issued by the structural engineer on completion, which is also required for insurance purposes.
• Monitoring — In some cases, crack monitors or level monitoring equipment may be left in place for a period after the repair to confirm the structure has stabilised.
• Cosmetic repairs — Once structural work is complete, you may need to hire decorators or plasterers to repair internal finishes.

Subsidence Repair Methods

There are a range of methods for fixing subsidence. Below is a list of the main methods along with the pros and cons of each type:

Mass Concrete Method

This is the most common and most straightforward method. Holes are dug in the ground around the existing foundations and concrete is then poured into these holes to provide additional strength to the existing foundations.

This is the most common and usually the most cost-effective option, good for tight budgets. The average cost for this type is around £1,400-£1600 per square metre.

Pros

• ✔ Cost-effective
• ✔ Some areas can still be used as normal during the repair
• ✔ No heavy machinery needed
• ✔ Retains and improves the existing foundations

Cons

• ✖ Time-consuming
• ✖ Concrete has to be left to cure
• ✖ Limited depths

Mini-Pile Method

Piling is best suited for deeper foundations. Specialist equipment is used in this method for deeper foundations with variable conditions. Therefore, this is the most expensive option for fixing subsidence.

This method is best suited for when you need to transfer foundations to more suitable soil and for foundations that need to be dug in further for additional support. Due to the additional depth, the use of a rig may increase the costs by quite a bit.

The average cost for this type is around £2,500-£2,800 per square metre.

Pros

• ✔ Useful for restricted areas
• ✔ Less disruptive
• ✔ Suitable for variable ground conditions

Cons

• ✖ Requires much more work
• ✖ Requires specialist machinery
• ✖ Most expensive method

Expanding Resin Injector Method

This method involves a type of glue that is mixed with a hardener and then injected into the ground underneath the existing footings. This results in a chemical reaction that makes the formula expand, and it fills out any gaps or cracks that may be present.

It also hardens anything in its path to make it much more robust. Using this method a few times can cause the property to rise, which can allow you to level it further.

The average cost for this type is around £1,100-£1,300 per square metre.

Pros

• ✔ Fast and efficient
• ✔ Clean
• ✔ Non-disruptive
• ✔ Budget-friendly

Cons

• ✖ Effectiveness can vary depending on the soil

Building Regulations & Planning Permission for Subsidence Repair

In the event of having to fix subsidence issues with underpinning, you may be required to submit a planning application in writing to your local council, especially if you live in a listed building or within a conservation area.

Planning applications generally tend to cost anywhere between £50 to £170 and usually take around 8 weeks to be approved, although this may take longer for more complex situations.

Any work carried out will require Building Regulations approval, with fees varying depending on your local council and the scope of the project. For domestic work, it's best to budget around £750.

All work must comply with The Construction (Design, and Management) Regulations. It's important to inform your local building control department about any subsidence work that needs to be completed.

Actual costs may vary by location, although a structural engineer can help guide you through all the planning permission and building regulations that need to be covered.

Checklist: Hiring Tradespeople for Subsidence Repair

Before hiring a contractor for subsidence repair, here are the key things to check:

• Get at least 3 quotes. Prices can vary significantly between contractors. Getting multiple quotes helps you understand the market rate and ensures you're not overpaying.
• Check their experience with subsidence specifically. General building experience is not the same as subsidence repair. Ask how many similar jobs they've completed and whether they can provide references or examples of previous work.
• Confirm they work with a structural engineer. All underpinning work requires structural engineer oversight. A reputable contractor will have an established working relationship with one, or be able to recommend one.
• Ask for a detailed written quote. The quote should break down costs for labour, materials, and any additional elements such as scaffolding or waste removal separately. Avoid vague estimates with no itemisation.
• Check their insurance. Ensure the contractor holds adequate public liability insurance before work begins. Ask to see evidence of this, not just their word for it.
• Look for relevant trade memberships. Reputable underpinning contractors are often members of the Association of Specialist Underpinning Contractors (ASUC), which typically provides a 12-year defect insurance guarantee. Membership of the National Federation of Builders is also a good indicator.
• Ask about guarantees. Find out whether the contractor offers any guarantee on their work, and get the terms in writing. Some modern subsidence solutions offer 10-year guarantees.
• Confirm waste removal is included. Check whether the removal of excavated material and debris is included in the quoted price, or whether this is an additional cost.
• Notify your insurer before work begins. If you intend to make an insurance claim, contact your provider before any repair work starts. They may need to approve the method being used and will likely send their own surveyor to inspect the property.
• Don't pay the full amount upfront. A staged payment structure tied to key milestones is standard practice for jobs of this size.

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