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Read Full Bio >By Dan Green, Home Selling Expert · Last updated: 7 August 2026
Subsidence typically devalues a UK property by 10–25%, depending on severity. Minor, repaired and well-documented subsidence may cost as little as 5–10% of value, while severe or active movement can wipe 25% or more off the price.
There is no fixed tariff: the discount a buyer applies depends on how bad the movement is, whether it is still active, what it costs to fix, and how well you can evidence the repairs. This guide sets out the typical devaluation bands UK surveyors and buyers work to in 2026, current repair costs, the insurance and mortgage consequences, your legal duty to declare subsidence, and the realistic ways to sell a subsidence-affected home.
TL;DR — key takeaways
- Subsidence typically reduces a UK property’s value by 10–25%, and a rough rule of thumb is the full cost of repairs plus around 10% for the remaining “stigma” discount.
- Historical subsidence that was professionally repaired and certified usually costs 5–10% of value; active, unrepaired subsidence can cost 25% or more and often makes a home unmortgageable.
- Underpinning a house in the UK typically costs £6,000–£25,000 in 2026, with an average around £13,000, according to industry cost data from Checkatrade and MyJobQuote.
- UK sellers are legally required to declare known subsidence, including past repairs and insurance claims, on the Law Society’s TA6 Property Information Form.
- Cash buyers such as Springbok Properties can buy subsidence-affected homes without a mortgage, which removes the biggest obstacle to selling one.
How much does subsidence devalue a property in the UK?
Subsidence usually devalues a UK property by 10–25%, and the widely used rule of thumb is that the loss equals the cost of repairs plus roughly 10% on top. The table below shows the typical bands used in UK valuations and negotiations in 2026.
| Severity of subsidence | Typical devaluation | What it means in practice |
|---|---|---|
| Minor and historical — repaired, stable, fully documented | 0–10% | Most lenders will still lend; insurance is available but premiums are often higher. |
| Moderate — underpinned with certification and a clean structural report | 10–15% | Sellable on the open market, but buyers negotiate hard and some insurers decline cover. |
| Moderate and active — needs underpinning, structurally salvageable | 15–25% | Most mortgage lenders refuse to lend, so the buyer pool shrinks to cash buyers. |
| Severe or active with no evidence of repair | 25%+ | Often effectively unsellable on the open market until repairs are done. |
These bands are indicative market ranges, not legal tariffs. They reflect how buyers price risk: once subsidence appears in a survey, most purchasers assume future movement, higher insurance premiums and resale difficulty — even where repairs were done properly. That is why a stigma discount usually survives a good repair.
What decides how much value you lose?
Five factors determine whether subsidence costs you 5% or more than 25% of your home’s value: severity, cause, whether the movement is active or historical, the quality of your paperwork, and mortgageability.
Severity — the BRE crack categories
UK structural engineers classify crack damage using BRE Digest 251 (Assessment of damage in low-rise buildings), published by the Building Research Establishment (BRE). Cracks do not need to be huge to matter: from Category 3 (5mm) upwards, damage may indicate foundation movement needing structural investigation.
| BRE category | Crack width | Typical repair |
|---|---|---|
| 0 | Under 0.1mm (hairline) | None required |
| 1 | Up to 1mm | Normal decoration |
| 2 | Up to 5mm | Filler and redecoration |
| 3 | 5–15mm | Repointing and some brickwork replacement |
| 4 | 15–25mm | Replacing sections of wall |
| 5 | Over 25mm | Major structural repair or partial rebuild |
Active versus historical movement
Active subsidence — movement that is still happening — is far more damaging to value than historical subsidence that was repaired and has been stable for years. A property underpinned five years ago with an engineer’s sign-off and a completion certificate is a completely different proposition to one with fresh, widening cracks.
Paperwork and evidence
Buyers and their surveyors price in uncertainty. A full evidence pack — structural engineer’s reports, details of works, building control sign-off, guarantees, insurance claim records and any monitoring data — consistently reduces the discount. Note that subsidence insurance claims are recorded on the Claims and Underwriting Exchange (CUE) database, so a claim history is visible to future insurers regardless.
Mortgageability
Active subsidence usually makes a property unmortgageable: most UK lenders will not approve a loan without a satisfactory structural engineer’s report. That cuts your buyer pool to cash purchasers only, and a smaller buyer pool means lower offers — often a bigger driver of the discount than the repair bill itself.
What are the signs of subsidence?
The classic sign of subsidence is a diagonal or stepped crack, wider at the top than the bottom, near a door or window. According to BRE and Association of British Insurers (ABI) guidance, the warning signs to check are:
- Diagonal cracks wider than 3mm that are visible inside and outside the property;
- Doors and windows that stick, jam or no longer close properly;
- Noticeably sloping or uneven floors;
- Gaps opening between walls and ceilings or skirting boards;
- Cracks where an extension meets the original building;
- Wallpaper wrinkling or rippling at the wall–ceiling join;
- Sinking or dipping paths and driveways around the property.
Not every crack is subsidence. Hairline cracks under 2mm are common in older homes and new-builds alike, caused by thermal movement and plaster shrinkage. It is cracks that keep growing, or several signs appearing together, that justify calling a structural engineer or RICS surveyor.
What causes subsidence?
The main cause of subsidence in the UK is the shrinking and swelling of clay-rich soils, which the British Geological Survey (BGS) describes as one of the most damaging geohazards in Britain, costing the economy an estimated £3 billion over the past decade. Clay soils — especially London Clay, Weald Clay and Oxford Clay across the South East, East Anglia and parts of the Midlands — absorb water and swell when wet, then shrink as they dry, moving the foundations above them.
Other common causes include tree roots drawing moisture from the ground near the property, leaking drains or burst pipes washing away supporting soil, and historic mining activity destabilising the ground. Pre-1950s homes with shallow foundations on clay soils are the highest-risk combination, and the BGS warns that hotter, drier summers are projected to increase shrink–swell subsidence in the decades ahead. You can check your postcode’s risk free using the BGS shrink–swell hazard maps.
How much does it cost to fix subsidence in 2026?
Underpinning a house in the UK typically costs £6,000–£25,000 in 2026, with an average around £13,000–£13,500, according to cost data from Checkatrade and MyJobQuote. The method — and therefore the price — depends on the ground conditions and the severity of movement.
| Repair method / cost item | Typical 2026 cost | Notes |
|---|---|---|
| Mass concrete underpinning | ~£1,500 per m² | Traditional staged excavation; usually 3–6 weeks |
| Beam and base underpinning | ~£2,000 per m² | Reinforced beam spreads the load |
| Mini-piled underpinning | ~£2,600 per m² | For deep foundations or variable ground |
| Resin injection | ~£1,200 per m² | Less invasive; often done in a day; not suitable for every case |
| Structural engineer | From ~£300 initial; £2,500–£5,000 project oversight | Required for diagnosis and lender sign-off |
| Party wall agreement | Up to £1,000 per neighbour | Needed where walls are shared |
| CCTV drain survey | £100–£250 | Checks for leaking drains as the cause |
Stabilising the foundations is rarely the end of the bill. Follow-on repairs commonly include brickwork repairs (materials around £120 per m² plus a bricklayer at £150–£400 per day), re-rendering external walls (£60–£80 per m²), replacing warped window and door frames (from £300–£500 per frame) and internal replastering and redecorating. Costs run higher in London and the South East, and where monitoring is required before work starts, the whole process can take a year or more.
Does home insurance cover subsidence?
Standard UK buildings insurance normally covers subsidence damage, but ABI guidance highlights three important caveats. First, most policies carry a subsidence excess of around £1,000 — much higher than the standard excess. Second, damage to garden walls, fences, patios and driveways is generally excluded unless the main structure is also damaged. Third, insurance will not cover pre-existing subsidence that was present before you took the policy out.
Once a property has a subsidence history, mainstream insurers may charge substantially higher premiums or decline cover altogether; specialist insurers exist, and the ABI recommends finding one through a British Insurance Brokers’ Association (BIBA) broker. If you are planning to sell, it is often worth claiming and letting your insurer manage and fund the repairs first, rather than passing the uncertainty to a buyer.
Do you have to declare subsidence when selling?
Yes. UK sellers must declare known subsidence — including past movement, repairs and insurance claims — on the Law Society’s TA6 Property Information Form during conveyancing, even if the problem was fixed years ago. Answering dishonestly exposes you to a misrepresentation claim after completion, which can mean paying damages that reflect the buyer’s losses plus legal fees.
In practice, concealment rarely works anyway: any competent surveyor will spot signs of past movement, and insurance claims are recorded on the CUE database. Being upfront early — ideally with a structural engineer’s report and, where relevant, the local authority completion certificate for underpinning in hand — keeps the negotiation measured and reduces the risk of the sale collapsing late. Around 24% of UK house sales fall through before completion, and late survey surprises are a leading cause; see our guide to why house sales fall through.
Can you sell a house with subsidence — and what are your options?
Yes, you can sell a house with subsidence. You have three realistic routes, and the right one depends on your budget, timescale and how severe the problem is.
- Repair first, then sell on the open market. Fixing the problem, with certification, recovers the most value — you will usually still see a residual discount of around 5–10%, but far less than selling unrepaired. This suits sellers who can fund the works and wait months (sometimes a year with monitoring).
- Sell as-is on the open market at a reduced price. Expect to deduct at least the full repair cost plus a stigma margin, and be prepared for mortgage-dependent buyers to drop out. A structural report and repair quotes shared upfront help offers hold.
- Sell to a genuine cash buyer. Because cash home buyers need no mortgage, active subsidence is not a deal-breaker and there is no chain. The offer will reflect repair costs, but the sale is fast and certain, with no agent or legal fees. Springbok Properties buys homes with structural issues, including subsidence, in as little as 7–28 days.
If your home has been underpinned and you are weighing up whether that alone affects the price, our guide to whether underpinning devalues a house covers it in detail.
Here is what selling to Springbok looked like for two owners whose properties were getting no interest on the open market:
Frequently asked questions
How much does subsidence devalue a property in the UK?
Typically 10–25%. Minor, repaired and documented subsidence usually costs 5–10% of value, moderate cases with certified underpinning around 10–15%, and severe or active movement 25% or more. A common rule of thumb is the repair cost plus roughly 10% on top.
Can you sell a house with subsidence?
Yes. You can repair it first and sell on the open market, sell as-is at a reduced price, or sell to a cash buyer. Active subsidence usually blocks mortgage lending, so unrepaired homes generally sell to cash purchasers such as investors or professional home-buying companies.
How much does subsidence cost to fix in 2026?
Underpinning typically costs £6,000–£25,000, averaging around £13,000, based on Checkatrade and MyJobQuote data. Per square metre, expect roughly £1,200 for resin injection, £1,500 for mass concrete, £2,000 for beam and base, and £2,600 for mini-piled underpinning, plus engineer and survey fees.
Do you have to declare subsidence when selling a house?
Yes. You must disclose known subsidence, past repairs and related insurance claims on the TA6 Property Information Form during conveyancing. Failing to do so honestly can lead to a misrepresentation claim, damages and legal costs after the sale completes, so full disclosure is both legally required and safer.
Can you get a mortgage on a house with subsidence?
Usually not while subsidence is active: most UK lenders require a satisfactory structural engineer’s report before lending. Where subsidence is historical, repaired and certified, many lenders will lend, though some apply stricter conditions. Unmortgageable homes can still be bought by cash buyers.
Does buildings insurance cover subsidence?
Most standard UK buildings policies cover subsidence damage, but with a higher excess of around £1,000, and garden structures are usually excluded. Pre-existing subsidence is not covered, and homes with a subsidence history often need specialist insurance at higher premiums, according to the Association of British Insurers.
Need to sell a home with subsidence?
If you cannot afford the repairs, or you simply do not want months of uncertainty, Springbok Properties will make a free, no-obligation cash offer on any property — subsidence included — and can complete in as little as 7 days, with no agent fees and no legal fees. As a founding member of the National Association of Property Buyers (NAPB) and a member of The Property Ombudsman (TPO) scheme, we do what we say we will. Learn more about how we buy any house, or read what to do if you feel your house just won’t sell.
