Condition
Subsidence Cracks: How to Spot Them in Your Home
Subsidence cracks are typically diagonal, wider than 3mm (about a 10p coin), wider at the top, and appear around doors and windows or where extensions join — often with doors/windows sticking. They differ from harmless hairline settlement cracks. Causes include clay-soil shrinkage, nearby trees, and leaking drains. If you suspect subsidence, get a structural engineer’s assessment — and know you can still sell, including as-is to a cash buyer.
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- Over 3mmdiagonal = concern
- Engineerconfirms the cause
- 7-28 dayscash, as-is
What subsidence cracks look like
| Sign | Detail |
|---|---|
| Diagonal cracks | Running at an angle, not straight |
| Wider than ~3mm | Thicker than a 10p coin edge |
| Wider at the top | Tapering, often a tell-tale sign |
| Near openings/extensions | Around doors, windows, where extensions join |
| Sticking doors/windows | Frames distorting as the ground moves |
Telling subsidence from harmless cracks
Most cracks in homes are not subsidence — fine hairline cracks from normal settlement, seasonal movement, or plaster shrinkage are common and harmless, especially in newer or recently renovated homes. Subsidence is suggested by cracks that are diagonal, over ~3mm wide, growing, tapering wider at the top, and concentrated around weak points (openings, extension joins), often with sticking doors/windows and visible inside and out. The pattern and progression matter more than a single crack — monitoring whether cracks widen over time helps distinguish the two.
What causes subsidence
Subsidence happens when the ground beneath the foundations moves or sinks. Common UK causes are clay-soil shrinkage in dry weather (clay swells when wet, shrinks when dry), tree roots drawing moisture from the soil near the house, leaking drains or water pipes washing away or softening the ground, and historic made-up ground or mining. Identifying the cause is the first step to the fix — for example removing or managing a problem tree, or repairing a leaking drain, sometimes resolves it without underpinning.
What to do if you suspect it
If you suspect subsidence, don’t panic — get a structural engineer’s assessment to confirm whether it’s subsidence, the cause, and the remedy. Notify your buildings insurer, as subsidence claims are usually covered (subject to an excess), and they may arrange monitoring and remediation. Remedies range from managing trees or fixing drains to, in serious cases, underpinning. Keep all reports and documentation — they’re essential when you come to sell (see selling with subsidence).
Selling a home with subsidence
A history of subsidence doesn’t stop a sale, but you must disclose it and provide the engineer’s reports, insurance and any remediation records — a resolved, monitored case is far less alarming to buyers than an unexplained crack. Where active or recent subsidence makes mortgage buyers cautious, a cash buyer experienced with structural issues can purchase as-is in 7-28 days, without a lender. The trade-off is price for speed and certainty. Provide all structural documentation so any offer is informed.
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Written & reviewed by Lisa Hayes, Founder
Lisa Hayes is the founder of Ready Steady Sell and an independent UK home-selling expert with over a decade helping homeowners weigh cash house buyers, property investors and the wider fast house-sale industry — without pressure or hidden fees. Every guide is reviewed for accuracy under our editorial standards.
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Frequently asked questions
Straight answers, no sales talk
How do I spot subsidence cracks?
Look for diagonal cracks wider than ~3mm, often wider at the top, near doors, windows or where extensions join, frequently with sticking doors/windows and visible inside and out.
Are all cracks a sign of subsidence?
No — most cracks are harmless hairline settlement, seasonal movement or plaster shrinkage. Subsidence is suggested by wide, diagonal, growing cracks around weak points.
What causes subsidence?
Ground movement beneath the foundations — commonly clay-soil shrinkage in dry weather, tree roots drawing moisture, leaking drains softening the ground, and made-up ground or mining.
What should I do if I suspect subsidence?
Get a structural engineer’s assessment to confirm it, the cause and the remedy, and notify your buildings insurer — subsidence is usually covered, subject to an excess.
Can I sell a house with subsidence?
Yes — it doesn’t stop a sale, but you must disclose it and provide engineer’s reports, insurance and remediation records. A resolved, monitored case reassures buyers.
How do I sell a house with active subsidence?
A cash buyer experienced with structural issues can purchase as-is in 7-28 days, without a lender. The trade-off is price for speed and certainty.