Guide
Subsidence signs: how to tell, and what to do next
Updated
Subsidence is downward movement of the ground supporting a building. It is less common than the cracking folklore suggests, and when it is genuine, the order in which you act affects both the fix and who pays for it.
The signs, in combination
- Diagonal cracking, wider at the top than the bottom, often stepped through mortar joints in brickwork, typically concentrated near doors, windows or where an extension meets the original house.
- Cracks visible inside and outside at the same position, appearing or growing after long dry spells.
- Doors and windows sticking as frames distort out of square.
- Rippling wallpaper or cracking at wall-ceiling junctions without a decorating explanation.
- Context: shrinkable clay soil, mature thirsty trees (oak, willow, poplar) near the building, leaking drains softening the ground, or a neighbourhood history of claims. No single sign is proof; the pattern is the evidence.
What it is not
Most cracking is not subsidence. New-build settlement, thermal and moisture movement, and lintel or plaster failures produce cracks too, usually vertical or horizontal, stable, and modest in width. The BRE damage categories put widths in context: below 5mm is usually cosmetic territory. See cracks: when to worry before assuming the worst.
The right order of calls
- Buildings insurer first, if you own and insure the property and the signs are credible. Subsidence is a standard buildings peril; the insurer appoints and funds the investigation and repair. Policy excesses for subsidence are typically higher than for other perils, commonly around £1,000, check your schedule.
- Independent engineer's report (£250–£500 typical 2026 fees) where you want an assessment before involving the insurer, where you are buying the property, or where a claim is disputed. Mid-purchase, this report is the difference between renegotiating and walking away.
- Expect monitoring, not instant verdicts. Genuine investigations often monitor crack movement across seasons before prescribing. Underpinning is the last resort, not the default: many claims resolve with tree management or drain repairs.
- Be sceptical of unsolicited diagnoses from anyone selling the remedy, the same conflict of interest that runs through building defects generally.
Selling or remortgaging a property with a subsidence history is manageable but disclosure-sensitive: keep the engineer's reports, the completion certificates for any works, and the insurer's claim records together; buyers' lenders will ask for them.