Updated October 2026
In short: You can get an initial view of subsidence risk from postcode-level ground data, such as British Geological Survey shrink-swell clay maps and environmental search reports. But the risk to a specific house depends on its foundations, nearby trees, drains and history, so a postcode check should be followed by the right survey and questions to the seller.
What causes subsidence
| Cause | Where it's common | Warning signs |
|---|---|---|
| Shrinkable clay soils | Much of London and the South East | Seasonal cracks that open in dry summers |
| Trees and shrubs near the house | Streets with mature trees on clay | Cracks on the side nearest the tree |
| Leaking drains | Any area; worse on sandy or loose soils | Localised cracking, damp, slow drains |
| Mining and natural cavities | Former coalfields, chalk and gypsum areas | Sudden or localised movement |
How to check risk by postcode
Useful checks
- British Geological Survey ground stability information
- An environmental or ground search through your conveyancer
- Coal Authority mining report in former mining areas
- Insurer quotes: a high premium or refusal is a red flag
- Local knowledge: ask neighbours and agents about past claims
On the property itself
- Look for: diagonal cracks wider than about 3mm, especially around doors and windows; sticking doors; gaps between walls and floors or ceilings
- Ask the seller (TA6 form): previous subsidence, claims, underpinning, monitoring and certificates of structural adequacy
- Commission: a RICS Level 3 survey, and a structural engineer if anything is suspicious
Buying a home with past subsidence
It's not necessarily a deal-breaker. If movement was historic, properly repaired and monitored, and the current insurer will continue cover, the property may be fine. Expect some lenders and insurers to be cautious, and factor that into the price and your resale plans.
How Fraser Bond helps buyers and sellers
- Flagging ground and structural issues early in your search
- Honest valuations that reflect past subsidence
- Introductions to surveyors and structural engineers
- For sellers: preparing documents so buyers aren't put off
Buying and worried about subsidence?
Talk to us before you commit to surveys and searches.
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