Is Your Postcode in a Subsidence Risk Area?

What a subsidence check by postcode tells you

A subsidence check by postcode screens the official ground-hazard datasets for the area around a property so you can spot underground risk before you pay for surveys, searches or a structural engineer. The checker above returns all six BGS GeoSure hazards for the 5 km cell your postcode falls in, and for each one it reports both the rating for that area and how far away the nearest higher-rated cell begins — because a rating on its own, covering 65 km², tells you far less than it appears to. HouseCheckup combines two official government sources: the British Geological Survey (BGS) GeoSure suite for natural ground movement, and Coal Authority data for former and present coal workings. It is a desk-based first filter — area and point-level data a surveyor cannot see by walking the property — not a substitute for a structural survey or a formal mining report.

What causes subsidence in the UK?

The dominant cause in England and Wales is shrink-swell clay: clay-rich soils swell when wet and shrink in dry spells, moving foundations. Roughly a quarter of UK homes sit on shrink-swell ground, and the risk is rising with hotter, drier summers. Other causes the GeoSure layers cover are landslides (slope instability), compressible and collapsible ground, running sand, and dissolution of soluble rocks — the mechanism behind most natural sinkholes.

Coal mining and ground stability

Around a quarter of properties in England and Wales lie within a coalfield. Old shallow workings can cause ground movement, and lenders often require a Coal Mining Risk Assessment (CON29M) where the address falls in a referral area. Our check flags coal-mining risk from Coal Authority data alongside the natural ground hazards, so you know up front whether a mining report is likely to be needed. For a deeper, single-hazard view, see the coal mining risk check.

Sinkhole and dissolution risk

Sinkholes form where chalk, limestone or gypsum dissolves underground and the surface collapses into the void. The BGS GeoSure soluble rocks (dissolution) layer screens for exactly this, and the checker above now returns it by name alongside the other five hazards.

What it will not give you is a sinkhole map of your street, and it is worth being clear why. GeoSure rates a 5 km hexagonal cell — about 65 km², which is a town and the countryside around it. The rating describes the geology across that whole area, not the ground under one house. That is why our result always reports two things together: the rating for your area and how far away the nearest higher-rated cell begins. A “Low” area with a Significant-rated cell starting 700 m away is a materially different proposition from a Low area with nothing higher for 200 km, and a single rating word cannot tell those apart.

A raised rating is a prompt to investigate, never a verdict on a building. It means dissolution features are plausible in the area and a specialist ground investigation may be worth commissioning before you commit.

Coal, and the mining data that is not coal

Two separate datasets answer two separate questions, and conflating them is a common mistake. Mining Remediation Authority data covers coal — that is the one lenders care about, and the one behind a CON29M coal mining search. The BGS mining-hazard layer covers everything that is not coal: tin, lead, salt, ironstone and the rest. Our checker returns both, labelled, because "no known record of mining activity" in the non-coal dataset says nothing whatsoever about coal, and a buyer reading one line without the other could reasonably draw the wrong conclusion.

Can you check subsidence history or past claims by postcode?

Not from any public source — and it is worth knowing that before you spend time looking. There is no public register of subsidence insurance claims by postcode in the UK. Insurers hold claims history commercially and do not publish it at address or postcode level; the ABI publishes national aggregate figures only. Any tool offering per-postcode “subsidence claims” is not reading a claims register, because no public one exists.

What you can do instead, in the order that costs you least:

• Screen the ground first. The checker above shows what the official BGS hazard data says about the area, free, in a few seconds.
• Ask the seller. The TA6 Property Information Form asks directly whether the property has been subject to a subsidence claim. That answer carries legal weight, and it is the only address-level claims history you can reliably obtain.
• Ask about insurance. If cover has ever been declined, loaded or excluded for ground movement, that tells you something the geology alone cannot.
• Commission a survey where any of the above raises a question. A Level 3 building survey assesses the actual building; ground data describes the area it stands in. They answer different questions and you may want both.

Why subsidence risk affects price and insurance

Subsidence is one of the few risks that can directly stop a sale or inflate costs for the life of the home. Properties with a subsidence history, or in high-risk ground, can face higher insurance premiums and excesses, and buyers routinely use a flagged risk to renegotiate. Checking the ground before you offer lets you price the risk in — or walk away — rather than discovering it during a failed mortgage valuation.

From a postcode screen to a full address report

The postcode check works at postcode level. When you've shortlisted a property, the Complete report (£24.99) goes deeper on the specific address, combining the ground-stability assessment with flood risk, radon, the EPC and more — 15+ official-source checks in one place — the underground and environmental picture that decides whether a home survives due diligence.