How We Assess Subsidence & Ground-Stability Risk

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In short

Our ground-stability assessment is built entirely on named, official government data: the British Geological Survey (BGS) GeoSure suite for shrink-swell clay, landslides, compressible ground and dissolution; BGS GeoClimate UKCP18 for the climate-adjusted outlook; the Mining Remediation Authority (formerly the Coal Authority) for coal-mining subsidence; and UKHSA for radon ground gas. We screen these at area level — never property-specific. The result tells you whether the ground beneath an address warrants a closer look before you buy; the report checks the exact address, and only a survey or site investigation can confirm a defect.

The official sources behind the assessment

Every hazard we screen maps to a named public dataset. We link each one so you can check the source yourself.

HazardSourceDataset
Shrink-swell clayBritish Geological Survey (BGS)GeoSure shrink–swell susceptibility
Landslides / slope instabilityBritish Geological Survey (BGS)GeoSure landslides; National Landslide Database
Compressible & collapsible ground, running sandBritish Geological Survey (BGS)GeoSure ground-stability layers
Dissolution / sinkholes (soluble rock)British Geological Survey (BGS)GeoSure soluble-rocks (dissolution) layer
Climate-adjusted shrink-swell outlookBritish Geological Survey (BGS) + Met Office UKCP18GeoClimate UKCP18 (projected shrink–swell)
Coal mining subsidenceMining Remediation Authority (formerly the Coal Authority)Coalfield / mining report data (CON29M)
Radon (ground gas)UK Health Security Agency (UKHSA)Indicative radon-affected-areas mapping

Natural ground movement — BGS GeoSure

The core of the assessment is the British Geological Survey GeoSure suite, the national reference for natural ground stability. It grades an area for six hazards: shrink-swell clay (the leading cause of UK subsidence), landslides, compressible ground, collapsible ground, running sand, and dissolution of soluble rock — the mechanism behind most natural sinkholes. We surface the susceptibility for each so a buyer can see, at a glance, which ground risks are present around an address.

A forward look — BGS GeoClimate UKCP18

Shrink-swell risk is getting worse as summers get hotter and drier. BGS GeoClimate UKCP18 combines BGS geology with the Met Office UK Climate Projections (UKCP18) to model how shrink-swell susceptibility is projected to change under future climate scenarios. Using it means the assessment reflects not just today's ground behaviour but the direction of travel — important for a home you intend to own for decades.

Mining subsidence — the Mining Remediation Authority

Around a quarter of properties in England and Wales lie within a coalfield, where former shallow workings can cause ground movement. We screen data from the Mining Remediation Authority (formerly the Coal Authority) to flag coal-mining risk, so you know up front whether a formal Coal Mining Risk Assessment (CON29M) — the definitive report your conveyancer or lender may require — is likely to be needed.

Ground gas — UKHSA radon

Ground stability is not the only thing the earth beneath a home affects. We include the UK Health Security Agency (UKHSA) indicative radon mapping so the same address check also flags radon — a naturally occurring ground gas — where the geology makes it likely. It is a different hazard from subsidence but belongs in the same “what's under this house” picture.

What this assessment can and cannot tell you

We want to be straight about the limits. This is an area-level screen of official data — never a property-specific diagnosis. It tells you whether the ground beneath a location is susceptible to a hazard, which is exactly the context you need before you offer. It cannot confirm that a specific property has subsidence, or that it does not. Only a site investigation, a structural engineer, a RICS survey or a formal Coal Mining Risk Assessment can do that. A flag is a prompt to look closer, not a verdict on the building — and most homes on susceptible ground never move.

Run the assessment on an address

Put the methodology to work. HouseCheckup screens all of the sources above for any England or Wales address, and the £24.99 Complete report turns them into a plain-English ground-stability read alongside flood, EPC and the rest of our 65+ official sources.

Check the ground by postcodeSee a sample report

Frequently asked questions

The ground-stability assessment draws on official government data: the British Geological Survey (BGS) GeoSure suite for shrink-swell clay, landslides, compressible and collapsible ground, running sand and dissolution (sinkholes); BGS GeoClimate UKCP18 for the climate-adjusted shrink-swell outlook; the Mining Remediation Authority (formerly the Coal Authority) for coal-mining subsidence; UKHSA for radon ground gas; and the BGS landslide database. We name each source so you can verify it yourself.
No — and we are candid about that. The screen works at area and point level from national datasets. It tells you whether the ground beneath a location is susceptible to a hazard, which is exactly what you need before you offer. It cannot confirm subsidence, or its absence, at a specific property — only a site investigation, a structural engineer or a formal Coal Mining Risk Assessment can do that. We treat our assessment as a first filter that tells you when to look closer, not a survey.
A conveyancer's environmental search is a formal, PI-insured report ordered after your offer is accepted. Our assessment uses overlapping official data (BGS GeoSure, mining data) but is designed for the pre-offer stage — so you can triage the ground risk cheaply before you commit to a property and its searches. The two are complementary: screen early with us, then let your conveyancer run the formal search on the property you actually pursue.
No. A flag means the underlying dataset records susceptibility in that area — for example high shrink-swell clay or a former coalfield. Most homes on susceptible ground never move, because foundation depth, drainage, trees and construction all matter too. A flag is a prompt to investigate — get a survey, ask the seller, check the insurance history — not a verdict on the building.
We refresh against the source datasets as the providers publish updates. BGS GeoSure and GeoClimate, Mining Remediation Authority coalfield data and UKHSA radon mapping are maintained by those bodies on their own cycles; we log every source and change in our public data-sources registry. Where a dataset is superseded, we update the screen to match the current official version.

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