Free subsidence risk postcode checker. Around 4.5 million UK homes are in areas with some level of clay shrink-swell risk. LocalRisk uses British Geological Survey GeoClimate data to show ground stability ratings for 1.8 million UK postcodes - essential before buying a property, remortgaging, or reviewing home insurance.
Most UK subsidence stems from clay shrink-swell. Clay-rich soils expand when wet and contract when dry, and this volume change puts pressure on foundations. Hot, dry summers speed the process up. Trees planted close to buildings can make things worse by drawing large amounts of moisture from the ground - species like oak, poplar, and willow are particularly thirsty.
Enter your postcode above for an area-level indication based on British Geological Survey shrink-swell data. The result shows whether the ground beneath your postcode falls into the Lower, Medium, or Higher band for clay-related movement potential. For a property-specific assessment - especially before buying - a structural survey or the BGS Property Subsidence Assessment service provides more detail.
A documented subsidence history can affect saleability and price, with the size of any discount depending on the severity of the movement, the quality of the repair, and the property's wider attributes. Sales of properties with a subsidence history can take longer to complete than typical transactions because of the additional documentation buyers and their advisers need to review. Simply being in a high-risk area without any actual subsidence doesn't have the same effect, but it's still worth knowing before you commit to a purchase.
No. Flood Re helps make flood insurance affordable for eligible high-risk homes, but there is no equivalent for subsidence. Cover is handled through the standard insurance market. Most buildings policies include subsidence as standard, but the excess is typically higher - often around £1,000 - and a documented claims history or higher-risk postcode can affect what insurers offer.
Subsidence risk is highest where clay soils are most common: south-east England, London, the Thames Valley, and parts of the Midlands. The BGS identifies these areas as having moderate to high shrink-swell potential. As summers grow hotter and drier, the at-risk zone is projected to spread further north and intensify in the south.
Keep trees and large shrubs managed - especially water-hungry species near foundations. Maintain gutters, pipes, and drainage to prevent water pooling unevenly around the building. Watch for early warning signs: new or widening diagonal cracks around windows and doors, doors or windows that stick, or visible gaps where walls meet ceilings. An arborist can advise on safe planting distances for your soil type.
We use the British Geological Survey's GeoClimate shrink-swell dataset, which classifies every area of the UK by the volume-change potential of the underlying soil. Postcode-level results reflect the predominant ground conditions in that area. This is an area indicator - individual properties can vary depending on their specific geology, foundation type, and proximity to vegetation.