Subsidence risk areas, postcode area by postcode area
Across the 411 postcode districts with a guide so far, in 14 postcode areas, the British Geological Survey rates clay shrink-swell, the usual cause of subsidence, as significant near 12 and moderate near 823 of the 3712 sampled postcodes (in B49, B50, B78, B93, BL7, BL8 and 96 more districts).
Old non-coal mine workings are a moderate or significant hazard near 340 of the 3712 postcodes we checked (in B20, B21, B42, B43, B62, B63 and 62 more districts). Coal mining isn't included: your solicitor orders that search separately.
From British Geological Survey GeoSure and mining hazard grids, checked at 7 to 9 postcodes in each district guide, the newest built in October 2026. These are the postcode areas we've built guides for so far, not a map of the whole country. Facts with their sources, not a rating: an area with nothing found isn't safe, and one with findings isn't unsafe. The maps describe the ground, not any home.
Check a postcode
Free, from the British Geological Survey. No account needed. Coal mining isn't included.
Postcode area by postcode area
Sampled: British Geological Survey ratings around 7 to 9 postcodes in each district
| Postcode area | Districts with a guide | Clay shrink-swell moderate or significant | Non-coal mining hazard | Found in |
|---|---|---|---|---|
| B Birmingham | 77 | 24 of 720 postcodes | 83 of 720 postcodes | B20, B21, B42, B43, B49, B50, B62, B63, B64, B65, B66, B68, B69, B70, B71, B77, B78, B93 |
| BL Bolton | 9 | 10 of 72 postcodes | None of 72 postcodes | BL7, BL8 |
| BS Bristol | 37 | 211 of 336 postcodes | 52 of 336 postcodes | BS1, BS2, BS3, BS4, BS5, BS6, BS7, BS8, BS9, BS10, BS11, BS13, BS14, BS15, BS20, BS21, BS25, BS28, BS30, BS31, BS32, BS34, BS35, BS37, BS39, BS40, BS41, BS48 |
| DE Derby | 23 | 124 of 196 postcodes | 26 of 196 postcodes | DE1, DE3, DE4, DE6, DE7, DE11, DE12, DE13, DE21, DE22, DE23, DE24, DE45, DE65, DE72, DE73, DE74, DE75 |
| LS Leeds | 29 | 53 of 260 postcodes | 32 of 260 postcodes | LS5, LS12, LS13, LS17, LS19, LS20, LS21, LS22, LS23, LS24, LS25, LS28 |
| LE Leicester | 21 | 208 of 208 postcodes | 5 of 208 postcodes | LE1, LE2, LE3, LE4, LE5, LE6, LE7, LE8, LE9, LE10, LE11, LE12, LE13, LE14, LE15, LE16, LE17, LE18, LE19, LE65, LE67 |
| L Liverpool | 40 | 33 of 364 postcodes | 2 of 364 postcodes | L21, L22, L23, L30, L38, L40 |
| M Manchester | 42 | 8 of 420 postcodes | 22 of 420 postcodes | M1, M11, M12, M24, M30 |
| NG Nottingham | 29 | 88 of 264 (12 significant) | 51 of 264 postcodes | NG1, NG2, NG3, NG4, NG5, NG6, NG7, NG11, NG12, NG13, NG15, NG16, NG17, NG19, NG31, NG32, NG33, NG34 |
| OL Oldham | 16 | 63 of 128 postcodes | 10 of 128 postcodes | OL1, OL2, OL8, OL9, OL11, OL12, OL13, OL15, OL16 |
| S Sheffield | 45 | 8 of 400 postcodes | 41 of 400 postcodes | S6, S7, S10, S17, S32, S33, S36, S40, S72, S74 |
| SK Stockport | 19 | 5 of 152 postcodes | 4 of 152 postcodes | SK13, SK14, SK17, SK22 |
| WA Warrington | 16 | None of 128 postcodes | 12 of 128 postcodes | WA10, WA13 |
| WN Wigan | 8 | None of 64 postcodes | None of 64 postcodes | – |
Each district guide checks 7 to 9 postcodes spread across the district, so "5 of 61 postcodes" means five of those centres, not a share of homes. Open a district for its own guide, with every postcode listed.
Subsidence and ground town by town
The same check, district by district, for the towns with enough guides:
What it means when you buy
Check the ground around it, then the house itself:
- British Geological Survey ratings for shrink-swell clay, landslides, compressible ground, collapsible deposits, dissolution and running sand.
- Whether the house has had a subsidence claim or been underpinned: ask the seller.
- Cracks, sticking doors and windows, and trees close to the walls: ask your surveyor.
- In coal mining areas, your conveyancer can order a separate coal mining report.
Subsidence can be expensive to put right and can make a home harder to insure. A past claim stays on the record and usually has to be declared.
Clay is common under many towns and most homes on it never have a problem. Knowing the ground helps you decide which survey to get and what to ask your surveyor to look at.
Questions to ask about a home
- Has the house had subsidence, or an insurance claim for it?
- Has it been underpinned, and is there a certificate of structural adequacy?
- Are there large trees close to the house, and whose are they?
- Is the area a former coalfield, and has a mining search been done?
The full report checks the house itself, not the postcode, and ties each question to what it found. See an example report.