A specialist subsidence survey is more focused than a standard homebuyer report. The surveyor is looking for evidence of foundation movement, the likely cause, and whether the movement is ongoing or has stopped. A typical visit lasts two to three hours and covers the external elevations, the internal walls and ceilings, the floors for slope, and the drainage where it is accessible.
Expect the surveyor to use a measured crack gauge, a spirit level or laser, and a moisture meter. They will sketch crack patterns, note their width and direction, and photograph each one against a reference. They will ask about the age of the cracks, recent building work, nearby trees, and any drainage issues you have noticed. Good surveyors also check the loft for evidence of roof spread and the cellar or sub-floor void where one is accessible.
The output should be a clear written report with photographs, a diagnosis, and a recommendation. That recommendation might be no action, a period of monitoring, a CCTV drain survey, soil sampling, or referral to a structural engineer. A useful report is one you can hand to your insurer or a buyer with confidence, not a vague document that simply suggests further investigation.
Timing matters more than most homeowners realise. Subsidence is a seasonal phenomenon in the UK, driven by the wetting and drying cycle of clay soils, and the picture a surveyor sees in late summer is often very different from the one in February. Where movement is suspected but not yet confirmed, a sensible report will recommend a monitoring period that straddles at least one full season, with measurements taken at fixed intervals and compared against a calibrated baseline.
The best surveys also look at history. Was the property extended in the last twenty years, and on what foundations. Are there mature trees within fifteen metres, and what species. Were the drains relined recently, and was the work signed off. Has the street suffered any sinkholes, mining issues or burst mains in living memory. Local knowledge and a careful read of the conveyancing pack often unlock a diagnosis far more quickly than any instrument on site.
