Subsidence is the word every homeowner dreads – but most suspected subsidence turns out to be something far less serious. Here is how to check for subsidence the way a surveyor does, and what to do if the signs stack up.
The five checks
1. Read the cracks. Subsidence cracks are typically diagonal, wider than 3mm, wider at the top than the bottom, and often stepped through brickwork rather than confined to plaster. Fine, straight hairline cracks are usually shrinkage, not movement.
2. Look at where they are. Movement concentrates around weak points: bay windows, porches, extension junctions and openings. Matching cracks inside and outside the same wall are more significant than either alone.
3. Test doors and windows. Frames distort as foundations move – doors and windows that suddenly stick or no longer latch are a classic secondary sign.
4. Check the floors. A marble placed on a hard floor should not consistently roll to the same corner. Sloping or springy floors near a cracked wall strengthen the picture.
5. Look outside. Large trees or shrubs within 10 metres on clay soil, leaking drains, and neighbouring building work are the three most common subsidence triggers in London and the South East.
Can subsidence be fixed?
Yes – and usually far less drastically than people fear. Most confirmed cases are resolved by removing or managing the cause: taking out an offending tree, repairing a leaking drain, then monitoring while the ground stabilises. Underpinning is the last resort, needed in only a minority of cases. Insurers handle subsidence claims routinely, and early, well-evidenced diagnosis is what keeps both the works and the premium impact small.
What to do if the signs stack up
Do not start with your insurer’s loss adjuster or a repair contractor – start with an independent diagnosis. Kingston Surveyors arranges RICS subsidence surveys across London and structural crack assessments UK-wide: a chartered specialist confirms whether it is subsidence, identifies the cause and gives you the evidence to deal with insurers from a position of strength. Call 0204 579 8270 for a free, no-obligation quote.
