Most homeowners search for photos before they call anyone. So what does subsidence look like in practice — and how do you tell it apart from ordinary settlement cracks that almost every property has?
The visual signs of subsidence
The classic sign is diagonal cracking, wider at the top than the bottom, running through walls near doors and windows. Look for cracks wider than 3mm (roughly a £1 coin’s thickness), cracks visible inside and outside at the same spot, wallpaper rippling at wall junctions, doors and windows that suddenly stick, and floors that slope or bounce. Cracks that keep growing over weeks are the strongest signal of ongoing movement.
What it is often confused with
Hairline cracks from plaster shrinkage, thermal movement and new-build settling are common and rarely serious. Our guide on how to check for subsidence walks through a five-minute checklist, and a structural crack assessment can classify the damage formally using the BRE scale.
Can subsidence be fixed?
Yes — and most cases do not need underpinning. How you fix subsidence depends on the cause: tree roots drying out clay soil, leaking drains washing away ground, or inadequate foundations. Remedies range from tree management and drain repairs to root barriers, with underpinning reserved for the minority of severe cases.
How much does it cost to repair subsidence?
Minor repairs tied to drainage or vegetation may cost a few thousand pounds; full underpinning typically runs from £10,000 to £50,000+, which is why insurers insist on proper investigation first. Buildings insurance usually covers subsidence damage, subject to a £1,000 excess.
Get it diagnosed before you panic — or buy
A subsidence survey establishes whether movement is historic or ongoing, what is causing it, and what to do next — essential evidence for insurance claims and invaluable when purchasing a property with suspicious cracks.
Speak to a surveyor before it becomes a dispute
Kingston Surveyors arranges RICS party wall surveyors, building surveys and valuations across London and the surrounding counties. If you are unsure where you stand, call us on 0204 579 8270 or request a call back and we will organise the right professional for your situation — usually with an appointment within days.
