Subsidence, settlement and heave
What does a crack that is wider at the top over a door suggest, and what does it not prove?
A tapering crack over an opening often means the masonry is moving around a weak point, sometimes because a lintel has failed and sometimes because support under a corner has changed. The shape is a clue, not a diagnosis of subsidence, and it is not a measurement of whether the movement is still live.
Last reviewed 24 October 2026. Written for buyers in England and Wales unless this answer says otherwise. No named surveyor has signed this page. It is general guidance, not a report on your house, and not legal advice.
What is the fuller explanation?
Surveyors describe width, direction and whether the crack goes through the bricks or only the render. A crack that stops at a lintel is a different sentence from one that runs down to the damp-proof course. A single visit cannot show whether it grew last year. The Association of British Insurers describes subsidence as downward movement of the ground under the building. One crack does not prove that definition has been met.
Further investigation might be a lintel exposure, a drain test, or monitoring. Those are different instructions and different costs, and none of them is silently included in a Level 2. Ask the surveyor which cause they think is likely and which they cannot rule out. Do not rake out and repoint before that, or you will hide the evidence.
What should you ask your surveyor?
- Does the crack pass through the lintel, past it, or only through the plaster?
- Is it wider at the top, and does it continue outside?
- What investigation would tell a lintel failure from foundation movement?
What are the typical next steps?
- Photograph it with a ruler before any decorating.
- Do not let a builder fill it until you know whether you need it as evidence.
- If you need to know before exchange, instruct the specific investigation the surveyor named, not a generic “structural survey” repeat.
Costs vary with the building and with who you instruct. Where this page does not cite a published figure, ask the surveyor, a relevant specialist, or your solicitor for a written quote. Do not treat a forum average as the price.
Also asked about this
Is every crack over a door a lintel?
No. Openings are weak points, so many causes show there. Ask what else was seen: a dropped brick, a rotting timber lintel, or movement in the wall beside it.
Does a hairline crack meet the ABI description of subsidence?
Not by width alone. The ABI is describing ground movement under the building. The surveyor has to connect the crack to that, and often they cannot on one visit.