Subsidence, settlement and heave
Does filler or mastic in a crack prove the movement has stopped?
No. Filler hides the crack for a while. If the crack opens again, the filler splits. If it has not split yet, you still do not have a history, because a home survey is one visit. The Association of British Insurers describes subsidence as downward movement of the ground. Mastic is not evidence that movement has finished, and it is not evidence it is ongoing.
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?
Fresh filler over an old crack is something the surveyor should mention, because it changes what they can see. They still cannot date the crack or say it is stable. Monitoring needs more than one measurement. A single filled line is not monitoring. ABI’s claims pages are about people who already insure the house. They do not tell a buyer the filler has worked.
Ask the seller when it was filled and whether it has been filled before. That is a question, not a confession of subsidence. Do not rake the filler out on a viewing. There is no RICS price for monitoring or for underpinning. Get advice on the crack the survey described, not on the colour of the mastic.
What should you ask your surveyor?
- Is the filler intact, split, or too new to tell?
- Are you saying the crack is live, historic, or simply not dated?
- What would need measuring if someone were to monitor it?
What are the typical next steps?
- Do not treat a neat bead of mastic as a structural repair.
- Ask the seller for any monitoring or insurance papers.
- If you need a trend, that is a further instruction before you rely on one photograph.
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
Does repointing over a crack do the same job as mastic?
It hides the brick joint. It does not date the movement. Fresh pointing is a clue, not a cure.
Should you fill the crack before exchange to tidy the sale?
No. You would be hiding the evidence the next inspection needs.