Damp and moisture meters
A stain on the inner reveal sits under a cracked outside sill, and the base of the wall is dry. Why does that pattern point away from rising damp?
The stain on the inner reveal, under a cracked outside sill, with a dry base to the wall, points away from rising damp. The pattern fits rain getting past the sill, not moisture climbing from the ground. The dry base is part of that reading. The crack and the stain are reasons to investigate this opening. They are not a diagnosis of the whole wall, and a meter on the reveal is only an aid.
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?
Position is what separates this stain from a rising-damp reading, and the useful word is pattern rather than proof. The mark is on the reveal, beneath a crack in the sill, and the base of the wall is dry. Water through a cracked sill can wet that reveal without involving the damp-proof course at all. The comment belongs to the opening.
Look at the sill before anyone talks of injecting the wall. Do not move this stain into a rising-damp paragraph merely because it is low in the room. Low on a reveal is not a tide mark along the base. One cracked sill is not the whole elevation, and no repair price should be invented from the visit.
What should you ask your surveyor?
- Is the stain limited to the reveal directly under the cracked sill?
- Was the base of that wall dry, away from the stained reveal?
- Are you reading this pattern as pointing away from rising damp?
What are the typical next steps?
- Investigate the cracked sill before you consider any damp-proof treatment.
- Do not relabel this reveal stain as rising damp.
- Keep the comment on this opening rather than on the whole wall.
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
Could a cracked sill and rising damp both be present in this wall?
They could, but this pattern does not show both. The dry base points away from rising damp. Do not add a cause the survey did not see.
Does the stain prove the cavity is full of water?
No. It records a stain under a cracked sill. It does not describe the cavity, and it does not prove how far any water has travelled.