Damp and moisture meters
If only one elevation is wet, and only after wind-driven rain, is that rising damp?
No. Wetting on one elevation, and only after wind-driven rain, is weather hitting that face. Rain is being pushed through pointing, render, a joint or a detail on the exposed side. Rising damp would not wait for a particular wind and would not spare the other walls.
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?
Houses have a weather face. In much of Britain that is the south-west, but the exposed side is whatever the site and the neighbours make it. After a driving rain the inside of that face stains, the other three stay dry, and a few dry days later the mark fades. That is penetrating damp. A cavity tray over one window can do a local version of the same thing. An entire elevation that wets only in driving rain is the wall face, not a single tray, and it is still not groundwater. The surveyor may not visit in a storm. They can still record which elevation is marked and which are not.
A visual survey does not hose the wall and does not guarantee the cavity. If the report names one elevation and rain, do not let a contractor rewrite it as a failed damp-proof course on all four sides. Ask what the outside of that face showed: cracks, open joints, failed render, or a detail they could not see. Repointing or repairing that face is a different job from injecting the base of every wall.
What should you ask your surveyor?
- Which elevation is affected, and were the others dry?
- Does the damp appear after wind-driven rain rather than all the time?
- What did the outside of that face actually show?
What are the typical next steps?
- Do not treat a weather-face stain as rising damp on the whole house.
- Match the inside marks to the outside face before you ask for quotes.
- If the surveyor did not see that elevation closely, say so. Do not fill the gap with a product.
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
Can one leaking window do this on its own?
Yes. A single opening can wet the reveal in driving rain. An elevation-wide pattern is broader than one window.
Does a dry survey day clear the weather face?
No. It means it was not raining then. The pattern after storms is the evidence.