Damp and moisture meters
Staining shows only behind a wardrobe on an outside wall. Why is that pattern closer to condensation than to a failed damp course, and why is it still unproved?
The pattern is closer to condensation because the stain shows only behind a wardrobe on an outside wall, where air cannot circulate and the cold surface can wet the plaster. A failed damp-proof course more often leaves a tide along the base of the wall, not a patch hidden only by furniture. It is still unproved. The survey did not monitor the spot, did not sample salts and did not open the wall. One stain on one day is a pattern, not a result that names the cause.
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?
Condensation forms where moist room air meets a cold surface and then cannot dry. A wardrobe against an outside wall makes that corner colder and stiller, so a mark can sit exactly behind the furniture and nowhere else. Rising damp from a failed course is a different mechanism, usually a low horizontal band that does not stop at the sides of a wardrobe. The pattern points. It does not finish the proof, because furniture, a spill or a leak in that corner could mark the same plaster.
Ask the seller how long the wardrobe has stood there and whether the stain returns if the wall is cleared and heated. A damp specialist can monitor humidity and the surface if you need a cause rather than a pattern. The survey has not appointed that specialist and has not failed the damp course. Tell a lender the stain is local, behind furniture, and unproved. Do not pay for a new damp course on this note alone.
What should you ask your surveyor?
- Does the stain stop where the wardrobe stops, rather than forming a tide?
- Were salts sampled or the wall opened behind the furniture?
- Has the damp-proof course been declared failed from this one patch?
What are the typical next steps?
- Read the mark as a condensation pattern that is still unproved.
- Ask the seller how long the wardrobe has covered that wall.
- Instruct a damp investigation only if you need the cause confirmed.
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
Would a tide mark at skirting level have pointed another way?
Yes. A fairly level band along the base of a wall is the pattern people associate with moisture rising from the ground. A patch only behind a wardrobe on an outside wall points the other way, toward still air and a cold surface. Even that contrast is not proof. The survey did not sample the plaster or monitor either pattern over time.
Was a humidity logger left behind the wardrobe?
No. Nothing was left in place to record humidity or surface conditions after the visit. The surveyor saw the stain once, with the furniture where it was. A logger, if you later want one, would be a new instruction. This report has the pattern only. It does not have a run of readings.