Damp and moisture meters
Mould is only behind furniture against an outside wall, and the meter was not a laboratory test. What has the survey not measured about how the room is heated and ventilated?
The survey has not measured how the room is heated and ventilated. Mould only behind furniture on an outside wall fits a cold, still pocket where the piece stands against a cold surface. The meter was not a laboratory test, so it did not identify the mould, sample the air, or track humidity. The inspection saw where the mould was. It did not log the heating pattern, the ventilation, how long the furniture has stood there, or the surface temperature over time. Those room-use facts are what has not been measured.
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?
Outside walls are colder than internal ones. A wardrobe or a bed pushed against them stops air moving, so the surface stays cold and moisture from the room condenses behind the furniture. The rest of the wall, open to the room, can look clean. That distribution is a clue about use and ventilation, not a chemical analysis. A hand-held meter, whatever it read, is not a laboratory test of the plaster or the air.
Pull furniture slightly off the outside wall, keep the room heated and ventilated, and see whether the mould is confined to that pocket. Tell the solicitor the report has not measured the heating and ventilation and has not diagnosed a failed damp course from this patch. The survey has not specified injection and has not said the wall is saturated. If mould is widespread on cold surfaces, that is a broader condensation note. This finding, as described, is the hidden patch behind the furniture.
What should you ask your surveyor?
- Was the mould limited to the hidden face behind furniture on the outside wall?
- What about heating and ventilation did you not measure?
- Did you record that the meter was not a laboratory test?
What are the typical next steps?
- Treat the patch as unmeasured heating and ventilation, not as a proved damp course failure.
- Move furniture off the outside wall and improve how the room is aired and heated.
- Do not specify damp-proof treatment from a meter that was not a laboratory test.
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
If the furniture is removed and the mould stays, what changes?
The pocket explanation gets weaker if the mould remains on an open wall, and someone then has to look again at the surface and the room. The survey still has not measured heating and ventilation, and one later look does not turn the original meter into a laboratory test.
Does mould behind a wardrobe mean the wall leaks rain?
Not from that position alone. The survey saw mould where furniture stood against an outside wall. It has not traced rain through the wall, and it has not measured the room's heating and ventilation. Asking about it again later still leaves this wardrobe point outside what the survey decided.