Damp and moisture meters
Can a pinless moisture meter read foil-backed plasterboard as if the wall were wet?
A pinless meter can react to metal in the wall, including foil on the back of plasterboard, as well as to water. A high number on its own does not prove rising damp, penetrating damp or a failed damp-proof course. Ask which meter was used and what the surveyor could actually see.
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?
A home survey is a visual inspection. A moisture meter is an aid, not a laboratory test. Capacitance meters read through the surface, so foil, a metal bead, a pipe or a tile can push the display up. Pin meters read between two probes and can be pushed up by salts left after a wall has dried. Neither instrument names the source of any water.
Property Care Association advice treats damp as a diagnosis of the building, not a meter score. Government damp and mould guidance is about finding the cause and the health risk. It does not say that a meter reading is a failed damp-proof course, and it does not set a price reduction for a buyer.
What should you ask your surveyor?
- Was the meter a pin meter or a pinless meter, and was it the whole diagnosis or only an aid?
- Was there staining, salts or a tide mark, or only a number on a display?
- Could foil-backed board, dot-and-dab adhesive or a metal bead sit behind that spot?
What are the typical next steps?
- Do not commission a chemical damp-proof course on the number alone.
- If the report still suspects damp, ask an investigator who will explain the cause before quoting for injection.
- Tell your solicitor what was not opened up. The survey has not tested the 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
Should you ask for the meter type to be written into the report?
Yes. “High readings” is not comparable with another surveyor’s phrase. The number still does not name the type of damp.
Can you ignore the comment if you think the board is foil-backed?
No. Foil can explain a false high on some meters. It does not explain staining, a musty smell or soft skirtings. Those still need a cause.