Damp and moisture meters
Can dot-and-dab plasterboard make a pinless moisture reading hard to trust?
Yes. A pinless meter reads through the surface, and the dabs, the cavity behind the board and any foil can all affect it. A high number on lined walls is not a map of water inside the masonry.
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?
Dot-and-dab fixes plasterboard to a wall with blobs of adhesive, leaving a gap. A capacitance meter can respond to that gap, to the adhesive, or to metal beads as well as to water. Pin readings in the board only tell you about the board. Neither reading sees the brick unless someone probes to it. A home survey that cannot open the lining should say so.
The Property Care Association treats damp as a diagnosis of the building. If the only evidence is a number on a lined wall, opening up is a separate instruction, not something the Level 2 fee silently includes. Costs vary with how much board is taken off and who makes it good. Ask before you authorise it.
What should you ask your surveyor?
- Were the high readings on the plasterboard, or on masonry you could actually touch?
- Did you allow for foil, beads or dabs at that spot?
- What would have to be opened to read the wall behind?
What are the typical next steps?
- Do not strip the lining before exchange on a number alone.
- Ask the firm to record that the wall was lined and not opened.
- If the purchase depends on the masonry, agree an opening-up visit in writing, including who makes good.
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
Is a dry board proof the wall behind is dry?
No. The board can be dry while the masonry behind a dab is not, and the reverse is also true. The meter on the board cannot settle it.
Should you drill the board yourself to check?
No. You may hit a pipe or a cable, and you may disturb materials you cannot identify. Leave opening-up to someone instructed to do it.