Damp and moisture meters
What does a surveyor mean by high readings at skirting level if the plaster was replaced last year?
New plaster at the floor can still read as damp if it was applied over salts, over a bridged course, or before the wall had dried. It can also be sound plaster that a meter is misreading. The recent replastering is a reason to ask what was done, not a reason to ignore the comment.
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?
Sellers often replaster and repaint a low-level patch before marketing. A surveyor who sees new plaster and a high reading should say both. They usually cannot know whether a damp-proof course was injected, whether the old plaster was removed to the right height, or whether debris still bridges the cavity. Those facts are in invoices and guarantees, if they exist, and in opening-up.
Ask the seller, through your solicitor, for any guarantee, the invoice and what was guaranteed. An old guarantee is not proof the wall is dry today. The Property Care Association’s advice is that the building defect has to be understood. A guarantee for injection does not cover a gutter that was never repaired.
What should you ask your surveyor?
- Are the high readings on the new plaster, on the skirting, or on both?
- Could you see a physical damp-proof course in the outside mortar joint?
- What would you need to open up to tell new plaster from an active leak?
What are the typical next steps?
- Request the paperwork for the replastering. No paperwork means you are buying the wall as it stands.
- Do not treat a one-year-old finish as a clean bill of health.
- If the rating is serious, get an investigation that is allowed to look under the new plaster. Agree that before you pay.
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
Does new plaster always read wet?
Fresh plaster holds water while it cures, and some lightweight plasters affect meters. “Always” is the wrong word. The surveyor should say whether they think the reading is the new material or a defect.
Should you ask the installer back rather than a new investigator?
If a named firm did the work and a guarantee is still in force, ask them what the guarantee covers. Also ask an independent person if the cause might be outside that guarantee.