Damp and moisture meters
Should you open up a wall before exchange if the only evidence is a meter reading?
Not automatically. Opening up is worth it when the rating, the visible damage or your plans make the hidden condition matter before you are committed. A lone meter reading is a reason to ask questions, not a reason to strip plaster on the eve of exchange.
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?
Further investigation means the visual inspection was not enough. RICS uses condition rating 3 where a defect is serious or needs urgent repair, replacement or investigation. A reading with no staining and a rating that is not urgent may not justify damage to someone else’s wall. The seller has to agree before you open anything.
Ask the surveyor what opening-up would change about the advice. If the answer is “very little”, do not pay for it to feel busy. If the answer is that joist ends or a cavity bridge cannot be judged any other way, ask the seller for access and ask a contractor for a written scope and price. Those prices vary. They are not in the home survey.
What should you ask your surveyor?
- What decision would opening-up actually change?
- Whose consent do we need before any plaster comes off?
- Is the element rated, or is it only a meter note?
What are the typical next steps?
- Put the question to the surveyor in writing and keep the reply.
- If you open up, agree who makes good, and do it before exchange only if the answer still matters.
- Do not exchange on the hope that a reading will turn out to be nothing, if the surveyor has said the risk is serious.
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
Can the seller refuse access for opening-up?
Yes. It is their house until completion. Your choice is then to proceed on the visual report, renegotiate, or wait. Your solicitor explains the contract, not the surveyor.
Does opening-up include a laboratory salt test?
Only if you instruct it. A builder with a chisel is not a laboratory. Say what you want back: photographs, a written cause, or a specification.