Damp and moisture meters
Chemical injection holes are present and a new path still bridges them. Why is another injection not the first reading of that detail?
Another injection is not the first reading, because a new path still bridges the holes. Those chemical injection holes mark an earlier attempt to form a damp course in the wall. A later path, step or render can sit across that line and let moisture step over it. The survey has seen the holes and the bridge. It has not tested the old chemical, and it has not decided that a second row of injection would stop the damp.
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?
The holes are a record of drilling, not a proof that the wall is dry above them. A chemical course only works on the line it occupies. Soil, paving, a concrete step or a render coat that finishes higher than that line gives rain and ground moisture a way around it. Calling for another injection first treats the chemical as the failed part and leaves the bridge in place. The survey can point at the crossing.
Ask a damp specialist to look at what is bridging the injected line before anyone proposes more injection. Tell your solicitor the report has not specified a remedy and has not priced one. If a lender asks what the damp note means, say the visible route is the bridge, not an untested second treatment. Do not let a contractor's offer to inject again stand in for the detail the survey actually recorded.
What should you ask your surveyor?
- Which material is crossing the line of the old injection holes?
- Did you test the chemical course, or only see the holes and the bridge?
- Would removing the bridge change the damp note before any further injection?
What are the typical next steps?
- Read the bridge across the holes as the first damp path.
- Ask which material is sitting over the injected line.
- Get a damp specialist to see that bridge before more injection is proposed.
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
Do the injection holes prove the chemical course is still continuous?
No. The holes show that someone drilled the wall. They do not show that the fluid still forms a continuous course, and the survey has not tested it. A new path bridging those holes can wet the wall above the old line whether or not the chemical remains in the mortar.
If the bridging path is later lowered, has the survey already cleared the wall?
No. Lowering the path would remove the crossing the survey saw. It would not, by itself, prove the old injection is sound or that the wall below the plaster is dry. The report has not opened the plaster and has not signed off the chemical course.