Damp and moisture meters
A new timber threshold sits higher than the damp-proof course and the plaster beside the jamb is marked. What bridge is that threshold?
The bridge is the new timber threshold sitting higher than the damp-proof course. Timber that stands proud of the course can carry moisture past the barrier and into the jamb, which matches the marked plaster beside it. The survey has seen the high threshold and the mark. It has not specified a chemical treatment, and it has not decided that the rest of the wall is bridged. The path named here is this threshold.
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 damp-proof course only works where it is not bypassed. A new threshold, often fitted with a replacement door, can be set too high so that its inner face connects floor, plaster and outside weather above the course. The mark beside the jamb is the clue that moisture is arriving there. It is not a map of every other bay. The survey did not prescribe injection, tanking or a new course. It recorded a piece of timber in the wrong relationship to the course that already exists.
Ask a joiner or a damp specialist whether the threshold can be re-set so it no longer bridges the course, and keep that advice separate from this report. Tell the solicitor the mark is beside the jamb at this opening. Do not treat the note as a specification for chemical damp-proofing of the house. Until the timber is altered, the bridge the survey described is still the threshold.
What should you ask your surveyor?
- Does the new timber threshold sit higher than the damp-proof course?
- Is the plaster mark beside the jamb rather than across the whole wall?
- Have you left chemical treatment unspecified?
What are the typical next steps?
- Treat the high threshold as the bridge, not a whole-wall diagnosis.
- Ask whether the threshold can be re-set below the course.
- Do not read the survey as a chemical damp specification.
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
If the mark is only at one jamb, is the course missing everywhere?
No. A mark beside one jamb fits the threshold that bridges there. The survey has not said the course is missing on the rest of the wall, and it has not specified a chemical treatment for the house. One jamb is not the whole elevation.
Does a weather bar on the door clear the bridge?
A weather bar sheds rain off the leaf. It does not lower a threshold that sits above the damp-proof course. The plaster beside the jamb can still be marked. The survey has not said the bar removes the bridge. The threshold is still the bridge.