Chimneys and parapets
A fireplace is boarded and the vent in the board has been taped shut. What moisture path up the flue was closed?
The moisture path that was closed is the air route up the disused flue. A fireplace has been boarded and the vent in that board has been taped shut, so the flue no longer has the opening that lets it breathe into the room. Moisture from the flue can then sit in the stack instead of drying. The survey has seen the board and the taped vent. It has not tested the flue, and it has not said the boarding itself is a structural defect.
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?
An unused flue still takes damp air and rain at the pot. A vent in the closure plate is the usual way to let that moisture out at the bottom and to keep a trickle of air moving. Tape over the vent stops that trickle. The risk is condensation in the flue and staining or salt lower down, not a judgement that the chimney breast has failed. The survey could see the tape. It could not see the flue lining, and it did not sweep or camera the shaft.
Ask for the vent to be reopened, or for a proper ventilated cap, if you intend to leave the fireplace closed. If the flue will be used, that is a separate appliance question for a competent installer, which this visit did not carry out. Tell the solicitor the survey closed nothing and tested nothing: it found a vent that someone else had taped. Do not read the board as a certificate that the flue is safe to light.
What should you ask your surveyor?
- Was the vent in the fireplace board taped shut?
- Did you leave the flue itself untested?
- Is the note the closed air path, rather than a fault in the breast?
What are the typical next steps?
- Treat the taped vent as a closed moisture path up the flue.
- Reopen a proper vent if the fireplace is to stay boarded.
- Do not read the survey as a test of the flue.
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 there is no smell, is the flue dry?
No smell on the day is not a dryness test. The vent is still taped, so the air path the survey described is still closed. The flue lining was not seen, and no moisture reading inside the shaft was taken.
Does boarding the opening mean the chimney can be removed?
No. Boarding hides the fireplace. It does not show how the breast is supported, and it does not test the flue. The survey's point is the taped vent. Removal of any masonry is a different question this visit did not decide.