Damp and moisture meters
Do trickle vents that the occupant has merely closed, not painted shut, still matter to condensation?
Yes, trickle vents closed by the occupant, but not painted over, shut a background air path the windows were given, and condensation can follow while they stay shut. They can be opened again. That is different from vents painted solid, and it is not a failed damp-proof course.
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?
Trickle vents are the small slots in many replacement windows. Occupants close them because they feel a draught, and then the glass and the cold corners mist. The vent itself is still capable of being opened. Paint that has sealed the slot is a different defect, because opening the lever does nothing until the paint is cut back. A surveyor can see a closed vent and can see if paint is bridging it. They do not measure an air-change rate, and a home survey is not a test of the ventilation system.
Condensation from shut vents is a use and ventilation finding. It does not show that the wall is saturated. If mould is sitting on the cold reveal and the vents are simply snapped shut, the first step is to open them and to see the pattern in ordinary use. Do not replace the windows because the vents were closed, and do not inject the walls. If the slots are painted solid, say that instead, because the repair is different. The survey should use the words that match what was seen.
What should you ask your surveyor?
- Were the trickle vents closed, or painted so they cannot open?
- Is there condensation or mould next to those windows?
- Are you describing use, rather than a failed damp-proof course?
What are the typical next steps?
- Open closed vents and watch the glass. Do not buy new windows for a shut slot.
- If paint has sealed them, say so. A shut vent and a painted vent are not the same repair.
- Do not treat the condensation as rising damp.
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 a house with no trickle vents fail the survey?
No. Older windows often have none. The survey describes condensation if it is there. It does not apply a design standard as a pass or fail of the purchase.
If the occupant opens them, will mould already on the reveal disappear?
New growth may slow. Staining already in the paint will not vanish. The cause and the decoration are different.