Damp and moisture meters
Is a salt-glaze air brick, together with paint across the holes, any evidence on the underfloor void it should serve, or only a note of what was visible?
It is only a note of what was visible, not evidence about the underfloor void. A salt-glaze air brick is a glazed clay ventilator, and paint across the holes blocks the face that was seen. The brick should serve the space under the floor, but this visit did not get into that void and did not test airflow. The survey has not decided the floor timbers are damp or dry. Paint on the holes is not a survey of the void.
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?
Salt-glaze air bricks are dark clay grilles low on an outside wall. In principle their holes line up with the void under a suspended timber floor. Paint can skin those holes over, so the visible face is obstructed. From that alone the survey cannot say whether the joists are wet or whether other paths still work. The floor was not lifted.
Tell the solicitor the painted air brick is a face note, not a floor-void inspection. If the floors worry you, a timber surveyor can look under the boards, which this visit did not do. Clearing paint from holes, if it is done later, still would not by itself describe the void. The lender has no underfloor result. The home survey has not passed the timbers and has not condemned them.
What should you ask your surveyor?
- Was the salt-glaze air brick only seen from the outside face?
- Did paint across the holes stay a visual note?
- Was the underfloor void left uninspected?
What are the typical next steps?
- Treat the painted air brick as a face note, not a void survey.
- Ask a timber surveyor if the floor void itself must be seen.
- Tell the solicitor the joists were not judged from this brick.
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 other air bricks are clear, is the void proved to breathe?
No. One clear brick does not describe the paths under the floor. This note is about a salt-glaze brick with paint on the holes. The survey did not map the rest and did not test airflow. Other grilles, even if open, were not a test of this void.
Does glaze on the brick make it waterproof and irrelevant?
No. The glaze is the finish of the clay unit. It is not a finding about the floor. Paint across the holes is the obstruction that was seen. The void the brick should serve was not inspected. Glaze does not turn the note into evidence of dry timbers.