Damp and moisture meters
Roughcast sounds hollow at one corner and solid a metre away. What does the hollow tap say, and what brick behind it was not opened?
The hollow tap says the roughcast is debonded at that corner, and the brick behind it was not opened. A metre away the same coat sounds solid, so the loss of grip is local on the evidence of the tap. Hollow means the coat has left the background and a void is answering the knock. Solid means, at that spot, the coat still seems keyed. The survey did not hack off the roughcast, did not see the brick face, and did not record a crack or a repair in brick it never exposed. The tap is a sound. The brick is still covered.
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?
Roughcast is a pebbled coat. It fails by parting from the wall, often at a corner where the coat is thin or has been struck. The surveyor’s tap can map a hollow patch against a solid one. It cannot name the brick bond, a failed key, or a damp stain on masonry that is still hidden. Opening the corner would be a different instruction, and this visit did not include it. Do not treat the hollow as a view of the wall.
Ask the surveyor how far the hollow extended, and ask a renderer to quote for the coat without pretending the brick has been seen. If there is a wider worry about the wall, that needs an opening under a brief, not a harder tap on the day you move in. The report distinguished hollow from solid. It left the brick unopened.
What should you ask your surveyor?
- Where did the roughcast sound hollow, and where did it sound solid?
- Was the brick behind the hollow corner opened at all?
- What did the tap not tell you about the wall beneath?
What are the typical next steps?
- Read the hollow tap as debonded roughcast, not as a view of the brick.
- Ask how far the hollow area extended beyond the corner.
- Open the coat only under a separate brief if the brick must be seen.
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 hollow is only at the corner, can the rest be ignored?
The rest sounded solid a metre away, which limits the hollow the survey found. It does not open the brick, and it does not prove every other bay was tapped. The finding is local debonding at the corner. The covered brick there was still not seen. Solid nearby is about the coat, not a licence to ignore an unopened face.
Does a hollow tap mean the brick is wet?
No. The tap says the roughcast has left its background at that corner. Wet brick would be a different observation, and the brick was not opened so it could not be made. The survey did not convert a sound into a damp reading. Hollow coat and unseen brick stay the limit of the note.