Basements and cellars
What did the visit record about a barrel vault, about the area steps, and about tanking nobody peeled back?
The visit recorded a barrel vault and the area steps as things that could be seen, and it recorded tanking that nobody peeled back. The vault is the curved cellar construction. The area steps are the external stair down to it. The tanking is a lining left in place, so the face behind that lining was not inspected. The survey has not decided that the vault is dry, that the steps are keeping water out, or that the tanking is working. It has described what was in view. The hidden side of the lining stays unknown.
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 barrel vault sheds moisture toward its haunches and the walls. Area steps sit in a well against that wall, so blocked joints or a poor outlet can wet the same masonry the vault springs from. Tanking is a render or membrane lining. If nobody peeled it back, the surveyor sees the lining, any blister or salt on it, and the steps outside. They do not see the joint behind the tanking. Three notes sit together. None of them is a damp test.
Tell the solicitor the tanking was not opened, so a guarantee, if the seller has one, has not been checked against the wall. A damp specialist can advise whether the lining should be investigated. This visit has not done that, and it has not traced water from the area steps into the vault. Do not assume the steps are the cause just because they share the paragraph. Keep the vault, the steps and the unopened tanking as three limits of what was seen.
What should you ask your surveyor?
- Was the tanking a cement lining, a membrane, or only described as a coating?
- What marks, if any, were on the vault or on the area steps?
- Could you see the outlet and the joints in the area well?
What are the typical next steps?
- Keep the vault, the steps and the unopened tanking as three separate limits.
- Ask the solicitor whether any tanking guarantee has been supplied.
- Do not peel the lining while you are still deciding on the purchase.
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 smooth tanking face mean the cellar is dry?
No. The face was seen and nobody peeled it back, so the masonry behind it was not inspected. An even lining can hide a damp wall, or it can be doing its job. The survey has not decided which. The barrel vault and the area steps were recorded as visible construction, not as proof that the tanking works.
Were the area steps tested by running water?
No. The steps were recorded beside the vault, which is a visual note of the well. The survey did not run water down them and did not test the outlet. Leaves or open joints would be observations if they were written down. They are not a drainage test. The lining on the cellar side remains unopened too.