Condition ratings

The cellar is NI because the pavement grating was bolted down. What tanking below that grating must you not assume is absent?

You must not assume that tanking below the bolted grating is absent. The cellar is NI because that grating stayed shut, so the space under it was not inspected. NI means not inspected, not a pass. Rating 1 means no repair currently needed. Rating 2 means defects that need repair but are not serious or urgent. Rating 3 means serious and/or urgent repair, replacement or investigation. Unseen tanking might be there or it might not. The report has not decided either way, and absence was not proved.

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?

Tanking is a waterproof lining. It lives on walls and floors you can only judge when you are in the cellar. A bolted pavement grating is a cover, not a view. People sometimes treat an unseen lining as one that was never installed. That leap is not available here. The survey could not see the lining, so it cannot delete it, and it cannot certify it. NI is the refusal to choose. The tanking you must not assume away is whatever lining may exist below that cover.

Tell your solicitor the cellar was not inspected and that no one should write tanking out of the building merely because the grating was bolted. If access is freed, a further inspection can describe damp, tanking or the lack of it. Do not tell a lender the cellar is dry or untanked. Rating 3 was not applied, and rating 1 was not applied either. The bolts kept the finding at NI.

What should you ask your surveyor?

Was the cellar NI only because the grating stayed bolted?
Has tanking below it been left neither present nor absent?
Were rating 1 and rating 3 both withheld?

What are the typical next steps?

Do not assume cellar tanking is absent.
Tell the solicitor the space below the grating was not inspected.
Arrange access before anyone describes tanking or damp down there.

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

Must you also avoid assuming the tanking is present and sound?

Yes. Not assuming it is absent is only half of the limit. NI means not inspected, not a pass, so you must not assume a sound lining is there either. The survey did not see the walls. Presence, failure and a bare untreated wall are all still possible. Wait until the grating is opened.

Does a dry hallway prove the cellar has no tanking problem?

No. The hallway is not the cellar. NI on the cellar means that space was not inspected, whatever the floor above felt like. A dry hall does not show linings, sumps or damp below the grating. Do not import the hall's condition into a room the surveyor could not enter.