Spray foam and lenders
Spray foam crosses the party line into the neighbour's roof. What has your survey not been able to inspect next door?
Not next door: spray foam that crosses the party line sits in a neighbour's roof your survey has not been able to inspect. The visit was to your side. Foam continuing past the party line is outside that inspection. You cannot say the neighbour's timbers are sound, or unsound, from a loft you did not enter. RICS says lenders have their own questions about spray foam. The survey does not set lender policy, and it does not inspect the house next door.
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?
Party-line foam is a limit twice over. The foam already hides timbers where it has been sprayed, and the part beyond the line was never in the instruction. A photograph that shows foam disappearing into next door's roof space is a photograph of a boundary, not an inspection of that roof. Do not guess that their rafters match yours. Some lenders ask questions. The survey does not write their rules, and it has not seen their roof either.
Tell the solicitor the foam appears to cross the party line and that next door was not inspected. Ask the surveyor how far the foam could be seen from your loft and where the view stopped. If a lender asks about foam, give them the survey's limit in plain words rather than an invented verdict. Offcuts on your boarding do not prove the far side is clear. Your report stops at the inspection it could make.
What should you ask your surveyor?
- How far past the party line, if at all, could you actually see foam?
- Did the instruction include next door's roof, or only this house?
- Which timber comments stop because the foam or the boundary blocked the view?
What are the typical next steps?
- State that next door's roof was not inspected.
- Do not describe the neighbour's timbers from your side of the foam.
- Pass the lender the survey's limit, not a policy you have invented.
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 neighbour says their loft is fine, does your survey adopt that?
No. A neighbour's comment is not your inspection of their roof. The survey still has not inspected the roof next door where the foam continues.
Does foam on the party line set the lender's rule?
No. RICS notes that lenders have their own questions. The survey does not set lender policy, and it has not inspected the roof next door.