Spray foam and lenders
Spray foam fills the roof void above a top-floor flat, and the hatch is in the common stair. What of the rafters has the flat inspection not seen?
Not the rafters. Spray foam in the void above a top-floor flat, reached by a hatch in the common stair, means the flat inspection has not seen the rafters. The foam covers the timber, and the hatch is outside the flat. A survey of the flat does not become a view of a common roof void the surveyor did not enter, and entering would still meet foam rather than bare rafters. What you do not have is the condition of those rafters. The ceiling of the flat is not a substitute for that look.
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?
RICS explains that spray foam hides the roof structure, so a leak can sit against timber you cannot see, and that removal can damage tiles. Those limits apply in a void over a flat. Here there is a further limit: the hatch is in the common stair, so the flat inspection may never have reached the void at all. Do not describe unseen rafters as sound because the rooms below looked dry. Dry plaster is not a view of the timber above the foam.
Ask who controls the hatch, and whether the surveyor was allowed to open it. If they were not, the report should say the void was not inspected. If they were, it should say the foam stopped a view of the rafters. Neither sentence is a lender's yes or no typed from memory. Not every lender treats foam the same way, so ask your lender what they need. Do not write the rooms up as a cleared roof.
What should you ask your surveyor?
- Did you open the stair hatch, or was the void outside the flat inspection?
- Where the foam is, which rafters were actually visible?
- What would you need removed before anyone could see the timber?
What are the typical next steps?
- State that the rafters above the foam were not seen.
- Do not use the flat's ceilings as evidence the roof timber is sound.
- Ask the lender what they need, without guessing from memory.
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 hatch is in the common stair, has the flat surveyor inspected the void?
Not unless they entered it. A hatch outside the flat is not a room of the flat, and foam still hides rafters.
Does foam only matter if every lender refuses it?
No. The immediate point is unseen timber. Lender policies differ, and the rafters remain unseen either way until the void is actually opened.