Spray foam and lenders

Spray foam is only in the dormer cheeks, and the main rafters are bare. What has the survey been able to see?

It has seen the main rafters that are bare, and it has not seen the dormer timbers stuck behind the foam. The dormer is still part of the roof, so lenders can ask their own question about that foam, and RICS does not say every lender will refuse. The home survey has not identified the product and has not instructed anyone to remove it.

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 dormer cheek is the side wall of the dormer, often timber studs with the covering outside and a lining inside. Foam sprayed there hides those studs the way foam under a slope hides rafters. RICS’s guide is about that loss of view, and about the risk that a leak rots timber nobody can inspect. The main roof being visible is good news for the main roof only. It does not let you tell a lender the property has no spray foam. It does not let a valuer’s question go unasked. Pass on the location accurately: cheeks foamed, main rafters visible and unfoamed.

Removal, if it is ever proposed, can damage the covering it is stuck to, which on a cheek may be tile, lead, felt or timber cladding. The survey has not said the foam must come off, and a seller’s contractor is not the surveyor. Ask the surveyor whether any staining was visible at the edges of the foam, and whether the dormer roof itself was a separate covering they could see. Do not upgrade a neat dormer into a passed structure. The studs inside the cheeks were concealed. Concealed timber is not certified sound just because the ridge of the main roof looked clean.

What should you ask your surveyor?

Which parts of the dormer are foamed, and which main-roof timbers did you see?
Was any leak staining visible at the edge of the foam?
Are you passing the dormer structure, or recording that it was hidden?

What are the typical next steps?

Tell the lender the location: dormer cheeks, not the whole roof, and not none.
Do not claim the main rafters being bare means the dormer was inspected.
If removal is discussed, ask what covering would be damaged. The survey has not ordered the work.

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 foam in a cheek ventilate itself because the ridge is clear?

No. The ridge of the main roof is not the cheek. The survey has not tested how the dormer was built.

Will this lender refuse a dormer-only foam job?

The survey cannot say. Not every lender refuses foam. Ask this lender, and give them the location.