Property fixes and removals
Open-cell vs closed-cell spray foam: why lenders care which you have
Open-cell and closed-cell spray foam behave differently, and lenders tend to be more cautious about closed-cell foam applied to the underside of a roof, because it is denser, harder to remove and can trap moisture against the timbers where a surveyor cannot inspect them. Which type you have, and where it is, drives how a lender reacts, so a professional inspection is the sensible first step.
Not sure what it is yet? Read the full guide to what spray foam is, open vs closed cell and is it bad on our sister site HomesAndHedge. This page focuses on the cost, the survey and getting it fixed.
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Get matchedWhat it is
Spray polyurethane foam comes in two broad types. Open-cell foam is softer, lighter and more vapour-open. Closed-cell foam is denser, more rigid and far less vapour-open, and it bonds hard to whatever it is sprayed onto.
The concern lenders and surveyors focus on is closed-cell foam sprayed onto the underside of a pitched roof, because it can restrict ventilation and trap moisture against the roof timbers and hide them from inspection. For the underlying science of what spray foam is and whether it is always a problem, see the HomesAndHedge guide linked below.
The survey and the work
The location matters as much as the type. Foam on the underside of the roof, in contact with the rafters and felt, is the situation lenders query most. Foam on a loft floor or elsewhere is generally viewed differently.
In March 2023 the Royal Institution of Chartered Surveyors published a consumer guide on spray foam, and the Property Care Association published an inspection protocol to help surveyors assess the condition of an individual roof rather than decline simply because foam is present. That means a proper inspection can sometimes distinguish a sound roof from a genuinely risky one.
A very limited number of lenders will consider a property with open-cell foam; closed-cell foam on a roof more often leads a lender to ask for removal and a report. Policies vary widely between lenders, so the type and location need confirming by an inspection, not guessed.
Who it is for
- Homeowners who have been told they have spray foam and need to know whether it is the open-cell or closed-cell type a lender queries.
- Anyone selling or remortgaging who wants to understand why a surveyor or lender has reacted the way they have.
- Owners weighing up whether they face a straightforward case or the more involved closed-cell-on-roof situation.
The mortgage and sale angle
- Lenders and surveyors are generally more cautious about closed-cell foam on the underside of a roof, because it can trap moisture and hide the timbers from inspection, which is exactly what a valuer needs to see (RICS spray foam consumer guide, 2023).
- The Property Care Association inspection protocol (2023) means a qualified inspection can assess your specific roof rather than a lender declining simply because foam is present, so an inspection can be the difference between a stalled and a completable transaction.
- Because a very limited number of lenders consider open-cell foam while closed-cell on a roof more often triggers a removal request, confirming the type and location by inspection is the step that tells you which path you are on.
Open-cell vs closed-cell spray foam: how they differ and how lenders tend to view them
| Feature | Open-cell foam | Closed-cell foam |
|---|---|---|
| Density and feel | Softer, lighter, more flexible | Denser, rigid, hard |
| Vapour openness | More vapour-open, lets some moisture move | Much less vapour-open, can trap moisture |
| Bond to timber and felt | Adheres, but generally easier to strip | Bonds hard, harder and slower to remove |
| Roof inspection | Timbers still partly obscured | Timbers obscured and harder to inspect |
| How lenders tend to view it on a roof | A very limited number may still consider it | More often leads to a request for removal and a report |
How to choose a vetted specialist
- Use a qualified surveyor or a Property Care Association member who can identify the foam type and assess the roof, rather than relying on a removal firm to self-diagnose the problem it is selling.
- Ask for the inspection to state the foam type, its location and the condition of the timbers, in writing.
- Confirm whether the resulting report is one your lender or surveyor will accept before you commit to any work.
Frequently asked questions
Is open-cell or closed-cell spray foam worse for a mortgage?
Lenders tend to be more cautious about closed-cell foam applied to the underside of a roof, because it is denser, harder to remove and can trap moisture against the timbers. A very limited number of lenders will consider open-cell foam. The type and location need confirming by a professional inspection.
How do I tell which type of spray foam I have?
Closed-cell foam is dense, rigid and hard; open-cell is softer and more flexible. A visual guess is not reliable enough for a lender, so a qualified surveyor or a Property Care Association member should confirm the type, the location and the condition of the roof timbers in a written report.
Does the location of the foam matter?
Yes. Foam on the underside of a pitched roof, in contact with the rafters and felt, is what lenders and surveyors query most, because it can restrict ventilation and hide the timbers. Foam on a loft floor or elsewhere is generally viewed differently. Location matters as much as the foam type.
Sources
Editor, VettedHome
Adam leads VettedHome's editorial coverage of UK home services. He is the founder and managing director of Muswell Rose, the commercial strategy and modern systems business behind a portfolio of UK information sites, and he researches and writes the plain-English guides that help homeowners choose between installers and trades, drawing on the standards set by bodies such as MCS, TrustMark, the Energy Saving Trust and the Property Care Association. He is clear about what to check before any work starts.
Last reviewed: 11 June 2026