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Open-cell vs closed-cell spray foam: what surveyors and lenders look at
Spray foam applied to the underside of a pitched roof can hide the roof timbers and seal in moisture unless precautions are taken, so surveyors and lenders look at it closely (RICS spray foam consumer guide, March 2023). The Property Care Association inspection protocol (March 2023) asks surveyors to record, where reasonably evident, whether the foam is open or closed cell, so a professional inspection is the sensible first step.
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What it is
Spray polyurethane foam is applied as insulation. Foam types are described as open-cell or closed-cell, and the PCA inspection protocol asks surveyors to record which it appears to be where that is reasonably evident [PCA protocol, March 2023].
The RICS consumer guide says spray foam applied to a roof timber structure restricts the view from within the roof space, so the timbers cannot be fully seen or inspected [RICS consumer guide, March 2023].
The survey and the work
RICS notes that most pitched roofs are designed to be ventilated and that spray foam is a change to that design: it creates a warm roof void and will seal in moisture unless adequate precautions are taken [RICS consumer guide, March 2023].
If a surveyor finds spray foam during an inspection, RICS says they may request an independent specialist report, and they must follow any policy set by their lender clients [RICS consumer guide, March 2023]. Lender policy therefore decides the outcome, not the foam type alone.
The PCA protocol is a framework for non-invasive visual inspections of spray foam on the inside of pitched roofs. It covers recording the roof construction, the foam, its bond to the surface and the moisture content of significant timbers, and it says it is not prescriptive [PCA protocol, March 2023].
Who it is for
- Homeowners who have been told they have spray foam and want to understand what a surveyor will look at.
- Anyone selling or remortgaging who wants to understand why a surveyor or lender has reacted the way they have.
The mortgage and sale angle
- Spray foam over roof timbers can hide them from inspection, which is what a valuer needs to see, so a specialist report may be requested (RICS spray foam consumer guide, March 2023).
- The Property Care Association inspection protocol (March 2023) gives surveyors a framework to assess an individual roof, so an inspection can establish the facts for your property.
What the RICS guide and the PCA protocol say about spray foam on a roof
| Question | What the guidance says | Source |
|---|---|---|
| Can the roof timbers be seen? | Foam over the timbers restricts the view, so they cannot be fully seen or inspected | RICS consumer guide, March 2023 |
| What about moisture? | Spray foam creates a warm roof void and seals in moisture unless adequate precautions are taken | RICS consumer guide, March 2023 |
| Does the foam type get recorded? | Surveyors should record, where reasonably evident, whether the foam is open or closed cell, and should not assume details they cannot confirm | PCA protocol, March 2023 |
| Who decides if a lender accepts it? | The surveyor follows the lender's policy and may ask for an independent specialist report | RICS consumer guide, March 2023 |
How to choose a 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?
The RICS consumer guide does not rank the two types. It says a surveyor who finds spray foam may ask for an independent specialist report and must follow the lender's own policy, so the answer depends on your lender and on the condition of your roof. Ask your lender or surveyor what their policy is.
How do I tell which type of spray foam I have?
The PCA inspection protocol asks surveyors to record, where reasonably evident, whether foam is open or closed cell, and not to assume details they cannot confirm. A qualified surveyor or a Property Care Association member can confirm the type, where it is and the condition of the roof timbers in a written report.
Does the location of the foam matter?
Yes. The RICS guide and the PCA protocol are both concerned with foam applied to the inside of pitched roofs, because it can restrict the view of the timbers and seal in moisture unless precautions are taken.
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 the relevant bodies for each job, such as Gas Safe Register, NICEIC, MCS, TrustMark and the Property Care Association. He is clear about what to check before any work starts.
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