This page sets out what the evidence actually says — calmly and without exaggeration — so you can make an informed decision about whether to have your foam inspected. The aim is clarity, not alarm.
Quick Answer: Generally Safe When Correctly Installed; Structural Risks Are the Main Concern
The IMA’s position, shared by the PCA, is that correctly installed spray foam insulation is in many cases safe and does not require removal. Where problems exist, they are most commonly related to moisture management and surveyor access rather than direct health hazard to occupants. That said, every property is different — and an independent inspection is the only way to establish the specific situation in your home.
Health Considerations
Isocyanates: The Chemical Concern During Installation and Curing
Spray foam is produced by combining two chemical components that react and expand. One component contains isocyanates — compounds that are known respiratory sensitisers. Exposure to isocyanates during the spraying and curing process can cause asthma, and in some cases irreversible sensitisation that prevents any future exposure, even at low levels.
For this reason, professional installation requires:
- Operatives to wear full respiratory protective equipment (air-fed hoods or respirators)
- Occupants to vacate the property during application
- Adequate ventilation during and after installation
- A curing period (typically 24 hours minimum, product-specific) before re-occupation
These risks are well understood and are managed by Health and Safety Executive (HSE) guidance on isocyanates in the workplace. The HSE’s guidance is directed at installers and operatives, not occupants of completed buildings.
Fully Cured Foam: What the Evidence Shows
Once spray foam has fully cured, the chemical reaction is complete and free isocyanates are no longer present in the foam matrix. The IMA states that fully cured spray polyurethane foam poses no significant health risk to building occupants under normal living conditions.
Concerns sometimes arise about poor-quality or incorrectly mixed foam that has not cured properly — this can leave tacky, partially reacted material that may off-gas. In such cases, or where foam has a persistent chemical smell well after installation, an independent assessment is advisable. Properly mixed and cured foam from a competent installer does not exhibit this.
There is no peer-reviewed UK evidence base establishing that living in a property with correctly installed, fully cured spray foam causes harm to occupants. Claims to the contrary should be treated with scepticism unless supported by credible sources.
Moisture and Structural Risks: The Main Documented Issue
While the health risks of cured foam to occupants are low, the structural risks to the roof are the area where the evidence is most clear and most consequential for homeowners.
Traditional UK pitched roofs — particularly pre-1970s properties with breathable bitumen felt — rely on natural ventilation within the roof void to manage condensation. When closed-cell spray foam is applied directly to the underside of the rafters and felt, it creates a vapour-impermeable barrier that can:
- Trap moisture between the foam and the felt, accelerating felt degradation
- Prevent natural drying of any moisture that enters the roof void
- Cause or conceal timber rot in rafters, purlins and other structural members
- Bond to the timber such that removal becomes necessary before any re-roofing works
Open-cell foam is more vapour-permeable but still restricts the surveyor’s ability to inspect the underlying timber. In some older properties open-cell foam has been found to hold moisture rather than allow it to pass through, particularly in cold conditions.
The extent to which moisture problems develop depends on the specific property: its age, the roofing felt type, the ventilation provision, the local climate and the orientation of the roof. This variability is why the PCA Spray Foam Inspection Protocol assesses each property individually — there is no single answer that applies to all homes.
Fire Safety
Spray polyurethane foam is combustible. Left exposed in a loft space, it will burn and can contribute to fire spread. UK Building Regulations (Approved Document B — Fire Safety) and relevant British Standards set out requirements for the fire performance of insulation materials used in buildings.
When installed in a domestic loft, spray foam is typically required to be protected from ignition by a suitable covering — commonly:
- A minimum 12.5 mm layer of plasterboard on the underside of rafters
- An intumescent coating applied over the foam surface
Whether the foam in your loft was installed with appropriate fire protection will depend on when and by whom it was installed, and whether Building Regulations approval was obtained. Foam installed under the Green Homes Grant scheme (2020–2021) was supposed to meet these requirements, but the quality of installation varied. An independent inspection will assess whether the installation meets current standards.
It is worth noting that exposed foam in a loft does not represent the same fire risk as exposed foam in an occupied room — a loft space has no ignition sources under normal circumstances. The risk is most acute during roof works, electrical faults or any scenario involving a heat source near the foam.
What Industry Bodies Say
Insulation Manufacturers Association (IMA)
The IMA has consistently stated that correctly installed spray foam insulation is in many cases safe and that removal is not always necessary. The IMA has also acknowledged the mortgage access problem and has engaged with lenders and government to seek a resolution. Their position is one of qualified reassurance: the product, when properly used, works as intended — but installation quality matters significantly.
Property Care Association (PCA)
The PCA developed the Spray Foam Inspection Protocol specifically to provide homeowners with an independent, standardised assessment rather than leaving them to rely on competing commercial claims. The PCA’s view is that inspection should precede any decision about removal, and that the outcome varies by property. The PCA does not take a blanket position that foam is dangerous — or that it is always harmless.
RICS
RICS has not declared spray foam unsafe; its position relates to the practical inability of surveyors to assess properties where foam obscures the roof structure. This is a professional methodology point — a RICS valuer cannot inspect what they cannot see. It is this inability to inspect, not a finding of inherent danger, that leads to mortgage refusals.
When to Get an Independent Inspection
We recommend arranging an independent inspection under the PCA Spray Foam Inspection Protocol if any of the following apply to you:
- You are planning to sell your home and want to understand the position before listing
- You are attempting to remortgage and your lender has raised a query about spray foam
- You are applying for equity release
- You are aware of spray foam in your loft but unsure of the type, coverage or installation quality
- Your loft has a persistent damp smell, or you have noticed moisture staining on ceilings near the eaves
- You bought your property recently and are unsure whether foam was disclosed or whether it was installed correctly
An inspection gives you a factual, documented picture of your specific situation. It may confirm that your foam is installed correctly and presents no current risk — in which case you have peace of mind and supporting documentation. Or it may identify problems that are better addressed now than discovered later in a sale or remortgage process.
See our spray foam inspection page for details, and our spray foam problems guide for a broader overview of the issues affecting UK homeowners.
For the mortgage implications specifically, see our spray foam and mortgages guide.
This page contains general information only. It is not medical, structural engineering or financial advice. If you have specific health concerns related to a recent installation or incorrectly cured foam, consult your GP. For structural concerns, obtain an independent survey from a RICS-qualified professional.