Spray foam insulation: what it means for your mortgage
Around 231,000 English homes have spray foam loft insulation, and it can complicate a mortgage, remortgage or sale. But the picture is more nuanced than “unmortgageable” — most major lenders judge each property on its merits. Here is what is actually going on, and what to do if it affects you.
A smaller problem than the headlines suggest
Spray foam insulation has become shorthand for “unsellable home”, and the figure you will see quoted everywhere is 250,000 affected properties. That number is worth pinning down, because it shapes how worried people feel. It traces back to an industry estimate of homes that could be hard to mortgage — not a hard count.
The primary source tells a tighter story. The government’s English Housing Survey 2024-25 found spray foam loft insulation in 231,000 dwellings in England — about 1% of homes with a loft. The vast majority, 214,000, are owner-occupied, with around 9,000 each in the social and private rented sectors. So the issue is real, concentrated among homeowners, but narrower than the round number suggests.
If your roof has spray foam, none of this means your home is worthless or unsellable. It means a lender will want to look more carefully — and that the gap between a smooth application and a difficult one comes down to evidence.
Why it can trip up a mortgage
When you apply for a mortgage, the lender sends a surveyor to value the property. Spray foam sits on the underside of the roof and covers the timbers — the rafters, trusses and sheathing — so the surveyor cannot see the condition of the structure underneath it. They cannot check for leaks, rot or woodworm hidden behind the foam.
The Royal Institution of Chartered Surveyors (RICS) puts it plainly: “the presence of spray foam insulation is a factor that could affect a surveyor’s professional opinion of value.” Where a surveyor cannot inspect, they may downgrade their valuation or ask for an independent specialist report before the lender will proceed.
There is a building-physics concern too. Closed-cell foam in particular can act as a moisture barrier and reduce the ventilation a roof was designed to have. Where that happens, trapped condensation can risk timber decay, mould and corrosion over time. It is the prospect of poorly applied or wrongly specified foam — not foam in every case — that makes lenders, insurers and surveyors cautious.
The problem is not the foam itself so much as what it hides — a surveyor can’t value a roof they can’t inspect.
It is not a blanket ban
The widely-reported line is that spray foam makes a home unmortgageable. That overstates it. A November 2024 BBC survey of the 20 largest UK lenders found that a quarter — five of them: TSB, Skipton Building Society, the Co-operative Bank, Principality and equity-release lender Aviva — would not lend on homes with retrofitted spray foam. Separate research by the HomeOwners Alliance put the share of lenders willing to lend on retrofit foam at around 25%.
But the big high-street names take a case-by-case view rather than refusing outright. Santander, HSBC, Lloyds and Nationwide all confirmed they do not ban it; Lloyds stated: “We do not have a ban or block to lending on homes with spray foam insulation.” Most lenders simply want extra survey evidence before deciding.
The harder line is equity release: as of mid-2025, no equity-release providers would lend against a home with retrofit spray foam. And all of this applies to retrofit foam — insulation added after the home was built — rather than certified, warranted installations with the right paperwork.
What it costs to put right
Where foam needs to come out to satisfy a lender, removal is a specialist job. Checkatrade estimates around £3,200 to strip a typical three-bedroom detached roof (roughly £40 per square metre), and costs across the market commonly run from a couple of thousand pounds to £15,000 or more depending on roof size, the type of foam and any damage found. Closed-cell foam is harder to remove and costs more.
Removal is not always necessary, though. In May 2025 the Property Care Association (PCA) and HomeOwners Alliance told the government that, of more than 500 properties inspected since their surveyor register began, 35% had at least one defect linked to spray foam — which means most did not. An inspection is what separates the homes that genuinely need work from those that just need evidence.
One thing not to count on is help with the bill. In March 2025 the government confirmed there is no public funding to remove spray foam. Its position is that homeowners with incorrectly installed foam should seek remediation from the original installer or through an insurance-backed guarantee, escalating via TrustMark where needed.
The numbers that matter
214,000 of them owner-occupied (English Housing Survey 2024-25).
BBC survey, November 2024 — a quarter of the largest lenders.
Checkatrade estimate; the wider range runs higher.
What to do if your roof has spray foam
The route back to a straightforward mortgage is about giving a lender enough to say yes — not about the foam’s mere presence. Start by gathering whatever documentation you have from the original installation, and get the roof inspected by an independent specialist working to the PCA/RPSA Sprayed Foam Insulation Inspection Protocol. That report lets a surveyor assess the actual condition of your roof rather than refusing on sight.
If the foam was installed badly, pursue the installer or the insurance-backed guarantee, and use TrustMark to escalate if you hit a wall. And if you are thinking about installing spray foam, RICS’s advice is simple: check with your mortgage provider first whether their policy allows it.
The lender that turns you down is not the whole market. Because criteria vary so much from one lender to the next, this is exactly the kind of case where a broker earns their keep — matching your property to a lender that will take an evidence-based view.
Spray foam: the verified figures
- English homes with spray foam loft insulation
- 231,000
- Of which owner-occupied
- 214,000
- Largest lenders refusing outright
- 5 of 20
- Lenders that will lend on retrofit foam
- ~25%
- Equity-release providers lending on it
- None (mid-2025)
- Inspected properties with a defect
- 35%
- Typical removal cost (3-bed roof)
- ~£3,200
Sources: English Housing Survey 2024-25, BBC lender survey, PCA/HomeOwners Alliance & Checkatrade · to early June 2026.
Sources & method
Figures verified against primary sources on 5 June 2026.
- English Housing Survey 2024-25 — Home insulation fact sheet (gov.uk)
- RICS — Spray foam insulation consumer guide
- House of Commons Library — Spray foam insulation and mortgages
- Property Care Association — Sprayed foam guidance
- Homebuilding & Renovating — four lenders on spray foam and government support
Figures verified against primary sources on 5 June 2026. Lender criteria change frequently and vary by lender — check the current position before you act.
Your home may be repossessed if you do not keep up repayments on your mortgage. This article is general information, not personal advice. Lender policies on spray foam differ and change — speak to an adviser about your specific property.