Spray Foam Insulation Problems: The Complete UK Guide
Every issue UK homeowners face with spray foam insulation — and exactly how to resolve them
Spray foam insulation was once promoted as the ultimate energy-saving upgrade for UK homes. Government-backed schemes like the Green Homes Grant encouraged thousands of homeowners to install it. But the reality has been far more complicated. Today, spray foam insulation causes serious problems for homeowners across the country — from mortgage rejections and insurance refusals to hidden structural damage and significant property devaluation.
This guide covers every major problem associated with spray foam insulation in UK properties, explains why each issue matters, and links to our specialist articles for in-depth guidance on each topic.
The Scale of the Problem
An estimated 250,000+ UK homes now have spray foam insulation, many installed through government energy efficiency schemes. With 70-80% of mortgage lenders rejecting these properties, hundreds of thousands of homeowners are affected. If you have spray foam, you are not alone — and there are proven solutions available.
What Are the Main Problems with Spray Foam Insulation?
The main problems with spray foam insulation are mortgage rejection, home insurance refusal, hidden structural damage to roof timbers, blocked ventilation, and significant property devaluation. These issues affect both open-cell and closed-cell foam types, though closed-cell foam tends to cause more severe structural problems.
What makes spray foam particularly problematic is that the issues are interconnected. Mortgage lenders reject it because it hides structural problems; insurers refuse cover because claims become more likely; and property values drop because buyers cannot secure finance. Here is a summary of every major issue:
Mortgage Rejection
70-80% of UK lenders refuse mortgages on properties with spray foam, blocking sales, remortgages, and equity release.
Insurance Refusal
Insurers increasingly decline cover or add exclusions, leaving homeowners exposed to uninsured risks.
Structural Damage
Foam traps moisture against timbers, blocks ventilation, and hides rot, woodworm, and decay until damage is severe.
Property Devaluation
Homes with spray foam can lose tens of thousands of pounds in value due to restricted buyer pools and lender rejection.
Survey Failures
RICS surveyors flag spray foam as a material defect, causing mortgage valuations to be downgraded or refused.
Difficult Removal
Removal must be done manually by specialists — it is labour-intensive, and costs range from £2,000 to £14,000 depending on property size.
For a thorough look at what installers often fail to disclose, read our article on the real dangers of spray foam insulation. If you are considering whether removal is worthwhile, our honest assessment of whether to remove or keep spray foam can help you decide.
Can Spray Foam Insulation Cause Mortgage Problems?
Yes. Spray foam insulation is one of the most common reasons for mortgage applications being declined in the UK today. An estimated 70-80% of mortgage lenders, including Nationwide, Halifax, HSBC, Santander, Barclays, NatWest, Virgin Money, and TSB, now reject properties where spray foam is present in the roof space.
The problem stems from RICS (Royal Institution of Chartered Surveyors) guidance, which instructs surveyors to flag spray foam as a material consideration during mortgage valuations. When a surveyor identifies spray foam, most lenders either decline the application outright or impose conditions that are difficult to meet. This creates a cascade of problems:
Property Sales Fall Through
Buyers cannot secure a mortgage, so the sale collapses. This is the most common scenario and can happen after weeks of legal work and survey costs have already been incurred.
Remortgaging Becomes Impossible
When your fixed-rate deal ends, you may find no lender will offer competitive terms. This can leave you trapped on the standard variable rate (SVR), paying hundreds of pounds more each month.
Equity Release Is Blocked
Equity release providers apply similar restrictions to mortgage lenders. Your wealth remains locked in your property, inaccessible when you need it most. Read our guide on equity release and spray foam.
Further reading: For a complete breakdown of which lenders reject spray foam and what alternatives exist, see our detailed guides on spray foam insulation and mortgage problems and mortgage declined due to spray foam: your lender-specific solutions guide.
Will Spray Foam Affect My Home Insurance?
Yes, spray foam insulation can cause home insurance problems. Many UK insurers now ask specifically about spray foam during the application process, and a growing number refuse to provide cover or add significant exclusions for roof-related claims. Some insurers increase premiums substantially for properties with spray foam.
The insurance industry's concern mirrors that of mortgage lenders. Spray foam hides the condition of roof timbers, making it impossible for loss adjusters to assess pre-existing damage. If a roof claim is made on a property with spray foam, insurers face uncertainty about whether the foam masked problems that existed before the policy began. This leads to:
- --Outright refusal to quote — some insurers will not insure properties with spray foam at all
- --Roof exclusion clauses — cover is provided but any roof-related claims are excluded
- --Higher premiums — insurers who do offer cover charge significantly more to account for the hidden risk
- --Denied claims — existing policyholders may find roof damage claims rejected if spray foam is discovered
Important: Even if your current insurer has not asked about spray foam, you are typically required to disclose material changes to your property. Failing to disclose spray foam could invalidate your entire policy, not just roof claims. For detailed guidance, read our article on home insurance and spray foam insulation: why cover is refused until removal.
Does Spray Foam Insulation Cause Structural Damage?
Spray foam insulation does not directly cause structural damage, but it creates the conditions for serious structural problems to develop undetected. By coating roof timbers and blocking natural ventilation pathways, spray foam traps moisture, prevents inspection, and allows timber rot, woodworm, and condensation damage to progress hidden from view.
Traditional UK roofs are designed as "cold roofs" with deliberate ventilation paths that allow moisture to escape. When spray foam is applied to the underside of roof tiles or between rafters, it seals these ventilation routes and fundamentally changes how the roof manages moisture. The consequences can be severe:
Moisture Trapping and Condensation
When warm, moist air from the living spaces below meets the cold underside of roof tiles, condensation forms. In a properly ventilated roof, this moisture evaporates and is carried away by airflow. With spray foam in place, the moisture has nowhere to go. It collects against timbers, saturating the wood over months and years.
Consequence: Persistently damp timbers are the perfect environment for wet rot and dry rot to take hold, weakening structural members that support your roof.
Hidden Timber Rot
Because spray foam completely encases roof timbers, visual inspection becomes impossible. Rot that would normally be spotted during a routine loft check goes unnoticed until it reaches an advanced stage. In some cases, rafters have been found with significant structural loss hidden behind foam that appeared perfectly intact from the surface.
Consequence: By the time rot becomes visible — through sagging roof lines, water ingress, or cracking — the damage may be extensive and expensive to repair, sometimes requiring partial roof reconstruction.
Ventilation Pathway Blocking
UK building regulations require roof spaces to have adequate ventilation. Spray foam installations routinely block soffit vents, ridge vents, and the natural airflow channels built into the roof design. Some installers claim the foam itself provides a "warm roof" system that makes ventilation unnecessary, but this is only true if the installation is done to exacting standards — which is rarely the case with retrofit spray foam.
Consequence: Without ventilation, moisture accumulates, and the roof structure is deprived of the drying capacity it was designed to have.
Understanding the difference between foam types matters here. Our guide on open-cell vs closed-cell spray foam: which is worse for your home explains how each type creates different structural risks. For an overview of what surveyors look for, see why surveyors flag spray foam.
How Does Spray Foam Devalue Your Home?
Spray foam insulation can reduce a property's market value by tens of thousands of pounds. The devaluation occurs because the pool of potential buyers shrinks dramatically — most buyers need a mortgage, and most mortgage lenders reject spray foam properties. Sellers are often forced to accept cash-only offers at 20-40% below market value.
To put this in real terms: a property worth £300,000 on the open market might sell for only £180,000-£240,000 if spray foam is present and the seller cannot access mortgage-backed buyers. This represents a loss of £60,000-£120,000 — far more than the cost of professional removal, which typically ranges from £2,000 to £14,000.
The Good News: Removal Restores Value
Properties that have spray foam professionally removed and certified return to full market value. The removal certificate gives surveyors and lenders the assurance they need, opening the property back up to the full range of mortgage-backed buyers. The investment in removal is typically recovered many times over through the restored sale price.
For a detailed analysis of how spray foam affects your property's value and what you can expect after removal, read our guide on how spray foam insulation devalues your home and how removal restores it. If you are trying to sell a property with spray foam, see selling a home with spray foam insulation and how to save a sale that has fallen through because of spray foam.
Can Spray Foam Insulation Be Removed?
Yes, spray foam insulation can be removed. Professional removal is a well-established process carried out by specialist contractors across the UK. The foam is manually scraped from rafters and roof timbers using hand tools — this is the only method accepted by mortgage lenders. Removal typically takes 2-7 days and costs between £2,000 and £14,000 depending on property size, foam type, and access.
Manual removal is essential because mechanical methods (such as grinding or chemical stripping) risk damaging the timbers underneath. Lenders require evidence that the removal was carried out carefully and that the timber is in good condition afterwards. A certified removal specialist will provide a completion certificate that confirms the foam has been fully removed, the timbers have been inspected, and any necessary remedial work has been completed.
What Does Removal Cost?
£2,000 - £5,000
Small property / partial coverage
£5,000 - £9,000
Average 3-bed semi-detached
£9,000 - £14,000
Large / detached property
After removal, many homeowners choose to re-insulate with a lender-approved alternative such as mineral wool. This restores energy efficiency without the problems associated with spray foam. Read our guide on re-insulating after spray foam removal: the best materials and methods.
Further reading: For a step-by-step walkthrough of the removal process, see our spray foam insulation removal guide. For detailed cost breakdowns by property type and region, visit our UK spray foam removal costs 2025 price guide. To understand what certification you should expect, read about spray foam removal certification.
What Should You Do If You Have Spray Foam Problems?
If you have spray foam insulation and are experiencing any of the problems described above, the most effective solution is professional removal. Acting sooner rather than later protects your property's value, prevents further structural deterioration, and gives you back full financial flexibility with lenders and insurers.
Here are the steps we recommend:
Assess Your Situation
Determine whether you are planning to sell, remortgage, or release equity in the near future. If any of these apply, removal should be treated as urgent. Even if you have no immediate plans, remember that delaying increases the risk of hidden structural damage. See our article on the cost of delaying spray foam removal.
Get Multiple Quotes
Obtain at least 3 quotes from reputable, specialist spray foam removal companies. Beware of unusually low quotes or companies promising chemical removal methods — these are not accepted by lenders. Our guide on how to choose a spray foam removal company explains what to look for and what to avoid.
Verify Credentials and Certification
Ensure the company provides a proper removal certificate that will be accepted by lenders and surveyors. Ask about their insurance, removal methodology, and what happens if timber damage is found during the process. Read our guide on spray foam removal certification and learn how to spot and avoid spray foam removal scams.
Complete Removal and Re-insulate
Professional removal typically takes 2-7 days. Once complete, the specialist will inspect all timbers, carry out any necessary treatment, and issue certification. You can then re-insulate with a lender-approved material to restore energy efficiency.
Move Forward with Confidence
With the removal certificate in hand, you can sell to any buyer, access the full range of mortgage lenders, secure competitive insurance rates, and have peace of mind that your roof structure is properly maintained and inspectable.
Free Quotes from Vetted Specialists
We connect UK homeowners with vetted, specialist spray foam removal contractors. Our service is free, with no obligation. Request your free quotes here or read about why homeowners choose National Spray Foam Advice.
Related Spray Foam Guides
Explore our specialist articles for in-depth guidance on every aspect of spray foam insulation problems:
Frequently Asked Questions
Is spray foam insulation banned in the UK?
Spray foam insulation is not banned in the UK. However, most mortgage lenders reject properties with spray foam, and RICS guidance requires surveyors to flag it as a material defect. This makes it effectively problematic for any property that needs mortgage finance. Read our full article on whether spray foam insulation is banned.
How much does spray foam removal cost in the UK?
Spray foam removal costs in the UK typically range from £2,000 to £14,000 depending on property size, foam type (open-cell or closed-cell), coverage area, and access requirements. An average 3-bedroom semi-detached house usually costs between £5,000 and £9,000. This includes removal, timber inspection, any necessary treatment, and certification.
Will I need a new roof after spray foam removal?
In most cases, no. Professional removal specialists carefully scrape the foam from timbers without damaging the roof structure. However, if the foam has been hiding significant timber damage, some repair work may be needed. A reputable removal company will assess timber condition during the process and advise on any necessary repairs. Read more in our guide on whether you need a new roof after spray foam removal.
I had spray foam installed through the Green Homes Grant. Am I affected?
Yes, properties with spray foam installed through the Green Homes Grant or similar government schemes face the same issues. Government energy efficiency programmes and mortgage lender risk policies are entirely separate. The fact that the installation was government-funded does not change how lenders or surveyors view it. Learn more about the unintended consequences of the Green Homes Grant.
Can I remove spray foam insulation myself?
DIY removal is strongly discouraged. Mortgage lenders require professional removal with proper certification. Without a recognised removal certificate, lenders will still reject the property. Professional removal also ensures the timbers are properly inspected and any damage is identified and treated. The cost of doing it twice (once DIY, then professionally) far exceeds getting it done right the first time.
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