Thousands of homeowners across the UK are discovering that spray foam insulation — often installed under the now-defunct Green Homes Grant — is making their properties impossible to remortgage or sell. Mainstream lenders have tightened their position dramatically since 2022, and surveyors are now required to flag it. If you have spray foam in your roof space, or you are buying a property with it, this guide explains exactly what the problem is, what your options are, and what it will cost.
Why Spray Foam Causes Mortgage Problems
Spray foam insulation is applied as a liquid that expands and sets rigid in the roof space, bonding directly to roof timbers, sarking boards, and the underside of roof tiles. This creates three distinct problems for lenders and surveyors:
1. It Makes Structural Inspection Impossible
Once spray foam has been applied to roof timbers, a surveyor cannot inspect the timber for rot, beetle infestation, or structural deterioration beneath the foam. In a standard property, the roof structure is inspected visually in the loft space. With spray foam present, this inspection is blocked — the foam bonds to and coats the timber completely. RICS guidance (April 2023) explicitly states that surveyors should report spray foam insulation as a material issue precisely because it prevents the inspection necessary to confirm the structural integrity of the roof.
2. It Can Trap Moisture
Timber roofs require a degree of natural ventilation and moisture movement. Spray foam — particularly open-cell foam — can trap moisture against the timber, creating conditions for rot that may not be visible or detectable without foam removal. This is not hypothetical: specialist contractors have reported significant timber degradation discovered only after foam removal.
3. Some Types Compress or Bow Rafters
Closed-cell spray foam is rigid and can, in some installations, apply compressive force to roof timbers as it sets — particularly where it was over-applied or where the loft space is poorly ventilated. This can cause deflection of rafters, which in serious cases may affect the structural performance of the roof. If you suspect structural issues following foam installation, see our structural engineer report UK guide for when and how to commission an assessment.
Open-Cell vs Closed-Cell: Does the Type Matter?
Yes — but both types are flagged by lenders and surveyors.
| Type | Characteristics | Lender/Surveyor Position |
|---|---|---|
| Open-cell spray foam | Softer, flexible when set; more permeable to moisture; typically cheaper to install | Most problematic — high moisture retention risk; flagged by all mainstream lenders |
| Closed-cell spray foam | Denser, rigid when set; lower moisture permeability; higher thermal performance | Still flagged by most mainstream lenders despite slightly lower moisture risk; structural compression concern remains |
The distinction matters marginally for the removal process — open-cell foam is generally easier and cheaper to remove — but for mortgage purposes, both types are treated with similar caution by most lenders.
The Current Lender Position
Since 2022, most mainstream UK mortgage lenders have moved to decline or impose conditions on properties with spray foam insulation in the roof space:
| Lender | Reported Position |
|---|---|
| Halifax / Lloyds | Will not lend where spray foam is present in the roof space without specialist assessment |
| Nationwide | Declines in most cases; specialist valuation required |
| NatWest | Requires specialist report; may decline depending on findings |
| Santander | Treats as material defect; specialist assessment required |
| Barclays | Similar position — case-by-case based on specialist report |
The RICS guidance note published in April 2023 requires RICS surveyors to report spray foam as a matter warranting further investigation in all cases. This means that on any mortgage valuation or homebuyer survey, the surveyor is obliged to flag it — which in turn triggers the lender's spray foam policy.
Specialist lenders (Kensington, Together Money, Pepper Money) may lend on affected properties at higher rates and loan-to-value ratios, but this is not a long-term solution for most homeowners — you are paying a premium rate precisely because mainstream lenders won't touch it. For a full picture of how specialist lenders handle difficult properties, see our mortgage on a property with issues UK guide.
The Green Homes Grant Problem
The Green Homes Grant ran from September 2020 to March 2021, offering homeowners vouchers of up to £5,000 to fund energy efficiency improvements including spray foam insulation. An estimated 30,000+ homes received spray foam under the scheme.
The problem: the scheme was closed abruptly, many of the installation companies that delivered the work subsequently went into administration, and the workmanship quality was highly variable. Homeowners who had poor-quality spray foam installations have largely no recourse — the companies are gone, there is no government-backed warranty, and the Microgeneration Certification Scheme (MCS) does not cover spray foam.
If you had spray foam installed under the Green Homes Grant, you should check:
- Whether the installer was registered with an appropriate trade body at the time
- Whether the installation certificate specifies the type of foam used
- Whether any insurance-backed guarantee (IBG) was issued at the time of installation — very few were
For context on energy efficiency grants more broadly and what is available now, see our renovation grants and funding UK guide.
Removal Costs
Spray foam removal is specialist work. The foam must be cut, chipped, and in many cases abraded away from roof timbers without damaging the underlying structure. If the foam has caused timber deterioration, repairs or full timber replacement may be necessary.
| Property Type | Roof Area | Estimated Removal Cost |
|---|---|---|
| 2-bed terraced house | 40–60 m² | £3,000–£5,000 |
| 3-bed semi-detached | 60–80 m² | £4,000–£7,000 |
| 4-bed detached | 80–120 m² | £6,000–£10,000 |
| Dormer bungalow or complex roofline | Variable | £8,000–£15,000+ |
| Timber replacement required post-removal | Per rafter | £150–£400 per timber |
These figures assume straightforward loft access and no underlying structural damage. Where foam has penetrated the sarking board or caused timber damage, costs escalate significantly. Always obtain at least three quotes from specialist contractors. For roof repair and replacement costs more broadly, see our roof repair costs UK guide.
Getting a Specialist Survey
Before committing to removal, instruct a specialist spray foam assessor. The BEIS (Department for Business, Energy & Industrial Strategy) commissioned assessor framework covers surveyors who have been trained to assess spray foam installations specifically.
A specialist spray foam survey:
- Cost: £300–£800
- What it covers: identification of foam type, assessment of adhesion and coverage, timber condition (where discernible), recommendation for removal vs remediation vs retention
- Output: a written report that some lenders may accept in lieu of full removal — though in practice, most mainstream lenders still decline without full removal
Do not rely on a standard RICS Level 2 survey for this — a general surveyor will flag the foam and recommend specialist investigation, but they are not trained to assess whether it can be left in place. For a comparison of standard survey types, see our home buyers survey vs full structural survey UK guide.
What to Do If You Have Spray Foam
- Do not panic — but do act before you need to sell or remortgage. Removal costs now are lower than removal costs under time pressure when a sale is at risk.
- Commission a specialist survey to understand the type, condition, and extent. This informs whether removal is urgent or can be planned.
- Get three removal quotes from specialist contractors. Avoid generalist roofers — spray foam removal requires specific training and equipment.
- Check your lender's position if you are planning to remortgage. Call the lender directly and ask their current policy on spray foam — it is changing, and some lenders are becoming slightly more flexible on closed-cell foam with specialist reports.
- Check whether any IBG was issued at installation — check your original voucher documents, email trail, and any paperwork from the installer.
What to Do If You Are Buying a Property With Spray Foam
- Ask the seller to disclose the foam type and installation documentation as part of pre-contract enquiries
- Commission a specialist survey before exchange — not as an add-on to the standard survey, but as a separate instruction to a specialist assessor
- Check with your intended lender before proceeding: can they lend on this property? At what LTV? What do they require?
- Negotiate the price to include a removal contingency. Use the mid-range removal estimate (£5,000–£8,000 for most properties) as a negotiation anchor — even if you ultimately decide to leave the foam in place, you have absorbed the risk into your purchase price.
- Consider walking away if the seller refuses to contribute to removal costs and the property is in an area where only specialist lenders will lend. Your exit options at resale will be similarly constrained.
What to Do Next
- Check whether your property has spray foam if you are unsure — a loft inspection will confirm it (look for foam coating on the underside of roof tiles and rafters)
- Find a specialist assessor through the National Insulation Association (nationalinsulationassociation.org.uk) or the Insulated Render and Cladding Association (INCA) spray foam register
- If you installed foam under the Green Homes Grant, check gov.uk for any updated guidance on the government's position — this area continues to evolve
Further Reading
- Mortgage on a Property with Issues UK — how spray foam and other property conditions affect lending decisions
- Structural Engineer Report UK — when to commission a structural assessment after spray foam concerns
- Roof Repair Costs UK 2025 — roof repair and replacement costs if foam removal reveals underlying damage
- Home Buyers Survey vs Full Structural Survey UK — why specialist surveys are needed in addition to a standard RICS report
- Renovation Grants and Funding UK 2025 — current funding options for energy efficiency improvements