How Spray Foam Affects Home Valuations: Surveyors Reveal the Truth

Spray foam insulation might help with energy efficiency — but it can quickly become a liability when it comes to getting your home valued. From mortgage approvals to down-valuations and surveyor reports, this article explains how spray foam affects home valuations in 2025, and what you can do to protect your property's worth.

1. Why Surveyors Flag Spray Foam During Valuations

Surveyors are tasked with assessing the condition, risk, and marketability of a home on behalf of lenders or buyers. Spray foam insulation, particularly in the roof space, presents a number of unknowns:

• It can hide defects like rotten timbers or moisture build-up
• It reduces ventilation in roof voids
• It can’t be inspected without partial removal
• It’s often poorly installed in older homes

As a result, RICS-accredited surveyors often label spray foam as a "material risk", which can reduce the valuation or lead to outright rejection by a lender.

Related: Why Spray Foam is a Red Flag for Homebuyers
https://snugandsecure.co.uk/blog/spray-foam-unsellable-homes

2. How Much Can Spray Foam Devalue a Property?

While the exact reduction depends on the condition and location of the property, industry experts suggest that homes with spray foam in the loft may be down-valued by 5–20% — especially if the surveyor notes risk to the structural timbers or restricted access for future repairs.

Even if the property is in good condition, the presence of spray foam can:

• Make buyers more cautious
• Reduce the number of mortgageable offers
• Trigger delays or renegotiations during the sale

If the insulation is old, discoloured, or obviously blocking ventilation, the chances of down-valuation are much higher.

3. What Do RICS Surveyors Look for With Spray Foam?

A RICS surveyor inspecting a home with spray foam will typically check:

• Whether the insulation is open-cell or closed-cell
• The extent of coverage (partial, full, rafter-level)
• Whether there’s any visible condensation or staining
• If the foam appears to compress or delaminate
• Whether roof timbers can be inspected at all

They will also check whether the installation has a BBA certificate — although this rarely changes their final assessment if moisture risks are present.

Related: What Does Spray Foam Insulation Look Like?
https://snugandsecure.co.uk/blog/what-does-spray-foam-look-like

4. When Will a Surveyor Recommend Removal?

In most cases, if the foam is obstructing a full inspection of the roof structure, or signs of damp are present, the surveyor will recommend removal before a mortgage can proceed. This can delay or derail a house sale or remortgage process.

Common triggers for removal include:

• Closed-cell foam applied directly to roof tiles
• No visible ventilation in the roof void
• Soft or discoloured timber detected by probe
• Foam covering 100% of joists, preventing inspection

To avoid this situation, many sellers are now proactively removing spray foam insulation before listing their property.

Related: Should You Remove Spray Foam If You’re Not Selling?
https://snugandsecure.co.uk/blog/remove-spray-foam-not-selling

5. Can Spray Foam Ever Increase a Property's Value?

In rare cases, if spray foam is:

• BBA-certified
• Installed by a trusted professional
• Open-cell, breathable, and well-ventilated
• Part of a newly built or recently renovated roof system

...then it may have neutral or slightly positive impact on valuation due to improved energy efficiency.

However, for older properties and loft retrofits, the market consensus — and the attitude of lenders — remains cautious. Surveyors often default to assuming risk unless they have clear visibility and documentation.

6. How to Protect Your Property Value if You Have Spray Foam

If your home has spray foam insulation and you're planning to sell or remortgage, here’s what you can do to protect the valuation:

• Book a pre-sale survey to identify issues in advance
• Get a spray foam condition report from an insulation expert
• Consider partial or full removal to restore breathability
• Document any past issues, repairs, or improvements clearly
• Include loft photos and ventilation details in your listing pack

Need help with removal?
https://snugandsecure.co.uk/spray-foam-removal

Frequently Asked Questions

Will spray foam automatically lower my valuation?
Not always — but in many cases it will lead to increased scrutiny or risk notes in the valuation report, which can affect lender decisions.

Do all surveyors treat spray foam the same way?
Most follow RICS standards, but their opinions can vary. What matters most is whether they can visibly inspect roof timbers.

Is open-cell spray foam less risky to surveyors?
Yes, it's more breathable than closed-cell, but it can still cause issues if it covers too much of the loft or blocks ventilation.

Can I challenge a down-valuation due to spray foam?
You can request clarification or commission a second opinion, but most lenders will defer to the surveyor’s judgment.

Is it better to remove spray foam before marketing a property?
Yes — you’ll attract more confident buyers, make the survey process easier, and improve your chances of securing a full-value offer.

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