Specialist Spray Foam Surveys in Devon & North Devon

What Is Spray Foam Insulation?

Spray foam insulation - technically Spray Polyurethane Foam (SPF) - is applied on site as a liquid and expands to form an insulating layer within roof spaces and loft voids. It’s often marketed as a way to:

Because it expands to fill voids, it’s sometimes seen as a quick fix compared to laying traditional loft insulation.

However, RICS — the Royal Institution of Chartered Surveyors - cautions that spray foam is a serious modification to a roof structure and should not be treated lightly.

Why Spray Foam Can Be a Problem

While spray foam has certain thermal properties, it can also introduce a range of risks when applied retrospectively to existing roof structures:

1. It Changes How the Roof Works

Traditional pitched roofs are designed as a ‘cold roof’, where insulation sits at ceiling level and the loft remains ventilated. Spray foam effectively turns this into a ‘warm roof’, altering heat flow and moisture behaviour in ways the original design did not anticipate.

Without careful design and ventilation control, this change can trap moisture inside the roof space - increasing the risk of condensation and timber decay, and potentially causing long-term structural problems.

2. It Obscures Hidden Problems

Once spray foam is applied directly to rafters, tiles, felt or timber, it becomes difficult or impossible for surveyors and roofers to see critical elements of the structure. This means issues such as:

can be hidden beneath the foam.

This lack of visibility is one of the reasons mortgage lenders are cautious - they can’t be sure the roof they’re lending against is sound. Many lenders will refuse to lend altogether if spray foam insulation is present, regardless of whether it has caused an issue.

3. It Can Be Hard to Reverse

Unlike mineral wool or other traditional insulation products, spray foam is not easily removed without damaging the roof structure. Once installed, it’s effectively permanent - which heightens the concern for future repair and maintenance.

Real Case Examples: Spray Foam Surveys in Devon & North Devon

To illustrate why spray foam insulation needs careful, case-by-case assessment, here are a few real-world examples from recent specialist spray foam surveys carried out by our team across Devon, North Devon and Torridge.

These show that outcomes are not always the same - some roofs remain structurally sound, while others require costly remedial work.

Case Study 1: Spray Foam Survey in Barnstaple, North Devon

In this property, the spray foam insulation did not fully encapsulate the rafters, which meant that large areas of the roof timbers remained visible and accessible for inspection. This is generally preferable, as it reduces the risk of hidden timber decay.

Where the rafters and battens were exposed, they were found to be in good condition with no visible signs of rot, decay or structural distortion. There was also no evidence of significant deflection to the rafters or purlins to suggest structural failure.

However, the inspection confirmed that:

This creates a major practical problem: the foam cannot be economically removed from the tiles. As a result, the roof coverings will need to be fully stripped and replaced when the roof is renewed.

Estimated future cost of roof replacement: in excess of £31,000

While the roof structure is currently performing, the presence of spray foam has significantly increased the long-term maintenance cost and risk profile of the property.

Case Study 2: Spray Foam Survey in North Devon (Mortgage & Moisture Risk Case)

In this case, the insulation installed was open-cell spray foam, which is generally considered less risky than closed-cell foam. A notice in the roof space also suggested the installation was intended to follow industry standards.

However, on closer inspection, several critical documentation and technical gaps were identified:

Because:

We recommended full removal of the spray foam insulation.

This is a good example of how even “less risky” open-cell foam can still cause serious lending and durability concerns if installed without proper design, preparation and documentation.

Case Study 3: Spray Foam Post-Removal Survey, Devon

In this case, most of the spray foam insulation had already been removed prior to our inspection.

Our findings confirmed:

We also found:

Following removal:

The recommendation:

 This is a good example of a case where spray foam did not cause structural failure, but did introduce unnecessary technical risk and future cost.

Case Study 4: Spray Foam Survey in Torridge, Devon

In this case, documentation confirmed that the spray foam product itself was BBA certified (Walltite). However, certification of the product is not the same as certification of the installation.

Our review found:

Although the product itself is approved, the installation does not appear to comply with the conditions of the BBA certificate, which creates:

This is a common issue we see - The material may be approved, but the way it has been used is not.

The Key Lesson: Spray Foam Must Be Assessed Individually

These cases show why:

What the RICS Consumer Guide Says

The RICS Spray Foam Insulation Consumer Guide (March 2023) provides clear, impartial advice to homeowners considering spray foam. RICS emphasises:

You can read the full RICS consumer guide here: 👉 RICS Consumer Guide - Spray Foam Insulation (PDF):

Why Lenders Often Refuse Mortgages on Spray-Foamed Properties

Even if spray foam is installed “correctly,” many mortgage lenders operate blanket policies that exclude properties with it - simply because:

Some lenders may accept a property only if accompanied by specialist reports (e.g. a PCA inspection protocol report) or certification that the installation is safe, but many will still refuse or require removal.

This can leave homeowners unable to remortgage or buyers unable to secure a loan - which is why professional assessment is crucial.

When Spray Foam Might Be OK - and When Specialist Help Is Useful

Spray foam insulation is not always a problem - for example:

But these scenarios are the exception rather than the rule.

If you’re buying a property in Devon or North Devon with spray foam insulation, or if you already own a home with spray foam and want to understand the implications for mortgageability, insurance, or future maintenance, it’s sensible to obtain a specialist assessment.

At Nova Surveyors we have specially trained chartered surveyors with experience in assessing spray foam insulation and its impact on:

Key Takeaways

✔ Spray foam insulation is a significant retrofit, not just “better insulation.”
✔ It alters roof ventilation and can trap moisture.
✔ Surveyors and lenders often struggle to inspect roofs with spray foam.
✔ Many lenders decline mortgages on properties with spray foam regardless of risk.
✔ An independent specialist assessment can help clarify risks and options.

At Nova Surveyors, we carry out specialist spray foam insulation surveys across:

If you’re looking for experienced surveyors in Devon or North Devon to assess spray foam insulation, get in touch - we can help you understand the implications for your property and support you through buying, selling, or lending challenges.