While a thorough property survey can identify a variety of building defects, the presence of spray foam insulation is one issue that can raise serious concerns.
Spray polyurethane foam (SPF) insulation has been on the UK market for more than 30 years. This liquid foam is sprayed beneath roof pitches to boost the property’s insulation. It is commonly used on sloping roofs in poor repair or as a convenient solution, and its popularity has grown in recent years as an alternative to traditional loft insulation like fibreglass, wool, or insulation boards.
Mortgage lenders are increasingly cautious about SPF insulation, and some may refuse to provide financing for properties where it is installed. This has led surveyors and valuers to either lower the property’s market valuation or call for a specialist inspection when spray foam insulation is present.
Is Spray Foam Insulation the Right Choice for You?
Spray polyurethane foam (SPF) is installed as a liquid foam that hardens after application. Typically applied in a 100mm layer beneath the roof, it may release persistent toxic fumes. The material is unsightly, cannot be covered with decoration, and costs more than conventional insulation types.
SPF offers better insulation than traditional mineral wool, meaning less material is needed to achieve comparable thermal results. Since it is sprayed onto the roof slope, it leaves the loft floor space free for boarding and storage.
Contractors promoting SPF insulation emphasize its energy-saving potential, claiming it can reduce energy bills by as much as 20%. It is also touted as a solution to prevent water tanks and pipes from freezing, while keeping the loft space dry. On top of that, the rigid foam is said to enhance roof strength and prevent roof tiles from slipping.
SPF insulation comes in two varieties: open cell and closed cell. Closed cell SPF is dense and rigid, which helps block moisture from passing through it, making it highly effective for insulation. In contrast, open-cell SPF is softer and spongier, offering reduced insulation performance but superior sound absorption and the ability to let water vapour escape.
Why Spray Foam Insulation Could Be a Problem.
One of the main drawbacks of SPF insulation is its tendency to block ventilation in the roof space, which can result in serious condensation problems. The issue is especially noticeable with closed-cell SPF, but even the open-cell variety, marketed as “breathable,” can cause condensation in areas where the foam meets the roof materials.
Over time, the accumulation of moisture can lead to wood rot in the roof timbers. Additionally, defects in the roof covering might be hidden from sight, allowing water to penetrate and cause timber decay. Damp problems in the roof may stem from either water penetration or condensation, so a thorough building survey is essential to identify the exact cause.
Spray foam insulation should be avoided in period homes or listed buildings, particularly those with stone flag, slate, or handmade clay tile roofs. While some roofing materials can be reused during re-roofing, SPF insulation makes this impossible, as it cannot be removed or recycled.
How Do Mortgage Lenders React to Spray Foam Insulation.
Lender guidelines for surveyors on spray foam insulation differ widely, from requesting a report from a structural engineer or roofing contractor, to reducing the property’s valuation due to the potential cost of roof replacement or even rejecting the loan altogether. Property surveyors and valuers must always be aware of the latest lender-specific guidance when they encounter SPF during a survey or mortgage valuation.
There is not always a clear lending policy from all mainstream lenders when it comes to properties with SPF insulation. If you are considering installing it in your home or buying a property that already has it, it is essential to contact your mortgage provider as soon as possible to clarify their requirement.