Data

Spray foam and mortgages: the UK numbers

Spray foam insulation in a roof can make a home hard to mortgage. An estimated 250,000 UK homes have it, much of it fitted under grant schemes. In a November 2024 survey, a quarter of the biggest mortgage lenders, and all of the equity-release lenders surveyed, said they would not lend against a home with spray foam in the roof. The Royal Institution of Chartered Surveyors has issued cautionary guidance because the foam can hide moisture, block ventilation and cause timber decay, so a surveyor will usually flag it and the lender will hold funds until it is professionally removed and the roof certified. Removal typically costs between £2,000 and £5,000.

~250,000
UK homes estimated to have spray foam insulation, much of it from grant schemes
A quarter
of the biggest mortgage lenders surveyed would not lend on homes with roof spray foam (BBC, Nov 2024)
All
equity-release lenders surveyed would not lend against roof spray foam (BBC)
£2,000 to £5,000
typical cost to remove spray foam and certify the roof

Why lenders react to it

The problem is not the insulation itself but what it can hide. Closed-cell spray foam applied to the underside of a roof can trap moisture, restrict the ventilation a roof needs, and make it impossible for a surveyor to inspect the timbers underneath for rot. Because a lender's security is the property, anything that risks the structure or that a surveyor cannot sign off makes the home a higher risk to lend against. That is why a valuation will flag spray foam and the lender will usually decline or hold funds until it is removed and the roof certified as sound.

What it means if you have it

If you are selling or remortgaging, spray foam in the roof can stall the deal until it is dealt with. The usual route is a professional removal followed by a survey or report confirming the roof is structurally sound, after which more lenders will consider the property. Costs vary with the size and access of the roof. Get a proper inspection before assuming the worst, as not all spray foam is the same and some lenders take a case-by-case view.

How this is measured

The lender position is from a November 2024 BBC survey of major UK mortgage and equity-release lenders, reported alongside the House of Commons Library briefing on spray foam insulation and mortgages. The structural concerns are set out in cautionary guidance from the Royal Institution of Chartered Surveyors. The estimate of around 250,000 affected homes and the typical removal cost of £2,000 to £5,000 are widely cited figures across surveyors and removal specialists rather than a single official count, so treat them as indicative. This is general information, not mortgage or surveying advice.

Adam Parker

Adam Parker

Editor, VettedHome

Adam leads VettedHome's editorial coverage of UK home services. He is the founder and managing director of Muswell Rose, the commercial strategy and modern systems business behind a portfolio of UK information sites, and he researches and writes the plain-English guides that help homeowners choose between installers and trades, drawing on the standards set by the relevant bodies for each job, such as Gas Safe Register, NICEIC, MCS, TrustMark and the Property Care Association. He is clear about what to check before any work starts.

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