Homeowners across Scotland are being warned that spray foam insulation could leave properties unmortgageable, as lenders continue to refuse applications on affected homes.
Research cited in the House of Commons estimated that around 250,000 homes across the UK are now potentially unsellable due to the presence of spray foam insulation.
The issue is also generating growing numbers of complaints.
According to Citizens Advice, complaints relating to spray foam insulation more than doubled in 2024 compared to the previous year, accounting for one in three insulation complaints and one in five complaints relating to low-carbon installations.
While these figures are UK-wide, Scottish regulators have reported similar concerns.
Trading Standards Scotland said in its 2025/26 Business Plan that complaints linked to spray foam insulation remained an ongoing issue throughout 2024/25, with consumer harm occurring during installation, ownership and removal.
Many homeowners affected by the issue had spray foam installed through government-backed energy efficiency schemes, including the Green Homes Grant and ECO4 programmes.
However, lenders have become increasingly cautious. According to the research, up to one in four major mortgage lenders will not lend against properties containing spray foam insulation, regardless of installation quality.
As a result, some homeowners are facing removal costs estimated at between £4,500 and £15,000 in order to proceed with a sale or remortgage.
Authorities have also warned of a second wave of consumer harm, with rogue traders targeting affected homeowners by offering removal services.
National Trading Standards said fraudsters have been cold-calling victims and, in some cases, identifying potential targets through planning applications.
Trading Standards Scotland has urged homeowners not to engage with unsolicited approaches and to seek independent advice before agreeing to any remedial work.
Michael Davie, home improvement specialist at PureBuilt, said: “We are now seeing spray foam turn up on surveys as a red flag, not an upgrade. People thought they were improving their homes, but instead they have ended up with properties that some lenders will not touch.
“External wall insulation, when it is properly specified and installed, does what spray foam was supposed to do: it cuts bills, keeps homes warm and protects property value rather than destroying it.”