A warning has been issued that as many as 250,000 homes – some likely to be in the private rental sector – are effectively unmortgageable because of their insulation.

The properties concerned are those with sprayed polyurethane expanding foams used in the lofts; a trade body says a tightening of lending criteria has left thousands of owners unable to sell as buyers get refused loans.

Alan Milstein, chair of the Residential Property Surveyors Association, says: “This has become a significant problem recently. Many of the installations we see are poorly executed and without proper consideration of moisture management within the property, leaving structural roof timbers at risk of damage or failure. And there are regular reports of mis-selling, and cold-calling of vulnerable homeowners, especially the elderly.” 

Currently there is no regulation of installers and Milstein says almost any cowboy salesman can get hold of the chemicals and the equipment to spray foam into the homes of unsuspecting owners. 

He insists that government intervention in the form of regulation is the only way through the current lending impasse.

He adds: “We have already started to engage with those in the spray foam industry to help facilitate a regulatory framework. And so our challenge to them is to come forwards and work with us to regulate as soon as possible. That means mandatory training and qualification of installers, effective audit and review procedures, and a strict non-supply policy by manufacturers to any installer who is not properly accredited.”

Milstein says that many owners who spend thousands installing the insulation now find, upon trying to sell, that they most spend thousands to remove it.