Warning over 'cowboy' foam insulation firms

People are putting their homes at risk by using rogue companies that offer spray foam insulation, according to one of the UK's largest mortgage providers.

Nationwide Building Society says thousands of pounds worth of damage can be caused if it is wrongly installed.

The lender says it expects inquiries about spray foam to "skyrocket" as more people seek to insulate their homes better.

It is advising people to make sure they only use reputable firms.

Sandra Burton from Nottingham says she was targeted by a "cowboy" firm which put spray insulation foam in her roof - causing problems which have cost £4,500 to repair.

"I thought I was doing the right thing. Cost of living going up, energy prices going up, and I thought 'yes, I'll do it'," she says.

"Terrible, absolutely terrible. They are obviously preying on the elderly. It's just awful.

"My husband is retired and is a very poorly man, he's got Alzheimer's. I've just got my pension so yes, it's been hard," she says.

Upstairs in Sandra's loft it looked like "a bomb had gone off" with foam "absolutely everywhere", says her daughter Jo.

"It was all over the wood, all over the water tank. It was in the water tank, all over the electricals - everywhere was just covered in foam," she says.

Damage to Sandra's water tank meant there was a flood in the loft which leaked through to her bedroom and caused the ceiling to collapse.

Spray foam insulation has been around for years, but Nationwide, the UK's second largest mortgage provider, says it is seeing a big increase in inquiries related to it now.

"Given the cost of living crisis, given the fact people are worried about climate change... this is a time when people are susceptible to taking out these products," says Rob Stevens who, as head of property risk at Nationwide, is in charge of a team which surveys hundreds of homes every day.

"We want to make sure people know the right way to do it and are able to insulate their houses in a safe way which saves them money," he says.

Some people have reported problems trying to sell a property, take out a mortgage or release equity from a property with foam insulation.

Part of the problem is that at the moment there's no easy way for consumers to tell the difference between reputable firms and rogue operators.

Simon Storer from the Insulation Manufacturers Association (IMA) says it is working on a new guide for consumers and industry due in the spring.

"We are well aware of the issues being raised," he says. "Therefore collectively, with insurers, mortgage lenders, with surveyors and other people within this sector, we are working to create a protocol which should give the reassurance to them, so they can lend against these properties when the installation has been done professionally and correctly," he says.

Yet even when spray foam is installed correctly by a reputable firm, there can be problems, as Yasemin Rowland from Surrey found when she tried to sell her house.

Her buyers' lender pulled their mortgage-in-principle offer after learning about the spray foam in her loft.

"We were really shocked when we saw that the [spray foam] loft insulation was a problem, particularly as we had given so much time and energy to investigating which option was right and the best and most energy efficient. We were stunned," says Yasemin.

Simon Storer from the IMA says it is not true that you can't get a mortgage at all for a property with spray insulation but there are problems around its reputation.

"It is completely unhelpful to have a blanket response to spray foam applications. What this does is... spread fear and doubt and opens the way for unscrupulous operators to target all applications for removal when this is patently not necessary," he says.

The Royal Institution of Chartered Surveyors says while it is not calling for an outright ban on spray foam it is advising homeowners to get an independent expert to check that it is suitable for their home.

There are much cheaper alternatives too, such as the more traditional roll insulation, available for a few hundreds pounds from most DIY stores.

As for Sandra she's just happy her spray foam is nearly gone:

"I feel absolutely over the moon because it's all cleared out now, because I've got peace, which I didn't have before."

You can hear more on this story on BBC Radio 4's Money Box podcast by clicking here.