In winter – especially this one – many homeowners turn their thoughts to loft insulation. But there is one form of insulation to beware of: spray foam. The insulation industry assures me there is nothing wrong with it if properly installed, but if you have spray foam in your loft then lenders will run a mile, properly installed or not.


If you want to sell your home, the buyer will find getting a mortgage very difficult. If your fixed rate mortgage is coming to its end, re- mortgaging will be difficult or expensive. And if you want to release some of the value of your home through equity release, it will be almost impossible to get a lender to agree.

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Spray foam is a polyurethane splurged between and over the rafters in the loft, filling all the little nooks and crevices with material that hardens in the air and acts as an excellent insulator. But it can also cut off airflow and cause condensation as the air finds nowhere to escape. That can result in damp, mould and lung problems. It is difficult and expensive to remove.

Some installers are cowboys who should not be in the business, and spray foam that is badly applied can damage the roof, the beams, electrical cables and water fittings in the loft. Even if done correctly, with all the necessary tests and paperwork, mortgage lenders and the surveyors they use are not keen on it at all. Some homes with it have been valued at zero.

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Later this year there will be a new protocol from the Insulation Manufacturers Association, which installers, surveyors and lenders will be
invited to sign up to. But there will still be no statutory regulation, and it is not clear how much change this will bring about.

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So my advice is to have your loft insulated with 300mm of rockwool between the joists. At well under £1,000, it’s around a third of the price of spray foam, does not cause ventilation problems, will not be a red flag to mortgage lenders – and is likely to be a plus not a minus when you want to sell.


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