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Dec 2023

Last Updated: 06/12/2023

Spray foam insulation can knock thousands off your home's value, warns property expert

by John Grainger

| 06 Dec, 2023

This story is sponsored by Kempston-Parkes.

A common form of home insulation can cause more damage than it prevents, and end up costing homeowners thousands to put right, a Harrogate property expert has warned.

Spray foam is sold perfectly legally by insulation companies – including several in our district – as a way of stopping draughts and improving heat retention, and some vendors even claim it can act as a pest repellent. There are an estimated 250,000 homes with spray foam insulation in the UK.

But chartered surveyor Andrew Kempston-Parkes said it can seriously affect a property’s value and structural integrity. He said:

"When I turn up to value a property, I’ll start with the exterior but once I’m inside, my first port of call is the roof void. My heart just sinks when I see that the underside of the roof has had spray foam insulation applied.

“All too often, the foam expands and encases the timbers, so if they become wet, they can’t dry out and will rot. In the vast majority of cases, the whole roof will have to be stripped off and replaced.”

He said as a result lenders will typically ask for full retention on the mortgage – that is, they won’t release the funds to the buyer until the vendor has carried out the remedial work.

The alternative is for the vendor to drop the price substantially – by around £15,000 off a small terraced house, or £25-40,000 off a large, detached property. Removing spray foam insulation from one listed building recently cost an eye-watering £200,000.

Andrew, whose firm Kempston-Parkes Chartered Surveyors sees several spray-foamed homes a year, said:

“When I tell a vendor that they’ll have to either have their house reroofed or lower the sale price, they’re often shocked, and embarrassed that they’ve been sold a pup. It never goes down well to have to renegotiate the price.”

The alternative to spray foam is 300mm fibreglass insulation, keeping the eaves clear to allow for air-flow. If a loft is being converted, the roof will need to be boarded and insulated, but even then, there needs to be air-flow behind the boarding.

Andrew said:

“There are still lots of firms going out and spray-foaming roofs, but generally speaking it’s a real no-no.

“There are some instances where it’s OK to apply spray foam insulation, but those are rare. More often than not, it’s a delaying action – a false economy.

“If you’re considering it, you should always seek professional advice from a chartered surveyor.”

Find out more:

Kempston-Parkes Chartered Surveyors provide surveys and valuations for all purposes, including purchase, inheritance tax, capital gains tax, matrimonial assessments, boundary disputes and Land Registry plans.

For more information, go to www.kempston-parkes.co.uk, or for a confidential conversation about your requirements, call 01423 789111.