United Kingdom

Spray foam is still legal, so there is no way to gain compensation, and the industry is not regulated – neither the installation nor the removal – so choices are open to abuse by companies supplying these services.”

Homeowners say they were misled by the government, which exempted the insulation from VAT to promote uptake, as well as issuing grants worth up to two thirds of the installation costs. They feel this suggested the insulation was being endorsed.

Sounds like a “well there’s your problem” situation.

I am not a construction expert, so check your sources on this.

My understanding is that, for new construction, spray foam is most often used in areas that aren't likely going to be damaged by condensation, such as against concrete, or metal. I had looked into spray foam for my home, because my home was built in the early 80s--before building codes existed in my area--and there's no cladding on the house and just fiberglass bats between the studs. Because there's no cladding, there's much more air incursion through the bats, esp. since the interior walls are lapped wood paneling rather than wall board. Spray foam would have been a total air barrier, but it would end up being applied directly to the inside of the exterior siding, which would be a nightmare when siding needs to be replaced, and would probably cause moisture issues.

The best solution appears to be to use 3" EPS foam cut to fit between the studs, and then use spray foam to fill any gap between the studs and the EPS. That still allows an air gap between the foam and the exterior siding so that moisture can evaporate.

In the case that's being cited here, I'm not sure why they opted for spray foam over EPS or fiberglass bats. If their home is well sealed, then bats should have been perfectly sufficient, although they have a lower R-value per inch than EPS. Oh, and the difference between polyisocyanurate and EPS/XPS is about R1.5/inch, but that difference drops to about R.25/inch after a decade. That meanst that you don't gain much in the long term when you use faced polyisocyanurate board. I'm not sure what blowing agents are used for polyiso; it might be more environmentally friendly to manufacture.

The insulation was supposedly improperly installed. There, saved you a click.

I looked into spray foam insulation but not only were there lots of risks, but it was more expensive than traditional warm roof insulation with PIR boards or similar. I do think people should research what they put in their own homes as it wasn't hard to find information that ruled out spray foam insulation fairly quickly.

Having said that, there is clearly some sort of regulatory gap here as not being able to mortgage your home is a very serious consequence of a relatively small and seemingly innocuous home improvement decision.

Important info not in title or body of post: Mortgage companies are worried that spray foam can cause condensation which damages timbers.

They accuse ministers of washing their hands of the consequences after they insisted that it was the responsibility of traders and owners to decide whether to proceed with the work, and that the availability of mortgages is a matter for lenders.