> Not sure if there is a significant climate difference in the UK that makes this construction more problematic, the article mentions moisture but the U.S. building scientists say 2 inches closed cell spray foam will block air and vapors from reaching the wood of the roof. Perhaps the issue is the open cell foam mentioned in the article - it seems that closed cell foam is the recommended type in the USA.
Implementation details matter. From the OP's article:
> At the root of the problem are cowboy traders who apply the foam without a full survey or appropriate expertise – but because of lenders’ caution, this is affecting other homeowners who had similar work.
One potential problem that could occur is ridge rot:
> Lots of attics insulated with open cell low density spray foam (Photograph 1, Photograph 2 and Photograph 3) are having problems – in hot humid climates, mixed humid climates, and cold climates. The problems are moisture related. The attics are “unvented” – open cell low density spray foam is installed directly on the underside of roof sheathing. The attics are humid. Very humid. Unacceptably humid. And the humidity collects at the upper portion of the attics.
> When you spray ocSPF into wall cavities from the interior the ocSPF can act as the air control layer and thermal control layer. It can’t act as the vapor control layer – it is too vapor open. This is a problem when you spray ocSPF on the underside of roof/attic assemblies you can end up with problems (“Ping Pong Water”).
Implementation details matter. From the OP's article:
> At the root of the problem are cowboy traders who apply the foam without a full survey or appropriate expertise – but because of lenders’ caution, this is affecting other homeowners who had similar work.
One potential problem that could occur is ridge rot:
> Lots of attics insulated with open cell low density spray foam (Photograph 1, Photograph 2 and Photograph 3) are having problems – in hot humid climates, mixed humid climates, and cold climates. The problems are moisture related. The attics are “unvented” – open cell low density spray foam is installed directly on the underside of roof sheathing. The attics are humid. Very humid. Unacceptably humid. And the humidity collects at the upper portion of the attics.
* https://buildingscience.com/documents/building-science-insig...
> When you spray ocSPF into wall cavities from the interior the ocSPF can act as the air control layer and thermal control layer. It can’t act as the vapor control layer – it is too vapor open. This is a problem when you spray ocSPF on the underside of roof/attic assemblies you can end up with problems (“Ping Pong Water”).
* https://buildingscience.com/documents/building-science-insig...