Closed cell foam bonded hard to roof timbers
Why it happens here
Closed cell polyurethane foam sets like rock and grips the timber. On Malinslee's 1960s roofs, it was often sprayed directly onto the rafters with no ventilation gap, so moisture has nowhere to go.
Our approach
We use dry ice blasting to freeze and shatter the foam off the timber without gouging the wood. It is slower than cutting, but it protects the rafters and the felt, which matters on older roofs.