Roof timber rot from trapped moisture
Why it happens here
Foam sprayed directly onto rafters seals the timber and stops it drying out. In a Peckham Victorian terrace with limited loft ventilation, that moisture sits against the wood through the winter and rot sets in quietly under a surface that still looks fine.
Our approach
We remove the foam in sections and inspect the timbers as we expose them, checking for softness and staining. Anything suspect gets photographed and treated before the roof space is closed up, so you are not discovering rot years later.