Spray-on Roof Insulation

Spray-on Foam Roof Insulation has been much criticised for its problems.

Problems

Does not permit water drainage or evaporation
No air gap between insulator & tiles/slates to allow airflow for drying
Increases chances of structural timber rot, and repacing a timber roof structure isn't cheap.
No ability to inspect timbers after insulation is sprayed
Prevents re-use of roof covering. This creates an additional expense & in some cases renders historic fabric unreusable.