I have a bay window that I want to insulate from the Inside. It is made up of cement render painted, over felt (looks like shed roof felt) then the stud work and was plasterboard over. In the gap was originally glass wool (through the whole gap).
I was planning to replace with a celotex board in the stud gaps directly replacing the fibreglass. Bit now I'm concerned that this may cause a condensation issue as the cement and felt arnt breathable.
What would be the best suggestion or is filling the full gap with celotex ok?
Cheers Will