Hi there, I have a cold roof in my new flat roof extension. I have a load of 100mm celotex and the joists they are fitted between are 150mm deep. What I have done is cut a slice of celotex to a thickness of 50mm, put that in first and then put a full thickness piece underneath it. Its messy work and im not done yet i would just like to check if you guys think this is ok. Obviously it would be better to have 150mm celotex in the first place. The thinner piece on top cant go into the vetilation void above because there are long battons running perpendicular.
also should I put a membrane over before putting the plasterboard up, and if so what type? thanks
also should I put a membrane over before putting the plasterboard up, and if so what type? thanks