fitting insulation under rafters

[marlb]

Hi, I have to fit 50mm celotex between the rafters and 80mm over the top with 12.5 plasterboard over the lot. I am going to use 150mm drywall screws to fix the 80mm celotex and 12.5 plasterboard to the rafters. Is this the normal way to do it?

 

[hog]

Hi marlb, I'm due to build my extension roof in the next couple of weeks. drywall screws are what I intend to use. out of interest are your rafters only 4" deep? Mine are 6" which allows for 90mm celotex boards inbetween and 50mm under

 

[marlb]

no mine are 100mm rafters so can only get 50mm under. I am going to tac 30 mm onto rafters and go 80mm under and 50 over.