I am using 37.5mm insulated plasterboard on the loft space which contains vaulted ceilings and dormer cheeks. It is secured with screws into the rafters/timber frames. The insulated plasterboard is 25mm rigid insulation glued onto a 12.5mm sheet of plasterboard. As I secure it onto the framework//rafters, there is a little bit of play. That is because there is 25mm of "soft" material in between the plasterboard and the timbers.
There are also some gaps (10mm+ in places) where two plasterboards meet, if they have not been cut perfectly. Those gaps are filled in with plasterboard adhesive. Is that a good practice?
There are also some gaps (10mm+ in places) where two plasterboards meet, if they have not been cut perfectly. Those gaps are filled in with plasterboard adhesive. Is that a good practice?