Fixing Insulation Over OSB

Hi,

I’ve been studying the YouTube videos by Steve. I’m a pro now after doing my balcony with internal gutter. I have built a roof with 1 in 60 fall leading to an internal gutter. 18mm osb3 deck vapour barrier 100mm of Celotex with a 6mm ply under the rubber.

My question is what grade 6mm plywood can I use? And what is the best way of fixing the insulation and ply to the deck?

I have seen it glued and I have seen it screwed, but which is best? There’s only one way to find out. I would be very grateful if you could put me in the right direction.

Kind regards

Mik

If its a fixed vapour barrier  such as two layers of mineral flet or something like  Visqueen Fully Bonded Vapour Barrier you can glue down.

Glueing the insulation  down  is best as  there  will be no thermal bridging thorough the screws. Fixing with a thermally broken fixing is second best and very close to gluing the insulation down.

Hope this helps