I'm building a warm flat roof with 200mm insulation sandwiched between two sheets of 18mm OSB. I'm wondering whether the top deck needs to be screwed into the joists or whether the screws only need to penetrate the lower OSB deck?
I thought I saw somebody online say that they should go into the lower deck, but I've just seen a video where somebody only screws into the OSB. I think it would be very hard for me to hit the joists as some joist are only 35mm and shaped like a banana. I'm planning to use the thermally broken tube washer things.
I thought I saw somebody online say that they should go into the lower deck, but I've just seen a video where somebody only screws into the OSB. I think it would be very hard for me to hit the joists as some joist are only 35mm and shaped like a banana. I'm planning to use the thermally broken tube washer things.