Good morning
I would like to flush mount a 10kg projector screen to the ceiling of our living room. The framing of our house is entirely of steel, including the ceiling joists, which are then covered in plasterboard. There are two brackets provided with the projector screen, each of which can take 4 screws to mount them to the ceiling (see attached photos). The screen can also be wall mounted and the company provided screws and drywall plugs, but I assume that is to screw into timber studs. Given we are trying to screw into metal joists, I was planning on using self-tapping screws and also drilling pilot holes to make the job a bit easier but I'm wondering what size screws are best. My plan at the moment is to use 8G STS screws of 32mm length (https://www.bunnings.com.au/zenith-8g-x-32mm-galvanised-button-head-metal-screws-25-pack_p2410086) but I'm not sure if I should use a higher gauge and a longer length?
Any advice would be very much appreciated!
Thank you!
Aisha

