I’m planning to make some floating shelves 150 cm wide and 30 cm deep.
I want to mount them on a wall that has a plasterboard of thickness 13mm behind which is a plywood backing of 15mm according to the details provided by the contractor (see the attached image). This construction was apparently intended for hanging TVs and they recommend using wood screws that are not longer than 30mm.
One of the shelves will have my record collection which could weigh between 25-50kg. What are some options for hardware I can use to mount the floating shelves?
Wow, 50 lbs (~20 kg) per stud, with a bunch of screw holes in the base plate. Problem solved, and you could just use a number of wood screws into the ply panel, just spaced well apart (like 2.5-3 cm), and anchor into a stud where you can with a long lag (3"/~8cm).
Or if you can only hit a stud on one side, use a single Molly on the other and a couple wood screws in between.