Hi @masi,
Thank you for your question about how to hang a heavy mirror on your wall.
Also, a warm welcome to the Bunnings Workshop community, it is fantastic to have you with us.
Due to the weight of the mirror, it must be connected to a stud. You might like to pick up a stud finder and have a read of How to use a stud finder for some guidance.
Hanging something of this weight from one single screw will place a lot of stress on that screw, so we must maximise the diameter and the length of the screw for our situation.
The screw head will have to be small enough to fit into the round part of the bracket on your mirror, so the width of this gap will dictate the largest the head can be. Similarly, the rectangle slot above it will dictate the size of the screw shank.
My suggestion would be to remove this bracket from the clock using a Philips head screwdriver and bring it in-store with you. Head to the Builders section and ask a team member for some assistance to test the largest gauge screw that can fit through your bracket.
Depth of embedment is also extremely important as the weight of the mirror will be cantilevered off the screw.
Standard residential plasterboard is 10mm thick and a timber stud is either 70mm or 90mm thick, so I would suggest nothing underneath 75mm in length should be used.
Something like these Zenith 10G x 75mm Galvanised Countersunk Head Timber Screws would be good for this purpose, but you would need to confirm its compatibility with the bracket.
Let me know if you have any further questions or need any clarification.
Jacob
