How to hang a heavy mirror without it coming down

The picture hook that came with the mirror is the reason most heavy mirrors fall. Here is how to do it properly.

Weigh it

Stand on the bathroom scales holding the mirror, then without it. The difference is what the wall has to carry, and you want fixings rated for at least twice that.

Find out what the wall is made of

Knock on it. A dull, solid sound is brick or block. A hollow sound that changes as you move along is plasterboard on timber studs. A slightly hollow sound with cracks in the plaster, in a house built before about 1930, may be lath and plaster.

Run a detector over the area to find cables and pipes. Cables usually run straight up and down from a socket or switch, so never drill directly above or below one.

Pick the fixing

• Brick or block: brown wall plugs and 50 mm screws, two at least.
• Plasterboard over a stud: screw straight into the timber stud. Find it with the detector or by tapping for the solid sound.
• Plasterboard with no stud where you need it: metal cavity fixings rated for the weight. Plastic ones are not enough for a heavy mirror.
• Lath and plaster: find a stud. Cavity fixings do not grip lath reliably.

Use a cleat or two plates, never one hook

A French cleat is two strips of timber cut at 45 degrees. One is screwed to the back of the mirror, the other to the wall, and the mirror drops onto it. It spreads the load and makes levelling easy. Two mirror plates, screwed into the frame and the wall, work for mirrors with a wide timber frame.

Mark, check, drill

Hold the mirror where you want it with someone standing back to look. Mark the top edge, then measure down to the fixing points. Draw the line with the spirit level, drill, fix, and check level again before you hang it.

If the mirror is over 30 kg, the wall is lath and plaster, or you just do not fancy it, a mirror is a 30-minute job in our job basket.