AC-03Work out what the wall is made ofAiring cupboard walls can be solid brick or block, timber stud, metal stud, dot-and-dab plasterboard, or old lath and plaster, and the right fixing changes for each one. Run a magnet or stud detector across the wall: a steady line of screw heads under plasterboard marks a stud, and the sound changes from hollow to solid over it. Drill a small pilot hole at a marked fixing point: pale wood dust means a timber stud, fine grey metal swarf means a steel stud, and immediate solid, dusty resistance means brick or block. Hollow everywhere with no regular stud pattern, and a gap before a hard blob behind the board, means dot-and-dab; old lath and plaster feels slightly springy and sounds like thin wooden strips knocking rather than a flat board.