MC-02Work out what's behind the wallRun a detector across the wall, then confirm what you've found: tap along the wall for a hollow sound between solid-feeling points, and look for a line of screw or nail heads under the paint or paper, usually at 400-600mm centres, which marks the studs. Drill a small 3mm pilot hole in an inconspicuous spot to check the dust: pale wood dust means a timber stud, fine grey metal swarf means a metal stud, and solid resistance with no give at all usually means brick or block. If the drill goes through a hard skim then hits an air gap before reaching anything solid, you likely have dot-and-dab plasterboard on dabs of adhesive over masonry. An uneven, slightly springy surface with narrow wooden strips felt behind it is lath and plaster, common in older houses.