SC-04Work out what's behind the wallLath and plaster is thin wooden strips (laths) nailed across timber studs, with gaps between each lath — there's always timber behind it, never metal studs, since this method predates metal stud framing. Run a detector over your marked spot, then tap along the wall: a dull, solid knock usually means a stud or a lath, while a hollow, lighter sound means you're over a gap. If you've patched in plasterboard elsewhere in the room, check that separately: trace a line of screw heads with a magnet or detector to find the studs, and a small pilot hole in scrap or an inconspicuous spot will bring out pale timber dust for a wood stud, or fine grey steel swarf for a metal one.