SB-02Work out what's really behind the plasterLath and plaster is usually found in houses built before the 1930s: thin timber laths nailed across timber studs or joists, covered in a lime plaster skim. Run a stud detector or a magnet over the marked area, looking for the line of nail heads that shows where a timber batten sits, and tap gently — a dull thud means solid timber behind, a hollower sound means you're between laths. Drill one small 3mm pilot hole at your mark and check what comes out: pale timber dust means a lath or stud, fine grey dust means solid brick or block behind a plaster skim, and bright steel swarf means you've hit metal — either an old metal lath repair or, in a part-renovated house, a modern metal stud or plasterboard fixing. If the wall doesn't behave like lath and plaster at all — completely flat, no give, feels like board — check whether the room has been re-plastered onto plasterboard (dot-and-dab) or a stud partition, and use the matching fixing method later in this guide instead.