BP-05Fix the starter trim to the wallBefore you drill, find your stopcock (usually under the kitchen sink) and check it turns, so you can shut the water off fast if you hit a pipe. Run a cable and pipe detector along the fixing line, but still assume something's there and prove otherwise — detectors miss deep cables, metal-backed board and anything outside the usual safe zones, and a metal stud frame confuses cheap detectors further. If in any doubt, isolate the circuit at the consumer unit before drilling and turn off the stopcock before cutting into anything that could carry water. Now fix the trim to match your wall: in solid brick or block, drill 6mm and fit a wall plug before driving a 40mm screw; in plasterboard on timber studs, drive a 40mm woodscrew into the centre of the stud; in plasterboard on metal studs, use a self-drilling metal-stud fixing or a rated toggle fixing — never a plastic plug or ordinary woodscrew, which strip straight through 0.5mm steel; in dot-and-dab plasterboard, use a fixing long enough (60–75mm) to pass through the void and bite into the masonry behind; in lath and plaster, aim for a lath timber where you can, or use a plasterboard-rated toggle fixing well clear of any crumbling lath edges.