PC-04Fit a new corner bead if the edge itself is brokenBefore drilling or screwing anywhere near the corner, use a cable and pipe detector to check the area — but don't rely on it fully. Detectors can miss deep cables, cables in metal conduit, or anything behind metal-backed board, and a metal stud frame can confuse a cheap detector further. Find your stopcock (usually under the kitchen sink) and check it turns before you start, so you can shut off the water fast if you hit a pipe. If in doubt, isolate the circuit at the consumer unit first, and turn off the water at the stopcock before cutting into anything that could carry a pipe. If the sharp edge (arris) of the corner is broken away, cut a new PVC or galvanised corner bead to length with tin snips. On solid brick or block, bed it into a layer of filler or bonding plaster — no screws needed. On a timber stud wall, fix it with 30mm wood screws into the centre of the stud each side. On a metal stud wall, use self-drilling metal-stud screws, never plain wood screws — they just spin and strip straight through 0.5mm steel. On dot-and-dab, press the bead into a bed of filler rather than screwing, since a missed dab gives a screw nothing solid to grip.