LP-02Check for cables and pipes, and know how to cut them offOld walls hide cables and pipes in places you wouldn't expect, and lath and plaster gives no clues from the surface. Run a cable and pipe detector over the whole marked area, but treat it as a guide, not proof — detectors miss deep cables, cables in conduit, and anything close to old rewiring chased into the wall. Find your stopcock now, usually under the kitchen sink, and check it turns freely so you can shut off water fast if you hit a pipe. If you have any doubt, isolate the relevant circuit at the consumer unit before you drill.