GW-04Check for pipes and cables before you drillCables and pipes can run almost anywhere in a wall, not just in neat vertical or horizontal lines. Run a detector over every marked point, but still treat the wall as if something is there — detectors miss cables that are deep, in metal conduit, or outside the usual safe zones. Before you drill, find your stopcock (usually under the kitchen sink, sometimes in the garage itself) and check it turns freely, so you can shut the water off fast if you hit a pipe. If you have any doubt at all about what's behind a mark, isolate the relevant circuit at the consumer unit before drilling.