KS-04Check for hidden services, then drillCables and pipes can run almost anywhere, even on an exterior wall — alarm wiring, satellite feeds and outside light cables are common culprits. Sweep the area with your detector, but still treat the wall as if something is there: drill slowly and stop the moment you feel any resistance or see anything other than brick or block dust. Before you start, find your stopcock (usually under the kitchen sink) and check it turns freely, and if you have any doubt at all, isolate the relevant circuit at the consumer unit first. Rendered walls are almost always solid brick or block behind the render, so drill through the render first at a slow speed, then switch to hammer action for the masonry, going to a depth of at least 50mm.