If a corridor in a building is less than 2 metres wide then the detector spacing (smoke detectors) can increase from 10.5 metres to 15 metres as the narrowness of the corridor helps to concentrate the smoke. If the corridor is wider that 2 metres then the area must be treated as a normal room and the maximum detector spacing is 10.5 metres (Smoke Detector). Heat detectors should not be used as a detection method within corridors.