I know that in line with part b of the building regs when rewiring a house you need to install smoke alarms upstairs and down and a heat detector in the kitchen. However what I can not seem to find is anything to this fact in BS7671 or the OSG. I have seen it in the red OSG, but nothing in the current green one. Can anyone please tell me if it is mentioned anywhere in the current BS7671 or OSG? Thxs