From what I've read there is all sorts of conflicting advice on whether purpose built flats need a fire a alarm system or not. I've just been to change some lights in some new build flats and all that had is Aico domestic smokes in each flat and the same in the domestic stairwell. I have been to another building owned by the same company that is a lot older but is being fully renovated and they have asked for a fire alarm but not given any spec for it. The building is purpose built block of 9 flats, 2 storey, probably built in the 70s. The 4 flats downstairs all have their own entrance and there is a communal door for the 5 flats upstairs and the mains room and an office downstairs. The building has solid concrete floors and brick walls throughout. The loft is traditional and open over the whole of the top floor area. The building will be occupied by people who are a bit loony but can support themselves to a certain degree, I think there may be a care team on site. At the moment there is a communal fire alarm installed that has detectors in every flat and a bell in every flat all linked to the one system but its as old as the hills and needs ripping out, it even looks home made to me. What is the most likely scenario for fire detection in somewhere like this, I think the local fire officer is a good bet to start with. I did tell the bloke to get a proper fire alarm firm in but he wants us to do it, we are doing the main wiring anyway (which I have another thread about) Cheers.