I recently had a pre-app meeting with a BCA with regards to a new multi-use 5-storey building - GF car park, 1st to 3rd floor office and top floor permanent accommodation for a single household (which happens to be the building owner). The building is not unit or strata titled. Also the building is served by a single safe path stair connecting all floors. Given the car parks on the ground floor, escape height > 10m in that single stair and having other Risk Groups on the lower floors than the SM Risk Group. Hence, A Type 7 system is required.
The part where I couldn’t fully understand is that why a fire rated lobby (act as a horizontal safe path) preceding the vertical safe path is required when a smoke lobby (with lesser protection) is not even required at that top most level. Unless I have missed something here the interpretation of paragraph 3.9.6 by the BCA seems contradicting with other requirements in the fire code for this particular scenario. Granted, it makes sense if there was a common corridor serving multi sleeping area firecells, e.g. motel units, hotel rooms or apartments but I just don’t see this is the case here.