i'm installing a false ceiling in what will be a coffee shop. our sitting room is directly above. so far we've put in a timber frame with 100mm of acoustic rockwool flexi between the joists, there is an airgap above that (150mm). above that the original lath and plaster ceiling, above that is deadening, its a victorian house (no idea about how in tact this is as in my experience lifting the floor when CH/ rewiring gets done a lot is removed), and finally floorboards (no carpet)
i am attempting to take what *practical* measures i can to soundproof. would an extra layer of plasterbaord be worth the effort?
also i'm confused about the fire rating. BC made no mention of a fire rated ceiling when the plans were approved, however the ceiling does seperate differnent "occupancies"... and what if we sold the shop or house at a later date?
double layer of plasterboard - or not worth it?