Ask a master, but in my opinion, if with one insulation the toilet can be narrowed.
The other option is to put a powerful fan, which makes a lot of noise - and it will smell faster.
Choose a Google option. There is an inner-outer floor for gypsum plasterboard for direct gluing. Only the plumbing package? Will the floor also break or will you insulate the ceiling from the neighbors? If it does not allow narrowing, the bedroom can be insulated. Lots of options.
There is no way because the outlet pipe and the vent are common to the entire entrance if you are in a block. If you're in a house, it doesn't make sense.
Around the vertical pipe of the channel - masonry to the ceiling with ytong - the thinnest that the master can make. Tiles on it, plaster with wallpaper ... whatever you want. Easy, clean, fast. We have been like this for years.
№10, the same effect will get with gypsum fiberboard, why with ytong?
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