I recently got ground floor piping extended to have drain, hot and cold in a first floor room. Only the pipes are there, but I'd like to install a sink and a washing machine as from the diagram. Note that the washing machine will be at a higher level, because it will be placed on a riser about 1m higher than the floor level. The drain pipe distance between the new sink and the lower floor sink is about 7-8 metres, while that between the new washing machine and the new sink would be about one metre. Questions: 1) How do I arrange traps? I plan to place one under the new sink, but should it also serve the washing machine or the latter would need a separate one? And would it be wiser to buy resealing ones? 2) Should I add an aav valve, given that the branch is now pretty long (around 10 metres)? If yes, where to place it? 3) Do you see any foreseeable problem with this setup, either practical or regulation-wise? (I'm in Scotland) Thanks!