I'm looking to add a powder room and laundry to the ground floor of our home. Most of the plumbing runs through the central wall on our side split and the W/C & lav will be on this wall too, making the draining/venting a bit simpler. However the laundry will not be on this wall so I'm hoping to use a cheater vent here so I don't need to drill half the joists in this room or open upper-floor walls to get a vent out the roof.
I've attached some diagrams of my plans and was hoping someone could give me some feedback / review things in general. Additionally, I have a couple more specific questions:
Is it better to connect the powder room and laundry both directly to the stack or am I okay joining them. I'm trying to avoid cutting too much of the copper out.
Is it possible to install back-to-back sinks that share a wall like the laundry/garage sinks in my diagram? If so what kind of fitting would work?