I am looking at the two upstairs bathrooms on the study plan for the universal cottage. I see a 6in wall for efficient back-to-back dwv layout but I don't see the wall continuing vertically through the main floor. (The bathrooms are over the dining room ceiling.) How are the drain pipe(s) continued through the main floor? I am hoping that this design would be easy to build but this plumbing layout looks like it could be difficult. Do the plumbing notes that come with the purchased plan address this situation?
The waste stack jogs over to the left side of the window header near the kitchen passover. I've yet to hear of anyone having a problem with this.
I would suggest foaming the pipe with insulation to avoid the "Archie Bunker" effect. You could also use cast iron here if you want to get fancy.