I'm in the process of planning the 2nd floor DWV lines for my house. Or more accurately redoing them with the reality of very limited space between floor joists that are 2x10s 12" OC. The attached drawing represents my current plan (1st floor plumbing is omitted). The first floor sits on a 4 foot crawlspace with open-web trusses, so lots of freedom for any plumbing once it hits that area. Any feedback would be appreciated but the particular question I have regards the section highlighted in red for bathroom 1. That toilet is already wet vented by the lavatory but I'm unsure if I need to carry the red section up through the roof as the vent stack, tying in the lavatory and shower vents (or if the red section in bath 1 isn't needed and I can just connect the shower and lavatory vents and go through the roof with that). Bathroom 1 is physically isolated and can't connect to the main 4" vent stack that goes through the roof for bathroom 2/3 and the rest of the house. The house is in NC so the relevant code is their version of IPC.