Attached is an image with constraints labeled. I'm having a hard time figuring out how to connect all this together. My best thinking so far is to run the shower with a center drain to the toilet with 2". Run the toilet out the double LVL (engineer says OK) with a 3" basically perpendicular to the West Wall into the attic space. Vent it with a new vent out the roof immediately upon exiting the double LVL (this is very close to about 5'4" from the P trap on the shower which I think is max distance... although maybe the conversion from 2" to 3" at the toilet gives me a few more inches of space to work with?). Then turn it with a long sweep 90 horizontally to go down the North side wall near the West wall of the laundry on floor 2 down to tie it into the main waste line under floor 2.

As for the vanity run a 2" waste pipe through the South wall into the attic space on the west and bring it back around and tie it into the 3" I sent down the laundry wall. I'd probably vent this immediately out of the south wall through the roof, or if code allows maybe just do an air admittance valve for the sink.

Any suggestions? How would you plumb this with all these constraints?enter image description here

Here is the option I'm thinking. enter image description here

  • 1
    It might help to draw in your prospective drain and vent lines.
    – FreeMan
    Oct 12, 2020 at 16:42
  • 1
    @FreeMan I added my thinking drawn over the image.
    – michael
    Oct 13, 2020 at 15:29
  • I don't think you can put the toilet in the middle of a wet vent in that configuration. There are restrictions on toilets so water (e.g. from your shower) won't flow past the toilet's drain connection and cause a suction effect on the contents of the bowl. You will probably need to install the east wall vent you have identified as an option in your drawing, or re-configure the way the shower & toilet wet vents meet -- the language the IBC uses is symmetrical fitting IIRC? Oct 15, 2020 at 16:28
  • shower drain, to vanity drain, to main and toilet to main??
    – gnicko
    Oct 15, 2020 at 17:26
  • Thanks @JeffWheeler. Are you familiar with a 45 degree rolled wye? I'm guessing I'd have to do a 2" rolled wye off the shower drain, before the toilet and then run it back into the east wall and up and out? Would that cover the toilet and the shower?
    – michael
    Oct 16, 2020 at 19:13


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