wwhitney
In the Trades
Attached in a rough sketch; the top is a floor plan, and the bottom is an elevation to clarify one option for the WC connections. Pipes in the plane of the drawing are shown as lines, while pipes perpendicular to the plane of the drawing (i.e. vertical for a floor plan) are shown as circles.I think I want to implement solution #1 for the shower and tub. I’m not able to visualize how to pipe things based off what you said, in that scenario. Could you make a rough drawing, or help me another way?
On the shower and tub, option #1 involved a soffit in the adjoining room so that they can be wet vented by the horizontal 3" line in the existing soffit. That makes the geometry simplest, it's all in one plane. I'm showing each trap as a circle and a short segment which is the footprint of the U-bend; you can probably rotate the u-bend around the inlet, along with the elbow, as required at each fixture to get the necessary horizontal separation between the tub and shower drains. [If not, to get more separation you can point the shower trap outlet at a 22.5 or 45 degree angle to the joists, then use a 22.5 or 45 degree elbow to bring it parallel to the joists.] The particular trap configurations I show are just examples, use whatever works for the geometry.
On the WCs, as discussed earlier, there is some debate about what the proper orientation of the wyes should be for the WC to be wet vented. I've shown the simplest option, which has the wyes fully upright, as it is easiest to draw and to execute. But if you are concerned that may not be proper, you can roll those wyes 45 degrees or 90 degrees and use a few more elbows to make the connection. In that scenario, I think you'd find it easier to move the entire 3" horizontal soffit drain closer or farther from the wall, so that it does not run directly under the near WC. That would make the near WC connection simpler.
For the tub and shower drains, and for the 2 WCs, I show closely spaced wyes, because in each case you have two drains coming in from the same joist bay. The tightest pattern there would be to use a street wye for the upstream drain, directly into a wye or combo for the downstream drain. So I suggest getting that fitting configuration worked out first, which will then tell you the spacing you need between the two drains as they approach the horizontal 3" soffit drain.
Cheers, Wayne