Venting Bathroom through shower

[wwhitney]

Wayne's post April 22 2023 (about a year ago) included a sketch of how the back to back bathrooms should be piped.
First the water closets should not be the way they're drawn. The water closet should be the first connection to the drain.
Only one fixture should be upstream of the lav in a wet vent.

That's not required. In the drawing I made, the showers are dry vented and they are wet venting the WCs. The wet vent ends at the 3x2x3 wyes where each WC joins the shower drain. The lavs are not part of the wet vent.

Moving the water closets to take place of the lavs would allow the shower to wet vent through the lav and would put the shower drain in an approved shower trap arm length of less than 5'and would eliminate the need for the 2 shower vents.

Yes, I did not consider solutions that would require moving fixtures.

If you swap the lavs and the WCs, it does make for an arrangement where the lavs can wet vent everything. At least, assuming you can get the 2" shower trap arm to hit the lav drain within 5' (UPC in Idaho) from the shower trap. That might require putting the lav san-tee in the wall between the lav and the shower, as if you put them in obvious place in the center wall, it looks to me to be too far away.

Cheers, Wayne