I'm working on the plumbing for the master bathroom in a new house (slab on grade) and I have a question about wet venting. Can a fixture be connected upstream of the wet vent connection and be vented by the downstream wet vent? Can the shower drain (2" be connected to the horizontal drain branch (3" upstream of the lavatory drain that will serve as the wet vent for the line?

Yes, as long as it is within 6' (codes vary) of the vent. Basically you're draining a shower into the back of a wye, and the branch is picking up the sink and wet vent ?

I would like to connect it like this. Will this setup work?





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the toilet/lav on the right is fine. keep the lav drain and vent full size 2 inch..
can the set-up on the left have the lav tied in over where it say 7 foot 8 inch? if you can then the seperate toilet vent can be eliminated as the toilet will be wet vented thru the lav.
an easy inspector may let the tub and 2 showers go with only a single vent.
if there is any way you can get the tub drain over the top of the long pipe and tie it into the lav drain that would solve the problem.

Probably too far away from the lavatory to work that way.