I understand a toilet needs to be the last fixture in a wet venting situation, but I'm planning to use an air admittance valve (AAV) for the sink, so it won't need that vent. I'm thinking I made an error in logic, though, and need to run the sink to drain up above the toilet. Will the current plan mean the toilet doesn't vent properly?

In other words, can I run a shower drain into the 3" sewer line, then toilet, then sink, with the first two relying on a wet vent and the third relying on an AAV?









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if you leave the shower attached where it is but change it to two inch and in that line put a two inch wye for the sink you will be OK

The toilet can be ANYWHERE you want it. It has nothing to do with the venting.

a simple isometric drawing of your proposed DWV would say a lot about whether it meets code.
if you do plan for a horizontal wet went the shower and sink must be upstream of toilet.

Also NOT true!

i think he meant downstream..