Wet venting bathroom fixtures

[Kohala]

Hi, my question here is about wet venting a bathroom, and I’ve been back and forth with my plumber friend about this. I’m told every fixture needs its own vent on its own branch. However, I’ll I see online is wet venting off the lav, toilet last, is common. In my case lav is separate so why not wet vent WC from tub dry vent as pictured. Red circle is a 2” vent going straight up between tub and WC. I’m running into this same situation in other baths that can easily share without drilling the heck out of TJI joists, thanks

 

[Tbone37]

You cant “wet vent WC from tub dry vent” because its not a wet vent. You can wet vent bathroom groups only (any combination of wc, tub/shower, lavatory, floor drain) the lavatory serves as the vent for the entire group. You are allowed one fixture above your vent. If you dont want to drill engineered joists, you can individually vent each fixture (like the tub currently)