I'm wanting to add a utility sink in my basement. 9 feet from the sink is the vertical 3 inch PVC drain pipe (home built 2001). I'd like to put the sanitary tee there and wonder if by the international code I need to vent the sink separately. About 4 feet up from basement foundation, the 3 inch pipe has a clean out and is reduced to a 2 inch pipe. the 2 inch pipe then goes up three more feet to a wye - the wye goes straight up to the 1st floor for the kitchen sink and dishwasher at 1-1/2". The branch out from the wye stays at 2 inches and goes up to the 2nd for for the master shower and bath.

It seems like that is enough to use as a wet vent but I would love advice... Code!

I have pictures but I don't see a way to post them on this forum.

If the 3" pipe you are teeing into has waste draining down from above, then the sink will have to be vented. You can't wet vent a fixture with one on another floor level.

if an AAV (studor vent) is allowed in your area, that would work..

If by "waste" you mean toilet, then no it doesn't. It has a kitchen sink and dishwasher I the 1.5 inch, a shower and a tub on the 2 inch.

We use the 2009 International Plumbing Code... which... As a software engineer that specializes is database technology, finding details on code is unnecessarily difficult in this age of technology. It's a shame.

Any water coming from the floor above prevents you using the stack as a wet vent.

"Any water coming from the floor above prevents you using the stack as a wet vent".

Really? Isn't that the very concept of a "wet vent"? Maybe I CA wet venting isn't allowed at all - wouldn't surprise me at all when it comes to CA and it's over-regulation.

MA wet venting has the same restriction. no wet venting from floor to floor.
maybe has something to do with the speed the water is falling and the amount of air pressure it creates as it moves down a longer pipe??

Ah, floor to floor. That might be the kicker. I'll keep looking into code if it's possible to find it.

2009 IPC
909.1.1 Vertical wet vent permitted. Any combination of
fixtures within two bathroom groups located on the same
floor level is permitted to be vented by a vertical wet vent.
The vertical wet vent shall be considered the vent for the fix-
tures and shall extend from the connection of the dry vent
down to the lowest fixture drain connection. Each
wet-vented fixture shall connect independently to the verti-
cal wet vent. Water closet drains shall connect at the same
elevation. Other fixture drains shall connect above or at the
same elevation as the water closet fixture drains. The dry-
vent connection to the vertical wet vent shall be an individ-
ual or common vent serving one or two fixtures .

Thank you, Steve.
This part "Each
wet-vented fixture shall connect independently to the verti-
cal wet vent" seems to be what the plumber I ran into at the store said. He said since it's about a 9 foot run to my sink, I should vent close to the sink, and go up then back over to the 2" section between the wye at the top and the 3 inch section below it. I've got about 4 ft of 3 inch, the cleanout, then about 3 ft of 2 inch before it splits.

That's are no "water closets" in that run.



Edited 1 times.

According to IPC, only bathroom fixtures can be wet vented and NO fixtures from a floor above can drain into the wet vent.