Best way to add sink vent after construction

Hello,

I have a small issue with a bar sink that was never properly vented.
This is in a two story house with gravity drains (no pumps required, etc.)

On the lower floor there is a wet bar with a small sink. The bad news is this sink was never vented - it just has a trap and drains into a pipe (1-1/4") that comes up from the concrete floor. The sink is on an exterior wall.

The problem is we frequently will have backflow bubble up in the sink when the dishwasher or clothes washer drain. Both of these are located on the upper floor.

My question is would an AAV work in this situation or am I best to just punch a hole in the exterior wall, install a Y and run a vent pipe up? I would prefer to not penetrate the roof so if I go this route would just under the eves work OK or should it really go through the roof and stick up 6" or so?

Thanks!

Rumrunner

vent

You are having a positive pressure problem so an AAV will do nothing to relieve it. And as a practical matter, even a proper vent may not eliminate the backup problem, since it appears to be a drain issue more than it is a vent problem.

Arg! Thanks!

There have been a few drain issues in the past and it was suggested at some point to
have all the drain lines cleaned... but this issue has been on going for as long as I can remember. I was really hoping a vent would cure it Thanks for the quick reply!