Help With Loop Vent......Maybe?

[SixDemonBlues]

Hi All,

Working on an addition/renovation project. I had a plumber come and do the rough in for me, and I figured I could handle the finish myself. Vanities, toilets, no problem. That all went fine. But then I got to my kitchen sink, which is in the new island. I had never done a loop vent before, so I went digging around to figure out what I was doing. It seems like I have an atypical scenario, so I'm not sure what to do. From what I've read, in a typical loop vent scenario the vent portion of the assembly is eventually tied into a traditional, vertical vent stack in a wall somewhere. I do not have that. The vent and drain risers coming up through the subfloor (they are labeled V and D respectively) both just tie into a waste line below the floor and that line just dumps into the main waste stack. I have attached a crude drawing below. Venting the plumbing in this addition was a total bitch. They had to get pretty creative to make everything work but I'm not sure how this was supposed to work. Is this a functional assembly? Do I just complete the loop and build the drain like normal? Or is there some other consideration I need to account for here. I could call them back out here to plumb the sink, but I'd sure love to figure out how to do it myself if I can, if just for the educational aspect of it.

Thanks in advance for any help!

 

[Breplum]

You should have the "plumber" shop owner back to correct the problem on their dime.
Or sue them.
It is a non functional island vent without a vent, just a stupid drain. Not to code and doesn't work physically. Just plain wrong. Your inspector should have caught it as well.
The only remedy is to use a AAV (air admittance valve) on whichever stub up you want, by adding a tee, a cleanout and the AAV on top.
You will have to disclose the non-code work to any buyer, but, it will function.
You should have the "plumber" shop owner back to correct the problem on their dime.

 

[Sponsor]

 

[SixDemonBlues]

You should have the "plumber" shop owner back to correct the problem on their dime.
Or sue them.
It is a non functional island vent without a vent, just a stupid drain. Not to code and doesn't work physically. Just plain wrong. Your inspector should have caught it as well.
The only remedy is to use a AAV (air admittance valve) on whichever stub up you want, by adding a tee, a cleanout and the AAV on top.
You will have to disclose the non-code work to any buyer, but, it will function.
You should have the "plumber" shop owner back to correct the problem on their dime.

I figured that was probably the case. Thanks for the reply. Couple questions if you dont mind. 1) Does the cleanout go above or below the tee for the drain, or does it matter? 2) I assume I just cap and abandon the other riser? 3) With regard to the AAV, that's still an IRC approved method for venting in this application, correct? So it's not necessarily a code violation?