Basement bathroom plumbing question (rough-in from builder)

[Chris Tjoumas]

Hello,

I'm finishing my basement and am starting to get a little confused on how everything will tie in. The builder roughed in the bathroom plumbing and I assumed I'd just tie the fixtures in. In the attached picture which I took years ago when the plumbing was being added, I know there is the shower drain in the back with the p-trap, the toilet pipe in the middle, and then, what I think is the sink drain closest in view. Not in the picture is a stubbed pipe coming from the floor above, which I'm assuming is the vent to tie the sink drain pipe into. I started doing some research on spacing so I know what I need to move when I bust up the concrete around here, and I saw a similar plumbing design but what I'm seeing as the sink drain pipe they are calling the vent. Maybe it's one in the same? I just want to be sure that I can use a sanitary tee for the sink which will go up to the stubbed out vent pipe and down into this drain.

Hopefully this makes sense - thanks!

 

[Tuttles Revenge]

In this case, the sink provides the Dry vent connection for the entire Horizontal Wet Vented bathroom group. The vent from the sink on top of your San Tee would connect to that vent undiminished in size.

The idea is that while generally only one person is using any fixture at any given time, there will only be water in the lower 1/3 of the pipe and the upper portion is used for venting that whole section. Some jurisdictions have limitations on what type of fixtures are allowed and their location / sequence in the system. There are many interpretations of what and how a horizontal wet vent works depending on your code.. My experience is in washington state where we use the UPC code with amendments.

 

[Sponsor]

 

[Chris Tjoumas]

Ok, thanks! That's what I figured (other than not knowing the full details you provided ); couldn't imagine the builder would rough in something that wouldn't work without having to break out the concrete to do something additional.

 

[Jeff H Young]

Yea it looks ok ! your code might allow an AAV above the lav in the piping in liew of a true vent or the plumber might have a capped off line or a vent from perhaps washing machine or a sink in basement. If available I prefer a real vent over an AAV

 

[Chris Tjoumas]

Yep, they did cap a vent coming from the floor above, so i'll tie into there. Unfortunately, on the other side of the basement where I had them rough in for a wet bar, they only roughed in the drain and not a vent, so I'll need an AAV