I am getting ready to install some bath fixtures in the basement where the rough in is already in place. As you can see in the photo, there is a sink drain into the stack (where I would expect it) and something else coming from the floor just in front and slightly to the side of the stack. Is this just another option for a sink drain or something else? If it is just another option, what are the pros and cons of using either?

 

I would say the pipe in the floor is the drain and the one in the wall is the vent but it needs to be above the flood plain of the sink. But nothing can drain in that main stack from above which looks highly unlikely. You cant use the line in the stack then

Who plumbed it?

Mike NJ

 

Drat! I hadn't thought about the dreaded vents again... You are correct; the stack drains the toilet right above, a second bath room from the other end of the house and a kitchen sink. You can see in the second photo where the stack vent comes in from the left side; and that would be the closet flange right behind it. Perhaps I can cut into this vent?

Along the wall to the left is a toilet rough stub that I will need next. Near it is a drain from the sink in the bath above, likely joining under the slab. Do I need to consider additional venting needs for the new toilet, too?

Not sure who did the work. LOTS of things to fix in this house because the previous owner built some of it himself. I just don't know what exactly. I have a list almost ready for him when I call.

 

Well who knows how he connected it under the slab. ( Might have issues might not )

But what you need to do at a minimum is cap the line in the floor. Make it a clean out.

Cut that arm coming out for the sink in the stack and turn it 90 degrees left or right. You can drain the sink to there but need to add a tee to get the vent out.

You need to vent that arm in a vent that is 3 ft above your highest fixture on that stack. Which will be up-stairs somewhere. Unless you have another bath on a second floor tied in that stack Or get it in the attic and tie in before the stack goes out the roof.

Mike NJ

 

I have confirmed that the line heading out to the left in the pic is vent, all the way up thru the attic, and the only thing on this branch is the toilet immediately above it in the photo. Everything else is vented separately prior to where the line comes into the picture from behind right. You are saying that I can't tie in to this vent directly where I can see it in the photo? I need the new sink vent to go separately up to at least 3 ft. above the toilet before tying in?

Now, there is an air admittance valve on the kitchen sink upstairs. Would this new sink be an appropriate application for an AAV rather than tying to the normal vent?

 

Vent should be above the flood plane. AAV I dont like. You did all that work, you should do it correctly.


I wonder why they ran 3" vent?

Mike NJ

 

>>>I wonder why they ran 3" vent?

 

Is is a vent stack? It looks like it should be a stack vent and tie into the vent stack. I will get my code book out but it just looks screwy to me. Where is the upstairs lav, and shower tie in?

Mike NJ

 

Upstairs is a half bath. The lav and laundry drain drops down in the wall opposite these photos, within two feet of the toilet rough-in for this room that I mentioned earlier. On the way down, it changes from 2" to a 3" drain. There is a 2" vent in the attic rising from the area of the lav which does tie into the 3" stack vent shown in the photos which then passes through the roof.

I suspect Shacko is correct about local codes. In my previous house, the two baths were serviced by a common 3" stack vent, while the kitchen and laundry shared a common 2" vent at the other end of the house. My assumption is that the vent must be the same size as the largest drain. Still, a phone call on Monday should clarify.

Now, by "flood plane" I had always assumed the highest water level of the highest device on the drain line. In this case, the toilet would be it. So, the top of the bowl? It won't save any work, since I'll still have to tear up a wall somewhere to get that far, but perhaps I'll understand it better.

 

Its the top of the lav is the highest point. Or the washer.

Mike NJ