half bathroom rough in cannot drain through wall floor plate

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justincan

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I'm adding a 1/2 bath but struggling with the plumbing layout.
The wall where the toilet and sink are located is an exterior wall and the concrete foundation is higher than the subfloor, so I am unable to run the drain down through the exterior wall (noted with the red line in the image).

The toilet is planned to be on the left side with a sink on the right. Plumbing for the toilet should be rather straight forward where the vent stack is running up through the left hand wall and out the roof.

My dilemma is when it comes to the drain and vent for the sink. These are the options I can think of:

1. Drain through the floor with an AAV.
2. Drain through back wall and then around the right corner down through the floor. Vent runs straight up the back wall and meets toilet stack in ceiling
3. Drain through the right wall, vent goes up and drain goes down. (would probably be slightly harder to install the vanity needing to cut a hole in the side rather than back)

Are there any other options? What do you think is the best & correct way to do this?
plumbing.jpg
 

John Gayewski

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If your cutting the floor to run a toilet drain then cut a little more and drain the sink into the same pipe as the toilet.

I'm not sure I'm understanding your dilemma. The sink would wet vent the toilet just wye off of the toilet branch.
 

Jeff H Young

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I dont see a problem. just your one way dosent work . put sink drain in side wall? bring drain through floor and then offset into the wall? are 2 ways that should work
 

wwhitney

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The issue is that at the red line below S, the top of the concrete is above the subfloor. So there's no way for a drain to pass down through that wall into the floor framing without breaking into the foundation. It would have to kick out outside the framing.

The drain routing on (1), (2), or (3) are all fine, whichever is easier (both for running the DWV and installing the sink base cabinet). But in (1) there's no reason to have an AAV, the vent can jog into the wall and be vented like (2).

How high is the concrete above the subfloor? If not too high, in (1) the drain can come up through the subfloor just next to the concrete, and then 45 into the wall framing as low as possible, and then go to a standard san-tee in the wall configuration. And then the drain segment outside the wall would end up fully or mostly within the toe kick space of the cabinet, where it would be hidden.

Cheers, Wayne
 

Jeff H Young

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you just come up through the floor in front of wall as I said , or side wall again should be simple based on provided info
 

justincan

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Thank you for the responses, the idea of coming through the floor and then 45 into the wall seems like the most straight forward and should be hidden enough behind the cabinet.
 

Justintime

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If you have access to the crawl space beneath and you only need a few inches, a rotary hammer can make very short work of getting a 2" or 1.5" pipe into the wall. The 45 degree method works, too.
 

Jeff H Young

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Or come up in side wall for the lav unless there are drwaers on the side in the way
 
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