Adding drain to wall for double sink

Users who are viewing this thread


New Member
Reaction score
syracuse, ny
Hi there. We are looking at moving our bathroom double vanity to a different wall where we had some cabinets. The wall is non-load bearing 2x4 and runs parallel to the 2x10 joists. getting the drain to the area along with water is easy - the challenge is that the wall is a few inches from the parallel joist in front of it (wall appears to be sitting on he plywood - can not confirm if there are braces installed) making access to run a 2" drain up rather difficult. adding to the fun is that the vanity will have an open seating area in the center. looking for options from those with more experience.

As of the moment all i have is:

1) run 1-1/2" drains up from the floor from the 2" leg in the floor - would need to make sure I can get far over enough to avoid creating an S-Trap. Would run two 1-1/2" vent into the wall and up joining them to a 2" in the attic over to the main vent.
2) run 2" over up and over the joist into the wall and up to a T with 1-1/2" to each vanity with 2" vent going up. T would be located near one of the vanities. I would use stud shoes on the 1-1/2". I'm building the vanities so I can accommodate.
3) drill a hole on the side 1/3rd of the joist and elbow up into the wall. the hole is within bore size for a 2x10 joist, not sure I can get in there to install the elbow through and I would need to run through 7 studs for the furthest sink.



The Plumbing Wizard
Staff member
Reaction score
Bothell, Washington
It's a little hard for me to picture some of this.
Two lavs on 2".
Each single lav can be 1.5"
Venting for both lavs combined is 1.5" or larger is okay too.
When drilling through a 2x10, a hole 2-3/4" is fine, and leave 2" on the bottom and 2" on the top of the joist.
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks