Single to Double Sink DWV in Condo

[Richard Ellis]

Long time reader. First time asking for help. I have read every post I could find on single to double sink DWV options, but have a configuration I could not find. In my condo, there are back to back sinks in adjacent units, as well as vents from sinks on 1st floor that my vanity sink vents need to tie in to.

Desired Input:
Q1: How do I tie vents together and meet code in Texas?
Q2: Which layout option is best?
Q3: Did I get the fitting selections right?



The tape in the first picture shows top of counter and top of backsplash.

Richard

 

[Terry]

Either one of those will work. The fittings look to be correct too.

 

[Sponsor]

 

[Richard Ellis]

Either one of those will work. The fittings look to be correct too.

What is the proper way to tie the (3) vents together at the top right corner? My sink vents will be in one vertical plane (my wall), but the vent from below is between the gap between the walls.

 

[Terry]

Fittings and pipe are cheap.
Just cut back farther on the piping to the right, throw on a coupling, then work your way over to your new stuff.
If it helps, you can 45 over the upper parts of then vent to space things over farther.

 

[Richard Ellis]

Thanks Terry. After I make the changes, I'll report back with a finished picture to add to the "single to double sink" body of knowledge.

 

[Richard Ellis]

Vanity Sink Rough-In Dimensions
Now that I have confirmed what the plumbing components should look like, I researched the rough-in dimensions for the fittings themselves. Here is a diagram that I drew in SketchUp based on the threads I read as well as looking at spec sheets for several different undermount sinks. Vanity will be comfort height, so 36" to top of counter and 60" long. As noted in the diagram, I laid out the plumbing to allow for installation of a standard height vanity in the future if someone chose to do so.

Question to answer...
Are the dimensions acceptable based on your experience?

 

[Richard Ellis]

I committed to come back and share the solution I implemented to convert from a single sink to double sink for my condo remodel. Here is a picture of the final installation.

The most challenging section was the center section, where the drain and vent ties together my unit and the one adjacent to me. Here is a close up of the fittings I had to use to make the connections. Not a challenge for a plumber I'm sure but cutting the existing pipe at the proper height to allow the new fittings to stack up took some trial and error, then there is that offset for my new vent line.

Finally, here is the end product with the H/C supply lines in place...

I hope this helps others looking to do the single to double conversion.

 

[Richard Ellis]

Here is the installation with Roxul insulation in place -- for sound, not climate control. Although more expensive than the pink stuff, this material will not burn, does not retain water, and meets code as fire blocking in multi-family units. Each batt had to be hand cut to width because none of the studs were on 16" centers - throughout the entire place.

And then with the 5/8" drywall installed...

In case someone wonders what the extra capped line just above, and to the right of the right drain, it's the primary condensate drain for the AC unit. My local AHJ requires it to be connected to a wet line, upstream of a trap.