Convert single sink to double

[Doublebonus]

New here so bear with me.
My daughter wants a double sink vanity,and since I'm her diy plumber!
All drains are 1 - 1/2 ". It will be centered over existing stubout. It may not be up to code but I have little options. Can't repipe entire drain due to it extending into adjacent finished part of basement ceiling. Looking for best option to have stubouts about 15" to both sides of existing vent stack and work. This will be the only things on this drainstack to main,nothing above or below. One floor house. Plumbing in ceiling of basement

 

[WorthFlorida]

https://terrylove.com/forums/index.php?threads/48-vanity-with-double-sinks.100004/#post-719401

 

[Sponsor]

 

[Jeff H Young]

works fine!

 

[Doublebonus]

What fitting to use in the stack where arms come in. My drain is 1-1/2". The Double fixture fittings I've seen have a 2"" at bottom to drain line. Also would I have to add AAV by trap or revent higher up the stack to roof?
Also ,everything is copper, would prefer to splice into copper stack drain with pvc or abs.

 

[Terry]

They don't make a double fixture fitting in 1.5" and a double sancross is the wrong fitting.
You will want to have two 1.5" santee fittings, which can revent together at 42", which is 6" above flood level.

Not to current code, but it's what I do when I only have 1.5" pipe to work with. Each sink will drain just fine, and snaking this is a breeze.
Any double fitting on 1.5" is impossible to snake later.

Or you can run each one on it's own, tying venting together at 42"

It's too bad you can't bring 2" over there from the 3" stack in the basement. For copper to plastic, they make a shielded coupling that has copper x plastic on the rubber insert. The metal wrap keeps it aligned and straight.

Like this, but make sure you have the "copper x plastic" sizing.

 

[Doublebonus]

They don't make a double fixture fitting in 1.5" and a double sancross is the wrong fitting.
You will want to have two 1.5" santee fittings, which can revent together at 42", which is 6" above flood level.

Not to current code, but it's what I do when I only have 1.5" pipe to work with. Each sink will drain just fine, and snaking this is a breeze.
Any double fitting on 1.5" is impossible to snake later.

Or you can run each one on it's own, tying venting together at 42"

It's too bad you can't bring 2" over there from the 3" stack in the basement. For copper to plastic, they make a shielded coupling that has copper x plastic on the rubber insert. The metal wrap keeps it aligned and straight.

Like this, but make sure you have the "copper x plastic" sizing.

Second pic not easy for me. Pipe from basement is in center. First pic I would use a Fernco on copper,short pc of pvc,then wye to split....... and Fernwood at top to attach 1-1/2 pvc back to copper stack (.pic 1.)
Would it be possible to to use Fernco at bottom to short pc 2" pvc to inlet of double fixture fitting, pvc pipe and the Fernco back to copper stack?(pic 2)

 

[Terry]

You can't reduce pipe size. You're better off with the example in green.

 

[Doublebonus]

You can't reduce pipe size. You're better off with the example in green.

So to clarify off the green photo I'll need 2 Ferncos with short pipe to wyes , 2 45's to 2 sanitary tees for arms, correct?
Which is better to use, PVC or ABS?

 

[John Gayewski]

So to clarify off the green photo I'll need 2 Ferncos with short pipe to wyes , 2 45's to 2 sanitary tees for arms, correct?
Which is better to use, PVC or ABS?

We use PVC in our area. There is very little ABS available. It depends on what's available for you.