rough in for converting single vanity to double

[marc1817]

Hello,

Just wanted to start out by saying I sincerely appreciate all of the advice on this forum, and was wondering if anyone might offer advice with my particular situation.

I am planning to convert the current setup with the photo attached to accommodate a 72" double vanity, with the supply lines and drains coming from the wall.

My original plan was to have a conversion similar to the second attached photo I found on this forum. This has a similar orientation of the drains to the stack. This would require moving the current 1.5" pipe lower and converting it to a 2" pipe after the double santee, with a 1.5" vent going back to the 3" stack, as seen in the second photo.

I had a plumber come by who felt that this additional venting was unnecessary, and that an AAV at the further trap would suffice. Therefore, we could just lengthen the current 1.5" trap arm and put in two drains with the AAV. This would also avoid drilling additional holes in the studs, which they were worried about weakening support. This is a second floor non-exterior wall.

What does the group think? Thanks in advance.

 

[WorthFlorida]

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

It has pictures of my single to double sink vanity I did a few years ago. I also had a plumber do the work. BTW, most of my home uses AAV's and no issues at all. Since my home was built in 2007, the drains were already 2".

Google search "stud shoe". It is used to support studs that have been cut or drilled for pipes. It also acts as a nail guard.

 

[Sponsor]

 

[marc1817]

Thank you so much for the reply.

I think I will plan on an AAV under the sink after the p trap on the lav furthest from the stack. This would be similar to this post:

https://terrylove.com/forums/index.php?threads/single-vanity-to-double-venting.93921/

My question is, does the arm between the stack and the closer lav need to be increased from 1.5" to 2", as it will receive waste from both lavs?

Thanks again

 

[WorthFlorida]

1.5" will work. 1.5 can handle 3 fixture units, each lav sink is .5 FU. AAV is allowed in NY STATE.

https://dos.ny.gov/2020-plumbing-code-new-york-state

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