Adding a sink, best way to tie in drain?

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dgold

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Hi all,
I’m wanting to add a sink to my laundry room. On the other side of this wall is a vanity, so I have supply, drain, & vent right here - which is convenient.

Can I use a tee or a wye (and which is correct?) at location B to turn out of the wall (eye swinging out to the left - so the water runs to the right, toward the drain) and then trap then sink (thinking in reverse of flow)?

Or, if I were to install a tee/wye at position C, is it okay to install use a fernco in the wall above the fitting to re-attach the vent?

Thanks to all in advance,
David
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dgold

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Sorry, don’t know why I can’t use the image link while creating the post. I pasted the URL for the photo into the body this time.

it’s here:

dgold-01.jpg
 

wwhitney

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So you have a double lavatory vanity on the opposite side of the wall?

What plumbing code? I think in AZ it varies.

Cheers, Wayne
 

Jeff H Young

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I have UPC code and a easy and good way would be cut the 2 inch and install a 2x2x1 1/2 santee. using a 2 inch shielded band coupling top and bottom easy as pie! might meet IPC code I don't know but across the river in CA its the way to do it
 

Jeff H Young

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I'd put a 2x2x1 1/2 santee at area c , use 2 inch banded and shielded couplings . passes UPC code and works perfect , your code I don't know but that's how Id do it .
 

Jeff H Young

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Whoops I double posted , I'll let you worry about your code good luck with project!
 

wwhitney

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OK, my brief googling suggests that location uses the IPC; please confirm.

If you had a single lav, then you could connect it at B using a horizontal combo. That's because the IPC allows "common venting" where two traps share a single vent, and their trap arms can even combine before venting. However, this brochure form the ICC indicates that the double fixture fitting is already a common vent: https://www.iccsafe.org/wp-content/uploads/20-18927_GR_2021_Plumbing_Venting_Brochure.pdf That means you can't tie in at B, as common venting is not allowed for 3 fixtures. [Not 100% sure I agree with that interpretation, but ICC writes the IPC.]

So, you're going to need to tie in the drain at A. Now since the IPC doesn't allow vertical wet venting outside of a bathroom group, you are going to need to use a separate dry vent takeoff on your new laundry sink trap arm. That can be an upright combo; the IPC also allows a san-tee on its back for the vent takeoff, but unless you are pressed for room, the combo is better. Since the drain is now vented, when it joins in at A you can use either a san-tee or a wye, as is convenient.

But now you have the dry vent you need to deal with. It can be 1.5" and can reconnect to the 1.5" vent shown above c. But the height of that connection has to be at least 6" above the flood rim of the two lavs and the laundry sink. So c is too low, you'll have to open up more drywall. And you have to figure out how to get that vent to rise across the lav trap arm.

Cheers, Wayne
 

Jeff H Young

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OK install the santee as I mentioned and throw a AAV cheater vent on the trap arm for the laundry sink and say good bye to the Wet Vent outside bathroom group just another way of doing it whatever works best , easiest , meets code and suits you!
 

wwhitney

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BTW, below is a drawing of another option. Blue is 1.5" pipe, and the blue circle is the opening of a horizontal combo cut in at B.

The idea is to eliminate the double fixture fitting so that you can use common venting for the new laundry sink and the lefthand (as seen from the backside) lav. So you change that to a san-tee. Then the righthand lav needs a drain and vent, it gets a separate san-tee to the right of the stack and the drain joins the stack below with a wye. The vent rises parallel to the existing vent until 6" above all the flood rims, and then it can join the existing vent.

This has the advantage of not requiring pipes to cross over each other within the wall. Instead of the san-tee plus combo for the lefthand lav and the laundry sink, you could use a san-tee with sanitary side inlet, assuming the laundry sink can line up with the stack. Except as far as I know those are only available in PVC as 2x2x2x2, so you'd have to do the new work in PVC and connect to the ABS with shielded couplings. But the shielded couplings are likely required anyway, at which point whether you use PVC or ABS for the new work doesn't matter.

Oh, and of course like Jeff says if you can use an AAV, that does simplify the venting on the previous layout, but some prefer to have a vent through the roof.

Cheers, Wayne


IMG_2298.jpg
 

wwhitney

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Id put a 2x2x1 1/2 santee at area c , use 2 inch banded and shielded couplings . passes upc code and works perfect
I don't think cutting in a san-tee at C would comply with the UPC, probably you meant A? Which would likely work better with a laundry sink, as they tend to be deeper than a lav, so you'd like the trap arm lower.

Cheers, Wayne
 

Jeff H Young

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Oops yes section a on the 2 inch and my thoughts too ,most or many are deep sinks
 

dgold

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Thanks everyone! Very much appreciate the input!

I’m covering this with base cabinets, so I might actually be able to fit in a loop if I can twist it to the side a little. Seems like that’s the most full proof method - no?

If I can’t do that, the AAV on the trap sounds a LOT simpler. I’ve never installed one before or owned a home with one (as far as I know)… Any reliability concerns with those? The idea of moving parts doesn’t give me the warm and fuzzies, but maybe I’m just paranoid.
 

Jeff H Young

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Thanks everyone! Very much appreciate the input!

I’m covering this with base cabinets, so I might actually be able to fit in a loop if I can twist it to the side a little. Seems like that’s the most full proof method - no?

If I can’t do that, the AAV on the trap sounds a LOT simpler. I’ve never installed one before or owned a home with one (as far as I know)… Any reliability concerns with those? The idea of moving parts doesn’t give me the warm and fuzzies, but maybe I’m just paranoid.

I'd install per my post #7 except I goofed and said area A I meant C. this works perfect but might not meet your code . If my house Id do it this way because I have 100 percent faith in it . but if I wanted to meet your code Id put the stupid AAV on which doesn't give me warm fuzzies either but half or more of our country uses them very very frequently. If anyone is that worried to meet code then don't forget to pull the permit!
 

wwhitney

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I like Jeff's suggestion. The UPC recognizes the in-wall configuration as an acceptable wet vent and wouldn't recognize the AAV. The IPC recognizes the AAV but doesn't recognize the in-wall configuration as an acceptable wet vent. Do both and you're covered either way. : - )

Cheers, Wayne
 
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