Master Bath Remodel - Double Vanity Venting and Drainline Advice
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James Henry
In the Trades
The only option you have is a continuous drain. You can't tie a p-trap into another p-trap.
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James Henry
In the Trades
Cute dog, though.
I realize a double trap is to be avoided, but I am out of room in my wall to run anything except what I have done. I thought that if I vented in between the traps this would be ok. Not ideal, but ok. Please explain further if possible.
Ahh...maybe I can install a tee off the original single sink drain and connect that to the new second sink. Is this what you meant by one continuous drain? If I do that, do I need to vent in between the tee and the second vanity? I will have to rework all the water lines, but that's easier than breaking concrete for a new underground drain line. Revised pic with question.
wwhitney
In the Trades
Looks at your photos, I think you could replace the combo below the existing lav san-tee with 2 stacked san-tees (probably top one street). You'd need to double check the height that takes up to be sure it would fit.
The uppermost san-tee would receive the laundry drain. The lower san-tee would receive the new lav drain.
In your first picture, the black line would be a new vent for the new lav, and where it hits the new lav trap arm, you'd use a san-tee. The bottom outlet would hit a long turn 90 to turn towards the lower of the double san-tees. That would hopefully be low enough to miss the laundry trap and the copper pipes.
Cheers, Wayne
The uppermost san-tee would receive the laundry drain. The lower san-tee would receive the new lav drain.
In your first picture, the black line would be a new vent for the new lav, and where it hits the new lav trap arm, you'd use a san-tee. The bottom outlet would hit a long turn 90 to turn towards the lower of the double san-tees. That would hopefully be low enough to miss the laundry trap and the copper pipes.
Cheers, Wayne
Jeff H Young
In the Trades
just dont put a ptrap on the lav tie to standpipe and it wont be double trapped. Ive never done that but think we have it legal in the code
How about a circuit vent? Bring the relief vent, if needed, over above the photo?
wwhitney
In the Trades
That would require that I read the section on circuit venting. : - ) Is the idea to circuit vent the two lavs only, so basically the piping drawn in black in both of the OP's photos?
Cheers, Wayne
That was my thinking -- least change.
See https://www.iapmo.org/media/22037/circuit-venting-problem-solved.pdf which is UPC (I think that says figure 2).
I wonder if IPC might permit it with 1-1/2 inch pipe instead of 2. Maybe not. I don't know if 2 inch would fit for Wally.
wwhitney
In the Trades
The OP is in Illinois, so depending on where, the Illinois State Plumbing Code would be in effect. It seems to allow circuit venting only for drains at floor level:
https://www.ilga.gov/commission/jcar/admincode/077/077008900K15200R.html
Cheers, Wayne
https://www.ilga.gov/commission/jcar/admincode/077/077008900K15200R.html
Cheers, Wayne
Thanks for the advice so far. I decided to remove all the water lines and basically start over. If you guys can help me redesign from here that would be great. See revised picture.
I don't have much room left on the main drain stack, or within the wall, to run separate lines, so I wanted to do this: Will this plan work?
a. Insert a tee connection at the existing single lavatory drain line.
b. Connect a second drain line to the right of that tee.
c. Install vent line in between the two vanities and connect to vent stack above.
Thanks for listening and the advice.
I don't have much room left on the main drain stack, or within the wall, to run separate lines, so I wanted to do this: Will this plan work?
a. Insert a tee connection at the existing single lavatory drain line.
b. Connect a second drain line to the right of that tee.
c. Install vent line in between the two vanities and connect to vent stack above.
Thanks for listening and the advice.
wwhitney
In the Trades
When you say "tee" you'd need a combo (tee-wye, wye + 45, lots of different names).
That looks to me to be a compliant wet vent per the Illinois Plumbing Code, as long as you use a 1-1/4" p-trap on the righthand lav:
https://www.ilga.gov/commission/jcar/admincode/077/077008900K15000R.html
Part (d) says if you used a 1-1/2" p-trap on the right, your horizontal lav drains would need to be 2", but it looks like the existing you want to tie into is 1-1/2".
Cheers, Wayne
That looks to me to be a compliant wet vent per the Illinois Plumbing Code, as long as you use a 1-1/4" p-trap on the righthand lav:
https://www.ilga.gov/commission/jcar/admincode/077/077008900K15000R.html
Part (d) says if you used a 1-1/2" p-trap on the right, your horizontal lav drains would need to be 2", but it looks like the existing you want to tie into is 1-1/2".
Cheers, Wayne
One of these guys......
wwhitney
In the Trades
No, that's a san-tee, you need a combo tee-wye (e.g. literally a wye and a street 45, or else the one piece fitting that does the same thing):
https://www.supplyhouse.com/Spears-P501-015-1-1-2-PVC-DWV-Wye-and-45-Elbow-Combo
Cheers, Wayne
https://www.supplyhouse.com/Spears-P501-015-1-1-2-PVC-DWV-Wye-and-45-Elbow-Combo
Cheers, Wayne
Jeff H Young
In the Trades
whats wrong with tieing into standpipe if its not double trapped? lav need to be in same room?
wwhitney
In the Trades
UPC 1001.2 "Each plumbing fixture shall be separately trapped by an approved type of liquid seal trap." (with a later exception for multiple sinks in some cases)
https://up.codes/viewer/california/ca-plumbing-code-2019/chapter/10/traps-and-interceptors#1001.2
IPC 1002.1 is similar.
https://up.codes/viewer/colorado/ipc-2018/chapter/10/traps-interceptors-and-separators#1002.1
Not sure about Illinois.
Cheers, Wayne
https://up.codes/viewer/california/ca-plumbing-code-2019/chapter/10/traps-and-interceptors#1001.2
IPC 1002.1 is similar.
https://up.codes/viewer/colorado/ipc-2018/chapter/10/traps-interceptors-and-separators#1002.1
Not sure about Illinois.
Cheers, Wayne
Jeff H Young
In the Trades
I thought a sink can tie into a laundry standpipe . but ive never done it seen it adressed on these forums
http://media.iccsafe.org/news/icc-enews/2018v15n13/2018SC-IPC802.pdf describes a standpipe trap shared with a laundry tub. As I read it, the 2018 change was to allow it in apartments, and this was available for houses in earlier versions.
This would not apply to Wally unless he was in Dupage County -- the only one to use IPC.
Jeff H Young
In the Trades
no idea what county he is in. most of illinois is upc? another point its not a laundry tray. could just cut it out and re do it
