How to drain a sink without an S trap?

[jzranger]

Hello. Basement renovation here.

My plumber provided a drain for the vanity 16" off the ground. Cleanout directly above it. Picture attached.

I plan on adding an access panel for the cleanout, and a vanity directly in front of the main stack to connect to the vanity drain. The vanity I would like to use has an inside compartment that starts 15" from the ground, so all plumbing needs to be 15" or higher.

1. Is it legal to add 2x elbows to increase the height of the drain to 20" so that I can then attach to a P trap? Or does doing so turn it into an S trap?
2. If I add elbows to raise the height of the drain, it seems like I would block access to the cleanout... Is that a code violation?


Is there a better way to do this that doesn't involve cutting the main stack apart? What do you recommend?

Thanks

 

[jzranger]

proposed vanity in red - proposed drain plumbing in blue... would this work?

 

[Sponsor]

 

[Reach4]

My plumber provided a drain for the vanity 16" off the ground. Cleanout directly above it. Picture attached.

Looks like the famous Philadelphia Single Stack System. I am confident that vents that lavatory fine, but it is not the way it is done most places. Are you in Philadelphia?

On your proposed elevation change, you would need to vent the trap before dropping down. Ao the answer to your #1 is it turns into an s trap. This could probably be done with an AAV, unless it is forbidden locally. #2 I don't know.

What you normally would do to make room for your drawers is to put the p-trap across the back behind the drawers. And jog the drain from the lavatory to the back wall, and then down to the trap.

 

[jzranger]

Hey Reach,

Thanks for the reply. You are correct this is suburbs next to Philadelphia.

I attached 3 images with drain vent options... Option 1 and 2 extend through the bottom of the vanity... Probably far enough back so that you won't see the pipe unless you're standing far away.I would just have to cut the vanity to make them work.

Option 3 shows the elevation change and does not protrude through the bottom of the vanity, but are we saying an AAV is required in this scenario? I can check with my inspector to see if he will allow it...

Any easier way to do this that doesn't extend below the vanity?

 

[Reach4]

Option 1 and 2 are OK. Option 1 is less likely to need unclogging, but would need some notching of the drawer. You could box in around the notch, or leave it open and only put stuff that doesn't roll around in that drawer. Option 2 puts the trap closer to the wall to be less visible, unless somebody is crawling.

Option 3 could be modified to put an AAV over a sanitary tee where the trap arm is horizontal. Normally you need the AAV to be 4 inches up from the trap arm, and the AAV must be replaceable.

https://terrylove.com/forums/index.php?threads/vanity-drain-connection-in-wall-too-low.60694/
https://terrylove.com/forums/index.php?threads/ikea-drawer-extend-1-25-pipe.92320/
https://terrylove.com/forums/index.php?threads/vanity-drawer-hitting-p-trap.59445/
https://terrylove.com/forums/index.php?threads/p-trap-install-stubs-out-too-low.68736/

and there are more.

 

[jzranger]

Option 1 it is. Option 2 and 3 seem like a lot of work for too little payoff. I believe even option 1 will be hidden from view from 20' away at eye level.

This was really helpful. Just wanted to cover all my bases before slicing up the new vanity. Thank you!

 

[Reach4]

This was really helpful. Just wanted to cover all my bases before slicing up the new vanity. Thank you!

I would start with a hole saw, and then use a jig saw or hand saw to turn that into a slot.

For your trap, you can use chrome-plated brass, rough brass, black brass, oil rubbed brass, white plastic, or black plastic. You can use a 1-1/2 inch trap, and adapt before the trap, or you can use a 1-1/4 inch trap, and use a reducing washer at the 1-1/2 trap adapter at the wall.

https://www.homedepot.com/p/Everbilt-1-1-2-in-Black-Plastic-P-Trap-CA9704B/205154221

You could also put a 1-1/2 in. x 1-1/4 in. PVC Hub x Slip-Joint Trap Adapter at the wall.

https://www.homedepot.com/p/NIBCO-1...p-Joint-Trap-Adapter-C48017HD112114/100348180

 

[jzranger]

I like the idea of the 1-1/4 trap with a reducer at the wall. I was thinking just white plastic for the trap to blend in with the white wall. The finishing options are interesting. If it was more visible I could see the oil rubbed brass matching the cabinet hardware working out, but I think it's going to be pretty hidden.

Now just to figure out if I want to remove that piece of drywall and relocate my water supply lines instead of modify a drawer.

 

[Reach4]

Now just to figure out if I want to remove that piece of drywall and relocate my water supply lines instead of modify a drawer.

Won't some nice Dahl right angle compression stop valves on your copper stub-outs feeding flex connectors make things nice?

Probably fits behind the drawer with no problem.

https://www.dahlvalve.com/products/mini-ball-valves/supply-stops/copper/supply-stops-611-33-31.php
https://www.dahlvalve.com/products/PDFs-submittal-sheets/TDS 410 (33-31).pdf

https://www.supplyhouse.com/sh/control/search/~SEARCH_STRING=dahl 611-33-31

Dahl 611-33-31LNS is the same, but they have left out the ferrule and nut, which you would have discarded. https://www.supplyhouse.com/Dahl-61...omp-Angle-Supply-Stop-Lead-Free-Chrome-Plated

 

[jzranger]

I really like that idea.

I might have to stick around this place.