Bathroom sink drain line setup.

[herman]

Complete tear out of bathroom and installing double sink vanity.
Due to the current height of the drain line, I need to raise the two drain outlets to approx. 21".
I was told to either come off the main line, 90 up a couple inches than out. OR
instead of the 90 deg. up, keep the two drain lines horizontal and make the drop a couple feet
before the main stack. Second option in red.
Current drain line is at 17" and that's too low for my vanity.

Thanks in advance.

 

[wwhitney]

Did you mean to post a diagram? Two things to be aware of:

- Each trap will need a vent connection at the elevation of the trap. It is possible for one lav to be dry vented and wet vent the other lav.
- If you previously had one lav and are switching to two lavs, and the lavs are wet venting downstream fixtures (common), then depending on the applicable code (IPC vs UPC) and existing sizing, some of the lav drains may need upsizing.

Cheers, Wayne

 

[Sponsor]

 

[herman]

Having issues posting pic. Tried cut and paste and "attach files" function with no luck.

 

[herman]

Having issues posting pic. Tried cut and paste and "attach files" function with no luck.

Here is what I have now and proposed in red.
I'm not confident the current two trap setup will not drain my traps dry.
The larger 3" drain pipe on the far right going up is the vent.


Thanks in advance

 

[wwhitney]

Neither what you have now, nor what you drew in red, is compliant. The vent connection for a trap has to occur at an elevation no more than one pipe diameter below the trap outlet.

So basically your horizontal trap arms, and their stub outs, all need to be in line with the 3x3x1.5 san-tee on the right. You can't have that drop in elevation between the stub out and the san-tee.

Also, which plumbing code are you under? The IPC will let you vent two lav traps like that, but the UPC doesn't.

Cheers, Wayne

 

[herman]

Neither what you have now, nor what you drew in red, is compliant. The vent connection for a trap has to occur at an elevation no more than one pipe diameter below the trap outlet.

So basically your horizontal trap arms, and their stub outs, all need to be in line with the 3x3x1.5 san-tee on the right. You can't have that drop in elevation between the stub out and the san-tee.

Also, which plumbing code are you under? The IPC will let you vent two lav traps like that, but the UPC doesn't.

Cheers, Wayne

Thanks for responding. I'm in Indiana.
Any thoughts on how to resolve my issue?
Guessing I either need to leave them in line with the 3x3x1.5 tee on right or cut out a section of the 3x3 and couple back to the height needed for the traps.

Thanks, Herman

 

[wwhitney]

Guessing I either need to leave them in line with the 3x3x1.5 tee on right or cut out a section of the 3x3 and couple back to the height needed for the traps.

Pretty much.

Indiana uses the IPC, so you're allowed to combine the two lav trap arms like that with the common vent at the stack. I'm assuming there's no drainage entering the top of that san-tee, just the dry vent.

Cheers, Wayne

 

[herman]

Pretty much.

Indiana uses the IPC, so you're allowed to combine the two lav trap arms like that with the common vent at the stack. I'm assuming there's no drainage entering the top of that san-tee, just the dry vent.

Cheers, Wayne

Correct, nothing above, its all vent. This is on second floor.