Back to back p traps

[Harris]

Hi all - new to the forum and had a (hopefully) straightforward question.

I recently had some professional work done and contractor put in a new vent through the roof, and installed a p-trap in the wall, and then 90'd to what will be a bathroom sink. Further down that pipe I have a utility sink utilizing that same p-trap.

With the p trap in the wall do I still need to have an additional p trap under each sink?

Rough sketch attached for clarity

Thanks

 

[Reach4]

What you sketched is not permitted.

 

[Sponsor]

 

[hj]

WHO would ever put a "running trap" inside a wall? That is one of the worst ideas ever. It is NOT permitted, and even if it were, it would be a bad idea. You CANNOT have any additional traps under the sinks if you want them to drain.

 

[Harris]

The walls are currently unfinished, so it sounds like an easy fix is to remove the p trap in the wall and just let the traps from the sinks do their thing?

 

[Plumber69]

Some are going say you want a vent between the 2 ptraps, or an aav on one

 

[hj]

An AAV would be completely useless on this system.

 

[Plumber69]

An AAV would be completely useless on this system.

I mean after the in wall ptrap is removed

 

[Terry]

Normally the lav has a higher drain anyway, so I would run a trap arm over to the laundry tray and vent that back to the stack at 42"
Then I would stack a santee over that and arm over for the lav.

Back to back p-traps are often done this way too.

 

[Harris]

Thanks, very useful and thoughtout reply. Appreciate the insight.

 

[Plumber69]

its very unlikely it will syphilis the other trap without a second vent.

 

[WorthFlorida]

The only p traps that can be hidden is one for a washing machine drain (in the wall 6-18" from the floor), and the other is a bathtub and shower drains below the floor level.

 

[Harris]

I've finally found some time to fix these traps and had a couple questions on material. The attached picture hopefully provides clarity.

Hopefully the rubber couplings are OK for splicing into the existing vent, but my main question is can I use a horizontal Santee to vent upwards or do I need to use a wye plus a 45 coupling to make the 90 degree turn up.

Thanks again.

 

[Reach4]

"Rubber couplings" should be shielded couplings. Dish detergent makes a nice lube for putting them on.

Thing circled in red should not be a santee. It can be wye plus a 45 coupling for sure.

 

[Terry]

Code for the fitting on it's back is a wye or combo.
A santee works though. It just won't pass inspection where I'm at.

These with the metal wrap prevent the pipes from shifting. The all rubber couplings aren't code approved.

 

[Harris]

Thanks again all!

I will use the wye and pick up a couple shielded couplings.