# Double lavs on single trap arm



## Miguel (Aug 10, 2009)

OK, I know I might get picked up on this during inspection but the new lav and cabinet was just delivered to the site today and I quickly reconfigured the waste and water to suit. It's a "dresser" type cabinet on legs (with shelves and a bank of drawers inbetween) and two lavs. Not a single basin as shown on the prints.

All I did was adjust my trap arm to the centers required by the vanity (two traps require individual venting in Ontario) and stubbed out for two traps on that single trap arm, both draining into an 1-1/2" trap arm which dumps into a 2" stack that wet-vents the WC.

I know it'll work but if it wasn't for the bank of drawers in the middle of the vanity I would've just dumped the 2nd lav as an indirect drain into the 1st. That would comform.

We're still at the rough-in stage with exposed studs etc.

WHat would you have done?


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## AKdaplumba (Jan 12, 2010)

Im lost:blink:


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## rocksteady (Oct 8, 2008)

If everything is still exposed it's nothing a quick change order and some pipe can't fix. I think I'd have redone the waste and vents to come out of the wall with 2 stub-outs. If the plans show one basin and that's what your roughed in for, this is extra.






Paul


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## luv2plumb (Apr 30, 2010)

rocksteady said:


> If everything is still exposed it's nothing a quick change order and some pipe can't fix. I think I'd have redone the waste and vents to come out of the wall with 2 stub-outs. If the plans show one basin and that's what your roughed in for, this is extra.
> 
> 
> 
> ...



I'm with Rocksteady on this one.....if the plans show one lav but they want two send a change order and rough-in for two.


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## stillaround (Mar 11, 2009)

AAV's allowed?

How far back do the drawers go...I'm trying to find an easy way out..


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## TheMaster (Jun 12, 2009)

I had the same job......but it was not new construction and the walls were not opened completely. It was roughed in for one bowl back in the early 60's with 1.5" copper. I cut the existing 90 off and sweat on a copper fip adapter and converted to pvc. Installed a combo for the 1st lav and a combo for the 2nd lav.....that was about 6' from the vent. 
The center of the combo came out for the new drain with a p-trap.....I installed a long sweep 90 coming into the cabinet out of the upstream portion of that last combination fitting...so I had two 1.5" pipes stubbed into the last lavatory cabinet...one for a drain and one for a cleanout and mechanical vent.

When you would fill either lavatory it would suck air from the vent......remove the vent and install a plug and it would drain super slow.


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## stillaround (Mar 11, 2009)

TheMaster said:


> When you would fill either lavatory it would suck air from the vent......remove the vent and install a plug and it would drain super slow.


 :laughing:


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## Redwood (Sep 8, 2008)

TheMaster said:


> When you would fill either lavatory it would suck air from the vent......remove the vent and install a plug and it would drain super slow.


Care to elaborate on this Phenomena?

Can you cite a reason for it's occurrence besides PFM or IDK?:whistling2:


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## TheMaster (Jun 12, 2009)

Redwood said:


> Care to elaborate on this Phenomena?
> 
> Can you cite a reason for it's occurrence besides PFM or IDK?:whistling2:


It needed air to drain proper. Simple as that. It drained 3 times as fast with the mechanical vent. 
The lav's sat side by side. 3-4' of 1.5" horizontal copper then converted to 1.5" pvc for another 3'. Two lavs on one 1.5" fixture arm.


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## Redwood (Sep 8, 2008)

TheMaster said:


> It needed air to drain proper. Simple as that. It drained 3 times as fast with the mechanical vent.
> The lav's sat side by side. 3-4' of 1.5" horizontal copper then converted to 1.5" pvc for another 3'. Two lavs on one 1.5" fixture arm.


So is that an *P*ure *F*reakin *M*agic or *I* *D*on't *K*now reason? :laughing:

Why did it happen?

Explain the logic! If it did there is a reason....:whistling2:

Better yet post a video... Prove it!


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## Optimus Primer (May 20, 2009)

stillaround said:


> AAV's allowed?
> 
> How far back do the drawers go...I'm trying to find an easy way out..


The ones I have seen the drawers are cut out for the plumbing. They look like a u.


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## RealLivePlumber (Jun 22, 2008)

A ewe?


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## TheMaster (Jun 12, 2009)

Redwood said:


> So is that an *P*ure *F*reakin *M*agic or *I* *D*on't *K*now reason? :laughing:
> 
> Why did it happen?
> 
> ...


No i answered you...it needed air. I cant go knock on the ladys door with a video camera but if the opportunity arises I will do:thumbsup:.


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## Optimus Primer (May 20, 2009)

RealLivePlumber said:


> A ewe?


Wrong thread. You're supposed to post your mug on the thread in plumbing pictures. maybe one of the moderators will move it for you.

http://www.plumbingzone.com/f21/updated-post-your-mug-thread-2329/


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## Redwood (Sep 8, 2008)

TheMaster said:


> No i answered you...it needed air. I cant go knock on the ladys door with a video camera but if the opportunity arises I will do:thumbsup:.


Right! It defies over a century of venting knowledge, and the laws of gravity...

But TM said it needed air...:laughing:

And he'll get Kennifer and Justin to agree with him...:thumbup:


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## TheMaster (Jun 12, 2009)

Redwood said:


> Right! It defies over a century of venting knowledge, and the laws of gravity...
> 
> But TM said it needed air...:laughing:
> 
> And he'll get Kennifer and Justin to agree with him...:thumbup:


The fact that I installed the mechanical vent and it drained alot faster proved it....take the vent away and it drained slow again. Real simple:whistling2:


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## Redwood (Sep 8, 2008)

TheMaster said:


> The fact that I installed the mechanical vent and it drained alot faster proved it....take the vent away and it drained slow again. Real simple:whistling2:


Yea I hear ya TM but before you muck up someone's thread with an off topic discussion why don't you head over to that other thread and elaborate on your simple explanation...

Something more than cuz it did....:laughing:


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## TheMaster (Jun 12, 2009)

Redwood said:


> Yea I hear ya TM but before you muck up someone's thread with an off topic discussion why don't you head over to that other thread and elaborate on your simple explanation...
> 
> Something more than cuz it did....:laughing:


Its important that the original poster be aware that the lavs may not drain proper the way he has them plumbed and it needs a vent or a mechanical vent. 

You trying to get me to explain my findings is whats mucking up the thread.....I am on topic.


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## Redwood (Sep 8, 2008)

TheMaster said:


> Its important that the original poster be aware that the lavs may not drain proper the way he has them plumbed and it needs a vent or a mechanical vent.
> 
> You trying to get me to explain my findings is whats mucking up the thread.....I am on topic.


I would say it is as simple as "That any plumbing done should be properly vented and installed per your applicable code."

:whistling2:Know what I mean...:whistling2:


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