Venting setup

[Smorrison0702]

Hi all,

First time posting to this forum but have been coming here for advice for a while! I am working on the DWV setup for a new bathroom. I want to make sure that the attached setup will properly vent the shower. I’ve seen wet vent diagrams showing both a WC and shower downstream of a vent but not where both are upstream as in my setup. FYI I am in Oregon and our plumbing specialty code is based on UPC. Thanks in advance for your advice!​

 

[wwhitney]

I’ve seen wet vent diagrams showing both a WC and shower downstream of a vent but not where both are upstream as in my setup.

That's because it's not allowed. Each fixture needs to be vented before (dry vent) or as (wet vent) its drain joins another drain. So you can't combine the unvented shower and WC drains.

You need to move the WC connection downstream of the lav connection. That will allow the shower to be wet vent by the lav as it joins another drain (the lav). It's also a UPC requirement that the WC be last on the wet vent.

Cheers, Wayne

 

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[Smorrison0702]

Thanks for the quick reply Wayne. That makes sense. Unfortunately the most downstream wye exists just inside the foundation (the plumbing to be installed is under a slab) so connecting anything downstream of that wye won't work. Any other options short of adding a second vent to the section between the WC and shower? For what it's worth nothing upstream of the 3"/2" wye is installed. Thanks again for your help!

 

[Smorrison0702]

Sorry for the extra reply. I’ve got. Good deal of vertical space to work with so I’m wondering if this setup would be permissible?

 

[wwhitney]

I'm unclear on vertical vs horizontal in your drawing, but yes that works. Vertical/horizontal doesn't matter for the WC, the limit there is 6' from the closet flange to the 3" x 2" wye measured along the pipe. On the shower, the limit is on the trap arm from the trap outlet to the 2" san-tee, it's 60" in length and no more than 2" in total fall. For the double lavs you'll want to use a double fixture fitting, rather than a double san-tee, or else stacked san-tees.

I guess if your 3x2 wye is vertical rather than horizontal, you have a potential issue, as UPC vertical wet venting requires that each pipe segment be one size larger than the minimum vent for the fixtures below, and one size larger than the minimum drain from the fixture above. So it would require 3" from the wye up to the double fixture fitting, which would require a 3" wye.

Cheers, Wayne

 

[Smorrison0702]

Thanks Wayne—apologies on the drawing; my 3D skills are lacking! The 3-2 wye is horizontal though so it sounds like I should be ok. The trap arm is 4’ from weir to vent. It also seemed in the code that there isn’t a requirement for a cleanout along the shower trap arm? Is that right? I have a two-way cleanout that was installed downstream of all this on the other side of the foundation, and am planning to put another under the lavs but want to make sure I’m covered. Thanks!

 

[wwhitney]

I'm not so familiar with the cleanout rules, all I can say is to look at section 707 of your plumbing code.

Cheers, Wayne