WC Vent Question

[Ntcarson]

Hi all - quick question here - thanks, in advance, for your consideration and perspective!

I pulled all of the cast iron out of an old ('56, I believe) joint and am re-plumbing to my new layout, single story. Crude drawing added for perspective.

The question - I'm struggling to find a way to directly vent WC-2 given the adjacent wall/joist locations. The lower 3ft section will make the turn through an existing punch out in the separating foundations and join the "stack". Is there a problem tying WC-2 in here and venting off the stack, recognizing that I need to pop in from the side (below 45) to avoid air flow disruptions?

I do welcome other comments/critiques of my solution.

Anticipated other questions/concerns:
- The 11ft section runs along (outside) the original foundation (brick+block) before reaching the busted out section to cross over.
- North of (up from) the 11ft section is an addition from who-knows-when
- 3in from Washer is overkill but am adding in-case future expansion in that direction
- I don't love the WC-1 vent, but it was most feasible, given constraints

 

[wwhitney]

My understanding of your drawing is that it's in plan view, and the red square represents a vertical stack into which everything drains.

The IPC allows horizontal wet venting for up to 2 bathroom groups at once. So if that 3ft 3" pipe that connects to your stack is receiving at its upstream end only the listed fixtures (2 lavs, 2 showers, and one WC), then it can be the wet vent for WC-2.

As a small technical point that doesn't matter for your layout, the 2" pipe carrying Shower 1, Shower 2, and the associated lav is undersized for it to act as a wet vent downstream of shower 2. It is carrying 5 DFUs once Shower 2 joins, and a 2" wet vent is limited to carrying 4 DFU. So in your arrangement you have two disjoint wet vents, one is from the left lav to shower 1 to shower 2, the other is from the right lav to WC-1 to WC-2.

That's all fine, it just means that if, for example, you deleted WC-1 and the right lav, you would need to upsize the section of pipe carrying the remaining lav and both showers to 3" in order for the remaining lav to wet vent WC-2.

Cheers, Wayne

 

[Sponsor]

 

[Ntcarson]

As always - thank you Wayne!

That will be all of the fixtures in the building, so based on your point, that is good. Though, once again, I find myself somewhat mixed up when something becomes a wet vent, since everything else is already vented before it gets there, but that makes sense.

Regarding the matter of wet venting Shower 1 and 2 - if I were to tie them both in directly to the vent off the Lav (a santee below deck) before going horizontal, would that solve the issue? If no, given that wall layout, I can add another dry vent at Shower 2, eliminating that wet vent section.

Given your last concern, and the fact that I've only plumbed up to the point where the 2in Lav/shwr/shwr section ties in, would you recommend that I just go ahead and make that a 3inch section receiving the 2in fixtures?

Thanks again,
Neil

 

[wwhitney]

Though, once again, I find myself somewhat mixed up when something becomes a wet vent, since everything else is already vented before it gets there, but that makes sense.

A wet vent is a section of pipe that serves as a drain for one or more fixtures while also serving as a vent for at least one other fixture. So just looking at the WC and lav on the right (pretend there are no other fixtures), the wet vent would be the horizontal 2" pipe you show, plus the vertical lav drain not shown, up to the point where the dry vent for the lav comes off the lav drain.

Regarding the matter of wet venting Shower 1 and 2 - if I were to tie them both in directly to the vent off the Lav (a santee below deck) before going horizontal, would that solve the issue?

There is no issue, the layout is fine where the only dry vents you provide are at the two lavs (usually via a san-tee in the wall, where the lav drainage turns downward before having fallen more than one trap diameter from the trap outlet, and the vent comes out the top of the san-tee).

Given your last concern, and the fact that I've only plumbed up to the point where the 2in Lav/shwr/shwr section ties in, would you recommend that I just go ahead and make that a 3inch section receiving the 2in fixtures?

If it is no trouble, making the combo where Shower 2 joins the Lav and Shower 1 into a 3x2x2 combo (i.e. a 3x3x2 combo with a 3x2 reducing bushing on the straight inlet) seems like a nice idea. But if it's any trouble, it's fine the way you drew it.

Cheers, Wayne

 

[Ntcarson]

A wet vent is a section of pipe that serves as a drain for one or more fixtures while also serving as a vent for at least one other fixture. So just looking at the WC and lav on the right (pretend there are no other fixtures), the wet vent would be the horizontal 2" pipe you show, plus the vertical lav drain not shown, up to the point where the dry vent for the lav comes off the lav drain.


There is no issue, the layout is fine where the only dry vents you provide are at the two lavs (usually via a san-tee in the wall, where the lav drainage turns downward before having fallen more than one trap diameter from the trap outlet, and the vent comes out the top of the san-tee).


If it is no trouble, making the combo where Shower 2 joins the Lav and Shower 1 into a 3x2x2 combo (i.e. a 3x3x2 combo with a 3x2 reducing bushing on the straight inlet) seems like a nice idea. But if it's any trouble, it's fine the way you drew it.

Cheers, Wayne

Got it - thank you again! Have a great night!