Is this a wet vent? Is it allowed?

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Gimper

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I'm working on the plans to finish our basement, and am thinking that it would be great to add a wetbar. There are existing stubouts for a shower, stool (under the air hockey table) and lav as can be seen in the attached pictures and drawing. I believe that the vertical line on the right in the photos is the vent for the stool and that I can stick a 2"x1.5" santee in that for a lav without issue. (Any disagreement?)

I've drawn out what I believe to be the existing lines under the slab. I dug back a couple of inches and can see the 2"x1.5" wye that goes off to the shower vent. The purple is the short bit I will add to position the trap. Ideally I would add another wye off of that to run the yellow line over to the wall against the shower for the wetbar sink drain.

We're under the 2012 IPC, and from what I can figure from the DFU calculations, if the yellow line came off downstream of the wye for the shower vent then it would be fine to share the 2" drain line with the shower. With it upstream, would it technically create a wet vent for the shower? Is that allowed?

From a practical standpoint, given that even if the vent to the sink became closed off completely, I can't imagine the flow from the 1.5" line wyed into the 2" for something like 6-8" could suck the shower trap dry. Considering that it's a bar sink that will likely rarely get used, I can't see it not working fine in perpetuity, however that doesn't mean that it will pass inspection.

Given that the wet bar vertical is only a foot away from the opening for the shower drain, I was thinking that I could simply dig under and core a hole to bring it up through; any reason I can't do that as long as I get the slope right? I could rent a concrete saw and break the short channel out with a sledge, or even use a masonry blade on an angle grinder to score it and rent a small demo hammer, but it looks like I can have the hole done for about the same cost as either of those options and it seems like it would be way easier and less dusty.

I'll probably ditch the plan if I need to split off the bar sink downstream of the shower vent, as I really just don't feel like demoing and doing concrete down for what would be a "sort of nice to have" feature, but if I can get away with it for a couple of hours of work... it seems worth it.

Please excuse the messy basement. :D

Any advice is appreciated! I'd be happy to provide more information/pictures if it will help.

-Kris

IMG_20190220_161556-painted.jpgIMG_20190128_141427.jpg IMG_20190220_161556.jpg
 

Gimper

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I was lying in bed last night after posting when a realization hit me like a sack of potatoes. Can I just tie the wetbar drain into the shower vent, and make that a true wet vent? I think I was originally trying to avoid wet venting (probably since I've simply never done it as dry venting has always fit with what I've worked on) and was worried that I might create one, but maybe that's the easiest route by far!

I was actually incorrect in my original post when I said I could see the 2"x1.5" wye for the vent under the slab, as it's a 2" wye and the vent transitions from 2" to 1.5" about 16" above the floor after it turns vertical as can be seen in the prior image. I'm thinking that I can cut it off where it reduces, and as long as I'm tying into it where it's 2" (I can bring it up more if needed), that it would be the same as the lav wet venting on the stool line, which it looks like the IPC allows.

Would the vent need to be 2" for the whole run? That would be an easy change as it transitions back to 2" toward the top right of the image. It seems like 1.5" would be sufficient in the dry portion, and from 912.3 and table 906.1 it looks like I could go 75' at 1.5" (at up to 12 dfus, where I'll only be serving 3).

The trap arm would only be 4' at most, even when adding some length outside of the wall to line up the trap, which as long as I go minimum slope should be well within the 6' max on a 1.5" line. (I'll be sure that the trap weir is not above the vent opening.)

What am I missing? Can I do this? For a bar sink that will rarely be used, I'm certain it would work fine, but there's that pesky inspection to pass. If I can do it without even touching the concrete, I'll be overjoyed!

IMG_20190220_161556-painted-revised.jpg Revised Sink Drain.jpg
 

Stuff

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IPC is that horizontal wet vents are for bathroom groups. Wet bar doesn't count so you can't tie them in like that.
 

Gimper

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Ha, I knew I must have been missing something obvious, but you're right---I read that plenty of times and didn't even think about it. That's a bummer because I'm sure it would work fine, especially for a sink that's hardly used.

Any suggestions on the best course? What about the original layout? I think it creates a went vent, which I suppose is then still not legal. I guess I'd have to tie into the shower line downstream of the wye to the shower vent?

Unfortunately it may just be more trouble than it's worth.

Thanks!
-Kris
 

Mliu

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I don't see a wet vent in your original proposal because you are venting your bar sink separately from the shower.
 
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Stuff

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In the original diagram you join the bar sink drain with the shower drain before its vent. This makes the old vent close to useless as the bar sink would wet vent the shower. So, as mentioned, you would need to tie in after the vent connection.

Put a snake down the drain to see which direction it goes as it might loop to the wall.
 

Stuff

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Also - the 2" to 3" vent transition doesn't look right as it is on the horizontal. Moisture/condensate can collect there.
 

Gimper

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Maybe I go with my revised plan and try to convince the inspector that it's a second lav. :D:rolleyes: It seems a shame that it would be fine if it was, but is not for a bar sink. But my better half has convinced me that it would be extremely rare that we actually use it and it's not likely worth the hassle for something that might help resale a bit down the road.

Incidentally, I had tried searching before posting without finding much, but have subsequently found a decent amount of info by googling "wet bar" "wet vent", the quotes being key, I think. Mostly questions from other basement finishing projects wanting to do approximately the same as me. :oops:

I don't see a wet vent in your original proposal because you are venting your bar sink separately from the shower.
In the original diagram you join the bar sink drain with the shower drain before its vent. This makes the old vent close to useless as the bar sink would wet vent the shower. So, as mentioned, you would need to tie in after the vent connection.

What I was thinking originally is how Stuff is describing it---that the existing vent is almost taken out of the equation and the new (yellow) line becomes the vent, which is wet, and which I now see wouldn't work because it's not part of the bathroom group. Thus I would need to tie in on the other side of the shower vent connection from the shower trap so that they would truly be vented separately, but I can't get in there to do that without concrete work, which I just don't feel like doing.

Put a snake down the drain to see which direction it goes as it might loop to the wall.
Assuming you mean the green line running away from the shower, I'm pretty sure it goes off that direction as the wye definitely points that way, and that points directly to where the main stack comes down from the floor above where there are cleanouts in the yard on the other side of the wall, so I assume the main connection is over that way.

Also - the 2" to 3" vent transition doesn't look right as it is on the horizontal. Moisture/condensate can collect there.
Do you mean the 1.5" to 2" transition in the upper right of the photo? That's a good point. Considering that it passed the original inspection and at this point I think all I'm going to be changing is sticking a santee in the vertical for the lav, I'm not inclined to mess with it unless anybody thinks it's truly going to cause an issue.

Thanks again!
 

Mliu

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Look up Common Vent in the IPC. Specifically, Sections 911.1 and 911.2.
 

Gimper

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Why wouldn't it be?
In reading 911.1-3, it seems to me that it allows/disallows the general situations as shown in the image below, but specifies only a vertical wet vent (as shown in the bottom right), not a horizontal wet vent as my situation would create.
upload_2019-5-23_15-52-27.png
 
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