Rolling Wyes with Horizontal Wet Vent

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Arca

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I am utilizing a horizontal wet vent for my master bath. I have fixtures meeting the trunk from both directions, and I overestimated the room I have between floor joists. I will now need to roll my wyes in order to fit everything. I have read that wyes can be rolled up to 45 degrees with a wet vent, and have also read that they can be on their back. I would think they can’t be rolled past 45, but would like to confirm with you all. Here is my layout for reference, if necessary. Thanks for the help, everyone.
upload_2021-7-17_19-13-38.jpeg
 

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Arca

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No roll other than 1/4 inch/ft for a shower or tub. A trap arm for a p-trap must stay horizontal until vented, even wet vented. The drain for lav, which is doing the wet venting, can come in from above or rolled 45 is good.

See diagram on page 12 of https://wabo.memberclicks.net/assets/pdfs/Plumbing_Venting_Brochure_2018.pdf

Thanks for the reply and resource. I couldn’t find anything about rolling fixture connections in there, however. Edit: I do see the diagram now…I was looking for specific literature.

You mentioned that the lav connection can be rolled or on its back…what about the toilet? If I can roll the toilet wye on its back, I can move the entire trunk to the right side of the joist bay…and that would solve my problem. Gimme some good news…
 
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Reach4

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You mentioned that the lav connection can be rolled or on its back…what about the toilet? If I can roll the toilet wye on its back, I can move the entire trunk to the right side of the joist bay…and that would solve my problem. Gimme some good news…
There is difference of opinion. Functionally, I think it would be good. I am not a plumber.

https://terrylove.com/forums/index.php?threads/is-this-wet-vent-of-a-toilet-ok-theoretical.89201/ has discussions.

Note that within 45 degrees of plumb is considered vertical.
 

wwhitney

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No roll other than 1/4 inch/ft for a shower or tub. A trap arm for a p-trap must stay horizontal until vented, even wet vented.
Mostly agree, the above is practically true.

The operative rule is the trap weir rule, which says that the vent connection has to be at a higher elevation than the trap weir. For a horizontal wet vent, where the fixture connects to the branch drain via the branch inlet of a wye, that means that the bottom of the inside of the trap elbow outlet has to be below the top of the inside of the straight barrel of the wye.

So for a very short trap arm, you could probably roll the wye up a little and connect to a 2% sloped trap arm with one or two 22.5 degree elbows while still complying with the trap weir rule. E.g. if the horizontal length of a 2" shower trap arm is only 3', but for some reason such as an obstacle you need more than 3/4" of fall between the wye and trap, you may be able to add another 1" of fall at the wye that way.

Cheers, Wayne
 

Arca

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There is difference of opinion. Functionally, I think it would be good. I am not a plumber.

https://terrylove.com/forums/index.php?threads/is-this-wet-vent-of-a-toilet-ok-theoretical.89201/ has discussions.

Note that within 45 degrees of plumb is considered vertical.
Thanks again! I am thinking functionally it’s fine as the wet vent end at the WC wye, but I wanna stick to code!

I am thinking I am going to roll the lav wye on its back, move the trunk to the right of the joist bay, and get cute with the WC as long as it’s permitted. I’m thinking of the closet flange pointing to the left of the bay, 60 or 45 it in the direction of flow, then have it enter the wye horizontally from the left. Sound wonky?
 

Reach4

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Thanks again! I am thinking functionally it’s fine as the wet vent end at the WC wye, but I wanna stick to code!

I am thinking I am going to roll the lav wye on its back, move the trunk to the right of the joist bay, and get cute with the WC as long as it’s permitted. I’m thinking of the closet flange pointing to the left of the bay, 60 or 45 it in the direction of flow, then have it enter the wye horizontally from the left. Sound wonky?
I am not going to make that assessment, but like crazy, sick, ridiculous etc, there is unfortunately there are opposing uses of "wonky". https://www.merriam-webster.com/dictionary/wonky :confused:
 

Arca

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I am not going to make that assessment, but like crazy, sick, ridiculous etc, there is unfortunately there are opposing uses of "wonky". https://www.merriam-webster.com/dictionary/wonky :confused:
I learn something new everyday on this forum, lol.

I’m pretty sure I was overthinking this. I went back and roughed out some more…I think I can just push my wye 45s for the shower and tub into the joist a little bit (larger hole but I’m within the rules) and that should give me my clearance on the other side for my WC and lav. It’ll be some tedious measures and glues, but I think I’ll be ok.

Thanks again for all the help.
 
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