Need some UPC help on my rough in!

[MarkDevlinn]

Just a suggestion. The shower vent might be in the way of the valve for the shower. If you roll that combo on a 45 and then correct it back to true verticle with a45 your still verticle and can be out of the way of the valve. There are actually a lot of ways to keep the vent from being in the way just keep it in mind.

If I wanted to push it further out of the way, could I roll the wye by 45 then ad a ~1' or 6" pipe out of the wye then 45? or should the 45 be a street directly into the wye.

 

[wwhitney]

Great information and it should not be a problem using 2" for the WC vent stack as the main house is only a 2br 1 bath with only 1 WC. So in total, the entire property currently only has 1 WC in the main house with the addition of 1 more WC in the ADU totaling 2 WC.

Then you're good as long as the existing house complies with UPC 904.1. If for some reason it doesn't, then between the house and the ADU you need (2) 2" roof vents and one more that is at least 1.5". (2) 2" roof vents alone is smaller in area than a 3" roof vent (2*2 + 2*2 = 8 < 9 = 3*3).

If I wanted to push it further out of the way, could I roll the wye by 45 then ad a ~1' or 6" pipe out of the wye then 45? or should the 45 be a street directly into the wye.

If you use a combo, you can roll it 45 and then put as long as a pipe as you like before using a 45 to go to plumb (true vertical). 45 degrees off plumb still counts as vertical for the plumbing codes.

If you are using a wye, and you roll it 45 degrees, then you would need to use a 60 degree bend to go to plumb. So the vent takeoff on a rolled wye is really only 30 degrees above horizontal and technically considered horizontal. In practice probably OK if you hit a 60 degree bend in short order. But using a combo would be better if you have the space.

Cheers, Wayne

 

[Sponsor]

 

[MarkDevlinn]

Well @wwhitney I think I am good! You two have been amazing and I cannot thank you enough! Beer on me if you are ever in So Cal!

 

[MarkDevlinn]

Got it done!

 

[Jeff H Young]

That rule on the vent not needing to be a 3 inch cross section on each building has been awhile now. but 5 w/c on 3 inch that's kinda wild I've done additions even permitted additions that didn't require upsizing the entire drain to the sewer lateral but it was AHJ discretion. I Think on new work 5 w/c should have a 4 inch for the 50 year plan. I'm guessing private use residential

 

[John Gayewski]

PPS: I think CA just adopted the 2021 UPC, which changes the limit of 3 WCs on a 3" drain to 5 WCs, so the previous postscript needs to be changed accordingly.

Chapter 7 Sanitary Drainage: California Plumbing Code 2022 | UpCodes

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Did not know about this change. I kind of thought the 3wc per 3" pipe seemed like a silly rule. If you've ever watched toilets flush inside of a 4" pipe you can see there isn't enough water flowing through them.

I watched a company prep the inside of some pipe to be lined. You could see toilet after toilet flush into 4"pipe and I could hardly believe they were flushing correctly. I think as time goes on the minimum pipe sizes for drainage will decrease in different ways.