New Construction - Multifamily

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Matthew Shultz

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Hey all, I'm a plumbing designer working in Texas - I have designed my fair share of apartments. Does anyone work as a plumbing contractor in the state, specifically with multifamily jobs? I have a few dissenting opinions in the office on the best way to route a typical bathroom.

I've done HWV for 2x lavs, WC, and tub/shr, standalone single stacks for bt/shr, standalone single stacks for lavs, etc. What is most common? Is there a 'best practice' and 'owner is a tightwad' routing?

The hardest part for me to get down is what happens in the field. Modern multifamily with truss construction is relatively simple, but a completely different ball game than traditional residential. I'm curious to get input from anyone with experience on these larger builds.

HWV example.png


(I attached a sample bathroom HWV riser, I've made hundreds of these damn things)

Thanks!
 

James Henry

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Your drawing is not really typical of how it would be done, the connection to the stack is unusual. you need to realize that their are five different ways to plumb any bathroom configuration. when designing a bathroom plumbing layout you need a floor plan with the location of the fixtures, wall dimensions, floor construction and where your going to exit with the main drain, it also helps a lot if you know your local plumbing code.
 

Jeff H Young

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I guess your IPC? but I'm UPC , I've never seen a 1 1/4 trap arm ? Minimum might allow an 1 1/2 wet vent but Id run 2 in the joist bay to santee above floor
A lot of our multi family is cast iron and you never run smaller than 2 inch any way. but just a general workmanship I'd want 2 inch at least to the santee above the floor.
Sometimes besides the code its good to know local practice If I had some experience in an IPC state I might feel a little different on the sizing.
otherwise it looks good
 

Matthew Shultz

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Everything that I've looked at on site down here has been PVC - some owners even want us to spec foam core... I have a nice sitdown with them and ask if they like to pay for concrete saw and backhoe rentals lol. Cast iron I could see being used down here in the sovent systems for taller buildings or in hotels etc. where noise more of a concern. Jeff you're right on that 2" to san-tee, I sized that wrong.
 

Reach4

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(I attached a sample bathroom HWV riser, I've made hundreds of these damn things)
https://www.iccsafe.org/wp-content/uploads/20-18927_GR_2021_Plumbing_Venting_Brochure.pdf page 12 shows 2-inch below the lavatory double fixture fitting.

Everything that I've looked at on site down here has been PVC - some owners even want us to spec foam core...
They want to specify foam core vs solid PVC? Seems odd... not that foam core is is not adequate. Maybe you mean vs cast iron.

And as James says, it would not be common to have a separate vent on the right of your drawing. Now if there is a standpipe for the roof AC evaporator drain in that path, then that makes sense.

You will also have to get the total venting too based on all of the stuff.
 

Matthew Shultz

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https://www.iccsafe.org/wp-content/uploads/20-18927_GR_2021_Plumbing_Venting_Brochure.pdf page 12 shows 2-inch below the lavatory double fixture fitting.

They want to specify foam core vs solid PVC? Seems odd... not that foam core is is not adequate. Maybe you mean vs cast iron.

And as James says, it would not be common to have a separate vent on the right of your drawing. Now if there is a standpipe for the roof AC evaporator drain in that path, then that makes sense.

You will also have to get the total venting too based on all of the stuff.

That's one of my favorite reference books! Yeah I changed that out to a 2". Yes one of the owner groups I work with says the price/LF of foam core PVC vs solid PVC makes it worth using. Only above ground though, they have a tendency to get ripped to shreds with a drill cleanout. I always recommend solid core PVC over foam core for that reason... even if the owners intend to sell the property 5 years after it's built.

There's a bit of confusion with the stack vent off on the right - yeah the 1F configurations don't need it but the multi level ones do, so I've just left it on. With engineering drawings we typically show the connections at top and bottom of stacks, then use 3D iso riser diagrams to depict what needs to happen in the middle. You wouldn't be able to read the floor plans if all this was detailed on every stack. See below for a 3F HWV linear full bath group with double vanity:

HWV example 2.png
 

Jeff H Young

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Everything that I've looked at on site down here has been PVC - some owners even want us to spec foam core... I have a nice sitdown with them and ask if they like to pay for concrete saw and backhoe rentals lol. Cast iron I could see being used down here in the sovent systems for taller buildings or in hotels etc. where noise more of a concern. Jeff you're right on that 2" to san-tee, I sized that wrong.
we can't go no more than 3 floors with plastic. I've done some projects up to 50 houses and condos maybe 10 to a building on my own with a partner but mostly field work and custom home so not much designing on bigger jobs. then I spent last 17 years in commercial industrial, and hospital, along with fitting in my little service , repair. love this trade ! and pipefitting for welders too, fabrication.
Good luck with project Matt!
 

Matthew Shultz

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we can't go no more than 3 floors with plastic. I've done some projects up to 50 houses and condos maybe 10 to a building on my own with a partner but mostly field work and custom home so not much designing on bigger jobs. then I spent last 17 years in commercial industrial, and hospital, along with fitting in my little service , repair. love this trade ! and pipefitting for welders too, fabrication.
Good luck with project Matt!
3 floors or less with PVC - that's a new one for me. I'll have to look into that a bit more as Houston and Austin both use UPC vs the rest of the state is IPC. Thanks, and nice to meet you!
 

wwhitney

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Jeff H Young

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I would expect a restriction like that to show up in CPC 701.2, but I don't see it. Although I guess apartment buildings are subject to the "HCD 1" restrictions (not sure), which 701.2(2)(a) restricts to 2 stories. In which case that would be a California amendment to the UPC.

https://up.codes/viewer/california/ca-plumbing-code-2019/chapter/7/sanitary-drainage#701.2

Cheers, Wayne
Thanks Wayne don't want to lead anyone astray! I think it applied to over 2 stories and not to over 3 story as I said. I have not been able to confirm that this requirement still stands or how it actually came about. I have just read about San Diego taking out of their code some years ago siting that it caused undue expense with little or no gain in fire sprinklered buildings.
So I would try to confirm with building department if I was building above 2 floors in California.
but I stop short of saying you cant do so , and haven't been involved in such projects since early 2000's sorry if I misled
 
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