DWV Setup for new Bathroom

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Chris W.

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Hello! New poster here!

I am living in a 60s house that has an addition on it (already long done). I am moving the old small bathroom to a space in the addition and making the old bathroom a closet. In that room, I will have a shower, lav, and closet in that order (left to right). I've attached a picture of what I am working with. This is all above a crawlspace. It's worth noting that all DWV piping is BELOW the joists, and no holes are created in the joists for any DVW piping. The closet piping is a little deceiving because of my artistry limitations. The whole closet bit occurs between a pair of joists, I just drew it going right to outline what is happening between the joists.



I have 3 questions regarding this setup:
  1. I am, of course, venting through the roof at the lav, as usual with a 2" pipe. But, since the lav is in the middle of the shower and the toilet, do I need to add an additional vent on either side of the line? I am thinking I probably should add one on the stack side where marked on the image. Could tie that one and the lav vent together in the attic.
  2. The original house has a basement and the addition is in a crawl space. That being said, to get the waste to the main stack, I have to drill through the concrete wall between the crawl space and the basement, then run the pipe to the main stack which is about 15' away. I will run it along the wall to keep it out of the way. Since the house is a 60s house, the main stack is the old iron pipe setup - meaning there isn't a good way to tie my new lines in. So my question is, is it kosher to use the cleanout at the bottom of the stack to tie in, provided that the very very first thing I do is add a Wye with a cleanout on the wye'd part?
  3. Aside from the first 2 questions, are there any things in this setup that stand out as wrong, or are there any suggestions on how I can improve this?

Thank you in advance!!!
Chris
 

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wwhitney

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1) No additional vent needed. The lav wet vents the shower and wet vents the WC.

For the record, what you have labeled "wet vent" is actually just the shower trap arm and is not involved in venting. That shower trap arm needs to be sloped at least 1/4" per foot, but can fall no more than 2" between the trap and the wye where the shower connects to the lav (and is thereby wet vented by the lav). The actual wet vent is from the fitting where the WC joins the branch drain upstream to the san-tee where the lav is dry vented.

2) Beyond my experience, but my first thought is that cutting into the cast iron is the preferred solution.

3) 3" 90 (LS) with 2" inlet is not a term I'm familiar with. You could use a 3" combo (wye plus 45) with a 3x2 bushing in the straight inlet. A low heel 90 is not appropriate as it is not long sweep.

As to the WC, I'm not following how you drew it, as you warned. If it's not directly over the 3" branch drain, you'd typically use a closet bend with outlet pointed perpendicular to the 3" branch drain at the correct elevation, then use a horizontal combo to join it to the 3" branch drain. Or if it's not over the branch drain but is close, you could turn your closet bend outle t45 degrees and have the WC fixture drain directly enter a 3" horizontal wye.

And if the WC is directly over the 3" branch drain, then there is some debate as to whether it can enter the branch drain via an upright combo, or if you need to move the branch drain over so that the WC fixture drain joins the branch drain with a horizontal fitting.

Cheers, Wayne
 

Chris W.

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Wayne, thank you very much for the prompt response and the detailed answers. I appreciate the help.
For point 2, I will do some more research and check with the inspector...cutting the iron doesn't sound too much fun :)

For point 3, I have some flexibility to the setup. The WC is the only thing between the lav and the 3" to the main stack, so I can pretty much set this up any way. If I am understanding you correctly, the attached drawing would be correct?
 

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wwhitney

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On (2), a picture of what you are dealing with could help.

One (3), assuming that's a plan view drawing (except for how you rendered the closet bend), i.e. both dimensions are horizontal, sure. But my comment was that you can eliminate the 45 degree bend by just turning the closet bend outlet to point at the branch drain at a 45 degree angle, and then moving the wye so it lines up.

Cheers, Wayne
 

Mr tee

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I assume the cleanout is a tee with threads for the plug. If so, a connection there would not be approved if it is a cleanout tee (most likely) because the branch has no sweep.
 

Chris W.

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This here is what I'm dealing with. The branch from the bathroom comes in far too low to attach to the 4 way on top. It appears not to have a sweep. :/
 

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wwhitney

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The branch from the bathroom comes in far too low to attach to the 4 way on top.
Really? How long is the horizontal pipe run from the shower trap to this stack? And what is the vertical distance from the bottom of the joists to the uppermost point on the fatter copper collar next to the cast-iron double wye branch inlet hub?

It appears not to have a sweep. :/
Then as Mr. tee stated it's not suitable for connecting a drain.

Cheers, Wayne
 

Chris W.

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The uppermost 4 way pipes are butted against the bottom of the joists. The lower wye is roughly 12 inches below.

The shower trap to this soil stack is about 38 feet, but it would need to pass that main return duct you see in the picture as well.
 

wwhitney

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Then I don't see any way to avoid cutting into the cast iron stack. If you do, make sure the portion above your cuts is very well supported--if it goes through the roof, there's a lot of weight above.

Cheers, Wayne
 

Chris W.

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That's what I was afraid of....For this part I'm thinking I'll bring in a pro.... I'm not comfortable with cutting this CI stack. I can have them add my fitting and cap it off until I get there.

Thank you very much for your help with this! I appreciate this forum and the time you all give to help people like me out.
 
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