Basement shower drain, what are my options

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Bonesteel

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I need to tie in a shower and toilet here for a basement bathroom, my original plan was to tee into soil stack, however the horizontal line is too high for my plan, so I need a different approach.
From what I gather, I could put the toilet upstream of the stack easily enough, but what do I do about shower. It appears I can't tie into toilet trap arm. And to tie in downstream of stack it seems id have to go at least 40 inches(10xD) which would lead to tons of concrete removal.
Could I tie in directly to bottom of stack with a fitting such as this https://www.winsupplyinc.com/charlotte-pipe/_/A-03940564
Any other options I might be overlooking. Really don't want to cut out another 4 ft trench just to extend shower arm by another 40 inches

20220814_143738.jpg
 
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Bonesteel

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Would something like this be ok? Assuming the broomstick is 2" pipe to shower drain.
Would I need to vent shower separately, or is it ok assuming proper slope and total fall of less than 2"

20220814_192932.jpg
 

wwhitney

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Your shower is going to need a wet or dry vent regardless, before it joins the WC. So how do you plan to vent the shower? The stack carrying drainage from above is not a vent. If you have a lav that is dry vented (through the roof, or via an AAV), and the lav drain joins the shower upstream of your picture, then that lav can wet vent both the shower and WC.

If you figure out the shower venting, so that the WC is properly wet vented, then the above configuration is not allowed in a 1 or 2 family residence in MI. That's because MI has adopted the IRC including the plumbing code sections, and part of P3108.1 on wet venting says "Each fixture drain shall connect horizontally to the horizontal branch . . ."


But the fix is not too hard, you just take that wye that current upright and roll it over to horizontal (both inlets at 2%, one shower, one WC). Since you don't want to move the WC, that means you have to move the wye away from the wall, which means that the WC/shower drain joins the horizontal building drain downstream of the stack with another wye, rather than the combo you have.

Cheers, Wayne
 

John Gayewski

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Technically legal assuming the vertical pipe is a vent and not a drain, but not optimal.

Edit : after looking at Wayne's post my suspicion that the toilet dropping in from the top is more than not optimal it's illegal.
 

Bonesteel

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Your shower is going to need a wet or dry vent regardless, before it joins the WC. So how do you plan to vent the shower? The stack carrying drainage from above is not a vent. If you have a lav that is dry vented (through the roof, or via an AAV), and the lav drain joins the shower upstream of your picture, then that lav can wet vent both the shower and WC.

If you figure out the shower venting, so that the WC is properly wet vented, then the above configuration is not allowed in a 1 or 2 family residence in MI. That's because MI has adopted the IRC including the plumbing code sections, and part of P3108.1 on wet venting says "Each fixture drain shall connect horizontally to the horizontal branch . . ."


But the fix is not too hard, you just take that wye that current upright and roll it over to horizontal (both inlets at 2%, one shower, one WC). Since you don't want to move the WC, that means you have to move the wye away from the wall, which means that the WC/shower drain joins the horizontal building drain downstream of the stack with another wye, rather than the combo you have.

Cheers, Wayne
I think I have enough room to just turn the wye still upstream of soil stack, id rather not go downstream, as, if I read correctly that fitting would have to be minimum 40 inches downstream which would require removing tons of concrete. Venting could be an issue, I was under the impression the stack could be used as a vent since there are no offsets, my plan was to just run the lav into stack with a santee as well, but perhaps that is not allowed. There is a plumbing wall directly above stack perpindicular to the trench I cut, so I can run up to the next story and across to stack above the main floor lav to vent basement lav, but that doesnt solve venting the shower. I could build the partition wall 2x6 (wall parallel to concrete wall in pics) and vent through there, but I believe that would require the drain to run over to that wall, and then back to other wall for w/c, for which I probably dont have enough drop to maintain slope. I do have 8" of dead space between shower and concrete wall. I could cram an aav in there if that would suffice(its accessable from adjoining furnace room) but ai dont think I can find a path to roof from there.
 

wwhitney

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And to tie in downstream of stack it seems id have to go at least 40 inches(10xD) which would lead to tons of concrete removal.

There are some requirements of that nature, but I'm not aware of one that applies residentially (though I've not looked it up). Do you have a reference?

Easiest way to vent the lav would be to use an AAV under the sink (accessible, at least 4" above the trap arm), and then use the lav drain to wet vent the shower and WC. The lav drain would have to join the WC or shower first; then the combined drain would join the other bathroom fixture; and only then the bathroom branch would join the stack or building drain.

Cheers, Wayne
 

Bonesteel

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There are some requirements of that nature, but I'm not aware of one that applies residentially (though I've not looked it up). Do you have a reference?

Easiest way to vent the lav would be to use an AAV under the sink (accessible, at least 4" above the trap arm), and then use the lav drain to wet vent the shower and WC. The lav drain would have to join the WC or shower first; then the combined drain would join the other bathroom fixture; and only then the bathroom branch would join the stack or building drain.

Cheers, Wayne
Ok that should solve my problems, I can easily run a dry vent from lav to main vent stack, shouldnt be hard to tie drain in before the shower and wc. One last question though. Would a double wye at 2° with the w/c entering middle, shower entering one side and vent entering other side with an offset reducer and a street 45 work?. Would the offset reducer and street 45 count as coming in above centerline and running vertical?

As for the 10xd thing it just came up when i googled tying into bottom of stack, no idea to whom it applies.

704.3 Connections to offsets and bases of stacks.

Horizontal branches shall connect to the bases of stacks at a point located not less than 10 times the diameter of the drainage stack downstream from the stack. Except as prohibited by Section 711.2, horizontal branches shall connect to horizontal stack offsets at a point located not less than 10 times the diameter of the drainage stack downstream from the upper stack.
 

wwhitney

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Thanks for the reference to IPC 704.3, which is here:


But as you are subject to the IRC, the corresponding code section is here:


I don't see how you can avoid the 10 diameter horizontal distance, the connection shown in your last picture I would consider a connection at the base of the stack and in violation of P3005.5. Perhaps someone more familiar with this requirement will comment.

As to a horizontal double wye, it should be avoided if at all possible. Separate wyes allow you to set the pitch of the side branches independently. While with a double wye, since it is a flat fitting, the best to you can do is get the two side branches level with each other. Then the side branches only end up with 70% of the slope of the barrel.

Cheers, Wayne
 
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