Water Closet Directly Over Stack

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Todd_M_S

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Good Morning All,

I searched and found a few threads on placing WC directly over a vertical stack, but nothing exactly like what I’m trying to do.

Please see the attached drawing.

upload_2019-3-15_11-5-46.png


So this is new construction in Massachusetts, and nothing has been run yet.

I have a WC flange directly over a 2x6 (non-bearing) wall. Soil stack into main 3” vent runs up through that wall. The top of the stack becomes the main 3” vent, runs horizontal about 60” then turns vertical and continues through the roof.

My plumber is spectacle about running the toiler drain as show, in large part because it’s not “typical” done that way. He believes there should be a 90 under the closet flange with a vent for the toilet in a short horizontal run before it hits the stack. I agree with him that that is certainly the most common approach but it does considerably impact the existing framing.

I'm think why would you ever want to add a horizontal run (anywhere!) if you can just drop it vertical; assuming the toilet is vented properly as shown and that short "wet" vented section is ok.

So is the drawing attached a legit approach?

Would appreciate all comments. Thank you in advance for your advice.

Todd S
 

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Reach4

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This is Terry's bathroom group picture. I am not a plumber. I think your drawing is superior as long as you increase the vent and drain from the bathroom sink to 2 inch. Maybe that increase is not even needed due to your big honking horizontal vent.



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Todd_M_S

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I normally put a "Y" in the riser to the toilet with a 2" vent out of it.

HJ,

That would be PERFECTO! Simple, neat, and all fits well.
I assume your thinking something like this:

upload_2019-3-15_13-4-24.png


I believe MA code allows me 1-1/2 on that 3" drain (only 4 fixture units), and Im under the 42' length limit...

I do appreciate your input!

Regards,

Todd S.
 

Todd_M_S

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This is Terry's bathroom group picture. I am not a plumber. I think your drawing is superior as long as you increase the vent and drain from the bathroom sink to 2 inch. Maybe that increase is not even needed due to your big honking horizontal vent.

Hey Reach,

Thank you for the skretch and the info.

I'm a bit different than than the sketch as my bathtub and sink are both independently vented at the fixture. I was hoping that the "big honking" 3" vent with the short vertical wet section was good enough to vent the toilet.

HJ presented a pretty easy fix. Just trying to present ideas to my plumbers as the MA code doesn't really have any "figures" or "diagrams" for this particular case.

Thank for looking!

Todd S.
 

Todd_M_S

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The lav and tub will wet vent if run in 2".

Nice,
Q1: So just up-size the drain @ vent on the lav & tub and I'm good to go as originally pictured?

Thank You for the advice!

Regards Todd S.
 

Stuff

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Is 5' of horizontal 3" venting (main stack?) allowed there? Instead just cap that off and increase that new 1 1/2" proposed vent to a 3"
 
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