Wet venting tub/shower

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Dostoy320, Nov 16, 2009.

  1. Dostoy320

    Dostoy320 New Member

    Messages:
    13
    Location:
    Minneapolis
    If I have a run of 3' from the tub drain to the main stack, I can wet vent that with a 1 1/2" pipe, correct? Am I reading the code chart correctly?

    edit: Turns out the distances are really close to code limits. Where does one measure for the 3' 6" critical distance? Start at the cast iron stack's hub flange, or center of the stack or what? Measure all the way to the tub drain or one side or the other of the P trap or what?

    From the flange on the side of the stack to the tub's actual drain is about 6' 7".

    Thanks,
    adam
    Last edited: Nov 16, 2009
  2. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Ok so let me get this straight.....

    You have a "main stack" that I am assuming is 3-4". And you want to run a tub drain from roughly 3' away and have it be wet vented through the main stack?

    A picture would really help....

    If I am understanding you correctly then what you are thinking of doing is most likely not going to work code wise. Mainly because there is likely to be a toilet upstream of the tub connection and you are never allowed to wet vent past a toilet.
  3. Dostoy320

    Dostoy320 New Member

    Messages:
    13
    Location:
    Minneapolis
    Thanks for the reply.

    Yes, I want to wet vent into the stack. The stack is old cast iron - not sure of the diameter but I'd say at least 4". The toilet actually connects to the stack at the exact same height as the tub drain.

    This is a main floor remodel, and originally the tub connected at this same spot, but it also had a vent pipe connected a few feet up the stack (visible in this photo and shown in red in my awesome diagram).

    [​IMG]

    The toilet is just off the left side of the photo frame here. You can see the shadow from the flange.

    I thought that I could get by with a wet vent, and maybe that would allow me to use the stack above for waste if I ever wanted to put a second bathroom in above this one. But I guess if I can't have a toilet upstream of a wet vent, then I might as well go back to the original vent or run a new vent all the way to the second story?

    Attached Files:

  4. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    Well then with them being symmetrically connected like that you are actually ok in doing what you're doing.

    But you MUST make sure that the toilet and the tub tie into the wet vent through the same fitting (IE double wye).
  5. dlarrivee

    dlarrivee New Member

    Messages:
    1,172
    Location:
    Canada
    Correct me if I'm wrong, but can he not just use one of these (whatever is cast compatible), without that extra "red" vent (which I believe is called a re-vent, not a wet vent)...

    If one drained above the other, it wouldn't be acceptable without more vent piping...

    [​IMG]
  6. Doherty Plumbing

    Doherty Plumbing Journeyman & Gas Fitter

    Messages:
    810
    Location:
    Penticton, BC
    [Edit] Oops read what you wrote wrong.

    Yes that's what I was describing to him. A double wye making them symmetrically connected. I should of pointed out he didn't need the red vent.
    Last edited: Nov 16, 2009
  7. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    27,255
    Location:
    Cave Creek, Arizona
    vent

    What he has is proper for HIS drain system. He cannot convert the main vent stack to a sewer/toilet drain stack by putting a vent on the tub drain. To do that would require a complete revision of the drain system, which might be more expensive and difficult than just running a new sewer pipe to the second floor.
  8. Dostoy320

    Dostoy320 New Member

    Messages:
    13
    Location:
    Minneapolis
    The tub drain and toilet pipe enter the stack at right angles to each other. If you're facing the wall, the toilet drain goes straight into the face of stack, and the tub drain enters from the right side.

    The photo dlarrivee posted clearly illustrates why you'd want the fixtures sharing the same fitting, as the openings direct flow away from each other, but this wouldn't be an easy conversion for me. If I put the vent pipe back where it originally was (the one in the photo) will I be OK?

    Is the tub drain more vulnerable to flow from the toilet as a wet vent? Is this even considered a wet vent if the fixtures connect at the same point?

    Thanks for all your help guys. If you're ever in Minneapolis, I owe you a beer.

    edit: and trying to get my terms correct - this thick cast iron pipe is the "soil stack" correct?
    Last edited: Nov 17, 2009
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