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Soil stack for new bathroom

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  • Soil stack for new bathroom

    I am putting in a small bathroom on the main floor of our ranch home. The main bath is on the other end of the house and the 4" cast iron drain and soil stack is about 40' away in the basement. I plan on cutting into the pipe in the basement and installing a booted pvc "y" connection and run 4" pvc from the new toilet to the "y". I have plenty of room for the required 1/4" slope per foot. My problem is the new toilet will be on an outside wall and I can't figure out how to run a vent stack up through the roof. I thought about creating a plumbing wall wide enough to accomodate the pipe up to the ceiling, but the roof line comes down right there and there is no attic space in which to work. I'm thinking I have to open up the ceiling enough to work above to get a hole through the roof.
    Any ideas or comments?

  • #2
    All you need for a vent would be a 1 and a half or 2 inch pipe running up through the roof. There's plenty of room between the studs for this pipe.


    • #3
      To meet code at least 2" for the vent! as for the vent location, you can vent a couple of feet down stream of the water closet, this may get you the space you need and give you a inside wall (non-bearing) to run your vent in. What about a sink, wet vented into the same line?


      • #4

        i am doing some research to answer some questions and came across this thread. i am a fairly talented DIY'r nor a plumber. my question is as long as you are tying into an existing drain line in the house, why do you need a new vent? also why do you need a vent for a sink? (also if tying into an existing drain in the basement with a vent?


        • #5
          Vents are installed in the plumbing system to protect the trap seals(trapped water) at the fixture drains. If we lose the trap seals then any of the sewer gases, bacterias, and vermin that are in the sewers will be free to enter our homes thru the drains.
          When the wastewater fills and flows down a drainpipe, it can and will cause a vacuum in the pipe behind itself as it pushes the air out of the pipe in front of itself. This will cause the water in the traps(trap seals) to be syphoned out unless there are vents in the system to allow air back into the drainline to equalize the developed vacuums and pressues. Backpressure is another potential problem that proper venting will negate.
          To install plumbing systems without code compliant venting is not only illegal but downright dumb. It creates a threat to the public health! That would set back the development of public health safeguards in our country a hundred years.
          And I'm not being overly dramatic here. Check out the link I've put at the end of this post.
          I believe too many Americans take too much for granted. They are unaware of all the planning, engineering, legislation, training and hard work that was involved to get to where we are today, with safe and reliable plumbing systems thruout America.

          Check out this link,

          Learn all you can so's you don't do sumthin' harmful!