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Thread: Adding bathroom in large loft style attic. Vent pipe needed?

  1. #1

    Smile Adding bathroom in large loft style attic. Vent pipe needed?

    Hello All,

    I have a three story building that currently has a toliet on the 1st and 2nd stories. There is a large attic that I'm going to add a bathroom to.

    Both toliets on the 1st and second story are hooked up to the same 4" poopie stack, and I plan to ti the 3rd story tolit into the poopie stack also.

    My question is about what I have to do, and how to do it.

    I am ok with cutting the cast iron stack, adding a 45 degree 4" booted T-pipe off the main stack, and add the flange for the added toliet in the position where I want the toliet.

    Is there anything else that I have to do with the drain for the toliet? i.e. do I need to do anything with vents, etc. to prevent water from flying out of the toliets on the 1st or 2nd floor or anything?


    Please help.

  2. #2

    Default

    Hello,

    Unfortunately, you cannot do what you are planning on doing. Unless, the second floor toilet is vented separately from the stack, which it won't be.
    You will have to run a separate drain line from the third floor toilet into the basement. Or, at least below the second floor toilet. But, really you need a plumber to come and look because we cannot see how the plumbing is run.

  3. #3
    DIY Senior Member taysan's Avatar
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    Default

    Sounds like it would be easier to vent the 2nd floor toilet separately through the roof given the to-be 3rd floor is an attic right now.

    Pics / diagrams!

  4. #4

    Question OK - See the diagram.

    (Wow.. you guys are quick!)
    Attached Images Attached Images  

  5. #5

    Default More info...

    So that there is no confusion, both the 1st and 2nd story toilets are on the same main 4" stack, both set up in the same configuration. thanks again.

  6. #6

    Default My Plan....

    Ok, so I plan to do the toilet on the 3rd floor in the same configuration as the ones on the 1st and 2nd floors... will it work? If not, what will happen, and why?

    I appreciate all the help.

  7. #7
    Forum Admin, Expert Plumber Terry's Avatar
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    Default


    You can't run waste down a vent.
    Doing so will siphon out all the traps below, and most of the time, they fittings on vents may not even be close to what you would need for a waste line.

  8. #8
    Plumber Cass's Avatar
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    Default

    Like Cookie said, you really do need a plumber to come out and look at what you have and what you want to do.

    If the plumbing is as you describe it is nothing I have ever seen and is wrong.

  9. #9
    Plumber jimbo's Avatar
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    Default

    In your drawing, the large pipe rising from the second floor towards the attic is presently the vent for the toilets on 1st and 2nd floor. If you turn that pipe into a soil pipe, by putting a toilet on the 3rd floor, that pipe can no longer serve as a vent. Vent pipes from the first and second floor must rise separately and connect back to that large pipe 6" above the highest fixture on the 3rd floor.

  10. #10
    Moderator & Master Plumber hj's Avatar
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    Default stack

    How the first floor toilet is connected to the stack is important to the discussion, since it would normally have an offset fitting with the vent as part of it. The second floor would not have the same fitting, although it could look similar outwardly. If so, then you would have to provide a vent for the second floor toilet, not easily done, and disconnect the vent connection from the second floor and reattach it at the same relative point on the third floor. You are not looking at a DIY job, and even an experienced plumber might be challenged depending on the situation.

  11. #11

    Default Spent more time looking at actual plumbing... Here it is.

    Here is an updated drawing of the actual plumbing.
    Attached Images Attached Images  

  12. #12

    Default Can I do it this way?

    Can I do it this way?
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  13. #13

    Default Would this work?

    Ok - how about this setup....
    Attached Images Attached Images  

  14. #14

    Default Or Do I Need To Do Lots O Work?

    Or Do I Need To Do Lots Of Work?????
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  15. #15
    Forum Admin, Expert Plumber Terry's Avatar
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    As long as you are dumping waste into a pipe, it's a waste stack, and not usable as a vent.

    You can tee off as many times as you like, as long as you are adding a vent each time,
    Those vents can tie together at six inches above the flood level of the fixtures served.
    And then that vent stack can go through the roof on it's own, or tie in above the highest fixture in the home on the top floor.

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