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Thread: Adding a second floor addition

  1. #1

    Default Adding a second floor addition

    I'm adding a second floor addition to my 1 story home.

    The existing main floor has only a bath, toilet, and 2 sinks connected to the main 4" stack. All fixtures are very close to the stack, I can tell for sure that the toilet and bath are not vented. I don't think the sinks are either.

    Isn't it true that when a fixture is close enough to the stack it doesn't need a separate vent?

    If this is the case, could I then use the existing 4" stack as the drain for the second floor? or Would I still have to go into the basement and Y off a new stack for the second floor addition?

    I want to plan this carefully.

  2. #2
    Forum Admin, Expert Plumber Terry's Avatar
    Join Date
    Aug 2004
    Bothell, Washington
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    You do need to provide a waste line or two to the upstairs bathroom.
    If I were you, I would get a permit and make sure an inspector sees the work.

    There are a few reasons for the 6000-8000 hours required working in the field before a plumber can get licensed to do this type of work.
    Last edited by Terry; 06-06-2006 at 09:12 AM.

  3. #3


    thanks for the reply.

    I will of course get a permit and have the work inspected. I am just now in the early stages of planning this project and need to plan around things of this nature.

  4. #4
    Moderator & Master Plumber hj's Avatar
    Join Date
    Aug 2004
    Cave Creek, Arizona

    Default vent

    That pipe is the vent for the existing plumbing, and therefore it cannot be used as a drain for the second floor, unless major revisions are made to the existing first floor drainage piping.


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