Adding bathroom on second floor, questions

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by JohnBinTN, Jan 20, 2012.

  1. JohnBinTN

    JohnBinTN New Member

    Jan 20, 2012
    Munford, TN
    Hi everyone. The subject line above should have been preceded by "maybe", I think. :) I'm just trying to get an idea of what will need to be done (probably by a "real" plumber for some/most of it).

    What we've laid out would situate the proposed bathroom almost directly above a 1st floor bathroom. There is attic space behind where the tub would go, as well as behind where the toilet will sit. Right behind the wall where the toilet will go is the main 3" (or 4"?) vent pipe through the roof, as well as another 1-1/2" vent pipe that the water heater and furnace drain to. On the exterior of the house, almost straight down from the location of the large vent is a (I think) clean-out at the foundation (two story house on a slab).

    My main question is what will be involved with plumbing the drain under these conditions? Will this require cutting into the slab to tie into the existing toilet drain line? If it makes any difference at all, we have a septic system, and the main drain to the tank is in the front of the house, while the existing 1st floor and proposed 2nd floor bathroom is along the rear wall.

    I'm almost scared to get someone in for an estimate, as we only have one child (so would rather not have to sell our first and only born to finance the project).

    Replies greatly appreciated (even if it's just something I can show to my wife that might dissuade her from this project!)


    John in TN
  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    Here is a nice link to Bert Polk's plumbing tips

    The vent remains a vent all the way through the roof.
    You will need to run waste lines down past the first floor bathroom, and tie in downstream.
    Vents for the lower bathroom will need to go through the roof, or at least tie in at 42" above the second floor.

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