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Thread: Adding a full bath to basement

  1. #1

    Question Adding a full bath to basement

    This is my first use of this forum. Your help is greatly apprecited. Our house is 11 ys old and I am not the original owner. There is a room unfinished in the basement that can easily be a full bathroom. However, I am confused on how it was roughed-in. It has a concrete floor. From the floor there is a 4 3/4" OD pipe 16 3/4" from side wall and 14 7/8" from back wall. Along the back wall there is a 2 1/2" OD pipe 2 1/2" from the back wall that extends up from the floor 32" and is centered 48" from the side walls. Both pipes are caped. There is ample room for bath tub along the wall.

    | O |
    | 2 1/2" |
    | Area pipe |
    | for O |
    | tub 4 3/4"pipe |
    | |
    | |
    | |

    Questions are: with no drain for bath tub, what would be needed to make it a full bath? What about vent pipes? There is no vent pipes in this room or immediately above it. The wall to the right is the front of the house. Gettign water into this room is not a problem.
    Last edited by handyman7; 09-23-2007 at 07:39 PM. Reason: attached photo

  2. #2
    Master Plumber Dunbar Plumbing's Avatar
    Join Date
    Apr 2005
    Northern Kentucky/Greater Cincinnati Area


    Piping for this bathroom is measured by inside diameter, not outside but we are pretty sure of the sizes you're dealing with.

    Take pictures if you can; this will help you help us answer your questions.

    The bigger pipe mentioned is the one for the toilet; rough from center should be 11-13" off the rough-in wall. AS Cadet/Kohler/Toto's are notorious now for being off the wall on a 12" rough.

    One of those pipes directly behind the toilet probably serves as the vent....the other the vent for the tub or catching the lav.
    Last edited by Dunbar Plumbing; 09-22-2007 at 07:48 PM.
    Read what the end of this sentence means.

  3. #3
    DIY scratch-pad engineer leejosepho's Avatar
    Join Date
    Nov 2006
    200 miles south of Little Rock


    Quote Originally Posted by handyman7
    with no drain for bath tub, what would be needed to make it a full bath?
    The floor would have to be cut to install a drain line connected either to an existing line or a sump. Do you have a private septic system or are you hooked to a municipal system? I ask because a sump might only be needed for a private system with a discharge line above the basement floor.

    Quote Originally Posted by handyman7
    What about vent pipes?
    A sump with an ejector pump would need venting all the way through the roof, and you would need a vent for the bathroom fixtures. If another bath or your kitchen is nearby above, you might be able to make use of a vent line already there.

    Are the walls in this basement room still open or covered? If they are covered, maybe there is already a vent line hiding inside.

  4. #4
    Commercial Plumber markts30's Avatar
    Join Date
    Sep 2006
    Phoenix, AZ


    OK - so the walls are still bare concrete...
    You have a WC and lav rough in with the lav drain probably the vent for the WC...
    Easy enough to cut the floor and tie into the 3" (likely) drain pipe below grade to put in a shower/tub drain...
    The venting is going to be the issue...
    Bring the shower vent up and tie the WC/lav vent into it then either go up into the attic and tie to an existing VTR or re-vent them with another vent in the first floor (min of 6" above the highest fixture's flood rim the main floor's vent serves).

  5. #5


    Have a municipal system.

  6. #6


    Basement walls are not covered showing the concrete block.


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