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Thread: Adding bathroom in basement - Venting question

  1. #1
    DIY Junior Member red22769's Avatar
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    Default Adding bathroom in basement - Venting question

    ok, this may be long and drawn out, but I have nowhere else to turn but the pros in these forums! I've been reading the forums here for about 3 weeks searching for answers, but feel the need to post my situation to hopefully get a solution.

    I have a home that is 13 years old, and I want to finish the basement complete with a bathroom.

    Before I begin breaking out the concrete floor to rough in the shower, sink and toilet plumbing, I want to be sure I have my ducks in a row.

    The following pictures show a mail drain stack in the vacinity of where I plan to locate the new bathroom.

    The 1st pic shows the stack penetrating the concrete floor.

    The 2nd pic is the top part of the stack where 1st level drains are tied into this stack, and what the connections serve.

    The 3rd pic shows the drain connection from the laundry tub to the horizontal run just below the floor joists.

    The 4th pic shows the drain connection from the straight pipe in the wall for the washing machine.

    The 5th pic shows the toilet and sink connections from the 1st floor 1/2 bath.

    There is no evedence of any vent pipe connected to this stack what so ever.
    These connections, and main stack are located in the front of the home, and there are no vent pipes penetrating the roof in this area.

    The only 2 vent pipes through the roof are on the other side of the house in the vacinity of the master bath and the 2nd bath, which are back to back, and above the kitchen sink. (which poses another question )

    How do I vent the new bathroom in the basement without tearing out the drywall of all the rooms above this area on the 1st and 2nd level, and cut a hole in the roof???

    2nd question: when replacing the kitchen sink, I had to open up a portion of the wall behind the cabinet where the drain connection is so I can lower the glued PVC assembly 5" to fit benieth the new sink....in doing so I noticed that the kitchen sink does not appear to have any vent connected to it either!!!
    Only the drain line through the wall down to the basement into a horizontal run that is tied to the 2 2nd floor toilets, showers, tubs, and sinks, that runs into a another main stack. Is the vent upstairs providing the proper drain for the kitchen sink?

    Here are the pictures I mentioned above.

    Please take a look and any info you can offer to help would be greatly appreciated!

    Thanks in advance!
    Attached Images Attached Images      

  2. #2
    Moderator & Master Plumber hj's Avatar
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    Default Dwv

    The only thing your pictures really show us is that you have an improper, unvented, "S" trap for the washing machine. EVERYTHING you have to know before a PLUMBER can tell where to cut the floor and install the piping is hidden under the concrete.

  3. #3
    DIY Junior Member red22769's Avatar
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    Quote Originally Posted by hj View Post
    The only thing your pictures really show us is that you have an improper, unvented, "S" trap for the washing machine. EVERYTHING you have to know before a PLUMBER can tell where to cut the floor and install the piping is hidden under the concrete.
    HJ,

    I know they installed the washing machine drain improperly...I plan to change this when I get started on the bathroom project because it has backed up and flooded the laundry room a few times already. When this happens it in turn floods the basement too! I need to rectify this before I put walls up in the basement to avoid future problems. (any suggestions before I buy a bunch of fittings and material at Home Depot?)
    I am going to tile the laundry room floor and incorporate a floor drain so IF it ever happens again it will not destroy the ceiling in the basement when done.

    I do know the main drain line is directly under the concrete where I plan to install the bathroom (directly left of the main stack shown in picture #1) I haven't opened up the floor yet because I was curious on how I am supposed to vent the system before I cut the floor, when there is no evidence of an existing vent line in this area. If I cannot properly vent the system I do not want to go through the trouble of breaking up the floor to be told I can't do it....

    Should I go to the township offices to see if I can obtain As-Built drawings for my house for the plumbing layout of the underground pipe? will this get me the answers I am seeking?

    Thanks for the reply!

  4. #4
    Master Plumber-Gas Fitter shacko's Avatar
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    The key question is do you want to tear into the walls and install the vents that you don't have or put another jerry rig in? your choice.

  5. #5
    DIY Junior Member red22769's Avatar
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    Washing machine drain aside, what is the prognosis on the new bathroom?
    washing machine drain vent will be tackled later.

    Can I run the vent line across the basement withon the floor joists of the 1st floor, and stub it out through the bond with a goose neck so I don't have to go up through 2 floors and the roof in the front on my house over my front porch?

    If I can run it out the wall in the back yard, how should I size it for just the 1 bathroom? 2" or 3" vent?

    Distance from the area the bathroom is to be located to the other wall where it would be least conspicuous outside is approx. 28' and my basement walls are 8' tall concrete to bottom of bond.

  6. #6
    Test, Don't Guess! cacher_chick's Avatar
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    If you are in an area that freezes, the vent should go up an interior wall into the attic where it can be run horizontally (with proper pitch) as needed to get to a location desirable for penetrating the roof. If it does not freeze in your area, you might be able to route the vent through the rim joist and up the outer wall, but it will still need to go through the roof overhang.

    If you are worried about doing a minor drywall repair to run a proper vent, you should probably hire out those portions of the project you don't feel that you can do properly.

  7. #7
    Moderator & Master Plumber hj's Avatar
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    Default plans

    VERY few houses have "as built" plans. Even when there is a plumbing diagram, which most DO have, it is a generic one and may have NOTHING in common with the piping in your house, other than the locations of the fixtures. We would have to be there to evaluate the venting possibilities.

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