remodeling and want to make a change to my drain lines

Discussion in 'UPC Plumbing Code Questions' started by qgsm33, May 20, 2014.

  1. qgsm33

    qgsm33 New Member

    Messages:
    6
    Location:
    Texas
    Hi folks - first time poster here...so be gentle :). I'm remodeling a spare bathroom on the 2nd floor. During the tear down phase, I noticed that the wet wall (2x6 studs) runs parallel to the floor joists. Unfortunately, the wet wall studs don't sit on top of a floor joist: the floor joists are about 2' apart, and the wet wall is almost exactly in the center of two parallel floor joists. I.e. the wet wall is just resting on the plywood subfloor.

    I'd like to improve that by laying another floor joist in under the wet wall floor plate. The existing floor joists are about 9 1/2" tall...so maybe a 2x8 for this added floor joist. The span is about 10 feet so it's not an unreasonable improvement.

    here's my problem: the drain lines for the tub, toilet and vanity run under the wet well (in that order...working towards the vertical drain pipe). the part of the drain line that's 3" (for the toilet and subsequent vanity) are not a problem. They don't take up all the space under the wet wall floor plate. The tub drain however ends up blocking the rest of the space under the wet wall.

    I've included a picture that shows this: the tub drain is a 2" line that joins the horizontal drain line via a 3x3x2 wye AFTER the 90 degree coming from the toilet.

    I'd like to change the layout so the tub drain line comes into the 3" line along the same axis. I'd like to take the 90 degree elbow coming from the toilet, and change it into a 3x3x3 wye. The wye would run to the toilet, and the "straight thru" portion would continue on to the tub drain. I've heard that the horizontal line running to the tub would have to be a 3" line to avoid any issues.

    there are vents near the toilet (3" if I remember correctly). the tub has it's own 2" vent line, as does the vanity.

    Am I nuts here? please send any and all comments... Em Bathroom - no tub.jpg
  2. Reach4

    Reach4 Well-Known Member

    Messages:
    2,432
    Location:
    IL
    Why? That wall presumably is not structural. Is there noticeable floor deflection? If the "wet wall" purpose is to carry pipes, wouldn't your new joist interfere with the vertical pipes?
  3. qgsm33

    qgsm33 New Member

    Messages:
    6
    Location:
    Texas
    good question. I forgot to mention that I need to cut out a bunch of the plywood subfloor in the bathroom. Some rotting from water damage, but a lot of "moving lines around" and it lets me put in some wiring for the floor below...so I can hang a ceiling fan in the floor below.

    So what do you think? Can I do what I want?
  4. qgsm33

    qgsm33 New Member

    Messages:
    6
    Location:
    Texas
    sorry, was kinda short with that last response. when I cut a bunch of the subfloor out, the wet wall plate and studs will be resting on the edge of the plywood coming from the next room over...more than a foot from the nearest joist. I'm just not that comfortable with leaving it that way...especially when I can support it with a new joist...

    ...assuming you folks think what I'm doing is kosher...
  5. Terry

    Terry Administrator Staff Member

    Messages:
    15,130
    Location:
    Bothell, Washington
    If the tub vents before enter the wye for the toilet, yes
    If the lav has it's own vent yes. The lav vent can be 2", and that winds up wet venting the toilet.
  6. qgsm33

    qgsm33 New Member

    Messages:
    6
    Location:
    Texas
    Thanks Terry, much appreciated. Thanks for setting up this extremely useful site...

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