Move a basement bathroom rough-in?

Discussion in 'Remodel Forum & Blog' started by jdc1040, May 21, 2009.

  1. jdc1040

    jdc1040 New Member

    May 21, 2009
    We're planning to finish our basement and have run into a big problem. Our basement is a standard 8 ft foundation. The bathroom rough-in is right under the main HVAC ducts that run down the center. That means after putting floor tile, soffits, and drywall ceiling, we're looking at 6'9" max bathroom height - which is a little on the claustrophobic side.

    The rough-in seems to be positioned directly below the bathroom on the first level and shares the same vent stacks. Given this, would it be possible, and how hard do you think it would be, to move the rough-in? It would be moved toward the front of the house, which means the new drains should be in line with where the existing ones are going under the concrete. I think I'd need to bust up the concrete, move the drains, put in some elbows to move the stacks along the joist cavities and bring them down in the new location. Does that sound right? Can the PVC pipes be elbowed like that?

    I realize it might be hard to visualize what I'm talking about, but any helpful hints would be appreciated.
  2. Ian Gills

    Ian Gills Senior Robin Hood Guy

    Jul 24, 2007
    Robber, with some DIY on the side.
    I would consider moving the ducts as an alternative and cost the two.

    6'9" does seem a little low. I try to keep to at least 7', which I think is required for a basement ceiling where I live. But with HVAC ducts you can often fall below that in spots.
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    There's a limit on how much changes in direction the drain can take. Also, your drain from upstairs can't be used as a vent for downstairs need to run new vents high enough above the highest drain's flood plane before you can join back in. Given that, you could probably abandon the existing rough-ins and make new ones. This is easier if the main drain line runs towards where you want to relocate the bath fixtures. As to venting, you'll need to find a way upstairs high enough to join into the existing vent system or run an totally new one all the way to the roof. Without being there, it's hard to tell you exactly the best way to do things...too many variables. Note that even a vent needs slope, but can afford more bends in it than a drain can...there are still rules, but not as stringent. You don't want them being blocked by condensation or rainwater, thus the requirement for slope.
  5. jdc1040

    jdc1040 New Member

    May 21, 2009
    First off, thanks for the responses. I appreciate the input.

    I don't think moving the main ducts is an option. Right now they're sandwiched in between the two metal i-beam supports that run the length of the basement and project downward just about the same depth. So, if I move the ducts, I'd actually wind up the even more area that I'd need soffits because now I'd need them for the ducts and the i-beams in different areas.

    As for code, I checked and our code is also 7' min. ceiling in basements, with the exception that bathrooms are 6' 8" min. - so it seems I'd actually make code if I could deal with low ceilings. Assuming I'm reading it correctly... Our location follows ICC Residential 2003.

    To be honest, everything I've looked up regarding proper plumbing makes me think I should either just leave it alone or get a pro in here to look at moving it...

    Bums me out too, because that is actually the PERFECT place for the bathroom if it weren't for the height!
  6. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    Since you already have a rough in for a bathroom, all you have to do is abandon it and then extend its main drain line to the new location and create a new system. Trying to modify the existing one for the new locations will usually take more time and money that it is worth.
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