Reversing tub drain- how much can I add to existing drain pipe?

Discussion in 'Shower & Bathtub Forum & Blog' started by derekmadge, Jul 8, 2011.

  1. derekmadge

    derekmadge New Member

    Messages:
    2
    Location:
    Waterloo, ON
    hello-
    This is entirely theoretical now. I don't know if I'll have trouble simply replacing an existing tub and drain. Here's my situation (Ontario, Canada; haven't been able to find code specific to this situation):
    I live in a semi-detached house, about 45 years old. The tub drain and supply pipes are all in the wall common to the two houses. So I likely only have about 4" or less of space to work with once I get the drywall off. Behind that is the concrete block firewall between our two houses. I may have to temporarily cut out some 2 x 4" framing.

    Everything I've read says there should be access to the plumbing and perhaps it wasn't code when the house was built but I'd sure prefer that now! I wonder if I could reverse the right hand drain to a left hand drain tub. This would put that end of the tub on a wall common with a hallway and make it easy to create an access door in the hallway. But that would add about 5 feet to the drain assuming I simply extended the existing drain. (I don't know what I'll find under the drywall and/or flooring.)

    Should I anticipate venting and/or drainage problems if I take that approach? If so, I won't try that - I'll somehow manage to replace everything in it's current location
  2. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    Well, since I have NEVER worried about an access door for any tub I have installed in the past 60 years, and it has NOT created any problems, I think you are trying to cure something that is not a problem.
  3. derekmadge

    derekmadge New Member

    Messages:
    2
    Location:
    Waterloo, ON
    Ha-ha... I DO tend to do that! Thanks for your reply.
    Derek
  4. jimbo

    jimbo Plumber

    Messages:
    8,997
    Location:
    San Diego
    You would make the trap arm too long, there would be an issue with the vent, and you would have trouble maintaining the 1/4" per foot mandatory slope.
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