Toilet drain extension for remodel

Discussion in 'Toilet Forum discussions' started by AlterB, Mar 31, 2013.

  1. AlterB

    AlterB New Member

    Mar 31, 2013
    Hi all,

    I'm a rather handy plumbing neophyte.

    I'm getting started on a bathroom remodel. My initial focus has been on the shower stall. Tonight I removed the toilet to start planning for the non-shower tile.

    The toilet is currently on OSB + CBU + tile. The new floor will be on the OSB + 1/2 ply + Ditra + a thicker tile. I don't have exact measurements yet, but the new height of the flange *may* be higher than the current one.

    The drain is 3" ID PVC, a closet flange cemented to the outside of the drain. There is no underneath access without cutting out ceilings below (upstairs bathroom). I will have access once I remove the tile.

    If I need to extend the drain higher, what are my options to research? I assume I need to keep the 3" ID drain, therefore an insert flange is not a good idea? When I have access to the floor, can I cut band extend the drain using a coupling?

    Thank you,

  2. cacher_chick

    cacher_chick Test, Don't Guess!

    Jan 5, 2008
    Test, Don't Guess!
    Land of Cheese
    An insert in a 3" pipe makes the I.D. even smaller, which is not something I would prefer on a toilet. Whether you can fit a coupling on the riser will depend on how long the riser is to begin with. If it is short, you will have to replace the closet bend and the riser.
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    It depends on what's actually there. They make an inside pipe cutter that would allow you to cut the old stuff out. If you can't put a coupler and a riser but you do have a socket in the fitting below, they also sell a special drill bit designed to cut out the pipe on the inside, allowing you to glue in a new riser. See if, once the toilet is out, you can tell how much drop it has (probably not much if it's on the second floor and in the ceiling) and if there's a riser at all rather than a closet bend. A pro may be able to remove the existing flange while leaving enough of the pipe to install a new flange, but it's chancy - a good joint literally welds the plastic of the two pieces together by melting the surface of each. They normally do not like to come apart!
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