Toilet stub is too short and wrong size

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by Trenhes, Oct 30, 2012.

  1. Trenhes

    Trenhes New Member

    Oct 30, 2012

    I'm finishing my basement bathroom that was roughed in by the builder 18 years ago. I pulled out the red plastic that was covering the pipe. My problems are:

    1. They left the pipe a 1 1/2" below the concrete.
    2. They didn't pour around it completely so there are voids. No concrete to screw down flange.
    3. A closet flange fit's sloppy in the pipe. After talking to the guys at a plumbing supply they determined that the plumber had stubbed up to the floor with sewer and drain pipe. The o.d. is the same as schedule 40 but the i.d. is slightly bigger so a flange falls right in. At first glance it looks like schedule 40, but a touch bigger on the inside. Walls of the pipe are a 1/4 in. The stub is 15" deep.

    My thinking is cut out the concrete around the stub, cut off the pipe to where I could glue a coupling on the existing pipe, and then stub up above the floor with schedule 40, leave it long, pour my cement back around the pipe, and they cut it off even with the finished floor and use an inside flange.

    The existing pipe is 4". I don't mind going to the work if this would be the proper way to fix this.

    Thanks for any replies, Tod IMG_0012.jpg
  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    They do make an inside cutter if you want to drop it down a few inches before adding a coupling.
    If you need to secure bolts on top, you can rotohammer in a flange repair ring with the attaching holes set farther out.

    Or maybe you can use a spigot closet flange, mated with a 4" coupling and 4" pipe since the pipe is 1.5" below slab now.
    Trimming the upper portion by .5" would not be too hard.
    Last edited: Oct 31, 2012
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  4. kreemoweet

    kreemoweet In the Trades

    Sep 7, 2009
    Seattle. WA
    So is the concrete supposed to be your finished floor? If not, keep in mind that the flange sits on top
    of the f.f., and there well may be something under it to attach to. Also, it is a violation of plumbing
    code to embed pipes directly in concrete. Those plumbers did good.

    Incidentally, wall thickness of 4 in. SDR35 sewer pipe is less than 1/8 in, so I don't think that's what you have.
    Illegal to use that stuff in/under a house anyway.
    Last edited: Oct 30, 2012
  5. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    That is NOT S&D pipe, but if it were the I.D. would be the same as sch. 40 pipe and the O.D. would be smaller. They poured the concrete EXACTLY the way it should be and you need a flange that fits around the OUTSIDE of the pipe, not the inside.
  6. Trenhes

    Trenhes New Member

    Oct 30, 2012
    Well I don't know what kind of pipe it is then, but I do know that a flange falls right inside, but a coupling fits tight on the o.d. I went ahead and cut out some concrete and did as Terry suggested and cut off the original pipe installed a coupling and came up above the slab with schedule 40. I'll finish my floor and cut off flush and install flange. When I re-pour my concrete what should I use for a barrier between pipe and concrete? Is some of that thin blue foam ok? Or how much clearance does there need to be around the stub.

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