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Thread: broken cast iron pipe

  1. #1

    Default broken cast iron pipe

    I am dealing with a concrete foundation ,and the toilet opening was chisled out larger than it should have been .The flange had nothing to secure to .the toilet was attached to the flange and the flange was not attached to floor.Upon removel found cast iron pipe was broken about three inches down What to do now ? Not very good at plumbing

  2. #2
    Plumber plumber1's Avatar
    Join Date
    Aug 2005


    Got a picture?

    If it were my problem, I would lead in the deepest or longest cast iron flange that I could. Longest is probably 4".

  3. #3
    Commercial Plumber markts30's Avatar
    Join Date
    Sep 2006
    Phoenix, AZ


    Couple questions....
    1. Do you mean that the WC sits on the concrete slab and that there is no open area underneath?

    2. Is the cast iron pipe proken fairly evenly around it's circumference? (is it a relatively clean break or is it very jagged)?

    3. Are you fairly handy (can you do your own concrete patching , chipping etc?)

    If you do have a slab home and that is where the pipe is broken, it should be a fairly easy fix... (It might take some work, but nothing too hard...)
    Chip the hole larger on one side so you can get your hand into the hole to manipulate tools beside the pipe...
    If the pipe is snapped of fairly square, the fix should be relatively easy - go to your local plumbing supply house and get a "mission band" (mechanical coupling for joining cast iron to plastic in this case).
    Use the coupling to extend the pipe to 1/2" below the surface of the slab (or new floor - allow for finished tile etc) with plastic pipe - cover opening with duct tape. These bands usually require a 5/16" nut driver/torque wrench to tighten them - I have used a small ratchet in tight spaces in the past - be carefull to make it tight but do not over tighten - you can break the clamp. The clamps require 60 in/lbs of torque)
    IMPORTANT - wrap some foam wrapping (similar to base plate/sill plate foam used in framing) around the pipe where it will penetrate the slab - this should be at least 1/2" thick and 4" wide. Secure with SMALL piece of tape - don't tape foam to pipe - only to self at the end of the wrap...
    Fill in around the pipe with dirt to within 4" or so of the surface of the slab.
    Pour back the slab with concrete.
    After curing (wait at least 24 hrs.), remove the foam wrap (I usually pry it out with a screwdriver...) and tape and glue new closet flange around plastic pipe (should fit in gap you have surrounding pipe after foam removed.)
    Anchor flang and re-set toilet.

    If the pipe is broken jaggedly... process is similar but you have to 'even out' the pipe before repairing it. - you can do this by using an adjustable wrench set to the wall thickness of the pipe to snap off the larger 'teeth' from around the pipe edge gradually working your way down to a fairly even edge....

    Some things to be careful about...
    Remember cast iron is very brittle and the edges are very sharp - the older the cast iron, the more prone it will be to shatter requiring a more elaborate repair...
    When working on the cast iron pipe, clean ANY and ALL cuts and abrasions you suffer with mind to what passes through the pipe - infection is a real risk...
    Chipping concrete around cast iron (any pipe for that matter) is a matter or being carefull and NOT hitting the pipe - go slow and take it easy... It is better to take an extra hour chipping than having to rip up a lot of floor to fix it....
    When setting the flange (gluing it) ensure it is flush on the floor (not elevated by the pipe or rocking...

    There is probably more that I have forgotten to say - someone else chip in if you can...


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