Removing waste pipe from foundation wall

Discussion in 'Toilet Forum discussions' started by patrick0042, Nov 20, 2006.

  1. patrick0042

    patrick0042 New Member

    Nov 20, 2006
    My home's cast iron 4" gravity waste pipe fractured comletely off at interior edge of 15" thick foundation wall. A second complete fracture exists 9" outside foundation. Pipe is strongly bonded to foundation concrete, and the concrete is over 50 years old. Is it acceptable to descale interior of pipe and retrofit by running 3.5" PVC through existing hole and using reducers at each end to unite remaining waste pipe?? Otherwise, is core drilling the only way to remove pipe/enlarge hole to fit 4" piping to match? -- Desperate for solutions. thanks!
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Hammer and chisel? If the pipe is 4" elsewhere, you can't throttle it down to go through the wall.
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  4. Gary Swart

    Gary Swart In the Trades

    Sep 1, 2004
    Yakima WA
    If I read your question correctly, you want to go for 3" PVC (no such thing as 3.5") to 4" cast iron then back to 3" PVC. If that's what you are suggesting, the answer is no. You can not decrease the size of a drain. If it was my job, I'd use a rotary hammer/drill with a long 1/2" bit and drill around the CI from both sides, removing as much material as possible. Then a good sledge hammer on the end(s) of the CI should break it out.
  5. patrick0042

    patrick0042 New Member

    Nov 20, 2006
    Thank you, Gary and Jim

    That's what I was afraid of...not OK to reduce a waste pipe. Time to earn some of that sweat equity!
  6. patrick0042

    patrick0042 New Member

    Nov 20, 2006
    Took your recommendations to stick with 4" piping. Rather than chisel, rented ($70) a chipping hammer which melted the concrete like butter, easily loosening the existing cast iron and also allowing me to slightly enlarge the hole so that I can pass the thicker walled 4" PVC through. Worked like a charm, now will add a backflow preventor outside the wall. Thanks again!
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