Rotting horizontal CI pipe between floors: how much to cut out?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by alex17, Jun 22, 2011.

  1. alex17

    alex17 New Member

    Jun 22, 2011
    Philadelphia, PA
    Problem: Between my 2nd and 3rd floors, we have a long (~10') stretch of CI pipe running fr 3rd fl bathroom to stack, sloped just enough to keep things flowing, but not much. Towards the stack end (lower end of the flat slope), the pipe has rotted through and is leaking -- I'm guessing water has sat in there over the years and finally just came through.

    1. Our plumber recommends taking out the rotten portion of pipe, a bit to each side, and replacing w/ CI.
    2. I'm inclined to take out the whole horizontal (almost) section running to tub / sink / toilet junction uphill, and to stack connector downhill. I'm worried if we just cut out a section, the rest of the near-horizontal pipe may well rot before too long and I don't want to rip out plaster and flooring yet again when that happens.

    So: your advice? 1. How much to remove / replace? And 2. with CI, or PVC?

    Either way, I'm not competent to do this, I'll have our plumber do the job. I'm looking for guidance so I'm more informed about our options.

    Thanks very much.
  2. SacCity

    SacCity In the Trades

    Mar 14, 2011
    Sacramento, CA
    My experience is that when a branch goes the whole thing is crap and needs to be cut out.
    Unless there is an obvious defect.
    Replaced one last week where there was a bad fitting, changed the fitting and a foot on each side of it.
    But on a pipe run, one patch leads to the next if not this month then next...

    I did a bandaid on a 4" Cast Iron line, made sure that my invoice made it clear that there were no guarantees to any remaining pipe.
    But the owner only wanted a patch until ....

    So I would recommend cutting out until you get good material...

    Last edited by a moderator: Jun 22, 2011
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  4. alex17

    alex17 New Member

    Jun 22, 2011
    Philadelphia, PA
    Thanks, that's helpful.
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