Replace cast iron trap with PVC

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by mhopper, Apr 17, 2010.

  1. mhopper

    mhopper New Member

    Messages:
    2
    Location:
    Dallas TX
    I recently completed renovating a shower in a pier and beam home from the 50's

    The shower has been dormant for close to 2 years. When I went to use it for the first time after the renovation, the drain clogged and backed up.

    I tried to use a hand auger to clear the trap, but it seems fairly solidly clogged, so I had an inclination to replace the P trap. It is cast iron, and I would replace it with PVC, which the shower drain starts out as initially.

    I have posted some pictures and have some questions about the task. I have no waste plumbing experience and this is my home.

    I assume that I can cut the cast iron pipe (2-1/2 inches) with a soil pipe cutter downstream of where the P trap connects to the run that leads away from the shower and replace all the cast iron with a PVC trap of the same diameter as the cast iron and connect the CI to the PVC with (from what I have read on this forum) "Mission style" no-hub couplings. I assume that I should replace the existing coupling that now connects the shower drain PVC to the cast iron.

    Does this sound like a reasonable plan for a first timer? Thanks for any help!

    Pictures attached:
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  2. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    I would cut the Cast Iron with a sawzall instead of snapping it.
    Use either a Lenox Gold 14 tpi blade, a carbide blade or, a Lenox Diamond Blade.
    Sometimes snappers crush tender old cast iron instead of cutting it.
    Use banded couplings...
  3. mhopper

    mhopper New Member

    Messages:
    2
    Location:
    Dallas TX
    Thanks Redwood. I used a diamond blade on the sawzall and it only took about 5 minutes. The CI seems to be in good shape. I used some no-hub couplings to hook up a new PVC p-trap and all appears to be well.

    Thanks for the advice.
  4. Redwood

    Redwood Master Plumber

    Messages:
    7,453
    Location:
    Connecticut
    Nice! Glad to hear it went well!
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