Replace Cast Iron DWV System with Plastic?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by wendelboec, Mar 17, 2006.

  1. wendelboec

    wendelboec New Member

    Mar 17, 2006
    I'm in the process of replacing an entire bathroom - had to rip out to the floor joists due to the shower pan leaking, etc. The home was built in 1975 so the DWV is a no-hub cast iron system. My main soil stack is in close proximity to the toilet, so it could be replaced, relatively easily, if needed. When I removed the no-hub fittings around the shower and toilet drains, I noticed the rubber gaskets surrounding the fittings are dry and starting to crack, when removing them. The other fittings going to the main soil stack appear to be in tack with no leaks, etc.

    My question: Should I replace the old cast iron system with plastic? Should I just replace the gaskets surrounding the existing fittings or would I be ok to leave well enough alone and not do anything? What is the average life of a cast iron DWV system? Any thoughts? Thanks for any input.
  2. finnegan

    finnegan New Member

    Aug 16, 2005
    The average life of a cast iron is pretty much forever. There is no good reason to replace a no hub cast iron system that is not leaking. Assuming that the system was properly installed with the correct no hub couplings, I would leave it alone. If you want to replace the visable and accessable couplings go for it.
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  4. Cass

    Cass Plumber

    Nov 12, 2005
    Personaly, I would change over to plastic if/while the floor is open. As you can see the rubber in the couplings doesn't last. You could probably leave it alone and be fine but I would change it over, and plastic is forever. The stack I wouldn't change unless there was a problem.
  5. lithnights

    lithnights New Member

    Nov 30, 2005
    But what about noise effects? We did rework in our home and had to have the main waste stack coming from the 2nd floor come right through a main wall in our 1st floor where we spent much of our time.

    Because of the noise (cast iron is quieter), I had them put in cast iron instead of the PVC. And I'm glad I did. I can hear the difference too. The section of the upstairs plumbing that is PVC (horizontal pieces..from shower to main stack) is much louder than the cast iron (vertical stack).
  6. finnegan

    finnegan New Member

    Aug 16, 2005
    Thre are a huge number of no hub connections in use all over the country. it is a very reliable connection. Generally a cast iron no hub system is considered an upgrade from pvc.

    Last edited by a moderator: Nov 7, 2013
  7. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    After a no-hub systems have been installed for a while the only rubber that is important is the small ring between the pipes, and that is usually so tight that when you remove the metal band and try to remove the rubber that ring tears off and you have to pry it out of the joint. But it is also almost impossible to get the new band to slide into that groove so it fits smoothly. In other words, do not disturb any No-Hub connection that is not leaking, or unless you intend to change the piping.
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