Replacing Cast Iron Sewer Lines In Crawl Space

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by DanMcD, Apr 29, 2006.

  1. DanMcD

    DanMcD Member

    Jun 19, 2005
    Dayton, OH
    I need some advice on replacing my cast main sewer pipelines with PVC piping. My plumbing is in a crawl space, so I have some concerns about possible leaks years down the road.

    I would like to know:

    1) Would it not be best if a plumber replaced my cast pipe with new cast pipe versus using PVC?

    2) What is the best way to connect new PVC to the old cast iron main sewer line pipes? I my pipes are 4 or 5 inches in diameter and I’m concerned about leaks in the crawl space that I may never see.

    3) When using rubber no-hub connectors, what is their life expectancy and reliability. For example, will expansion cause the connection to come apart?

    4) What would be best when replacing the cast pipe:

    a) Bring the PVC pipe all the way outside through my foundation wall and avoid any inside connection?

    b) Or use some type of non-rubber connector to make connections that must be done.​

    5) I have a 2-inch cast iron drainpipe From the laundry room) that must also be connected. What is the best way to connect new PVC to the this 2 inch cast pipe?

    6) My existing cast pipes are on the ground supported by 3 bricks every 5 feet or so. What is the best it hang the new PVC pipes or support them to the floor? What are the best quality pipe hangers that plumber’s would use?

    7) Should I have an access drain installed outside of the foundation wall.

    Dan McD
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona


    A plumber would have an easier time replacing it with PVC or ABS pipe. It will be cheaper, and there is no reason why it should leak at any time in the future. Cast iron is heavier, costlier, and more labor intensive to install. The pipes should be hung from the building, not supported from the ground. Definitely install an access cleanout outside the building.
    Last edited by a moderator: May 3, 2007
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  4. brownizs

    brownizs In the Trades

    Feb 9, 2006
    Springfield, IL
    The only thing that is a pain when installing drain piping in a Crawlspace (been there done that with a single wide trailer), is that it gets uncomfortable. A plumber would be able to have all the fittings on hand, whereas if you do not plan it out ahead of time, it can take a couple of trips to get the fittings.

    I find it is easier to overbuy on fittings when doing a job, then underbuy, so that way if I do not use it, I either keep it for a future job, or return if it ends up being too much. I still have a length of PVC sitting in my basement that was never used in a plumbing job, so we have been thinking of using for hanging clothes on if I ever come around to getting it up.

    There are always uses for PVC when you are done with the job and have parts laying around.
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