Replacing Cast Iron Shower Drain With PVC

Discussion in 'Shower & Bathtub Forum & Blog' started by silverrhino, Apr 4, 2014.

  1. silverrhino

    silverrhino New Member

    Mar 4, 2014
    Retired Population Biologist
    I am in the process of planning a total bath remodel that will include re-building existing shower. Our shower is a 30 X 60 with a center drain and will be re-built using the Kerdi Shower System, including the Kerdi base and drain. Our home was built in the mid 60's and has cast iron drain lines and is built on a concrete slab.

    I will be removing the floor tile and mortar bed but had not planned on breaking out the concrete unless absolutely needed. My questions are:
    1) I am assuming that the drain cover and assembly is leaded into the system, would that be correct?
    2) What is the easiest way to remove the old drain, with the least amount of disturbance to the slab?
    3) Am I being totally foolish by thinking there is a way to do this install without breaking into the slab?

    I am just trying to get an idea of what this drain assembly looks like prior to starting the demolition, so as not to destroy more than I need to. Any help and/or suggestions will be greatly appreciated. Thanks.
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona
    quote; 1) I am assuming that the drain cover and assembly is leaded into the system, would that be correct?

    Probably, BUT, since it is a "2 piece drain" the waterproofing membrane is clamped between the two pieces, so your new membrane should do the same. But if not, a plumber could crack the drain off without damaging the piping.
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    IF you have a traditional clamping drain, Schluter does make a clamping drain adapter for their drain (you may not want the kit, since it comes with a solvent welded version of the drain. There's another big IF in this equation...the existing height of the CI clamping drain may not be at the right height to work with the foam pan...the odds are small. Last, you MUST ensure that the surface is totally level before you try to install the foam tray.

    The drain cover normally either just sits there, or has screws holding it in. If it is a clamping drain, there will be 3 or 4 bolts holding it together and if you do use the conversion drain, you MUST NOT THROW THOSE AWAY! It is likely you'll need to remove the existing drain entirely, and while you have that out, inspect the pipe and trap. No sense in putting in a nice new shower with a potentially weak or leaking trap or should be able to tell with careful inspection. My guess, you'll either need to replace the drain and riser to get things the proper height to use the drain in the kit (or the conversion drain), or, you could make your own pan out of deckmud and then cover it with Kerdi using their drain.

    Check out for tiling issues and building a shower....lots of tiling pros there that do that for a living on that site. Terry's site is great for the plumbing questions, and other stuff like electrical and HVAC...not as 'deep' for tiling help as that site where that is pretty much all they do.
  5. johnfrwhipple

    johnfrwhipple BATHROOM DESIGN & BUILD for both Canada & the US

    Jul 20, 2009
    Design Work World Wide: Bathrooms Vancouver Area
    North Vancouver, BC
    Replacing Cast Iron Shower Drain With New Foam Shower Pan

    We just helped out someone else here on the Terry Love Forum with the same question.

    Read this discussion -

    Covers all the questions you asked.

    Not a big fan of foam based shower pans, but that might be because I don't sell any or sell any ebooks telling people how to install them. Maybe then I would be a fan.

    You understand that Laticrete, Wedi and Noble Company all make their own shower pans - right? And with there shower pans you can use a slightly easier setting material to install the tile afterword!

    Most DIYers like the improved modified thin-sets for installing tiles. Less sag. Better grip. You know - all the things rookies struggle with. Best keep this in mind when choosing a complete system.
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