Replacing Cast Iron Shower Drain / P-Trap & Replacing with ABS

Discussion in 'Shower & Bathtub Forum & Blog' started by n0teye, Aug 29, 2011.

  1. n0teye

    n0teye New Member

    Aug 29, 2011
    First off - thanks to all of you who contribute to this message board as it has a wealth of information.

    I am in the middle of remodeling our master bathroom and would appreciate some guidance.

    Where I stand now is a 2'x2' demo'd area of concrete from the foundation of the house in order to remove the old drain assembly, cast iron p-trap (found it was cracked once I removed it.

    What I am unsure of is how to properly assemble / re-cement the area that I demolished. I've already purchased the following:

    2"to2" No Hub Fernco Adapter
    2" ABS
    Oatey Square Drain w/ clamping ring
    2" ABS P-trap

    The problem I have is when it comes to filling in the concrete etc to make the area whole again. Do I reconstruct the drain plumbing but not attach the drain itself? I'd imagine I'd want to make the floor flush with the riser portion of the ABS plastic? Or do I install the bottom portion of the drain into the cement and make the cement flush with the bottom portion of the drain? Are there any walk-throughs available online?

    This picture from leads me to believe that the bottom portion of the drain should sit above the foundation slightly in order to properly slope the pre-slope making the bottom drain portion flush with the mortar pre-slope. If so - how much above the foundation?

    Is it ok to embed an abs drain in concrete?

    Apologize in advance if my post is confusing as it's a lot more difficult to describe the predicament than I thought.

  2. Terry

    Terry Administrator Staff Member

    Aug 17, 2004
    Bothell, Washington
    The lower plate is at the lowest point where you will be installing the pre-slope.
    The top of the lower portion accepts the water at it's lowest point.
    The two pieces, top and bottom clamp together and seal it.
    The ABS can be embedded in the concrete.
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    Over a cement slab, you can have your mudbed get pretty thin near the drain. Over a wooden subfloor, you generally want it closer to at least 1" thick. So, the clamping ring would be even with the lowest, thinnest section of the mudbed.
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