Wierd shower drain set up

Discussion in 'Shower & Bathtub Forum & Blog' started by Mark JW, Oct 22, 2007.

  1. Mark JW

    Mark JW New Member

    Oct 22, 2007
    I don’t know if this question has been addressed before, I’m sure it has, but I couldn’t find anything after a quick search. Anyway, a little background.

    I live on the first floor of a quad four condo building. There is another unit above mine. I am currently in the process of remodeling the bathroom off the main bedroom. This room has a shower stall in a 48†x 32†alcove. This has been a typical job that has stated small and has kept expanding as I went on. Anyway the building was built circa 1979. The original installation consisted of a fiberglass shower pan with ceramic tile walls. At first, I was just going to go the lazy way out and just repaint/ resurface the existing fiberglass shower pan and install new walls. The problem was that the pan badly scratched, it was never quite level and the water tended to pool in one end. Furthermore, they used construction adhesive on the lip where they attached the original drywall tile backing so there is residue on that portion that needs to be removed. In addition, after the walls were removed the whole pan was just sitting loose on the floor. I discovered that all I had to do was just lift it straight up to pull it out.

    That is when I discovered, (insert scary movie sound effects) The Drain!

    It seems that the shower drain consisted of a 10†long, 2†PVC drop tube into a 4†cast iron trap. The cast iron is located in a rectangular opening in the concrete slab (rouhly 15†x 17†the lip of the cast iron is slightly below the top of the slab elevation and the opening is infilled with pea gravel.

    This rectangular opening appears to be acting as a French drain for when the sewer backs up and overflows. (I’ve lived here for just under 10 years and that happened once).

    So here is my dilemma.

    1) Resurface the existing original fiberglass shower pan and reinstall it in the original plumbing configuration (level this time). After all, it has lasted this long. Don’t fix it if it ain’t broke.

    2) Install a new shower pan matching the existing original plumbing installation and hope that the modern equivalent is at least as sturdy as the original.

    3) finding a no-hub adapter to tie a new 2†drain to the existing 4†drain, fill in the rectangular opening and rebuild with either a fiberglass pan or a tile floor pan and hope that a back up doesn’t overflow the shower pan, into the rest of the house.

    Breaking into the slab is not really an option at this point.

    Any suggestions?
  2. hj

    hj Moderator & Master Plumber Staff Member

    Aug 31, 2004
    Cave Creek, Arizona

    You imply that the shower drain is just hanging into the 4" trap. If so then it would also overflow into the floor anytime your shower drain became obstructed, and it can happen to a 4" one the same as to a 2" one, it just takes longer and would be more difficult, or impossible, to cure. Connect the drain to the trap with a positive connection, and deal with a backup when it happens.
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  4. Mark JW

    Mark JW New Member

    Oct 22, 2007
    That's the thing, any overflows go into the gravel surrounding the trap and drain out under the slab.
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    That's not particularly healthy. I'd go the rest of the way, and build a new shower with a proper P-trap. You didn't indicate if there was a vent line to the shower. This is equally as important as a good p-trap. If you dug down and exposed the CI pipe, does it actually have a trap and vent?

    The building inspector would not like the situation. Normally, (depends on the exact wording of the condo association) infrastructure repairs are a group thing. If it isn't right, it is a shared expense, not entirely yours. Any upgrades to the unit's contents would be your cost, but often that also needs to be reported to the association so that the group insurance policy can reflect that.

    Take a picture of what's there so people can get a better idea and post it here.
  6. frenchie

    frenchie Jack of all trades

    Dec 30, 2006
    Brooklyn, NY and Fire Island, NY
    Nicely stated.
  7. Mark JW

    Mark JW New Member

    Oct 22, 2007
    Some pictures

    OK, here are some pictures: (I posted this over at the John Bridge site as well.

    The horror:

    (Note that the white paper on the edge of the pipe is exactly what you think it is. This was from a major back up about 10 years ago)


    The original shower pan drop into the riser:


    The top of the pipe is a bit uneven and appears to be slightly out of plumb. It is a bit over an inch down from the floor slab grade


    What I want to know is can I simply use a 4" fernco coupling on the riser and clamp a Kerdi drain to the body of the drain?


    The height would work out perfectly and it is definitely the cheapest and easiest solution.

    (yes, there is a P-trap and a vent on the drain line.)
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