Shower drain installed flush with subfloor without flange.

Discussion in 'Shower & Bathtub Forum & Blog' started by Cactus_King, Jun 1, 2021.

  1. Cactus_King

    Cactus_King New Member

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    Jun 1, 2021
    Location:
    Florida
    After tearing out mud bed I found out the drain is flush with the concrete floor. There's no flange, just a threaded 2 inch hole that the drain screws into. Will I be okay with doing the pre-slope, then gluing or puttying around the threaded drain before I put down my pan liner and installing the mud bed or do I need to jackhammer it out and start again?

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  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    New England
    Are there any bolts in the ring beneath that threaded section? Was there a liner installed at all?

    If this is a clamping drain, it was not installed correctly. A conventional liner shower pan has three layers:
    - preslope
    - liner
    - setting bed.

    It's not uncommon, but wrong per plumbing codes, to put the liner flat on the floor, and Florida seems to think a liner isn't requires on some slabs at all.

    Per plumbing code, the liner MUST be properly sloped to the drain. The threaded portion is on top of the clamping ring of the lower section of the drain that holds the liner.

    Since that portion is flat on the floor, you could make it all work because over a a slab, you can make a bonded mudbed that can taper to essentially zero thickness. Then the liner is installed, then the setting bed is installed that is parallel to the preslope, thus keeping the slope of the pan intact.

    If there are no bolts, or bolt holes to attach the clamping ring and liner in that lower part, you MIGHT be lucky and find a clamping ring that would attach, but more likely, you'll be tearing it out.

    My preference is to not build a conventional liner shower and go with something a bit more modern (if you can call 30-year old tech modern), and use something like Kerdi which only requires one mud bed, then the tileable Kerdi membrane is applied, then tile. Makes the floor thinner, simpler, and totally waterproof along with the walls...it also requires its own drain assembly.

    www.johnbridge.com is m go-to place for shower and tiling help.

    This page shows the parts of a typical clamping drain for a tiled shower... Oatey® 130 Series Shower Drain For Tile Shower Bases | Oatey

    This video shows the parts better but makes a big mistake by installing the liner flat on the floor without any preslope as required by code. Water does not drain out from a flat surface properly and the mud bed will stay damp unless the shower is very rarely used so it can dry out in between uses.

     
    Last edited by a moderator: Jun 3, 2021
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  4. Cactus_King

    Cactus_King New Member

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    Thanks for the advice. The lack of a requirement for a liner in Florida helps explain why there wasn't one. It appears they cut (or poured) a 3 inch recession in the concrete for the shower stall but it must not have been square - the bottom plate of the wall overhung the shower cutout in some spots by over an inch and was set back from the cutout in other spots about the same. On top of that they put green wallboard in but didn't waterproof it at all. The difference between where the wallboard ended and the bottom of the cutout was so significant in places that the tile was eventually pushed in at the bottom which caused the top of the tile to push out and that's when the leaking started. They did put in a mud bed but stopped an inch shy of the wall all the way around and it was filled with water. It's almost like they planned for it leaking instead of proactively preventing it.
    To answer your question, unfortunately there aren't any bolts sticking up, just a threaded pipe that is flush with the concrete. It does have vertical channels cut in the threads so I think it is at least intended for water drainage. I think it might be one that's used for those fiberglass inserts instead of tile. Without being able to clamp the liner down I'm hesitant it will prevent leaking no matter what I do if I just leave it. I saw the Kerdi stuff in the store but I don't know much about it so I'll do more research. I'm really worried about breaking the drainpipe if I jackhammer it out but I don't know if I have a choice.
     
    Last edited by a moderator: Jun 4, 2021
  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Retired Systems engineer for defense industry.
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    Are there any threaded holes in the part in the slab? They might be full of mortar. If there are, it's a clamping drain without the clamp.

    FL seems to think a recessed hole in a slab is fine for a shower.

    FWIW, neither tile nor grout is considered waterproofing in the industry (or the plumbing code!), and code does want a pan to be waterproof...FL seems to just ignore the national code. As you found, it doesn't work all that great. Moisture resistant drywall has not been approved for use in a shower for a while, either, and really has no practical use there. Once you put a hole in it with either screws or nails, and on any cut edges, moisture can easily get inside, and through it.

    If there are no threaded holes in what's left...I don't see a reliable way to make a waterproof pan without changing the drain. The riser/grate holder doesn't count!

    Schluter has lots of videos on their website to see what it is and how it works. It's been around since the 1980's, so it's not new. Millions of showers around the world have used it successfully.
     
  6. Cactus_King

    Cactus_King New Member

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    After removing the concrete around the drain, here's what I found - a 3 1/2" OD pipe sticking up approximately 4 1/2" with the threaded insert for the drain cap glued on top. At the bottom of the 3 1/2" pipe it's glued inside what I'm guessing is a reducer because I can see water from the trap but the water is definitely not filling the entire diameter of the 3 1/2" pipe. It's hard to tell but my guess is 1 1/2 inches? It feels like the threaded top goes down into the 3 1/2" pipe approximately 2 inches so I'm wondering if I just cut the 3 1/2" pipe down to 2" if I'll have enough to glue the new drain flange inside the 3 1/2" pipe? Not sure if that's possible or if the flange can only be glued on the outside.
     

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  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Retired Systems engineer for defense industry.
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    New England
    It looks like you have a 3" riser. 3" pipe has typically 1/4" sidewalls, so the OD would be 3.5". You CAN find 3" shower drains. They tend to use them on larger showers with lots of heads or body sprays, but they are generally available.

    I think this is what I would do. I'd cut the pipe back further, use a 3-2" reducer, then whatever 2" you need to get it to the new drain assembly the proper height.

    An alternative would be to use a special bit like a RamBit, which is designed to ream out the pipe from the socket of the P-trap below.

    If you're lucky, a 3" shower drain would just glue on and end up the desired height for your shower pan.
     
  8. Cactus_King

    Cactus_King New Member

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    Location:
    Florida
    Thanks for the advice. I found out Oatey makes a drain flange they claim can fit both 2" by gluing it inside the flange or 3" (with a LOT of force) by gluing it outside the flange. After cutting the top off just below the glued in threaded piece it was at least an inch lower than than flush with the floor and there wasn't enough of the pipe left to cut it lower and add a coupling. I went ahead and cut more concrete out and was able to trace the line far enough back to cut it past the trap. Found out all if it was 2" with the exception of the last verical section coming up from the trap. They went from 2" to 3" just to put in the incorrect drain cap. Anyway now I'm left with the correct size pipe and plenty of room to fix the problem. Once I got over the worry about making things worse it actually turned out for the best. I did come VERY close to putting my rotary hammer through a water line too but I didn't so I'll take the win. Thanks for all your help!
     

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  9. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Joined:
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    Occupation:
    Retired Systems engineer for defense industry.
    Location:
    New England
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