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Thread: Help! Tiled shower drain leaking

  1. #1

    Default Help! Tiled shower drain leaking

    I finished my large walk-in double shower last year. Today was under the house and noticed there is a leak. Removed some insulation and see that the subfloor around the shower drain is black with moisture. The area around the drain appears to be the only wet area. I really hate to tear up the tile. Any suggestions on what might be causing the problem. My only guess is a bad seal from the PVC liner to the drain. Any chance i can repair this from under the house instead of tearing up tile?

  2. #2
    Master Plumber master plumber mark's Avatar
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    Feb 2005
    indianapolis indiana - land of the free, home of the brave....
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    Talking installed correctly???

    Are you sure you installed it correctly????

    I recently went to inspect a 10k bathroom remodel

    where the "plumbers" actually used a normal pvc
    shower drain and simply lapped the membrane into the crawl space..
    and the n poured concrete right up to the shower drain...
    and it leaked in less than two months....

    did you use the right type of shower pan drain with the
    locking clamps to lock down the membrane??

    if you didnt , then you are screwed

  3. #3
    Moderator & Master Plumber hj's Avatar
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    Aug 2004
    Cave Creek, Arizona

    Default drain

    No way to reseal the membrane to the drain, but there should also not be a leak in the tile that would allow water to get to that point this soon after construction was finished.

  4. #4

    Default Tear up the tile

    Installing tiled showers for a living I can tell you that about the only way to correctly fix the problem is to start removing tile to get at the root of the problem. Installing tiled showers with tiled floor in the shower leaves no room for shortcuts!
    1. The drain that was installed should have a thin base of concrete underneath it to create the pitch for the membrane along with the base of the drain containing 4 bolt holes.

    2. The membrane should then be installed over the first layer of concrete, over the drain and up at least 4" along the walls before the concrete board is put on the walls. Feeling for the bolts on the drain, cut outs are made for each bolt and the top portion of the drain is bolted over the membrane cutting out the center of the membrane over the drain hole itself.

    3. Before the final layer of motar is applied over the membrane, pea gravel should be placed around the weep holes of the installed drain so they dont clog up with concrete. The weep holes are there in the event water penatrates the surface anywhere on the floor which in turn allows leakage to continue to drain through the drain and not back up on top of the membrane.

    4. Using grout addmix to give the grout strenth and flexibility prevents cracking down the road.

    5. After grouting a premium gold sealer is ALL I use to ensure the grout NEVER alows water to penetrate it.

    Who ever installed your shower should have followed these basic procedures or your always going to have trouble down the road as is evident already. I do agree that the shower should not be leaking at all if the grout job was done properly and sealed properly. Have you taken the trap apart under the floor to see if the installer piled grout, concrete or other debris into the drain as part of the installation causing it to slightly back up and water is maybe entering a crummy job of joining the top flange to the pipe going into the trap?
    Last edited by tonykarns; 06-09-2007 at 03:51 PM.

  5. #5

    Default leak

    I did the install myself and followed all the correct procedures that you listed. The only thing I can think of is that there is not a good seal from the liner to the drain. If i start removing tile, how do i get up the mortar under the tile to get to the liner and drain without tearing up my liner?

  6. #6
    Homeowner geniescience's Avatar
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    Nov 2005
    humid summers hot, humid winters cold


    to answer this question and any other question, we need to know more. PVC liner is all we know so far. Which drain, did you clamp it, how do you know you did it right, etc.


  7. #7

    Default If you did

    If in fact you did everything I suggested as you say you have, when installing the liner, then either you have one of two problems:

    1. The liner has a hole in it which could have been caused by a sharp stone in the concrete installation.

    2. The plastic drain has a crack in it or bad joint seal from overtightening the top portion of the drain during installation.

    Even if you remove the tile surrounding the drain area and there is a leak in the membrane located somewhere other than the center of the drain area then you really have a problem.

    I also would refer to HJ's response: How is water getting through the grout in the first place?

  8. #8

    Default removing tile?

    On close inspection there is a small hole in the grout line between the floor and wall. Actually it is in the silicone which was used for the transition from wall to floor tiles. It may be accounting for how the water is getting to the liner, but of course doesn't explain how the water is getting to the subfloor. The liner was brought up 8 inches on the walls behind the hardibacker. The drain i used is a clamping type i don't recall the brand. I'd really appreciate any tricks of the trade on how to get down to the drain / liner without tearing out the drain. The usual method of removing mortar is hammer and chisel after the tile is removed with a dremel tool. Chisel around liner - would not be good. I am assuming that the leak is at the drain, because that is the only place i am seeing the moisture in the subfloor from underneath. Of course its possible that the water is getting through the liner, than flowing on top of the pre-slope down to the area around the drian. I've included pic of drain
    Attached Images Attached Images  

  9. #9
    Master Plumber Dunbar Plumbing's Avatar
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    Apr 2005
    Northern Kentucky/Greater Cincinnati Area


    Certainly never had these problems with sheet lead shower pans. Got your daily dose of lead poisoning and that gray foot syndrome was the reminder.
    Read what the end of this sentence means.

  10. #10
    Homeowner geniescience's Avatar
    Join Date
    Nov 2005
    humid summers hot, humid winters cold

    Default little diagnostics

    flashPD, since you have access underneath, I can understand your wanting to do a little diagnostic testing before breaking the tiles around the drain. If I had your situation, I'd stopper the drain, fill the drain pan with water to the brim, go underneath for a few hours, remove some material from around the drain to figure out whether the leak was fast or slow, coming more from one side or the other, and whether it was coming from under the clamping drain (water seeping outside of the drain pipe). I'd try to locate the edge of the PVC pan liner material under the drain flange.

    The problem is serious so I wouldn't be concerned about the fact that cutting stuff out will weaken the support around the drain. There is still the tile and thinset, and I'd not stomp on the drain while showering no matter how upset I was.


  11. #11


    A tiled shower floor is going to let water through. That's the reason for the shower pan. The pan is the watertight fixture, not the tile and grout.

    A tiled floor is supposed to breathe, so sealing it up tight is not the way to go. The sealer used should be moisture transmissible. As new water enters the mud bed through the tile and grout, the old water is pushed toward the drain weep holes. That's how the thing works, so if you have a leak it's the fault of the pan or drain, not the tile and grout.
    John Bridge, Ceramic Tile Setter :-)



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