Shower mold/caulking problem

Discussion in 'Plumbing Forum' started by nobody102, Oct 29, 2013.

  1. Oct 29, 2013 #1

    nobody102

    nobody102

    nobody102

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    We have a tile shower stall that was built several years ago. The pan is composed of a membrane liner and concrete pad, with tile over that. The caulking around the perimeter of the floor would get moldy every 6 months or so, and I have to replace it. I think there is moisture behind the caulk that was causing the mold growth. When I remove the caulk, it was soft and wet. There is no leak that I can see. I’ve had a fan blowing in the shower for a week on/off, and there was still moisture in the gaps. I don’t want to fill the gaps again w/o knowing if there is a bigger moisture problem, and how to correct it. If you look at the pictures, the gap between the wall/floor varies from almost none to 3/16” Should I use grout to fill the void, or caulk? Any suggestions appreciated! Images are here -
    http://imgur.com/a/fLo1V

    [​IMG]
     
  2. Oct 29, 2013 #2

    CallMeVilla

    CallMeVilla

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    Sorry, but that is not a very good tiling job. Gaps that wide are not acceptable. The tile should have been cut properly in the first place.

    This might be your problem because wide gaps can allow water to infiltrate. Important questions (not trying to insult you, just being systematic):

    -- Did you dig out all the old caulk or grout?
    -- Did you clean the line with denatured alcohol to remove all traces of old silicone above and below the caulk line, then wipe it as clean as possible?
    -- Did you use mold killer (laundry bleach) before re-caulking?
    -- Did you completely dry the gaps with a blow dryer before caulking?
    -- Did you apply a properly sized bead of caulk, smoothing it with a finger dipped in water?
    -- Did you let the caulk set-up overnight before getting it wet?

    If you did all of this, then the water might be infiltrating through your concrete because it has accumulated in the membrane. THAT is a big issue ... We will have to solve this once you are sure your did the re-caulk correctly ...

    http://www.thisoldhouse.com/toh/skill-builder/0,,203700,00.html

    Have fun in the shower!
     
  3. Oct 29, 2013 #3

    nobody102

    nobody102

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    Thanks for the response. See below:

    -- Did you dig out all the old caulk or grout? Yes
    -- Did you clean the line with denatured alcohol to remove all traces of old silicone above and below the caulk line, then wipe it as clean as possible? - used rubbing alcohol, Yes
    -- Did you use mold killer (laundry bleach) before re-caulking? Yes
    -- Did you completely dry the gaps with a blow dryer before caulking? No
    -- Did you apply a properly sized bead of caulk, smoothing it with a finger dipped in water? Yes.
    -- Did you let the caulk set-up overnight before getting it wet? Yes

    I am going to try to let it dry our for as long as possible and try again. If there is water in the liner, Ripping apart my shower is not an option.
     
  4. Oct 29, 2013 #4

    handypierson

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    There is definitely a water issue. Grout should be sealed twice per year and repaired/replaced as it fails. Caulk is used to seal corner joints ONLY.

    If you have been pumping air on this location for a week and there is still visible water, it's possible you have a leak in the plumbing that is getting behind the tile. Chances are that you have a potential mold situation and should really consider ret-tiling the shower.

    Good luck
     
  5. Oct 29, 2013 #5

    nobody102

    nobody102

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    There is no visible water at this point. So I should apply GROUT between the wall/floor, not caulk? When you say corner joint, you mean literally, just the 4 corners?
     
  6. Oct 29, 2013 #6

    nealtw

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    No, he means all corners including to the floor. Before ripping and tearing if you fear there is water problems with a shower cut into the drywall in the next room and inspect things from the outside.
    It can take a long time for water to come out if the water down to the membrane.
     
  7. Oct 30, 2013 #7

    handypierson

    handypierson

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    Thanks for the clarification, Neal. I meant any joint that changes planes.

    As far as cutting walls, that is an excellent idea. Choose a spot where you will be able to see both the supply lines AND the drain. Sometimes the drain seal fails, allowing water to seep under the tile.
     
  8. Oct 30, 2013 #8

    nobody102

    nobody102

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    So once I get everything dry and tidy, given some of the larger gaps, should I be filling them with sanded GROUT or sanded caulk, or what material?

    Thanks,
    Leor
     
  9. Oct 31, 2013 #9

    nealtw

    nealtw

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    Sanded grout and then cover that with bathroom silicone, redo the corners between the sides and then seal all the gout lines with 5% silicone.
    But I'm no expert with this stuff, others may have better ideas.
     
  10. Oct 31, 2013 #10

    CallMeVilla

    CallMeVilla

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    Tiled showers work best with sanded grout IF the grout lines exceed 1/8" (they do). Sanded grout is stronger than unsanded ... The fine sand prevents the grout from shrinking too much as it cures. That’s why it is used for larger grout lines and should be used for tile floor installations.

    Use a tool to push the grout into the grout line, depressing it. Allow to dry and you can caulk over it if your choose. If you do not caulk it, it MUST be sealed with grout sealer (I typically apply three coats).

    BTW, I NEVER use grout on the tile line between a wall and a tub. When the tub is filled, it flexes, causing the grout line to fail. Always use caulk to seal the tile line between the tub and the tile.

    Nontheless, Nonbody needs to be sure there is no leak inside the shower pan. Cutting a little drywall to inspect the area is the best approach. I did this with a shower leak and pinpointed the area almost immediately.
     
    Last edited: Oct 31, 2013
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