Redgard for tiled shower? Waterproof...

Discussion in 'Shower & Bathtub Forum & Blog' started by worrywell, Feb 24, 2008.

  1. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Except during a flood test, a typical shower should never see much of any liquid water on the liner; and, if it is constructed properly, any that does get there will flow to the drain through the weep holes, if that kind of a drain is utilized and the liner is properly sloped (people that put the liner flat on the floor deserve any grief they get!). If it is something like a surface membrane shower, there may not be any weep holes, and, since it is then immediately beneath the tile which should be bonded well with thinset, there couldn't be much liquid water there at all since the thinset and tile are nearly a solid mass, bonded to the surface membrane.

    Kerdi tends to bead water if you just drop some on the surface, so if you flooded it, it could take awhile for it all to become totally wetted, thus the initial drop in level. Then, any exposed thinset would absorb a little as well. Once equilibrium has been reached, except for evaporation, it should be stable. A drop after that reaching that initial equilibrium would indicate a leak.
  3. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  4. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  5. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    A big baking pan left out in my home, filled to the brim, was down more than an 1/8" in 24-hours. Now, add the fleece on the waterproofing membrane to the sides, and it could easily have been more. Vancouver's average humidity levels are pretty high. Some places are not. Then, throw in central heating, with or without humidification, and the variances you'll get can be significant from season to season and home to home. To state the level will not drop is condition dependent, and ignoring simple physics. Any evidence of moisture penetrating things is a cause for concern and remedy...a slight drop, may not be. Any rapid drop is a great concern.

    Your box, coated with Kerdi does not appear to be well adhered to the substrate with a full coat of thinset. For the material and seams to work, both they and the entire material needs to be properly embedded. I've touched a cardboard box, filled with ice and water for months, waterproofed with Kerdi only on the inside that was still intact, entirely dry. Installed properly, it does not leak. No special materials used...just Kerdi and thinset plus good technique. If you can't replicate that, you're doing something wrong.

    A Hyundai has a 10-year warranty on the drivetrain...a Mercedes 4-years...which is a better car? The length of a warranty isn't necessarily an indication of quality.
  6. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  7. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    I went away for two weeks and the (lid-closed) toilet bowl was down a couple of inches...relative humidity levels vary radically across the country. Flat saying any water sitting out will not drop in level is just wrong...it may be true in the summer without a/c and close to 100% RH, but not in many locales. All I can tell you is that I filled the pan to the brim - overflowing, and the next day, it was down over 1/8". No fans running (radiant heat), the pan sitting in the sink.
  8. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  9. ggoose

    ggoose New Member

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    Hello John,

    Interesting posts. I was wondering if you might elaborate on the process of setting the 3-piece drain using Redgard as the liner. I think I have it figured out from your photos, but am not quite sure.
    Thanks...:)

    ggoose
  10. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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  11. ggoose

    ggoose New Member

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    Thanks John...
  12. Jayw

    Jayw New Member

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    Iam at the stage where my shower floor is ready for tile. Couple questions:
    image.jpg
    1. Do I have to seal the bottom edge where Duroc meets floor with mesh tape?
    2. Wht do I use for sealing joints? Same thinset used to set tile?
    3. I have vapour barrier on walls and PVC pan liner... Can / should I use red guard?
    It seems that red guard on the floor will prevent water that gets through the grout/tile to get through dry pack to liner? Tht correct? If red guard is used will it not hold water at grout level, which I think would not be good?
    4. Red guard on walls seems more practical but I read somewhere it will trap mositure in if used on walls with vapor barrier.
    5. I made my curb a little too wide and in stages ( long story/nightmare ...wholly f is a neo angle hard for a first time!!) I had to create the front ( outside ) of the curb last, after the top and inside had set... The outside is rough and damaged on outside edge in one spot. Not sure if I need to correct or just leave small void under tile? Thoughts? If I do want to smooth it out do I use same cement as original or tile thinset or something else? Pic attached

    image.jpg

    Thks in advance
    J
  13. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    I see the wrong fasteners used and missing blocking.

    The holes for the water lines through the studs look to tight. I don't see any Donald Duck Clips clips on the wall studs either for the water lines.

    Is your shower's mud bed all graded to the drain? It looks off some how - almost like it is draining to the front left side.... Maybe it's just the angle.

    Before any waterproofing like RedGuard would be used we would first scratch coat the backer board and tape the seams. But your backer board is not being installed as spec'd - go look up the install instructions for this first.
    Last edited: Mar 15, 2014
  14. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    FWIW, the mesh tape and thinset on the joints of CBU are to tie the sheets together to approximate (as close as possible) a mudded, monolithic wall - it isn't really for sealing things. You don't need it between the bottom edge of the walls and the pan if that area is blocked well - read the installation instructions.

    IF you are going to use something like RedGard on it, the mesh and thinset must be done first and allowed to cure before you add the RedGard. Otherwise, you may just want to do it as you tile. Unlike drywall, you do NOT want your seam to end up with any hump, commonly used to hide the tape or mesh on the seam...you really want it nice and flat. Tiling over speedbumps is a major pain!

    Personally, RedGard is okay for a wall or say around a niche, but I prefer other methods. I think the average DIY'er will have trouble getting the proper thickness of the layers when it is used for waterproofing and avoiding thin spots or pinholes. While not expensive, most do not buy and use the wet thickness gauge. The stuff MUST be applied at the right thickness, and no, thicker is not better! The thickness must be between the min/max stated in the instructions or you might as well not install it in the first place.
  15. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    LOL - Now that comment I can agree with Jim. Except for the part of wanting a hump in drywall. We level coat all the wall and produce flat Level 5 drywall finishes.

    Your mentor like speed bumps. I think tons of showers have been butchered following this "Major Pain" of a shower...

    Here is a photo of John Bridge's Speed Bump Design

    [​IMG]
    Image Source

    Pretty sure there is a code (shower grading code TCNA & TTMAC) that requires no slope be greater than 1/2" per foot.

    [​IMG]
    Image Source

    http://www.johnbridge.com/articles/showers/accessible-showers/


    I think this is John Bridge's one and only curbless shower build. I might be wrong but I can find no other examples.
  16. johnfrwhipple

    johnfrwhipple Bathroom Design & Build - North Vancouver, B.C.

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    Improper Coverage of Red Guard

    File under "How not to install Red Guard"

    [​IMG]

    Coverage is far to thin.

    Tie in to the tub deck is poorly done.

    Almost perfect - but not quite.
  17. jim mills

    jim mills New Member

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    Any opinion on doing kerdi DS on the shower pan and taping the floor wall joint with kerdi band, then redgarding the walls? I hate kerdi overlap!
  18. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    No warranty from either company.
  19. jim mills

    jim mills New Member

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    Not too worried about the warranty. I doubt either company has ever paid a warranty claim anyway. I'm more concerned if there is any chance it would work. I believe JB even mentioned using it before on a compound curved shower surface.
  20. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    They all work if you are careful, follow the rules, and have good workmanship. Some are easier than others. With RedGard, there's a sweet spot, too little and it works as a decoupler, but isn't waterproof, too thick, and you risk other issues. Since it's hard to judge your exact wet thickness, and testing the cured thickness puts a hole in it, your best bet is an inexpensive wet thickness gauge and careful application.
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