I Need Advice Before I Tile Shower

Discussion in 'Shower & Bathtub Forum & Blog' started by Rasta Linus, Jun 25, 2014.

  1. Rasta Linus

    Rasta Linus New Member

    Messages:
    6
    Location:
    Texas
    In the picture I have attached I circled little bumps that the Redgard or thinset made and I'm wondering if I will needing to be shave them down before I tile? When they are removed it leaves a hole in the membrane and I guess I will be patching each one if y'all think they need to be smoothed out. Thanks for any help!!

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    DiegoMello likes this.
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,268
    Location:
    New England
    You'll have problems if you don't get rid of them. BTW, there is a min/max on the coating's thickness, did you happen to use a wet film gauge to check? In this case, more is not necessarily better, and less may be worse. Only if you are setting something like a thick stone tile or a very large one where you need to use a medium bed mortar would you possibly be able to leave the bumps there, but even then, it may be a pain.
  3. DougB

    DougB Member

    It's best to sand the thinset before you apply the waterproofing. I used a coarse 3M sanding sponge.

    Also, what are those vertical striations in the Red Guard?
  4. Rasta Linus

    Rasta Linus New Member

    Messages:
    6
    Location:
    Texas
    That's where the Redgard has not been applied thick enough; they're in the concrete board.
  5. Rasta Linus

    Rasta Linus New Member

    Messages:
    6
    Location:
    Texas
    I really hate that I didn't sand before I put the redgard on. Oh well, I'm just going to go through with a utility knife cutting them off and then reapply a little redgard to patch it back. I am putting up 12"x24" tiles so maybe a little unevenness won't be a problem. I'm going to do my best to get rid of them though. Thank you
  6. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,268
    Location:
    New England
    Industry standards want an even flatter surface for big tile than for smaller ones! The only potential saving grace is that unless they are VERY flat with no cupping or warping or twisting (put two of them together face-to-face and check), you should be using a medium bed mortar to install them, and that CAN (not necessarily needs to) be reliably thicker than thinset. Keep in mind, thinset is NOT designed for anything thicker than 1/4" thickness installed (nominally, 3/16" is the design goal with most). If applied thicker than that, it is subject to shrinkage and cracking, not something you want underneath your tile. A medium bed mortar is designed for thicknesses up to about 3/4" or so (while there's an industry spec on thinset, there is no testable spec for a medium bed mortar on max thickness...IOW, you have to go on the manufacturer's installation instructions, and that varies by brand and product). You can only reliably get a good bond and a good result with a thinner layer when the tile AND the surface are perfectly flat and plumb...that can happen, but it is not the norm.
  7. Rasta Linus

    Rasta Linus New Member

    Messages:
    6
    Location:
    Texas
    jadnashua, thank you very much for your input. I will be using a medium bed mortar on these tiles.
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