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Thread: Mortar ok for walls but not floor?

  1. #1

    Default Mortar ok for walls but not floor?


    I'm using Simpleset brand, Thin-Set Pre-Mixed Mortar I bought from Home Depot for tiling my shower. So far it has worked very well on the walls. But, now that I'm about to tile the bottom 10" of the walls and the shower floor I noticed under 'Uses' it says on the container 'Do not use on shower floors or areas exposed to prolonged water exposure or steam.' I looked at the other pre-mix mortars (just for ease of use, Im new at this at Home Depot but I don't see anything on their labels about using them on shower floors or not.

    Do I now have to buy some of the mix your own stuff and discard the large amount of this pre-mix I still have? Thanks



  2. #2
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    That premixed is probably a mastic, not necessarily thinset. To be used in wet locations, it needs to be rated....if I remember it needs to be Type 1 designated.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    IMPO, mastic should be banned! Think about it, it stays soft in the bucket for what, a year or more? Then, you stick it in a spot where it will get damp again, maybe daily from a shower? Guess what, it can take months or more to set up fully, and then if it gets wet, it can re-emulsify - it only dries out, not sets. Real thinset, on the other hand is made with (among other things) cement, and once mixed with water will actually chemically change into something that will harden and be effectively permanent.

    If you read the fine print, few if any mastics are rated for use in showers.

    The thing might last, but you really want to use the real stuff (regardless of what it says on that bucket, it's NOT thinset) for the lower part of the shower and the floor...those areas get the most spray, and you have a chance of things not just staying soft and coming off the wall.

    Check out www.johnbridge.com for pro help on tiling.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4


    Thanks guys. Looking into this more I'm getting the drift that this stuff is exactly what I should NOT have used unfortunately. Me being a begginer at this stuff I made the mistake of taking the Home Depot tile 'experts' advice that this stuff would be best for a novice tiler to use.

    I've already spent several crappy weeks struggling to get hundreds of 3x6 'subway' tiles to line up half way decently and it has not been fun, at all. This far into it I'm not about to start over. I'll switch to something like Versabond for the bottom rows and the floor tiles.



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