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Thread: Shower pan install - over plywood or tile?

  1. #1

    Default Shower pan install - over plywood or tile?


    I am installing a pre-fab shower pan and need some advice. I have laid a 5/8" plywood over the subfloor for a clean, level tiling surface. The manufacturer says I can install the base directly on the unfinished floor and tile around it. However, there are some opinions that I should install over a finished tile floor. Which should I do?

    One other question: should I lay some thinset mortar under the pan for stability?

    Thanks, Dave in Toronto!

  2. #2
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    It will work fine over the plywood. As to putting something underneath, often that is a good idea, but it depends. If you're tiling around it, the walls and floor will lock it in place. But, if the thing doesn't sit flat or has voids underneath, You probably want to put more than thinset under it. Often, they recommend deckmud (a mostly sand and cement mix). The goal is a fully supported (not necessarily adhered) pan that is both level and not able to rock or deflect. If you ever decide to remodel, having it adhered might give you or the remodeler unnecessary fits.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  3. #3



    Thank you for the advice. Instead of trusting the plywood to support the base fully, I will use deckmud as an added precaution. Thanks, again.

    Dave in Toronto


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