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Thread: Building a Shower Pan - Recommended Mortar Mix?

  1. #1

    Default Building a Shower Pan - Recommended Mortar Mix?

    I have gutted my master bathroom including removing the original cast iron tub which I'm replacing with a ceramic tiled shower. I want to make certain that I have a trouble and leak-free installation, so I've been doing a lot of reading on building shower pans. Although there are a number of systems out there that claim to make the job easier (Schluter, Kerdi, Quick-Pitch, Kirb-Perfect, etc), I've decided to build a traditional pan and curb using a mortar bed. The process I plan to use is pretty much as outlined on the North American Tile website:

    Building a shower pan with pre-sloped mortar bed, liner and curb.

    I have a few questions:

    1. Anybody see anything pitfalls with this method? Any suggestioned variations on the idea?

    2. I've read of varying recommendations as to the preferred mortar mix for the sloped pan. Supposedly, a brick mortar mix (ie: Quickcrete Mortar Mix) is easier to work with, although this may not be as strong as other materials. Portland Cement mixed with sand (1:5) is also recommended. Some people recommend using latex, others say water only. Any recommendations?

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


    No lime (as in the brick mortar), just sand and portland cement. WOrking with it is like working wet beach sand. It does not flow and is porous (which is required to work right). It will be sandy on top, but it is great in compression which is what you want.

    Following any one of the TCNA approved methods will give you a long-lasting shower. Personally, I still think Kerdi is the best one. There are distinct advantages of using a surface waterproofing layer - there is much less to get wet, the whole thing dries out faster. Tile and grout are not waterproof, and some moisture will get underneath (thus in a conventional pan, the sand and cement mix is good since it allow this moisture to migrate to the weep holes). With a Kerdi shower, you only need one mortar bed, then apply the membrane rather than building two making for a lower shower floor height, getting your liner to sit flat without bowing out the corners or bottom edges of the cbu, and another layer. In a conventional shower, the cbu and setting layer of the pan can get and stay damp for a long time if the shower is used a lot; doesn't happen with a surface membrane. Plus, with Kerdi, you drywall the walls and the curb...much easier and quicker. No need to tape and mud the corners or joints, either as the membrane performs that task. You will need a rich mud for over the kerb, as it needs more stikum and strength to hold together on the lath in that thinner layer. A Kerdi curb can be smaller because it doesn't need as much mortar over it or the lath.

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

  3. #3
    ACO Shower Drain Sales johnfrwhipple's Avatar
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    Jul 2009
    North Vancouver, BC
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    Default The 'BEST' Mortar Mix for your shower depends on the design of the shower

    post(s) deleted by John Whipple
    Last edited by johnfrwhipple; 03-17-2014 at 04:31 AM.

    jfrwhipple@gmail.com - www-no-curb.com - 604 506 6792

    Always get construction advice double checked by your local city hall. Flood Test Every Shower - Every Time.

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