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Prefab Shower Base (Sterling) install

bk1000 | Posted in General Discussion on February 2, 2008 06:05am

I’ve got a 48″ shower stall going in. Pre-fab Kohler Sterling “Ensemble” in three parts (base, back, walls)

My plumber is balking at the install because this is an 1800s house and the floors are off-level. About 1″ over 48″ run left to right (it’s it’s un-level both side to side and front to back).

I think I found the combination of shims in the corners that levels it, but it needs more support than some shims.

Here’s what I’m thinking. Comments appreciated (useful comments, that is):

– Leave the shims in place,
– dam around the hole already cut in the floor for the center shower drain (so the mortar doesn’t spill into the basement)
– form up the front of the shower, to keep the mortar in place (mortar will end up with a 1″ reveal in one corner, but I’ll use some kind of base molding to hide)
– pour in cement to level,
– press in the shower base, pushed down to the shims, most of which will be under the cement level,
– let dry and done.

How much mortar would I need? I’m thinking the formed ridges of the shower base only need to be touching the mortar, not swimming in it. Correct?

Final question — my plumber says he’d use drywall compound, but the install info says explicitly that’d void warranty. And, given the large gap to make up, I’m thinking joint compound wouldn’t hold up long term.

What do you think?

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Replies

  1. mike_maines | Feb 02, 2008 06:33pm | #1

    Do what you suggest, with mortar mix.  It should be damp, well-mixed and a bit crumbly.

    No way on the joint compound, unless he means Durabond setting-type compound which might work but mortar's the accepted method.

  2. Jamwats | Feb 02, 2008 07:17pm | #2

    I ran into this situation in an older house we redid.  All of our showers used Swanstone bases that sound similiar to your Kohler.  When I ran into the same issue you have (floor out of level almost an inch) I came up with a similiar solution that I ended up using on all 3 of the shower bases because it worked out so well.

    I was worried about any sort of mud base cracking because of flex in the subfloor (you didn't mention what kind of subfloor you have), so I started out by screwing down a sheet of Hardi-Backer on top of a good quality Thinset.  On the base that was out of level, I actually started building up the low side during this step (use more thinset on this side).

    With the shower base, I have never liked the hollow feeling of these kind of bases (but the budget didn't allow for a tile shower floor), so I decided to fill up all those voids with a mud base.  I turned the bases upside down and just packed in a mud base into all those voids, even the curb.  I also learned that the base needs to be well supported and flat while upside down (not twisted).  The weight of that mud can twist the pan otherwise.

    Once that dried, I treated the shower base lilke a giant tile and used thinset to lay it on the hardi-backer.  I back-buttered the base and was actually able to get the out of level one back where it should be.  These bases don't have much slope to them, so it's critical that they're level.

    I have never heard of anyone trying this before, but it's what I came up with to solve this problem.  I am very pleased with the end result, it has been a year now and those bases are dead level and very solid feeling underfoot.  I'm open to any suggestions on possible problems or issues anyone foresees doing it this way.  Hope this is helpful -

    Jamie

  3. User avater
    EricPaulson | Feb 02, 2008 09:16pm | #3

    These types of units are typically set in Structolite; a light weight perlited gypsum product.

    I'll bet you can find that fact in the instructions!

    And if your plumber doesn't know this, get another one.

     

    [email protected]

     

     

     

     

    1. bk1000 | Feb 03, 2008 12:46am | #4

      >"These types of units are typically set in Structolite; a light weight perlited gypsum product.I'll bet you can find that fact in the instructions!And if your plumber doesn't know this, get another one."<You can find the below reference from the installation instructions at http://www.sterlingplumbing.com/onlinecatalog/pdf/1064904_2.pdf page 13To wit:
      "IMPORTANT! Mortar cement is required to level an uneven subfloor. Do not use
      plaster, gypsum cement or drywall compound for this application, as these materials
      do not provide adequate structural support.
      Spread a layer of mortar cement on the subfloor where the receptor supports will
      be located."You assume I didn't read the instructions, only to give me directions that the instructions specifically counter. Hope you don't regularly insult people and then give them wrong advice on the job. Sheesh.

      1. bk1000 | Feb 03, 2008 12:52am | #5

        Thanks Mike and Jamwats. This approach made sense to me, so I'm glad to hear some validation. I'll think about the backer board approach. I don't want to raise the floor too much, but this might be a way to "pre-level", then put the receptor into thin-set. That sounds easier than using my shims approach. I know what you mean about the base always feeling "flimsy" but I'm a little nervous with loading the base with mortar, then trying to turn it over. I'll look at it again, and see if I can get comfortable with the approach.

        1. User avater
          BillHartmann | Feb 03, 2008 03:08am | #8

          You can setup some forms that are tapered to level the floor.Then either use self-leveling or a concrete patching material that will cover that thickness and go to feather edge. Some or limited to 1/2" or need to layers.I used a product that worked like sand mix. But instead of sand it used an ultra fine silica power.That gives you a flat surface to work with.Then if need or desired you can add other material to support the base when itis installed.But this breaks it into 2 steps wich gives a flat surface to support the base around all of it's edges and any ribs that it has..
          .
          A-holes. Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.

      2. jayzog | Feb 03, 2008 02:10am | #6

        Structolite has been the stuff for setting shower bases and tubs forever, and it will work fine.

         I don't think Eric gave you the wrong advise or insulted you, lighten up.

      3. User avater
        EricPaulson | Feb 03, 2008 02:42am | #7

        Having read all the ways that you were considering "leveling" the base with shims, wonderboard, thinset etc., I made an assumtion that perhaps no one had taken the time to read the instructions.

        We are, after all, men here.............apparently my assumption made an azz out of one of us.

        Have fun.

        Please post again in five years when you have a cracked base.

        Eric[email protected]

         

         

         

         

  4. User avater
    JeffBuck | Feb 03, 2008 03:41am | #9

    no matter how U do it ...

    wood or concrete.

     

    why not level the pad first ...

    then simply set the shower on top of that now level surface.

     

    U know ... almost like it was meant to work?

    Jeff

     

     

        Buck Construction

     Artistry In Carpentry

         Pittsburgh Pa

    1. bk1000 | Feb 03, 2008 04:52am | #10

      You mean just pour a level pad? Yeah, I was just thinking about that tonight. I think I'm over-engineering this. Problem was, we could've leveled the floor the right way, but we didn't need to with the original plan. Now, the HO changes her mind, and wants to move things all around. New location is not level, but so much other work has been done. I don't have time to start over with this. Just want to wrap up and move on to the next thing, but (of course) not short change her in quality.Thanks for the input.

      Edited 2/2/2008 8:54 pm ET by bk1000

      1. User avater
        JeffBuck | Feb 03, 2008 05:45am | #11

        pour a level pad or tear out that part of the original sub floor, rip some tapered 2x's to shim the whole deal up then lay a piece of 3/4 ply.

         

        if it's a wood floor I'd probably go wood ...

        concrete floor pour a level pad.

         

        whatever way works best with the original construction.

        but I'd rather work off a level pad ... then everything else is easier.

         

        Jeff

        Jeff    Buck Construction

         Artistry In Carpentry

             Pittsburgh Pa

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