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Slab Shower on old masonry partition walls

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  • Slab Shower on old masonry partition walls

    We are budgeting a bath renovation for a client. The demolition has been done and part of the scope involves converting the bath tub to s shower.

    The clients are looking at doing the walls in 2 cm slab (probably Statuary White) marble, with an accent of tile inset horizontally which will continue through the remainder of room, outside the shower. This means that there will be a seam/ joint in the middle of the wall.

    The exisitng walls are tile (which we have removed) over the plaster, over terra cotta and gypsusm block, which is a common material here for interior partition walls in early 20th century buildings. Removing the plaster finish from the block is likely to disturb the walls and damage the paneling in the dining room on the other side of the wall.

    The question become how to waterproof the assembly, Our plan would be to cut the chloralloy liner into the existing plaster so that the plaster is proud, much like durock is proud of the liner when doing a shower in typical frame construction. We would then put a water proof membrane on top of the plaster (probably kerdi or Noble TS) and set the slab and tile on this. I am concerned about moisture coming through the stone/ tile and damaging the plaster.

    The building is requiring a traditional Chloralloy pan, as they have had bad experiences with poorly done alternate receptors.

    Any thougths on adhesion and potential for issues with slab on the sheet membrane? We have done lots of tile over kerdi or other membranes, but not slab.


  • #2
    Re: Slab Shower on old masonry partition walls

    If they haven't had a problem with a Kerdi drain and pan, I would go that route. It is really the better system. If they can't get behind it in the pan, the probably wouldn't be comfortable with it on the walls. Test data shows incredible resistance to pounds of water pressure in properly installed Kerdi pans and it is easier to install that product correctly, than Chloralloy.


    • #3
      Re: Slab Shower on old masonry partition walls

      Hi Total,
      To simplify the installation and avoid compatibility issues, I recommend you pair Nobleseal TS with the Chloraloy. Since this is a non-standard use for the TS, I suggest you contact the Noble company for their recommendations. I have done this type of installation before and have found that one critical element - to enhance waterproofing (in corners) and prevent cracks between the slab and the tile accent strips - is the inclusion of movement joints. Refer to TCNA EJ171.


      • #4
        Re: Slab Shower on old masonry partition walls


        thanks, not quite sure why did not think to contact the manufacturer or consult the TCNA book which sits on a shelf above my desk.

        Sometimes we miss the obvious.

        thanks again


        • #5
          Re: Slab Shower on old masonry partition walls

          What I forget at times (and since I have worked on the TCNA Handbook committees and am a voting member of the ANSI committee whose standards form the basis for the TCNA Methods, I really do not have an excuse) is that almost every year new standards and methods are proposed, and many are voted in as part of the overall tile installation standards. I have often seen, in court cases, where an architect used tile installation standards that were ten years old, or older, and totally inappropriate for a project. Also, it is not uncommon for manufacturer's instructions to trump an industry standard. This is allowed and OK - and in accordance to the ANSI tile standards.