Setting Americast tub in mortar with grid on bottom

Discussion in 'Plumbing Forum, Professional & DIY Advice, Tips & ' started by justinae, Feb 16, 2012.

  1. justinae

    justinae New Member

    Messages:
    49
    Location:
    Portland, OR
    Just got the tub and ready to set in a mortar bed. I have one question first. I plan to cover the mortar in plastic, but the bottom of the tub is a grid with cavities about 1" or so deep, lots of them. My concern is that the plastic will prevent the mortar from completely filling the cavities and I'll have a bunch of small air pockets. I don't think it would affect the tub in terms of flexing because they would be so small, but still wonder. I could go without the plastic, but that just flies in the face of conventional wisdom for preparing for when the tub will eventually come out.

    thoughts?
  2. johnjh2o1

    johnjh2o1 Plumbing Contractor for 49 years

    Messages:
    1,141
    Location:
    South*East
    I don't think American Standard recommends setting there tubs in mortar.

    John
  3. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,249
    Location:
    Cave Creek, Arizona
    A/S says not to set it in concrete, but even if you did it, the grid is what supports the tub, NOT the air pockets.
  4. justinae

    justinae New Member

    Messages:
    49
    Location:
    Portland, OR
    I called them and they said no problem it won't void the warranty. The instructions even provide it as an option.
  5. justinae

    justinae New Member

    Messages:
    49
    Location:
    Portland, OR
    From the manual:

    "INSTALLATION - BEDDING MATERIAL (MORTAR, SANDMIX, ETC.) IS ACCEPTABLE. SUB FLOOR MUST BE STRUCTURALLY SOUND & FREE OF MOVEMENT / FLEXING"

    This may sound naive, but if there were several small air pockets in the grid, could condensation collect in there or have some other undesirable consequence or am I over thinking it?
  6. ballvalve

    ballvalve General Engineering Contractor

    Messages:
    3,261
    Location:
    northfork, california
    Overthink.....Dont sweat the air pockets and forget the plastic. It WILL all come out on demo day.

    If you still cant sleep, butter the bottom with plaster of paris to fill the voids and in a half hour you can turn it over. Mortar shrinks when it sets, unless you do a very dry mix with almost no slump. That is worth thinking about.
    Last edited: Feb 16, 2012
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