Install cast iron tub in mud?

Discussion in 'Shower & Bathtub Forum & Blog' started by Kmoninger, Nov 4, 2009.

  1. Kmoninger

    Kmoninger New Member

    Nov 4, 2009
    Kansas City
    We are remodeling our 2nd floor bathroom and have purchased a 72" Toto cast iron tub. The tub will be placed in the corner of the room and our carpenter has built a surround and a plywood base. The subfloor is in good condition.

    Our plumber intends to place the tub in a bed of cement mud but I have heard it's better to place shims under the feet instead. What would you recommend? I appreciate if several of you experts can respond as I need to get advice quickly. The tub goes in on Monday!

  2. thebigsee

    thebigsee DIY Member

    Sep 24, 2009
    Southern California
    From researching here and many other web forums, it's overkill.
    cast-iron tubs are the only tubs that DO NOT require to be set in mortar. They are so rigid and strong by themselves, they cannot possibly flex and subsequently fail. But if your plumber wants to do it, it certainly won't hurt it.
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  4. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Sep 2, 2004
    Retired Systems engineer for defense industry.
    New England
    A mudbed allows for exact placement and getting things perfectly level. Wood shims can compress over time as they dry out and from the repeated addition of the maybe 500# of water and a body or two sitting in it. The mudbed won't compress.
  5. johnfrwhipple

    johnfrwhipple BATHROOM DESIGN & BUILD for both Canada & the US

    Jul 20, 2009
    Design Work World Wide: Bathrooms Vancouver Area
    North Vancouver, BC
    Set it with Mortar Mix.

    Cement is the way to go. Shims can crack. Shims can shrink.

    I like designing the tub deck so that about 3/4" or a finger width of mortar mix can be used. We drop the mortar mix in all fluffy and good 1.5" plus in thickness. The tub gets installed and then the mortar mix squishes down and around leaving full support.


    This Kohler Tub is free standing and adjustable on four feet.

    Last edited: Dec 27, 2013
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