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  1. #11
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    1,180

    Default Re: Drywall over tub flange

    Whenever I hear someone is planning to drywall a tub surround, then use mastic to adhere the tile, I move into emergency intervention mode, because these are two things that should never happen independently, much less in tandem.
    If you ask for tile mastic, that's what you will be sold. Thinset is not mastic, for cryin' out loud, even though it's used to stick something to something. In tiling nomenclature "mastic" is a specific material, not a generic term.
    I was being coy at times, and opinionatedly emphatic. I need to mellow out more, I guess. It's no skin off my nose if he uses rabbit-hide glue for his tile.
    S_M
    Remove not the ancient landmark, which your fathers have set.

  2. #12
    Join Date
    Jun 2007
    Location
    Fayette County, Ohio
    Posts
    5,803

    Default Re: Drywall over tub flange

    Sombreuil_mongrel I am not criticizing the information you provided, or your well founded concern. Just a reminder that you are dealing with DIYers, many times first time posters, that may not be familiar with tiling nomenclature and to harsh a stand sometimes scare posters away. It is sometimes very difficult to draw a line and tell someone they need professional help when they have sat and watched how easy every thing is on TV. Just be gentle, it may be their first time.

    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  3. #13
    Join Date
    Mar 2009
    Posts
    1,387

    Default Re: Drywall over tub flange

    Quote Originally Posted by Sombreuil_mongrel View Post
    Are we talking about a tub without an integral surround? Just a tub, right?
    So drywall down to the tub flange is not the greatest idea; the only product to make that situation have any possibility of success is Kerdi membrane to waterproof it, but even then it's better to use a wallboard that will not break down when wet, like Durock cement board.
    Now, another snag, you said mastic, I heard you so don't deny it! Mastic is a very very bad thing for tub surrounds and showers. You will be doing the job over again very shortly, because all the tiles are guaranteed to fall off if you use mastic (or premixed thinset, for it is mastic + sand). You must, must, must use the proper thinset, determinant upon what kind of substrate and what type of tile you are working with. Thinset is made in many formulations from unmodified, which is just portland cement plus very fine sand, and the variations are created by adding various acrylic or other resins to the mix either in the dry mix or as a liquid additive. The more highly-modified, the longer it takes for them to set; plain portland will set without the presence of air, because it is a pure chemical reaction. Modified thinsets however DO require air, and if applied over a membrane or impermeable material (Redguard, etc) they would require months to harden. Stone tiles demand an unmodified thinset to avoid the bleeding out of the resin to the stone, which causes a permanent stain. White marble has to be laid in white thinset for a similar reason; a grey mortar would reflect through the white tile, resulting in an unsightly condition.
    Similarly, white mortars are called for under most transparent glass tiles that are not lined.
    You must get some straight answers and good free advice from your tile supplier as to what materials are appropriate for the job.
    S_M
    Hi S M. AAA+ you are the Man.

  4. #14
    Join Date
    Aug 2007
    Posts
    7,078

    Default Re: Drywall over tub flange

    Quote Originally Posted by JLMCDANIEL View Post
    It is sometimes very difficult to draw a line and tell someone they need professional help when they have sat and watched how easy every thing is on TV. Just be gentle, it may be their first time.

    Jack
    Stay in this business long enough and we ALL need a little professional help!
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

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