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  1. #1
    Join Date
    Oct 2011
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    19

    Default NO thinset between Hardibacker and subfloor

    My contractor told me that despite hardibacker installation requirements he did not need to put thinset between the subfloor and hardibacker as long as he nailed the hardibacker down well.

    Should I have him take it up and put the thinset down?

  2. #2
    Join Date
    Jul 2010
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    Default Re: NO thinset between Hardibacker and subfloor

    You contractor is correct, providing he placed a 6 mm moisture barrier between the two.

    I'd use screws instead of nails and follow the screw schedule precisely.

    You use thinset to set the porcelain tiles on the hardibackers.

  3. #3
    Join Date
    Oct 2011
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    19

    Default Re: NO thinset between Hardibacker and subfloor

    No moisture barrier was used between the two.

    He did not use a vapor barrier underneath the tub surround hardibacker he put up as well. The wall is interior with no insulation.

    Thank you!

  4. #4
    Join Date
    Dec 2010
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    Houston Texas
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    Default Re: NO thinset between Hardibacker and subfloor

    I will politely disagree with my colleague. TCNA guide lines are very clear as well as manufacturer instructions. The board was installed incorrectly and should be removed.

    The sheet vinyl or plastic underneath can do more damage than good.

  5. #5
    Join Date
    Mar 2009
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    1,387

    Default Re: NO thinset between Hardibacker and subfloor

    Howdy go to the John Hardi web page an look at the best practices ( more information the then instruction section my opinion0 an the instillation instruction pages- very informative.
    Any an all of my comments are just my opinion and not to be confused with facts.

  6. #6
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    Default Re: NO thinset between Hardibacker and subfloor

    Quote Originally Posted by HoustonRemodeler View Post
    I will politely disagree with my colleague. TCNA guide lines are very clear as well as manufacturer instructions. The board was installed incorrectly and should be removed.

    The sheet vinyl or plastic underneath can do more damage than good.
    Thanks Houston for correcting me...I was thinkind a different scenario!

  7. #7
    Join Date
    Dec 2007
    Location
    Tennessee
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    1,381

    Default Re: NO thinset between Hardibacker and subfloor

    In a This Old House magazine issue a couple of years ago, the late Joe Ferrante recommended using construction adhesive instead of thinset under the cement backer board on the floors. I followed this advice and it has worked for me. I did not use a vapor barrier on the floor except in the shower pan, but I did use tar paper behind the hardi board on the walls. BTW, I did not use the hardi board brand of cement backer board on the floors but I did on the walls.

  8. #8
    Join Date
    Dec 2010
    Location
    Houston Texas
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    2,360

    Default Re: NO thinset between Hardibacker and subfloor

    When used on the walls sheet plastic or tap paper can be used as a moisture barrier behind ceement board. It should be overlapping the tub flange. The ceement board should almost set on the top of the tub flange, firmly against the studs and not sloped out at the bottom from overlapping the flange.

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