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  1. #1
    Join Date
    Dec 2013
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    1

    Default When do you use shower membranes?

    I am having a new shower built in my bathroom and my contractor is using Hardie board without a membrane. The shower is going to have tile installed over the Hardie board with thin set. Shouldn't he be using the membrane too to make it water tight?

  2. #2
    Join Date
    Jul 2010
    Location
    SoCal
    Posts
    5,103

    Default Re: When do you use shower membranes?

    CBU is not waterproof, I'd stretch 6mm plastic on the walls before I hang it.

  3. #3
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    975

    Default Re: When do you use shower membranes?

    Quote Originally Posted by Jod View Post
    I am having a new shower built in my bathroom and my contractor is using Hardie board without a membrane. The shower is going to have tile installed over the Hardie board with thin set. Shouldn't he be using the membrane too to make it water tight?
    A pvc membrane should be used on a shower floor when a mud base is used. For walls, tarpaper or heavy plastic sheeting is fine. It needs to overlap the pan liner. A shower pan can't be made with CBU because there would not be any slope. A special drain fitting with weep holes is also employed to allow water that permeates the mud bed a way to drain.
    For reasons like that, we have switched over to Schluter system shower pans, they have built-in slope, and you tile after swaddling the whole shower surround in Kerdi membrane, which is applied right over the drywall using thinset.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  4. #4
    Join Date
    Dec 2010
    Location
    Houston Texas
    Posts
    2,371

    Default Re: When do you use shower membranes?

    What they said plus,

    All ceeement board manufacturers require the seams to be taped and floated.

    IMHO a surface membrane such as kerdi is superior to sheeting behind the ceement board especially if there is a bench or niche involved.

  5. #5
    Join Date
    Jan 2008
    Posts
    1,109

    Default Re: When do you use shower membranes?

    The way you describe things is a future failure waiting to happen. Tile installations are not waterproof in and of themselves. Thus the use of membranes, being a more modern and better way than using poly to waterproof, is what we do here because done properly they cannot leak ever period.

    I like doing jobs that never require warranty work!

    Phil

  6. #6
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    975

    Default Re: When do you use shower membranes?

    I forgot to state that you want a mud pre-slope underneath the PVC liner so the weep holes work and the mud bed stays as dry as possible. Without the pre-slope things tend to get wet and stay wet, which means that a stone tile floor turns darker and looks water-logged, which it is.
    Casey
    Remove not the ancient landmark, which your fathers have set.

  7. #7
    Join Date
    Dec 2013
    Location
    Montreal Canada
    Posts
    96

    Default Re: When do you use shower membranes?

    don"t let him do it, i have repaired many of these handy man showers. get a license contractor to give a price with a membrane, and a guarantee.

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