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  1. #11
    Join Date
    Mar 2014
    Posts
    8

    Default Re: Tiling bathroom floor with DITRA Underlayment

    Quote Originally Posted by HoustonRemodeler View Post
    TCNA is the Tile Council of North America which sets the industry accepted standards for setting tile, making tiles, along with installation methods and materials. They've been printing these guidelines for 50 years. Recently they have incorporated natural stone and glass tiles. The TCNA works side by side with ANSI, the UPC, and international bodies of related industries.

    Ditra isn't waterproof on its own. To achieve waterproofing, the sheets must be seamed with kerdi band as prescribed by Schluter. Ditra does offer some measure of in-plane sheer movement protection, which is its main claim to fame for the last 27 or 28 years. There is no membrane which offers protection from vertical displacement. Ditra is used to replace CBU for several reasons; moisture management, thickness (DitraXL for example) labor savings, weight savings, speed of installations, and integration into an overall waterproofing system such as balconies or decks.

    All of the manufacturers of CBU's agree that ceement backer boards add nothing to the reduction in deflection. Visit their websites to double check if you'd like. You will find no such claims of reducing deflection even when properly installed.

    If you want to discuss the measurable, scientific standards for the "Jump Test" I'd be happy to do so. But please, for the sake of the DIY folk reading along, do not try to pass the Jump Test off as some sort of industry standard which they should find acceptable, even if you do.

    Please for the sake of DIY folk reading along, don't go on random DIY forums and attempt to sound high-headed for no other purpose than to sound correct about everything. There ya go. We can each make plea's and since neither of us are admins we are both free to ignore them. What a waste of words.


    One can say something is fecal matter by conducting a mass spectrographic analysis on it, or one can just see if it smells like fecal matter. Both are technically scientific methods of testing to see if something is fecal matter. If you can jump on your sub-floor and it visibly bounces / flexes up and down within a 1-2 foot area around your feet, you're going to have cracked tile or grout sooner rather than later. It is an easy / DIY test and to say the least does not hurt anything. At best it is a final "smell test" to see if your installation stinks or not. I have used dozens of professional tile installation contractors in my state and most of them advocate doing this.


    Thanks for the info on the Ditra. After reading everything you've written about it and reading up on their website / watching installation videos etc., it seems like it suites very specific scenarios better than CBU. But I don't see how it could save time or labor costs as a general replacement. Seems a lot more complicated of an install process than using cement board which everyone is familiar with. In any case I'll withhold judgement till I've used it.

  2. #12
    Join Date
    Jan 2010
    Location
    Northern Virginia
    Posts
    1,180

    Default Re: Tiling bathroom floor with DITRA Underlayment

    Quote Originally Posted by maplemale View Post
    This is the first I've heard of this stuff...


    So, how strong does my sub-floor need to be? My test which has served me well over the years: If a 200lb guy can jump up and down on the hardiebacker, and it doesn't give / move at all, I'm good for tiling it. Usually I end up with 3/4 inch subfloor and hardiebacker. If my subfloor is something in the 5/8- range, I end up having to supplement it with more sub-floor and possibly blocking between joists to get the zero movement.


    I guess my question is, how does a DITRA underlayment help with any of that? Or does it? For instance, I can a get away with a 3/8 subfloor on 16 inch center joists or even TJs if I'm using this stuff? Or, is just a little bit of extra protection on top of my stable subfloor in place of hardiebacker? If that's the case, then it seems like it's more expensive and doesn't provide a whole lot of extra benefit?
    It is for decoupling the plywood (or concrete slab) movement from the tile job. Lateral (shrinkage/expansion) movement, not flex. You need to shore up/confirm floor system stiffness before proceeding with any large-format tile or stone job.
    No, it won't magically turn thin plywood into a stiff subfloor. It's better than hardibacker, because it's thinner, and it's waterproof.
    BTW a 3/8" subfloor is never structurally sufficient under any circumstance. 5/8" fir ply on 16" center framing is OK for carpet. It's a rule of thumb that you need 1 1/8" of plywood on 16" OC framing for tile jobs. The framing is ideally at least L= 1/480 (deflection factor 1/480 of the span length.) L720 is a factor safer but of course is more costly because of more material.

    Casey
    Last edited by Sombreuil_mongrel; 04-01-2014 at 11:26 AM.
    Remove not the ancient landmark, which your fathers have set.

  3. #13
    Join Date
    May 2014
    Location
    Southeast Texas
    Posts
    2

    Default Re: Tiling bathroom floor with DITRA Underlayment

    Quote Originally Posted by HoustonRemodeler View Post
    TCNA is the Tile Council of North America which sets the industry accepted standards for setting tile, making tiles, along with installation methods and materials. They've been printing these guidelines for 50 years. Recently they have incorporated natural stone and glass tiles. The TCNA works side by side with ANSI, the UPC, and international bodies of related industries.

    Ditra isn't waterproof on its own. To achieve waterproofing, the sheets must be seamed with kerdi band as prescribed by Schluter. Ditra does offer some measure of in-plane sheer movement protection, which is its main claim to fame for the last 27 or 28 years. There is no membrane which offers protection from vertical displacement. Ditra is used to replace CBU for several reasons; moisture management, thickness (DitraXL for example) labor savings, weight savings, speed of installations, and integration into an overall waterproofing system such as balconies or decks.

    All of the manufacturers of CBU's agree that ceement backer boards add nothing to the reduction in deflection. Visit their websites to double check if you'd like. You will find no such claims of reducing deflection even when properly installed.



    If you want to discuss the measurable, scientific standards for the "Jump Test" I'd be happy to do so. But please, for the sake of the DIY folk reading along, do not try to pass the Jump Test off as some sort of industry standard which they should find acceptable, even if you do.
    ~~~~~~~~~~~~

    I work with Paul and, if you want to trust someone that relies on the "Jump Test," God bless you.....but keep Paul's number. You might very well need it in the NEAR future. You wanna "Jump Up & Down" on the floor and try to convince any reasonable homeowner that you know what you're doing? Good luck with that......
    Last edited by Lazarus; 05-13-2014 at 05:53 PM.

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