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Thread: Waterproof a Laundry Room?

  1. #1
    Questions from readers Guest's Avatar
    Join Date
    Nov 2005
    posts, emails and comments from readers reposted by Terry

    Default Waterproof a Laundry Room?

    I would like to know how to waterproof a Laundry Room floor that I am going to tile. I am using 1/2 " treated plywood over the existing plywood and then using Durock 1/4" or 1/2" which ever you think is better. I need to know where to put the waterproofing and what to use. I have not located a pan that will fit. The laundry room is on the second floor and I have installed a center drain rough in. It measures 8'9" x 4"6".
    Thank You,
    Stephen Ayers

  2. #2
    Plumber jimbo's Avatar
    Join Date
    Aug 2004
    San Diego


    1/2" hardibacker over the plywood should be sufficient. However, you said waterproof and cement board of any type is NOT. You would have to have a moisture barrier under it, as is done in a shower. A better choice for a floor would be redgard coating, or something from the schluter family.

  3. #3
    Retired Defense Industry Engineer jadnashua's Avatar
    Join Date
    Sep 2004
    New England


    To ensure the water runs to the drain, you need slope. What you need is essentially a large shower pan with a curb to keep it from running out into the hallway. You could effect a low one with a marble threshold, which MIGHT keep it from running out, depending on the flow rate. Keep in mind, you'll need to run the waterproofing up the wall a little, or it will just run underneath the wall plate. Check out www.johnbridge.com for some additional ideas.

    If you have a pan underneath the washer and run the drain line from it, you wouldn't need the slope. This would NOT help (much) if a hose burst, though.
    Jim DeBruycker
    Important note - I'm not a pro
    Retired Defense Industry Engineer; Schluter 2.5-day Workshop Completed 2013, 2014

  4. #4
    I&C Engineer (mostly WWTP) Lakee911's Avatar
    Join Date
    Aug 2005
    Columbus, OH


    Don't use treated plywood. It can have enough movement (shrinkage) to crack tile. Use a schluter product as is done in a shower.


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