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  1. #1
    Chris Gordon Guest

    Default Durock and shower pans.

    I'm a master plumber and I have installed a lot of showers. Many are shower pan showers with tile or Corian. I don't do the tile work. Not because I can't, but because I choose not to. Where I work, most tile showers are done with copper pans. Vinyl pans are starting to be used. I'll do the vinyl if I have to. But I usually cover the thresholds with vinyl and use preformed dam corners to lead any water back into the pan. When it leaks, they always call the plumber.

    I just did this job where a copper pan was used and I covered the threshold. I set the drain height for a proper height and the carpenter installed the durock slightly above this point. As I have always seen it done, allowing for the finish tile height. The European expert tile installer came and made them rip the durock off and install it into the bottom of the pan and poured the base to this. I was horrified. I've seen this application wick water through capillary action and leak over the edge of the pan. The tile installer was adamant that this was the proper way to install the Durock.

    I don't think that this is correct and the USG Durock instructions say to leave a space for expansion and sealant at the bottom board and tile. Which is what I have always done and seen done.

    What are the thoughts here? I'm very interested.

    I'll probably not live long enough to see the total disaster of this job, but I might,

    Chris Gordon

  2. #2
    e3 Guest

    Default Re: Durock and shower pans.

    Either way depending on the board.see tca detail b-415 and b-426 In some case the mortar bed is used to hold the bottom edge so no nails or screws go into the membrane below the membrane.

  3. #3
    Kevin Tindall Guest

    Default Re: Durock and shower pans.

    If it is a traditional pan, I set the board about a 1/8-1/4" off the pan to eliminate wicking issues. If I plan on using a surface waterproof membrane then I will set the walls to the floor and pour the pan. Both can be done just a mattter of which product you are using.

  4. #4
    Jeff Miller Guest

    Default Re: Durock and shower pans.

    I can't believe that anyone uses durock for a shower pan. How can you achieve a flat sloped surface with a ridgid panel? Why not use a mortar float, as shower drains are designed to be used with this method. The end result is much better, and if the tile installer is competent, the cost increase is minimal. When we do a shower, we float all walls, and pans, and this only adds about 6 hours to the job, and ensures perfectly flat walls, and a pan that is both easy and comfortable to stand on, and will also drain well.

  5. #5
    DIck Seibert Guest

    Default Re: Durock and shower pans.

    Jeff:

    Agreed, and the better tile setters tell me they can float the walls and install the tile faster than they can try to shim the mortar board and install the tile straight. In California a bow in the walls (from a crooked stud) means a license board complaint, or worse, a lawsuit.

  6. #6
    Jeff Miller Guest

    Default Re: Durock and shower pans.

    Dick,
    I know all too well about the CA hazards, as that's where I live. My thought is that if people don't want to pay the extra for doing it right, then I don't want to work for them. Perhaps I'm among the unique, or elite, in that I am able to pick and chose the jobs I take, rather than have to beg for them, but I have found that the people who don't want to pay the price are the ones I always have problems with. Cheap people definately emphasize the saying that no good deed goes unpunished.

  7. #7
    Join Date
    Jun 2004
    Location
    Friday Harbor, San Juan Island, Washington
    Posts
    13,029

    Default Re: Durock and shower pans.

    Quote Originally Posted by Jeff Miller
    I can't believe that anyone uses durock for a shower pan. How can you achieve a flat sloped surface with a ridgid panel? Why not use a mortar float, as shower drains are designed to be used with this method. The end result is much better, and if the tile installer is competent, the cost increase is minimal. When we do a shower, we float all walls, and pans, and this only adds about 6 hours to the job, and ensures perfectly flat walls, and a pan that is both easy and comfortable to stand on, and will also drain well.
    Jeff, I believe the discussion is about durock on the walls, not the floor.... but I could be wrong. In any case, embedding the wall backer in the floor is not a good idea. Better to leave it up and caulk the bottom edge. Better yet to just float the whole thing.

  8. #8
    Join Date
    Jun 2004
    Location
    Martinez, California
    Posts
    14,882

    Default Re: Durock and shower pans.

    The so-called wicking is caused by caulking the bottom edge and sealing the water in behind the tile with no way to drain out, whether there is mortar board *or* a real mortar bed, the European expert tile installer is right. Mortar board is nothing but a precast mortar bed, and a saturated mortar bed is a conduit for the water in the walls, to drain down and out through the mortar bed in the floor through the weep holes in the shower drain. Caulking the bottom edge is an absurd attempt to stop the inevitable cracking of the grout joint. The water in the mortar board, or the mud bed, must be allowed to drain through the grout joints. I know the TCA calls for caulking at this juncture, but that is what causes the so-called wicking. Wicking is an inappropriate term, that's not what is happening at all, what is happening is that the mortar bed, or mortar board, becomes saturated and cannot drain out because of the damn caulking! Where does the TCA think the water in the mortar bed (or board) is going to go, dry out through the mortar joints? Well it will take a long time, and in the meantime it builds up in the bottom of the mortar bed, giving rise to the absurd "wicking" theory. Just explain to your customers that cracking of the bottom grout joint is inevitable and natural, that the cracked grout has to be removed and replaced periodically depending upon the movement of the house. I now see some tile setters installing the caulking to satisfy customers' desires to not have to periodically replace the bottom grout joint, but they are leaving 1" open gaps in the sealant joint about every 2 feet to allow the walls to properly drain.

    If you live and work in an area that has a building code, you must install a waterproof barrier behind the mortar bed or mortar board, and that means that the mortar bed or board is going to get saturated and must drain. In areas like Rob Z lives in that either don't have building codes, or don't enforce those codes, then you can install a surface barrier behind the tile so that the mortar bed doesn't get saturated and then you can caulk the bottom joint; however, I've never seen a caulking (including ColorCaulk specifically formulated for tile installations) that will last more than a couple of years before it has to be dug out and replaced anyway, so why use it?

    This issue is driving building inspectors nuts around here, because tile setters are following TCA recommended installations and sealing water in the walls, violating basic construction principles. The inspector okay's the waterproof barrier on the walls when he performs the 48 hour shower-pan water test, then he comes back at final inspection and finds the bottom joint in the tile sealed!

  9. #9
    Join Date
    Jul 2004
    Location
    Nantucket & Brewster, MA
    Posts
    1

    Default Re: Durock and shower pans.

    I posted the origional message. It was about tile installers wanting to set the durock into the bottom of the shower pan and then pouring the floor slab against the durock. My contention was that it was wrong, that the durock or cementious board would absorb water, and be carried up the back and on to the framing. The term that has been used here is "wicking". Someone denies that it happens as explained. I don't agree. But the so called "wicking" is actually capillary action or attraction, the same thing that causes candle wax to rise up a string against gravity, if a towel left in a bucket of water and hanging over the side, to drain the bucket of its contents. You can buy a product/device that will water your house plants that works on this principle.

    In a recent discussion with a tile installer, I made the statement. No one EVER calls the tilesetter when water is coming through the ceiling. They call the plumber (me). In my 40+ years of experience, 99.999% of all calls involving water coming through a ceiling that is not a continuous drip (like no one is using the shower at that time) is a leak in the tile surround or water getting into the wall around the plumbing trim. Once in a great while, I find something leaking in a packing on a valve. If said shower should leak, the chances are excellent that the origional installer will never see what the problem was. And someone else will repair the problem. Someone well versed in repairing leaking shower surrounds. So the origional tile setter never learns from the mistake and how to resolve it.

    A bit of advice for anyone who cares, if there is a water stain on a ceiling, and you want to try to find it, DO NOT rip a hole in the ceiling except as a last resort. You will probably have a large hole to try to patch and it will always look like a patch. And you will feel like a pennt waiting for change while trying to explain away the needless hole.

    My rules of engagement.

    If the water is coming down steadily, and you turn off the water to the bathroom, and the water stops, it is a leaking pipe.

    If the water leaks when you run the water directly into the pan or tub and only leaks when you do this. And stops when you turn off the water, it MAY most likely be the drain.

    If it doesn't leak when you run the water for a long time, but leaks whe someone uses the shower, it is the wall surround leaking. If you look carefully for the leak. you will find it.

    Its worked for me for a long time.

    Chris Gordon

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