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gyp in bathrooms

bill clinton_3
bill clinton_3 Member Posts: 111
My policy for many years now has been to recommend that gypsum-cement not be used in bathrooms. My information is that, should some leak cause the gyp to sit wet for long periods of time, it will get soft and crumbly. Better to use mortar.

The answer I am given from gypsum cement purveyors is that the proper course is to install an elastomeric membrane over the gyp, guaranteeing water does not get to it.

How good is that guarantee? I think of a bathroom with a tub, or a shower with a pan. If the membrane butts up to it, isn't there risk of a crack developing where membrane meets tub/shower?

On the other hand, if you place the tub on top of gyp and membrane, maybe this works?

How about the joint of membrane to wall. Will that remain water tight.

What are your experiences: I'm being asked as an "expert" to deliver an opinion and I sure could use your experience.




  • hr
    hr Member Posts: 6,106
    I'm with you, Bill

    How would you seal the edges, and what about a seal to the closet flange? Or any othe leak prone penetrations. Gyp the rest of the house but have the tile setter install a 1-1/2" mud set for the bath tile.

    What goes over the membrane, on the gyp, to adhere the tile to?

    I don't have a problem with gyp jpobs, per say. But I have had bad experiences with gyp in wet locations, entry ways,baths, condo kitchens with spills and leaks from sinks, dishwashers and icemakers, etc. Even with the sealer they told us to use years ago.

    hot rod

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  • scott w.
    scott w. Member Posts: 146

    Oh good grief, just last year gutted three baths and the kitchen and installed radiant in gyp in all locations without a membrane. Is this going to be a future problem? Doesn't the tile, marble and stone keep the water out unless you have a long term drip or leak?

    Please tell me it ain't so, walking in the kitchen door with wet shoes on the sealed limestone floor will ruin the gyp!

    My parents house is 40 years old which they built and the only leak in 40 years was the supply
    to a toilet tank.

    One thing i didn't do but should have used under the tile was a schluter(sp?)system. It is used in show rooms of car dealerships to keep the tile from cracking if the concrete cracks. Schluter makes a system for radiant heated floors so tile won't crack upon expansion and contraction of the tile.

    It is expensive and I think schluter guarantees the product.
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