Greenboard in shower

Old 04-15-03, 06:39 AM
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Greenboard in shower

I read in a prior post that when building out a bathroom, the greenboard that is used should only go down to where the shower base "lip" starts. I will be putting tile up and am not sure if the greenboard should go inside the lip or not. If not, what is done to eliminate the gap that will be there? Tile, tile cements??

thanks for the help!
Old 04-15-03, 07:40 AM
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The installation of greenboard inside a shower surround as a base for tile is not recommended. Greenboard is gypsum dust compresed between two pieces of cardboard. Neither of these materials are good at keepng their shape when wet.

Use a cement board product inside the shower surround. (durock, wonderboard, hardibacker are some common brands). Greenboard is ok for high moisture areas, but direct water contact (such as inside a shower surround or on a kitchen counter) requires a product that will not get soft when wet (like cardboard and gypsum).

The lip: The cement board (and the poly vapor/moisture barrier behind it) should extend down over the shower base nailing flange to within about 1/4 inch from the lip of the shower base. In order to get plumb walls, the studs that the shower base are attached to should be notched out the thickness of the nailing flange where the flange attaches to the studs. Alternatively, the length of the studs above the flange can be shimmed with wood the thickness of the flange, then the poly and cement board attached to the shimmed studs.

The tile is then set on the cement board using thinset mortar cement (not mastic). Leave about 1/8 to 1/4 inch gap between the bottom row of tile and the shower flange lip. This gap between the tile/cement board and the shower base lip, is filled with pure silicone caulking after the tile and grout are completed.

If you use cement board and thinset mortar, your installation should last forever. Installations using greenboard and/or mastic will eventually fail, and the tiles will start falingl off when that happens.

Post back if you have any more questions. Good luck!!
Old 04-15-03, 09:49 AM
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Perfect. Thanks for the help!
Old 04-15-03, 03:22 PM
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swe936 ,

What Brewbeer gave you is good but to help in visual, check these out;

Hope this helps!

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