Why tape cement board?


  #1  
Old 11-26-08, 05:53 AM
D
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Why tape cement board?

im laying cement board with thin set first, then im going to screw down the cement board, the 1/8 gaps between cement board, why do i have to tape those gaps, if im going to spread cement on top of it and lay tile, i dont mind doing this process, but just want to know what is the resson. thank you.
 
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Old 11-26-08, 06:08 AM
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Best reason, is that the manufacturers of cement board all require this step. If you leave it out, you dont get their warranty. Taping and mudding the joints makes one monolithic unit out of the individual boards. This will prevent cracks over the seems from telescoping through to the tile and grout. No tape means cracked tile. Dont skip this step. You can mud and tape at the same time you set the tile. Make sure you get the right kind of tape, the one thats meant for cement board. Its alkalai resistent mesh tape.
 
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Old 11-26-08, 12:37 PM
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Thanks for the info Johnny. I've worked around a lot of tiles guys that said it wasn't necessary and..... I believed them
Always nice to know the correct way and why
 
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Old 11-26-08, 01:05 PM
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Taping the seams of CBU's is required as Johnny said with the exception of WonderBoard brand cement board. Wonderboard is made with "open-mesh" edges, and so do not require mesh tape. (It's best to do it anyway, I think). However, if you have cut off the factory edge, and are using a non-factory edge, you need to tape the seam. This applies to both 1/4" and 1/2" on floors.

Wall applications are similar except that in addition, all corners must be taped even if the open-mesh factory edges have not been cut off. Again I recommend taping even factory edges.


Jaz
 
 

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