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Question:

Does Cement board have to be screwed down? this is for an exterior installation.?

I am building a balcony. We were going to do tile, but may do a waterproof product instead. There is currently cement board glued (not screwed) to the torch down. Screws were not used because we don't want to have an area where water can seep in. Now I am worried about the glue failing and the cement boards lifting (same issue with tile come to think of it). Is the glue enough to hold down the cement board so I won't have problems in the future?

Answer:

If your to do ceramic tile then yes you need to screw and glue: it down. This glue isnt really to hold it down like most people think, its part of the support base for ceramic. You still must nail or screw it down in the require amount in the field ( 8 on center and seams a minimum of 4/6 apart.) If you live in a climate that gets cold enough for freezing , the I recommend you don t use a ceramic or porcelain tile ( frost proof or not) Using a cement board isn t the proper way to do an exposed balcony , even to rain. You need to treat it as a shower flooring and use a drain , liner , and s special cement to form a slight slope to the drain from all direction. It is possible ( Ive never done it yet) to properly do a cement board and water proof the top . The water proofing will have to be flashed up the sides to make a water proof flooring and still incorporate a draining system. If you have any questions you can e mail me through my avatar and check my qualifications there. GL
May 11, 2017

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