Cement backerboard and trowel questions

Old 05-07-05, 03:27 PM
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Cement backerboard and trowel questions

I'm in the middle of a bathroom remodel, and have two questions concerning the installation of backerboard and tile:

1. I'm installing 1/2" backerboard around my shower walls on top of a cast iron tub. On the wall furthest from the spout, there is a hairline gap (maybe 1/16") between the 1/2" backerboard and the lip of the tub. My walls were slightly more than 5', and I thought the best place for this gap would be furthest away from the water source. My question: Can I just caulk this gap really well with a silicone caulk, or should I think about installing a layer of 1/4" backerboard on this wall only to close up the gap, then caulk?

2. I'm installing 2" x 2" tile (in 12" square mesh sheets). What type and size of trowel is best? I thought V-notch, but the Versabond instructions say square, 1/4 inch.

Thanks in advance!

Old 05-07-05, 03:38 PM
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Brian caulk the gap and you'll be fine. I wouldn't use silicone tho, I would use latex caulk because the additional products you are getting ready to layer-on won't stick to the silicone. Not a big deal but not a good idea in my thinking.

Now the trowel thing. When using (matted) 2" X 2" tiles you most certainly don't want to use a 1/4" notched trowel. Too big, you'll have thinset purging between the tiles everywhere.

I use a 1/8" X 1/8" X 1/8" square notch. You may also find that the same style trowel in a 3/16" notch may work also, just depends on which backerboard you are using.

SECRET: These size trowels can be found in the wood flooring department of your local Home Center. Don't tell anyone though.

You are taping and filling the backerboard seams with thinset also, right?
Old 05-07-05, 04:02 PM
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Thanks for the info. I will be taping and filling with thinset. How long do I need to wait before beginning tile? The full dry time?
Old 05-07-05, 08:31 PM
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Tape and thinset the seams while tiling, no bumps to deal with, use CBU tape, not sheetrock tape.

Use a grout float to push down on this size tile to keep them all even.

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