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Unread 09-08-2013, 07:52 PM   #3
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Join Date: Jul 2001
Location: Boerne, Texas
Posts: 91,892
Welcome, Pres.

Kitchen backsplashes are among the most forgiving of tile installations. There is generally no need to replace the existing (usually) drywall with a CBU, but you certainly can if you like. If you do, I'd certainly recommend replacing the entire section between upper and lower cabinets, but, again, that's not a requirement.

1. If you elect to replace only a narrow strip with CBU, I'd strongly recommend blocking at the seams both top and bottom. Needn't be attached to the studs at all, just to both wallboards. My choice for such blocking would be 1/2" or 3/8ths" plywood rips.

2. In that dry application, drywall screws would be fine, but you may need to use manufacturer's recommended screws for the CBU to get them to set flush.

3. You appear to be anticipating quite a bit of water there and that's something we don't usually anticipate. If you do expect that much water, I'd strongly recommend you replace all the drywall with CBU.

But normally, any drywall joint in that wall, including drywall/CBU, would be finished with drywall compound like any other wall in the kitchen.

4. I would use none, but if you want one, and if you have installed a CBU, you can use any of a dozen or more available as direct bonded waterproofing membranes that can be tiled over. Look for ANSI A118.10 on the product.

We generally recommend 100 percent silicon caulk in the joint between the tile and the countertop, which would customarily be about 1/8th" wide.

My opinion; worth price charged.


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