Granite Tile Countertop Underlayment [Archive] - Ceramic Tile Advice Forums - John Bridge Ceramic Tile


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02-21-2008, 01:37 PM
I just recently found granite tile edging for countertops that has a 3/4" lip (from bottom of tile to bottom of lip).

My original plan was to only use 3/4" plywood as an underlayment, but I've read here that a cement board should also be installed.

That means I'd have to use a 5/8" plywood plus a 1/8" cement board so none of the underlayment would be exposed.

Does anyone know if 5/8" plywood plus 1/8" cement board would provide enough rigidity for the 3/8" granite tiles?

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02-21-2008, 05:42 PM
never seen me any 1/8" cement board before.

but here is a cut on how a counter top should be done.

3/4" ply - 1/2" tile underlayment

02-22-2008, 09:35 AM
You could still use that 3/4" granite edging by applying a double band around the base. While the picture below might not accurately represent the exact profile you want to use, it shows the concept.

Even a single layer of 3/4" plywood is marginally acceptable as a suitable counter top base for tile. Two layers would be much better so I wouldn't even consider a 5/8" single layer as an option. And like other posts you have undoubtedly read, backer board or a membrane Ditra is required over the ply. A 1/4" backer board will do.