kitchen granite tile countertop, grout and second question

[Evert]

We are starting on the kitchen counter, and are using 12" granite tiles. Two questions are: what type of grout should we use, unsanded? Epoxy? The color is Ghibili, a soft gray.

The second question is whether we need to use poly film in the sink area, between the cement board and the plywood, and if we do should we thinset the CB to the poly or just screw the CB down over the poly?

The bath tub surrond and all floors are done, thanks once again to John and this site. Will post pictures soon.

[GraniteGirl]

I am not going to even try to advise on your other questions, but I will tell you to test your stone for absorption. Ghibli is a a pretty thirsty Indian stone and will most likely need some sealer.

Would LOVE to see your pictures.

[kerdibird]

No poly, just screw it.
You could use thinset under the cbu, but it's not necessary for a countertop.

You should consider using Ditra instead because it gives you less build-up, and more waterproofing.
You could also use a liquid/bonded surface applied membrane like Kerdi or Redguard for water control.

[Ken]

Not sure what art is thinking, however you should always thin-set CBU down to a horizontal substrate and properly fasten it.

[kerdibird]

And why pray tell is that?
We're not talking about a floor here.
I'd be happy to see two layers of ply alone with tile right on it for a counter top.
Adding cbu with redgard or plywood with ditra are both options for the guy who's concerned about water damage.

[kerdibird]

You can't use redguard very well over plywood, which would be my only reason to use cement board on a tile countertop, which is why ditra with one layer of 3/4 ply is the most sensible option imo.

[Ken]

Because thin-setting the backerboard down to the top's plywood, would be in according to TCNA Method C513 (Wood Base Countertop Installation) in the 2008 handbook.

[bigd777]

why not just mud the counter top

[kerdibird]

Tiling directly over plywood is also deemed respectable in some circumstances.

[Ken]

Mudwork, obviously would be the best option, in my opinion. But it does not seem to me like a very friendly time for a DIY to try. Though I could be wrong. We've walked many people through mud work on here.

[kerdibird]

Mudding countertops?
Come on guys.

[bigd777]

u would never tile over plywood . how long have been doing tile .i would never do that .its going to fail

[kerdibird]

What do you know of tiling over plywood?

[bigd777]

thats its not a good thing to do

[Ken]

Back on subject guys. Quit debating the undebatable.

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