Two comments-- First, I don't know that I'd trust tile to be installed that's been sealed on the backs of the tile, where the thinset's supposed to bond. On the edges, it's not so important, as there's no stress whatsoever on the grout. On the thinset bond, there IS a mild amount of stress, and if you don't have the strength of bond, or if the sealer should let go after a time, the thinset's only going to stick to what it's stuck to, in this case, that being the sealer. Carrara's not that super absorbent where you need to worry about sealing it prior to grouting. It won't "suck" the grout in like some tumbled stones will.

Secondly, I've used the tile-ready shower pans, and they're a royal pain in the.... neck! Unless the walls are framed around the pan, it'll never perfectly line up with the cement board above it, and then you have humps in the walls where the two meet.

Thanks for the quick response bill! I guess we are all looking for bullet-proof & low maintenance carrara, but it sounds like a no go. So tumbled or polished carrara, but not honed, is fine over a mud bed? (I think I read somewhere that you thought honed would only be possibly ok on kerdi. I'm sorry, I tried to read all the pertinent posts first, but am finding that I am getting a litte confused!) Or should all marble shower floors be installed over kerdi? I then seal post-install & maintain the sealant, right?

Sounds to me like you've got a bad case of information overload!

I would not use honed or polished carrara on a shower floor. Either one would be much too slippery. Tumbled carrara is fine, so long as you're aware of the need to keep it sealed and clean.

As far as using marble over Kerdi or a conventional shower, either one is fine, and yes, you seal post install and then maintain afterward.

Thanks, Bill! You don't know how grateful I am that you took the time to respond! I don't know what we'd all do without you. Thanks again.

You're very welcome. :-)