PEI vs grade?

My wife and I bought ceramic tile for the bathroom floor based solely on appearance before I had even heard of PEI or knew there are some tiles meant only for walls. Now I am wondering if what we have is suitable for a bathroom floor. What worries me is that it does not show PEI on the box, but does list the "GRADE" as "1A".

Please tell me "grade" is not another term for PEI, and that I have not bought wall tile for my floor. The place I bought it from says not to worry, but it is a discount warehouse kind of place, and they didn't even know what PEI is, so I don't really trust their advice on this. (They say "grade 1A means it's the best".)

The Lamosa web site ([www.lamosa-revestimientos.com]) does not show the PEI, either. It does show my tile (called Cima), but that leads me to my other question. They show it as an "interior" tile, but not as one of their bath (or kitchen) tiles. Assuming that it is a floor tile, could there be reasons I would not want to install it in a bathroom? Are some floor tiles just not designed for the humid conditions in a bathroom or something? Or is it simply that Lamosa isn't marketing it for bathrooms, but it will work fine?

You'll be fine with the tile you purchased, as long as it is properly installed. Come back with information about the floor (subfloor).

Grade and PEI are not the same. PEI is numeric wear rating assigned to the glaze on a glazed porcelain or regular old fired clay bisque ceramic. An unglazed porcelain will not have a PEI rating because there's no glaze to rate.

Marco - I have 2 x 10 joists, 16" oc, and a span of about 12 feet. I tore up 2 layers of vinyl and underlayments, leaving the 5/8" plywood subfloor. I'm in the process of screwing down 1/2" BCX with 1 1/4" exterior screws. I bought 1/4" cbu to put on top of that, with unmodified thinset. Then I plan to use modified thinset to lay the tiles.

I've never tiled, but I've read many of the posts here, especially the ones containing the words subfloor or plywood, so hopefully I've got a good plan.

Thanks for your help.

I've read many of the posts here, especially the ones containing the words subfloor or plywood,

Too bad you didn't read the posts warning against using CDX plywood.

I used BCX. It was stamped "Exterior" and "Underlayment". Isn't that what I was supposed to use?

Sorry Doug, I have my glasses on now. Coulda' swore I saw "C"DX earlier.