I'm getting ready to install 12x12 ceramic tile on our tub walls. What type of thinset should I use?

Ancillary to that is the type of grout to use? Sanded or unsanded?

While researching the background for this question a bit, I learned that the 12x12 tiles we're considering are Semi-vitreous, and aren't recommended for wet areas like showers. If I thoroughly water proof the Durarock wall (using RedGard as recommended here), can I use those tiles? If so, what grout?

I'm interested in using these tiles specifically to cut material costs. This was an unexpected repair, not a remodel, so our budget isn't the greatest. We have approximately 56 sq feet to tile, plus materials and needed tools.

Edit: If I went with this tile, what thinset and grout would I need? This is not a good choice, as it's not impervious. It's not even semi-vitreous.

Edit: OK, I think I'm figuring out the choices. Home Depot has a 12x12 porcelain tile that's rated impervious. It's also $0.99/sq. But, with porcelain, do I use a sanded or non-sanded grout to avoid scratching the surface?

The bottom line is that I'm going with a porcelain tile that's rated impervious with less than 0.5% absorption. I'm prepping the walls by covering the seams with a kerdi band, then painting the wall with Redgard waterproofing. I'm using a fortified white thinset and then finishing with a sanded grout, the only determining factor there is the color. Thanks everyone for the answers, and I hope future readers find this helpful.

Thanks for the feedback and help. I did this job over the weekend (what I thought would take a few hours turned into two days -- mostly due to prep and cutting the tiles), and I'll be doing grout sometime today. I'll post the final picture once I get the grout in and the tiles cleaned.

2 Answers 2


Shower tiles are not a place to cut corners. If they are porous then you will have a host of issues. Basically you will breed mold faster and the tile install won't last as long - mold gets in cracks and pops tiles out or at least loosens bonding. You need to get a non-porous stone, plastic, glass, or porcelain.

If going with 12x12 tiles you will need at least 1/16th of an inch given they are uniform - and perfectly cut 12x12 are not cheap. So you are looking at 1/8-3/16. Which means you need sanded grout.

For cheap I suggest you go on craigslist or whatever is equivalent locally (even try job leftovers at tile store). The bottom 3 feet of your install needs to be a good tile - you will need about 34 sqft. You can get decent porcelain for $2 a sqft and even cheaper if it is a job leftover or end of stock. You can still use your ceramic up top. And when switching tiles I usually put in a narrow trim of glass mosaic in between - will need 3-4 sheets.

  • Could you check my edit and see what you think of the tile I linked to?
    – cigarman
    Commented Feb 21, 2014 at 0:58
  • @Coleman - that link to the tile is not a good choice for a shower. I don't even know if I would use it for the bathroom floor. Here is a thinset you can use - homedepot.com/p/…. Also grout is dependent on the grout width more than type of tile. Unless you get rectified tiles (which are expensive) you will need sanded grout. A tile example - homedepot.com/p/….
    – DMoore
    Commented Feb 21, 2014 at 2:38
  • Thanks for answering my questions, and the links for the thinset and grout. Here's a link to the tile we're going with: homedepot.com/p/… It's an impervious tile, yet $0.99/sq ft. We're found of the look too.
    – cigarman
    Commented Feb 21, 2014 at 14:36
  • 1
    Coleman - That will work. I'm not 100% sure but I think that might be the cheapo sample one of my old crews used. It's a good tile for tub surrounds. Go with a light beige (sanded) grout. If you are confident with your walls use 1/8" spacers.
    – DMoore
    Commented Feb 21, 2014 at 14:56

Here is a post I found on JLC's website.

Re: Vitreous or Semi-Vitrious tile in shower?

The absorption problem is behind the tile - not on the surface, so sealing the face of the finished job will not prevent moisture from penetrating the tile body (via moisture seeping in through grout joints. Unless the shower will be used so much there is not enough time for the installation to COMPLETELY dry out in between uses, semi-vitreous tiles are a poor choice. Whether or not this (degree of use) is the case, the density of the tile grout, and the adhesive contact are critical: grout mixed, applied, packed, and cleaned properly with an absolute minimum of cleaning water; 95% minimum adhesive contact between backs of tiles and setting bed. If you remove a tile and can see ANY trowel marks - there is not enough adhesive contact: voids in the adhesive layer will collect moisture and guide it into the tile body. When both are saturated, mold will grow: once established, you cannot kill it.

Make sure that the customer knows that impervious tiles are the best choice in wet areas. Semi-vitreous tiles are not the worst choice, but I would not recommend them. A disclaimer in your contract will help once discoloration or mold appear.

End of post

It sounds like a really bad idea....

  • I saw that article, too, which actually prompted my question here.
    – cigarman
    Commented Feb 21, 2014 at 0:02
  • But thanks for recording here for future readers.
    – cigarman
    Commented Feb 21, 2014 at 0:57

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