1/8" is really a very small joint for such a large tile, even if it is rectified. There's also the issue of sanded versus nonsanded grout. While I'm not a tile expert, I understand sanded grout is much more durable, and that you may have trouble getting sanded grout into a 1/16" grout line.

Thanks, sweeby. I hadn't considered that there might be a difference in the durability of the two types of grout. I guess it's similar to the smaller particulate quartz products (like the often-mentioned Lagos Blue Caesarstone) that are described as made with a stone "flour" rather than larger chunks of quartz. Also, you have a good point about the large tile size. 1/8" is relatively tight for a tile of that size.

In my book, smaller grout is better looking (except for antiqued tiles or saltillo etc).
For our 16" x 16" travertine we went with 1/16" grout. In our friends' new highrise home, the porcelain 20x20 are laid with 1/16". Looks great.
use unsanded for that. no quality issues in our 3 year old unsanded grout...

personally, I like the 1/16" tile joints.

Rectified porcelains average joint size is 1/16".

The only reason grout joints exist at all in tile is because of tile size variance in order to keep the installation square.

The smaller the joint the better it will look.

If your installer questions the 1/16" size using a rectified tile, then he has no experience in rectified tile isntallation, which suffice it to say is more exacting than your average tile with 1/4" joints, plus more time consuming, then I would suggest finding another installer, but be prepared to pay more for it.

I stand corrected. After taking another look at the Crossville literature, I called the tile supplier again. The person I spoke to this time said that Palais is not rectified but has such tight tolerances that an experienced tile installer should be able to set 1/16" joints using something called wedgies.

This person also explained to me that tile joints appear wider when the tile edge is chamfered and that the degree of bevelling can vary from one tile selection to the next. His opinion was that I might consider saving some money by going with the 1/8" joint as currently specified. Since the Palais tile is not bevelled, a 1/8" joint yields a 1/8" grout line.

Floorguy, if I'm spreading misinformation here, please correct me.

If the tile is not a true rectified, you could think about using a brick or running bond pattern when using 1/16" spacing.

Thanks for the tip, jerry_t. As luck would have it, my KD suggested the 12"x18" size tile with a running bond pattern. She talked to the tile installer, and he said he will look at the tile when he gets ready to install and then get the grout lines as tight as the tile will allow. We'll see how that plays out when he gets here.

From what I've learned on this forum, tile joints smaller than 1/8" should be grouted with unsanded grout. I also recall some talk about epoxy-based grout. I'll search the older threads on that detail.

Thank you to everyone for your help!

~docdom