Ahhh-got it! So Aqua Mix is good for pre grouting. Do I need to use another sealer for the stone after grouting or w/the Aqua Mix pre grout be sufficient?

Bill V - I found one of your comments in an old GW post from 2008. I copied and pasted below. So I'm thinking unsanded. If I am wrong, please let me know! Thank you so much for all of your help! As for the explanation of the different grouts, I just posted this in an FAQ thread on the gallery side of the bathrooms forum. Here it is, copied and pasted: Although there are others, for all intents and purposes, there are two kinds of grout-- portland cement based, and epoxy. The portland cement based grouts are the conventional grouts that have been around for millenniums. Although in the last few decades, they've been modified with latex and other polymers to make them stronger and more resistant to mold and mildew, they're basically the very same grouts that have been used since Greek and Roman days. There are two kinds of portland cement based grouts. One is sanded, and the other unsanded. The only difference between the two is, as their names imply, the sand. The ONLY thing that determines which grout should be used is the joint size. NOT the glaze, NOT aesthetics, NOT the material (ceramic vs. glass or polished marble), NONE of those. I'll repeat-- the ONLY thing that determines which is used, is the joint size. Anything under an 1/8" takes unsanded grout. Anything 1/8" or bigger, you use sanded grout. If you use unsanded grout in larger joints, the cement in the grout will shrink way too much as the water evaporates out of it, and the joints will end up shrinking and cracking bigtime. If you try using sanded grout in smaller joints, the grains of sand will literally clog the top of the joint, and not allow the grout to get down INTO the joint, and the grout will flake off in a matter of days.

The caulking should be where the tile butts up to the window frame. one thing you might consider is using a piece of travertine slab for the shelf.

"The GC is telling me the cracking will soon stop (in other words, within the first year) -- is that more BS or is it true?" Maybe yes, maybe no. In lightweight frame construction, the framing lumber can take several months to a year to come to an equilibrium of sorts. During that time, the wood can move. Moreso if the framing lumber was green (not pressure treated green, but non kiln-dried green) instead of kiln dried. Still...houses move. There is still seasonal movement due to humidity, subtle movement from wind loading, etc, etc. So while grout in changes of plane is more likely to crack within months of the initial installation, it could crack year after year. Or after every other year. Or never again. There's just not a one answer fits all solution. Cracked grout in decorative tile is cosmetic cracking. But cracked grout in a wet area like a shower represents another avenue for liquid water and water vapor to get behind the tile. Normally not a problem with a topical membrane like Kerdi or RedGuard. But still, industry standard, and best building practices, dictate that with inside corners in wet areas, it's best to use color and texture matched caulk instead of grout. Caulk flexes. Grout doesn't. If their caulk is failing, then they need educate themselves on how to properly caulk, prep, application and tooling, and on using the proper caulk. Mongo