I'd prefer that more grout had been left in the joints. They look dished out a bit too much, where too much grout was removed during the cleanup phase. I'd have preferred the grout to be more flush with the face of the tile. Looking closely at the first two photos, the darkened grout lines are all parallel to one another. In the first photo you can see the wet grout lines are all parallel to the edge of the drain. That leads me to believe that the "uphill" edges of the tiles are acting like mini dams and holding water, they are preventing water from easily flowing downhill to the drain. The second closeup photo, you see the same effect. All the damp grout lines are again parallel to one another. Again, to me that reflects a drainage issue. Not necessarily with the amount of floor pitch, but with the grout lines being so dished out that they hold water and slow drainage. Marble is porous and can absorb water. With the grout lines being a bit too raked out, the edges of the marble hexes are exposed. Water held against the tile edge can lead to absorption into the marble. The crack in the grout in that second photo, you also wrote that there are other cracks. That's usually a sign of too much water used in the grout mix, or that sanded grout should have been used instead of unsanded. Unsanded should be used in joints less than 1/8" wide. Cracks can also indicate movement in the floor, but that shouldn't be an issue with a properly set Kerdi Tray. As far as him having used a preformed Kerdi-Tray, if he did, it appears that is was certainly cut down in an awkward manner. The drain is no where near centered in the shower. So if he did some filling here and there with mud or thinset to even out the floor pitch or edge elevations, that could have be part of the problem. But that's supposition on my part. About the only other thing I could question is that often times with small tiles, when the sheets are set into the thinset, thinset can ooze up between the hex tiles and partially fill the grout lines. That thinset needs to be cleaned out so the grout lines can be completely filled with grout. If it's not, you can get uneven thicknesses of grout, think of it as a veneer of grout over a blob of thinset. That can result in uneven water absorption, the grout cracking, etc. All that aside...with this being your second go-around, he should have install the sloped Kerdi Tray and thinsetted it to the subfloor. Then he should have set the Kerdi drain. Then he should have thinsetted Kerdi Membrane (an orange colored sheet material) over the Kerdi Tray, then tiled on the Kerdi Membrane. I'd be interested in how he tied the Kerdi Membrane in with the wall membrane IF he used Kerdi Membrane over the Kerdi Tray. Best. Mongo

Well, from looking at your pictures, there are at least 3 possible causes of this discoloation on the tiles. The first one, though remote, is that they used a different color grout instead of the light grout they were suppose to use. I highly doubt it, they usually mix enough up at one time and do the whole tile job at once. The second one, is that moisture is getting down behind the tiles and that is mold showing through. The third is they used a cheap horrible grout on the job, and the shower may have to be regrouted. Did you use a good grout cleaner with bleach just on the dark tiles yet? Do you notice any odor at all? If you are not satisfied with the action that the builder takes, I would call a professional for his opinion, and see what he thinks. The builder, might not be totally honest with you, he might just want to run a warranty out.

Thank you all for your wonderful advice. We decided to call the tile guy early this morning and play it safe and just go with the white grout. I just figured I rather be safe than sorry! : ) I will try to post pictures tomorrow of the longest kitchen remodel in history, almost two years, but who is counting, besides me! Thanks again for all your advise~

Probably because you don't NEED a mudset job on a Kerdi Shower. If the framing and walls are true, why the mudset? Make no mistake, I have done tons of them and they certainly are great. Straight, plum and true. As to being "overpriced," yes, there is a proprietary drain assembly....which looks MILES better than the average PVC/FHA $9.00 drain and will cosdt you a hunnerd bucks or so. (big whoop!) When I factor in the time differential of mudding walls, putting in a preslope, setting and folding a rubber liner, metal cladding the curb for fat mud, putting in a final slope....all before you tile, as opposed to simply ONE mudbed, Kerdi the walls and floor and tile away...in many cases, I'm less expensive than the "Traditional" way...simply because of time. Warranty? Don't care about the Company. I warranty my stuff for life...and have yet to have a callback. What is "Life?" Until either you die of I die.....lol