If your quartz countertop is solid or just has flecks of sparkle, it's nice to bring some pattern in with the floor tile. You can also add some pattern to the floor with the way you lay the tile. Try to find a tile store that also sells quartz so you can coordinate the two. Be aware that you may have to add a new subfloor for the tile, which would make the tile higher than the hardwood in the hallway. This happened in our kitchen when we replaced sheet vinyl with porcelain tile. I do not like the wooden "speed bump" strip between the hardwood and tile. We would have liked to use porcelain tile in our guest bath remodel, but again, it would be higher than the adjacent carpet. We used Armstrong Alterna LVT. There aren't as many color and pattern choices as porcelain tile, but it it has a limestone composite base and is grouted just like real tile, so it's not really vinyl-y. Nice stuff, and a lot cheaper than porcelain tile.

I've only used the pre-mixed grout a few times, not a big fan. The instructions for cement grout warn about color variation but, in 20+ years of installing tile, I never had an issue. You can get color variation if you add more water to the grout after it's started to set up. The bigger concern there is that it will weaken the grout. Another cause of color variation is using different bags. If the job calls for more than one bag of grout, you're supposed to "box" them (mix them together). A kitchen backsplash is unlikely to need more than one bag (probably only a quarter of a bag.) My advice would be to use un-sanded cement grout. For 1/16th joints, add water and mix it until it's about the consistency of peanut butter or just a bit wetter. Let it set for about 5 minutes to "slake" then mix it up again. As for the brand: PolyBlend by Custom, Laticrete, and SGM are a few I've had good luck with. I've heard but never saw first-hand that Mapei had color variation issues. If you have to use the pre-mixed stuff, it won't scratch your marble. Pre-mixed grout typically contains sand (silica) which won't scratch the marble but will be difficult to get into 1/16th joints so you will probably end up with several unsightly holes in the grout that will need to be touched up.

A properly designed curbless shower DOES contain the water! The important part is "properly designed". The best waterproofing that exists can be all for nothing if the shower underneath it is improperly built. That goes for curbed or curbless. Be sure the pre-slope is correct, and correct for the materials chosen. Be sure the interface with the drain is correct, and no weep holes are blocked. Be sure the curb is built correctly, and detailed correctly. The details Behind the waterproofing are just as important as the waterproofing. And the framing behind those details is included in those things that not enough people pay attention to, until it is too late, and they have a wavy tile installation because the walls were framed poorly. You won't be using any contrasting grout with wavy walls!

Grout shmears over already full grout lines generally don't work with fully cured grout. Open and partially used bags of anything portland cement based, like your grout? While sitting in that basement, the powder is being exposed to atmospheric moisture. It can start to hydrate in the bag. Any hydration prior to being used reduces the strength of the final product. Since you have the bag? Call the manufacturer's tech department. The number should be in the fine print on the bag, if not, you can find it on the manufacturer's website. This is exactly what they are there for, don't at all be intimidated by the idea of calling. Have the photos ready, often times I'll have them attached to an email, and while talking to tech, I'll get his email addy and email them while we talk. Instead of describing the issue, the tech can see the issue with his own eyes while you are on the phone. See what the tech say. Instead of a schmear that will likely flake off over time...and likely be horrifically blotchy in color, they may recommend a grout cleaning, and then the application of a grout colorant. You can get a head start on that discussion by looking at grout colorants by the manufacturer of your grout. Is the colorant a semi-transparent dye that penetrates the grout, like staining wood? If so, because the colorant is somewhat transparent, there may still be shading and color differential in those blotchy areas. Is the colorant a topical film, an opaque epoxy-based colorant? While epoxy-based colorants will be perfectly uniform in color, the result can sometimes result in somewhat shiny plastic-looking grout lines. Epoxy colorants can be tedious to install. Any sort of colorant usually requires a grout cleaning before the installation of the colorant. Have the tech write you what is needed, or refer you to a website. Print out those instructions, along with the emails from the tech, and present those when you have your discussion with the GC. The other alternative, and this one can open up a host of other problems, is removing the grout and reapplying new grout. Because the prep work has to be somewhat meticulous...the cleaned out joints have to be even in depth, and the chance of the tiles being damaged during grout removal, and the chance that they may bugger up the new installation as well? Sometimes the application of a topical grout colorant is the easier path. Regardless of the path you choose, I recommend you discuss your expectations for remediation with the GC ahead of time. Get them in writing. You both know what you have going in. Make sure you're both expecting the same outcome. Lastly, "Should we be buying a new bag of grout for this touch up work?" You should not be buying anything. Here's why. You provide the grout. It fails. Might not be because of the grout, it might be because of poor prep, or the choice to do a thin schmear, and the schmear was doomed from the start. Regardless, the installer blames you for providing old grout. Or for not providing a grout cleaner. Or the wrong grout. Or...(pick your poison). when they do the work and they provide the materials? They own responsibility for the entire chain of materials and labor. Good luck!