There will be a bit of ambiguity in my answers...because there's no true right or wrong way. But here I go anyway: 1. Is the decision to go with epoxy or non-epoxy grout based primarily on resistance to mold and/or staining or is one type better than the other as far as preventing water penetration? Epoxy grout will allow less water penetration than a cement-based grout. Being non-porous, it'll also be less liable to staining. I consider epoxy to be overkill in residential showers, unless you're into dying your hair in the shower, etc. One other thing, you have a kerdi shower. That will limit water penetration, so it's sort of one more reason that epoxy could be considered overkill. 2. If we don't go with an epoxy grout in the shower, would the Polyblend grout used on the floor be suitable or would you recommend something different? Polyblend or any other manufacturer's cement based grouts would be fine. I use product from several manufacturers. Some people are preferential to just one manufacturer. 3. I think I'm confusing "caulk" and "silicone"... Are they used in the same applications? If not, what is the difference? Think of silicon as a type of caulk. There are, in general, three types of caulk typically used in residential shower construction; latex, siliconized-latex, and silicon. Latex is easy to work with, but the least durable and the most prone to mold and mildew staining. Silicon is the most difficult to work with, but has the best water-repellent capabilities. Siliconized-latex is a hybrid, it's in between the other two. In a well-built shower, any of the three could work fine, though I usually use caulks with some silicone in them, either S-L or 100% silicon. Look for a caulk that is color and texture matched to your grout, that way the caulk will look like your grout. Some 100% silicon's are only offered in color-match, but not texture. Since you mentioned Polyblend, here's a link to Custom's Color Matched Caulk. 4. Is caulk and/or silicone necessary in a Kerdi shower? I have nightmares about mold forming on my caulk (or silicone?) and having to tear it all out. The only proper way to avoid caulk completely is to do a floated mud shower with reinforced corners. Other than that, properly pitched surfaces, proper ventilation, and 100% silicon caulk will give you the best chance. 5. If we do caulk/silicone, I've heard that it should be done at every change of plane. Would this include areas that would not be taking a direct hit with water or having standing water on them? Correct. In lightweight shower construction (tile backer board over wood framing, for example), adjacent surfaces can move independently of one another. Caulk will flex. Grout could crack. Now you have a Kerdi shower, that works in your favor, as water can only penetrate to the membrane. But in general, yes, for lightweight construction, caulk all changes in plane. 6. Specifically which product would you recommend? A caulk that is color and possibly texture (sanded or unsanded) matched to your grout. A caulk that has some silicon in it. So the brand of caulk could be related to the brand of grout used if your goal is to color match. 7. Although our tile is porcelain, we are using a travertine base molding that has many nooks and crannies that will need to be filled. I understand that they get filled in by grout. This base molding is lighter that our wall and floor tiles and the matching grout that we're using there. Can I use a lighter grout for just the base moldings? Yes, you can change grout colors within the wall itself. 8. Finally, would you recommend sealing everything once it is done? Or just sealing the travertine pieces? I'd just seal the travertine. Porcelain is already non-porous. Sealing grout can be an adventure within itself. Regardless, use a penetrating, vapor-permeable sealer.

I’ve had the same issue of mold growing along the bottom horizontal frame of my shower door frame. The upright vertical frame pieces will rarely get spots of mold “under” the thinner areas of caulk (ie. Toward the edges, not in the thicker transition/corner portion of the caulk line). This drove me crazy as the bottom would mold so much faster. Well, obviously it stays wetter, but what makes it mold sooo much more & faster is that there is mold that has penetrated through AND under the caulk and is actually inside the horizontal rail of door frame. Bleaching NEVER really rids the area of mold under this bottom portion of the frame. Even without caulk, theres only a slight crack between the frame and fiberglass tub. I’ve removed caulk from the inside & outside and squirted bleach cleaner under there from both sides as best I could multiple days in a row then recaulked and still mold would grow. THE MOLD IS COMING FROM INSIDE THE RAIL/FRAME/WALL/TILE (whatever) and working it’s way OUT. It’s possible even condensation may be enough moisture for mold. If I figure out a way to ensure not making a mess, I may spray some foam under the frame to see if that stops it.

I'd probably use white silicone caulk if I were going to use caulk at all. Clear caulk might come out looking dark next to the white cabinets and white sink. I found the non-silicone caulk a lot easier to work with, but i think it dries out and looks bad after a while. However, either caulk would be hard to apply in such a tiny crack. But I don't think I'd caulk at all. It looks barely noticeable. In fact I wouldn't have perceived it as a mistake at all. We worry about every imperfection while we're in the middle of something, but never once notice it again when it's all done. That's been my experience, anyway. By the way, you put me to shame. I made my own cabinets, and am embarrassed to say I didn't think to cut a curve into the base at all -- I have a square base and a rounded sink bottom. Making a little curved cut-out is on my list of things to do, but that list seems endless, so I doubt I'll get to it any time soon!

My contractor didn't use any caulking or vinyl cove to the wall when prior to new cabinet install. Also, in places, he didn't even lay vinyl (underneath cabinets or underneath where the oven will go. So just the subfloor is there. Now, I'm not sure about if there is just the subfloor or vinyl underneath the sink. But I do know, that even if it's vinyl, he did not caulk it. The problem is, that tonight I used the sink, and all of all sudden I heard water go down into the cabinet. I immediately toweled, and placed fans. The reason for fans? There is about 1/8 to 1/4" gap between the bottom of the kitchen sink cabinet and the wall. So, about 2 gallons of rinse water when down onto the bottom cabinet and undoubtedly in that 1/4" stip against the wall and down onto the flooring/subfloor. Of note, the whole reason for this remodel was because my ice maker leaked and caused extensive damage to my kitchen floor and cabinetry. I am worried about the potential damage. In conclusion, should he have installed the the flooring to the wall to cover all subfloor, and then caulked/vinyl cove, prior to installing cabinetry? ( Incidentally, should the dishwasher leak, it will go directly onto subfloor. ) Unfortunately the granite is played. All that is left is range, dishwasher and range hood install.