Very nice looking job Jared, congratulations! It is very normal for unsealed grout to change to a darker color when wet. This will happen even with fully cured grout. Feel free to buff any excess grout or haze off your tiles, it won't hurt anything and that also is normal for newly installed tile. If the darker color when wet bothers you, then go ahead and put a couple of coats of grout sealer on after about two weeks from the original grout date. Even though the manufacture claims stain resistance, it does not claim to stop the temporary color shift when wet. Sealing the surface of the grout will stop the wetting of the grout and end the color changes. You may find you need to reapply some sealer every year or so in a shower surround. Apply the sealer with a small foam brush just to the grout, Buff excess off the tiles 15 to 20 mins later. Looks Great!!! Good Luck.
I'm a little concerned by the fact that "this one has had issues," but it sounds like this part of the job is being done correctly.
Just a couple of definitions, quickly:
- Drywall (aka sheetrock, plasterboard, wallboard, gypsum board) is gypsum plaster covered in paper, and is used on most walls and ceilings in dry areas.
- Cement board (aka CBU) is used in wet areas like showers; drywall - even the green or blue stuff - will eventually disintegrate in wet areas.
I'm assuming that the 4" patch at the top of the shower walls is cement board, same as the lower part.
It's standard to use fiberglass tape over joints between cement board to minimize movement between the boards, and apply thinset and tile over that area as usual. You might fill the gap with a little extra thinset while tiling, but you don't use drywall mud in there since moisture will just weaken it.
The fact that the cement boards aren't flush to each other shouldn't be a problem unless the gap is more than 1/8". Even a little more than that isn't going to cause problems, depending on the size of the tile used.
The most important thing to be aware of when a new shower is being installed is preventing water from getting into the walls. For this reason, a vapor barrier (plastic sheet) should go between cement board and the wall studs, and extend down over the lip of the shower base (or pan). This allows any water that gets into any joints between cement boards to run down into the shower base and down the drain.
The cement board should extend down to about 1/8" above the lip of the shower base - there's no need to overlap it, since the plastic is doing so. The bottom row of tile should extend over the bottom edge of the cement board, mostly covering the lip of the shower base, then silicone caulk should be applied to seal that gap.
Best Answer
You likely need more coats of sealer. Depending on the porousness of the tile and the quality of the sealer you may just need more to get the job done.
When you do the shower walls, I would follow these steps:
If you're using the glossy sealer this might be a bit much. I would use the clear penetrating kind for the pre-grout coats.
The pre-grout coats are not strictly necessary, but do serve two purposes. The first is that if you have porous tile it will give you the extra protection you need. The second is it makes cleaning up the grout easier if you're sloppy. Adding sealer to the grout is supposed to help with bonding it to the thinset - not sure if that's true, but if you have extra on hand it works fine.