I just set 50 large (8"x 10") tiles on the upper back wall over my fiberglass shower unit. These tiles go along the top (to the ceiling) and down along the sides to the floor. The will not come into contact with direct water. (hopefully) I had planned on mixing grout that would have matched my tiles, however, I found that DAP as a bathroom caulk that doesn't mildew, doesn't get hard, or any of that other bad stuff. THis color would look so much better than the grout. It just can't install itself. Question, would it be practical and okay if I just used the caulk in place of the grout. It would be easy to finger slide a smooth "grout" line and the fact that is will always be flexible. It sounds as though it would be functional and certainly waterproof. . I have seen dining room tables where they used silcone caulking between tiles used on table tops, and there would always be a chance of someone knocking a glass of liquid over on that... please help advise. Bruce out...

Did you lay grout as a base to apply the tile to the bathroom? My understanding is that caulking is only for water tightness, if you need to structurally hold the tiles in place or keep them from coming apart you would need to grout them. If they are already secure then maybe you could just use the caulk? If the application specifically calls for grout then you cannot substitute it with a caulk.
I could check a general spec for you to make sure, do you have the specific info (manufacturer, etc.) of the tile?

Do not use caulk for this application. Grouting is about the only way to finish a tiles wall. Grouting is cheaper, better and a bit messy but it is the way to go.

I have a water stan on main floor ceiling and the shower is on the second floor has not been used in along time so it does not leak in pipes so the leak must be in the tiles but they look ok i was told to put sealant on them and i donot know about the drain suggestions please and hoe do i paint to cover the stain in the ceiling
Thanks

TDan, if this is a new post or question you need to open your own post. Attaching to someone else just confuses people. Zinsser 123 Bullseye primer will seal the satin, then ceiling white paint. You must find the source of the stain/water before starting repairs. Pour a few buckets of water into the shower pan, if the ceiling gets wet your pan is leaking. If it doesn't get wet come back and tell us.