The vertical wall seams crack more readily because the house shifts and moves. Ive tried grouting only and going back to caulk with sanded grout caulk or silicon only after a crack develops, hoping in some cases it will not. Sometimes it does not crack. Some contractors caulk all seams as a matter of course, no callbacks, safer. I liked the idea of sanded grout caulk to match your grout color It has not held up for me in wet conditions, such as the top of the bathtub where the wall tile starts, etc. , definitely not along the shower floor where the wall tile starts. It has held up in other areas though, and looks nicer when it all ties in. I agree, mildew on silicon is unsightly. Every bathroom has different conditions, including ventilation, moisture, etc. Some people have to clean out and recaulk the silicon every year or two. Whether its allegedly mildewproof silicon or not.

It's not to stop the water-- it's to keep movement between the tub and the walls from cracking what would otherwise be a grout joint.

Catbuilder, I don't know the answers to most of your questions, since I did not do the work, nor did I witness the work done. He did not show me the type of caulk (he does this for a living--I trusted him to use what was appropriate). He did not report seeing any visible mold (I asked.) There was no delay between removal and recaulking. It dried for at least 24 hrs, maybe a little longer--I cannot recall. I presume the surround was *adequately* waterproofed, but again I did not do the work. I saw that they did do the waterproofing.

With the work being done a few weeks ago, there is nothing wrong with calling the installer who tiled and asking why grout was used in the changes of plan instead of caulk. Ask about the corner grout cracking. What if? Will remediation be offered? Caulking a shmear of caulk over a grout joint is not going to prevent the grout underneath from cracking if the grout is prone to cracking. Some corner grout never does crack. With your house being an "old 1060s", it may be nicely settled in. You may not have differential movement between the wall planes that leads to corner grout cracking. Grout sheds water. Caulk sheds water. Both are superficial things that "pretty up" tile installations. The real waterproofing should be behind the tile. Caulk needs some depth to it, if it's just a veneer over grout it may peel delaminate over time. Latex caulk versus silicone? Both will shed water fine, but 100% silicone will perform better in standing water than 100% latex. You'd be correct to make a phone call and to ask questions. And to get answers. Sometimes I'm of the mind that although best practices may not have been followed, second-best practices can still turn out fine. Meaning, you could leave the installed latex caulk until you have issues. You may never have issues. But if you do, then replace it. Same with the grout in the corners. Leave the grout in the corners until it cracks. Then replace it. When you talk to the installer, if he offers to come over and remove the grout and replace it with caulk? Sure, you could take him up on it. Or just get an assurance from him that if problems develop down the road, he'll swing by to make things right. It's best to get those assurances in writing. It's really what you feel most comfortable with. And how accommodating the installer is with regards to backing up his work.