Marins, you're right, silicon was a bad idea. Bud, thank you for your help. I think I have a plan in place, I'll use a shim to make sure there's a gap between the floor and the cove base tile. What do you recommend, 1/16 inch? My thought on the caulk is that by caulking behind, I would still get the water barrier so that water sloshed from the tub won't get to the wall, but the caulk wouldn't be visible. It seems no matter how nice the caulk looks when you do it, after a couple years it looks like crap. Of course, that's probably my less-than-skillful caulking abilities.