Change of plane: grout or caulk?

[Steve C]

I posted a question on my thread big bath build/remodel on the Tile Forum/Advice Board this a.m. and have yet to receive any replies, so here goes.

I'm building a 6' square Kerdi shower, and am installing tile now. In the Kerdi Shower book, John mentions using grout instead of caulk for changes of plane, although the conventional wisdom is to use silicone. Since the Kerdi is waterproofing everything any hairline cracks in the grout will be cosmetic.

I've explained this to the homeowner, as well as given him access to the shower book, and he would like to use grout (we already have Spectralock on hand). I'd like to use grout too, but would like to verify that we're doing the right thing.

Anyone here interested in giving me their opinion on this? Seems like everyone recommends the shower book, so just wondering if this bit of info is still valid.

[Shawn Prentice]

You need expansion joints at changes of planes because of the variations in expansion and contraction of the different planes. You also need them when dissimilar materials come together, i.e. fiberglass to tile, etc. Silicone is better than your latexes (sp?).

Use a neutral cure silicone for the best results. Laticrete, TEC both have them, or in a pinch, GE's silicone II is neutral cure.

[MNTileGuy]

Steve-

You'll get responses all over the board on this. In fact, I recall a pretty spirited thread we had going awhile back on this.

Personally, I use color matched caulk. But for every person like me, you'll get one that says grout...

[The Kid]

Neither, i use silicone. Latasil that is. Grout cracks, color match caulks are short lived, but silicone works great. its more expensive and its harder to apply but its good stuff.

[MNTileGuy]

I agree that silicone is best, at least in showers if you can get it color matched.

In my area, you can't just buy it off the shelf. You have to order it in for big $$$.

You folks in the more evolved parts of the tile world don't have that problem I guess.

[muskymike]

I grout every corner. Using Kerdi you won't get cracks too often.

[LAtileman]

Caulk is good. I've heard that spectralock in corners can actually cause the tile to crack rite next to the joint, apparently the tensile strenght of spectralock is higher than the tile.

Moral of the story - keep epoxy out of the corners!

[Steve C]

Thanks for all the quick replies. Tomorrow I'll see if my supplier (Prosouce) can get Latasil. Their website makes it look like I should be able to match the Spectralock.