Question for Boris and the other BT tile gurus:

When installing terrazzo shower bases, do you caulk the tile to shower base joint?  The instructions for a base I installed a few months ago said not to, and to leave a breathable gap of 1/8 – 3/16″ from the bottom of the tile to the little curb of the base.  The concrete board sits right on the metal flange of the base (not inside it) and supposedly that’s waterproof enough.

I ask because it’s pretty scurvy under the tile – and I’m not sure I trust the metal flange to not leak at all.  I’ve seen them installed other places with caulking (I’m assuming with a backer rod, since there’s a pretty big gap in there.)  So I’m curious.

thanks