I don’t have to worry with much freezing in Louisiana, but we get our fair share of rain. The area in question is mostly covered, yet that doesn’t mean it will not get wet. I guess I could leave some gaps in the mortered edge to allow for drainage. Most likely I will put down a thin bed of sand on top of the existing tile to act as a cushion to avoid any grinding noises.
But what about the any voided areas under the tile? Do I rip up those tile and fill in with sand?