A properly installed tile shower should always have a 6 inch lip liner going up around base of the shower walls.
Tile shower floor grout or caulk.
The vast majority of showers that i ve tiled have had no problems when i use grout in the corners.
In addition to caulking shower fixtures experienced tile setters caulk in all changes in planes in showers including corners surface edges and wall to floor intersections.
On one hand there is little chance for movement around the base of a properly installed tile shower floor.
Where grout is just good for bonding together tile caulk is good for creating a seal between multiple materials say between glass tiles and a porcelain tub.
Doing so protects against moisture related issues and common expansion cracking associated with these areas.
Caulk is impermeable meaning it won t let in water.
Or where the edge of a tile meets the wall.
Tom meehan a second generation tile installer and co author of working with tile who lives and works in harwich mass responds.
Since you are joining two different materials together you should use caulk in the space where the floor tile and tub meet.
Grout is not flexible so it s not the best material for the job while caulk allows for movement and also provides a better sealant.
If mold gets into that space it can cause damage to your subfloor.
My tile installer recently told me that he wanted to use caulk in the corners of a tiled shower instead of grout is that necessary.
An area of controversy has always been whether to caulk or grout around the base of a tile shower floor.