Fill gaps larger than 1 8 inch.
Gap between shower floor and wall tile.
Grout the gaps between the wall tiles take out the spacers and prepare the sanded grout mixture.
This joint should then be filled with 100 silicone to allow for expansion and contraction as well as providing a waterproof layer.
Plus a 1 16 gap allows the caulk to properly fill the space and waterproof the transition between the tile and tub or shower.
Grout is generally the best choice for filling joints between tiles in showers or elsewhere.
If you have tile on the wall adjoining the tub select a caulk that matches the color of the grout.
Soak a sponge in water and wet the tile with it.
However due to different rate walls and floors expand grout will eventually crack again leaving you with the new hairline crack.
Another option would be to fill the gap with grout.
If your gap is smaller than 1 8 inch in width use regular caulk.
Or fill the gap with grout.
Leaving a 1 16 gap between the tub and tile will prevent the tile from cracking when the tub expands.
In addition leave a 1 16 to 1 8 expansion joint between the main wall tile and shower floor tile or adjacent wall tile.
Since you are joining two different materials together you should use caulk in the space where the floor tile and tub meet.
Hopefully these tips help you with your project.
Some like to use a ledger or other space saver to indicate where your missing row should be.
As with any other gap near your bathtub you ll want to close the opening to prevent any possible water damage or the onset of mold and mildew.
But where two tiled shower walls meet or where a shower wall meets the floor called change of.
Fill in the gaps between the tiles using a rubber grout float.
So to accommodate the flooring tile many like to leave a small gap between the last row of wall tile and floor.
This gap may widen over time as your home shifts.
Similar to the gap that can exist between your wall tile and tub you may have a space between the floor and your bathtub.