What Do You Do With Cracked Grout in the Corners of a Custom Shower?

Remove the grout in the corners with a grout removal tool. This tool has a diamond or carbide blade with a handle that grinds away the old grout. Remove as much grout as possible. Be careful not to nick the corners of individual tiles, as they can chip.

Vacuum the dust and debris from out of the grout line. The area must be completely clean.

Apply masking tape along the tile on both sides of the joint.

Cut the tip of the siliconized grout's tube with a utility knife at an angle. Cut it so an approximately 1/8-inch hole is exposed. Insert the tube into a caulking gun.

Squeeze the lever of the caulking gun steadily to dispense the siliconized grout into the grout line. Siliconized grout is thicker than regular silicone or caulking, so you may have to squeeze hard to keep a steady flow.

Smooth the bead of siliconized grout into the grout line with your finger. Some grout will "snowplow" in front of and to the side of your finger. This is fine; that's why the tape is there. Wipe your finger on a damp towel.

Remove the masking tape with the excess siliconized grout. The grout line should be straight and neat. Wait the appropriate amount of time for the grout to dry before using the shower. It should say on the tube, but waiting at least a full day before getting the siliconized grout wet is a good idea.