Tile grout creates a clean, finished appearance on tiled shower surfaces and helps to hold tiles in place. Unfortunately, grout lines are subject to cracks and fractures, particularly in new construction due to the drying and settling of building materials. Cracked grout doesn't have to mean replacing the tile job, however, as repairing cracked grout in shower areas is an easy do-it-yourself project for homeowners.
Mix grout with water in a wide, shallow container according to the package directions.
Dig out loose grout from the cracked area using the tip of a nail. Run the tip of the nail along stable grout areas to slightly score the surface.
Scoop prepared grout mixture onto the grout float and apply to the repair area holding the float at a 45 degree angle, applying pressure to work the mixture into the grout joints.
Run a finger down the wet grout lines to create a smooth surface. Allow the grout to dry for half an hour.
Dampen the sponge with water and wipe across the surface of the tiles to remove excess grout.
Allow the grout to dry for three days. Do not use the shower during this time as excess moisture will prevent the grout from properly curing.
Cut the tip off the silicone sealant nozzle at a 45 degree angle using a utility knife. Hold the nozzle at a 45 degree angle to the tile surface, and squeeze the bottle to apply a thin layer of sealant to the grout.
Allow the sealant to dry for 24 hours before using the shower.