Cracked or missing tiles and deteriorated grout allow water intrusion and create safety hazards. Tile repair involves removing damaged tile, preparing the substrate, and setting new tile with mortar; grouting fills joints with waterproof material. These tasks require patience and precise work but prevent costly water damage.
Practice on a small area or learn with professional guidance; focus on proper tile spacing and grout consistency.
Tile installations are essentially armor over vulnerable surfaces. In a bathroom, the wall behind the shower or the floor around the toilet is often moisture-sensitive material — drywall, wood substrate, or concrete board — that would quickly degrade if exposed to water. The tile and grout system's primary job is waterproofing; the aesthetic appeal is secondary. When grout cracks, discolors, or when a tile chips or loosens, the waterproof barrier has been breached, and water begins infiltrating toward the substrate behind. This is why your prerequisite on interior finish damage focuses on assessment: tile damage that looks minor on the surface often indicates ongoing water damage that's been happening invisibly behind the wall.
Grout is the mortar-like material that fills the joints between tiles. It serves two functions: sealing the gaps against water infiltration and distributing load so tiles flex together rather than cracking against each other. There are two main types. Cement-based grout (sanded for joints wider than 1/8 inch, unsanded for narrow joints) is traditional, porous, and requires sealing. Epoxy grout is far more water-resistant and stain-proof but is harder to work with, sets quickly, and is much harder to remove if you make a mistake. In high-moisture areas like showers, epoxy grout or well-sealed cement grout is important; in lower-risk areas like a backsplash, either works. Matching the existing grout color is the main challenge in repairs — bring a photo or a chip to the tile store.
Regrouting means removing deteriorated grout without damaging the tiles and refilling the joints. The removal step uses an oscillating tool with a grout-removal blade or a manual grout saw; this is tedious but important — applying new grout over old failed grout just seals the crack temporarily and the problem returns. After removal, clean the joints thoroughly, let them dry, and apply new grout according to the manufacturer's ratio (too much water weakens grout significantly). Work in sections — grout sets faster than beginners expect — and use a grout float to press the material firmly into the joints. The cleanup step involves wiping the tile surface with a damp sponge before the grout fully hardens, leaving a thin haze that polishes off when fully cured.
Replacing a cracked or hollow tile requires the same careful approach to the underlying system. Tap tiles gently with a knuckle — a hollow sound means the adhesive bond has failed and the tile is no longer supported. A hollow tile will eventually crack under foot traffic or thermal expansion. To replace it, remove the grout around the damaged tile first, then carefully break the tile itself with a hammer and chisel (work from the center outward to avoid cracking adjacent tiles), remove all old mortar from the substrate, and reset the new tile with fresh thinset adhesive. The tile must be pressed firmly into the adhesive and left to cure fully before grouting — setting tile and immediately grouting are a common beginner mistake that produces weak bonds.