Regrout Cracked and Missing Bathroom Tile

Grout cracks and crumbles. It's not a failure—it's age. Bathroom tile sits in constant moisture, temperature swings, and the movement of the wall behind it. Eventually the grout between tiles pulls apart or chunks out, and when that happens, water finds its way behind the tile where it causes real damage. Catching this early and regrouting is exactly the kind of preventive repair that keeps your bathroom watertight and your tile looking sharp. The work is straightforward: remove what's broken, fill the gaps with new grout, and smooth it back to where it should be. This is a repair that rewards patience over speed—rushing the wiping stage means a hazy, uneven finish. Done right, fresh grout looks intentional and restores the clean geometry of your tile layout.

1. Map the Damage First. Walk the bathroom tile with your eyes and fingertips. Press on grout lines to find soft spots, look for visible cracks, and note where grout is missing entirely. Mark these areas with a pencil or tape so you don't miss anything mid-project. If more than 30 percent of the grout in a wall section is compromised, plan to regrout the entire wall for a consistent appearance. Isolate your work area with painter's tape along any trim, baseboards, or areas you want to keep dust-free.
2. Prep Your Workspace. Set up drop cloths on the floor and any vanity or fixture below your work area. Grout dust is persistent. Open a window or run a bathroom exhaust fan for the duration of the job—grouting creates fine powder that settles everywhere. Lay out your rotary tool or grout saw, your grout float, sponges, bucket, and mixing paddle. Fill one bucket with clean water for rinsing. Have rags or old towels ready for immediate cleanup.
3. Cut Out the Bad Grout. Use a rotary tool with a grout blade attachment or a manual grout saw to cut out the old grout. Work slowly and deliberately along the grout line, cutting to a depth of at least one-quarter inch. A rotary tool is faster but noisier and dustier; a grout saw takes longer but gives you finer control. Remove grout from both horizontal and vertical lines where you've marked damage. The goal is to expose clean, empty grout lines ready for new material. If grout is deeply crumbled, you may need to cut slightly deeper to get down to solid material.
4. Clean Every Dust Speck. Use a handheld vacuum or shop vac to remove all loose grout dust and debris from the empty joints. Be thorough—leftover dust creates voids in your new grout and weakens the bond. After vacuuming, wipe the tile and joints with a damp sponge or cloth to remove fine dust. Don't oversaturate the tile; you want damp, not wet. Let the surface dry for 10 to 15 minutes. The tile should look clean and the joints should be clearly visible and empty.
5. Get the Consistency Right. Pour unsanded grout (for joints under 3/16 inch) or sanded grout (for wider joints) into a bucket. Add water slowly while stirring with a mixing paddle attached to a drill. The consistency should be thick but spreadable—like peanut butter. It should hold a peak when you lift the paddle but still flow slightly. Start with a small batch, around three cups of dry grout. Stir thoroughly for two minutes to remove lumps. Let it sit for five minutes, then stir again briefly. This second stir activates the binding agents.
6. Pack Grout Deep. Load a grout float (a flat, rectangular trowel about 10 inches wide) with a generous amount of grout using a putty knife or margin trowel. Hold the float at a 45-degree angle to the tile surface and press the grout firmly into the empty joint lines. Work diagonally across the tile in overlapping sweeps, forcing grout deep into the gaps. Don't be timid—you want the grout packed solid, not sitting on top. Cover a section roughly three feet by three feet before moving on. Keep your float at a consistent angle and let your arm do the work rather than your wrist.
7. Wait for the Right Moment. Once you've applied grout to a section, wait 15 to 20 minutes before wiping. The grout should feel firm to the touch but still slightly yielding when you press it. This timing is critical—grout wiped too soon pulls material out of the joints; wiped too late, it hardens and becomes very difficult to clean. Test a corner section to gauge when it's right. You're looking for a surface that's no longer sticky but hasn't fully hardened.
8. Smooth and Clean. Rinse your grout sponge in clean water and squeeze it out thoroughly—it should be damp, not dripping. Hold the sponge at a 45-degree angle and wipe diagonally across the tile, using light pressure. You're removing excess grout from the face of the tile while smoothing the grout lines slightly. Rinse the sponge frequently in your clean water bucket, changing the water when it becomes cloudy. Make overlapping passes and work methodically so you don't miss spots. The grout lines should be smooth and flush with the tile surface.
9. Remove the Haze. After the grout has set for about an hour, take a clean, barely damp cloth and go over the tile one more time to remove any remaining haze or dust. This second pass pulls off the light, chalky residue that shows up as a film over the tile. Wipe gently—the grout is mostly hardened now and won't come out of the joints, but aggressive wiping can still scratch it. Stand back and look at the work under good light. The tile should be clean and the grout lines should show consistent color and texture.
10. Let It Harden Fully. Once wiping is done, leave the bathroom alone for at least 24 hours. Grout needs time to fully cure and harden. Don't splash water on it, don't use the shower, and don't touch the joints. Keep the door closed to prevent dust from settling on the still-soft grout. Some grout formulations benefit from light misting with water during the first 24 hours to slow drying, but check your product instructions before doing this. After 24 hours, the grout should be solid enough for normal use.
11. Seal for the Long Haul. After 48 hours, inspect your work. The grout should be hard and consistent in color. If you see cracks forming or soft spots where you press gently, the grout didn't cure properly—humidity, temperature, or mixing issues are usually the culprit. Properly cured grout can be sealed with a penetrating sealer if the grout color or your bathroom humidity makes you want extra water resistance. Grout sealer is optional for bathroom tile but extends grout life significantly. Apply sealer per the manufacturer's instructions, typically 72 hours after grouting is complete.