How to Regrout a Tile Shower

Use an oscillating multi-tool fitted with a carbide grout removal blade to cut out the old grout from all joints. Hold the tool at a slight angle and run it along each grout line, removing at least 2/3 of the grout depth. Work carefully to avoid chipping tile edges. For tight corners and small areas, use a manual grout saw. Vacuum out all loose debris when finished.

After removing the old grout, vacuum all joints thoroughly with a shop vac or hand vacuum. Wipe the joints with a damp sponge to remove remaining dust. Check for any loose or hollow-sounding tiles — press on each one. If a tile feels loose, re-adhere it with tile adhesive before regrouting. Let everything dry completely before applying new grout.

If using powder grout, mix it with water according to the package directions until it reaches a thick peanut-butter consistency. Let it slake (rest) for 10 minutes, then remix briefly. Don't add extra water to thin it — watery grout is weak and will crack. If using pre-mixed grout, stir it and it's ready. Only mix as much as you can use in 30 minutes.

Scoop grout onto the rubber float and press it diagonally across the tile joints at a 45-degree angle. Push the grout firmly into each joint, making multiple passes to fill them completely. Work in 3-4 square foot sections. After filling all joints in a section, scrape off excess grout by holding the float at a steep angle (nearly 90 degrees) and pulling diagonally across the tiles.

Wait 15-20 minutes until the grout begins to firm up (it will lose its wet sheen). Wring a large sponge almost completely dry and wipe the tile surface in gentle diagonal strokes. Rinse the sponge frequently and wring thoroughly — too much water washes grout out of the joints. Two or three passes should clean the tile surface while leaving smooth, slightly concave grout lines.

Apply painter's tape on both sides of corner joints, floor-to-wall joints, and around fixtures (showerhead flange, faucet escutcheons). Apply a bead of color-matched silicone caulk along the joint, then smooth it with a wet finger. Remove the tape immediately while the caulk is wet for a clean line. Silicone caulk stays flexible and won't crack in corners like grout does.

After the grout cures for 24 hours, buff off any remaining haze with a dry cloth or grout haze remover. Then apply a penetrating grout sealer to all grout lines using a small applicator bottle or brush. The sealer soaks into the grout and creates a barrier against moisture and stains. Wipe excess sealer off the tile surface. Reapply sealer annually for best protection.