Regrout a Tile Shower

Grout fails. Not from poor installation necessarily, but from what a shower does — cycles of hot and cold, soap scum working into pores, water finding the smallest crack and widening it freeze-thaw style even indoors. You'll see it as darkened lines that won't clean, as gaps where grout has crumbled away, or as that musty smell that means water is getting behind your tile. Regrouting stops that progression before it becomes a tile replacement job. Done properly, new grout seals the envelope again and resets the clock on your shower's useful life. This is a weekend project with a cure time tail. The physical work happens in four or five hours across Saturday, but you can't use the shower for 72 hours after grouting. Plan accordingly. The hardest part isn't technique — it's the removal phase, which is repetitive and generates fine dust. Everything after that is methodical. You're not creating art; you're filling gaps uniformly and wiping excess before it hardens. The difference between adequate and excellent work shows up in how consistently you maintain joint depth and how thoroughly you clean as you go.

1. Scrape Out Failed Grout. Use a grout saw to scrape out old grout to a depth of 1/8 to 1/4 inch along all horizontal and vertical joints. Hold the saw at a slight angle and pull toward you in steady strokes. Work section by section — don't try to do the whole shower at once. Vacuum out dust every few passes to see your progress clearly.
2. Clear Joints Down to Bare Tile. Vacuum all loosened grout and dust from joints using a shop vac with a brush attachment. Scrub the tile and empty joints with a stiff brush and water to remove soap residue and remaining dust particles. Wipe down with clean water and let dry completely for 2-3 hours. Any moisture left in joints will weaken the new grout bond.
3. Get Consistency Right. Pour recommended water amount into a clean bucket first, then add grout powder gradually while mixing with a margin trowel or gloved hand. Let it slake for 10 minutes, then remix without adding more water. Consistency should be thick enough to stay on a rubber float held vertically but smooth enough to press into joints without air pockets.
4. Press Grout Into Every Joint. Load grout onto the float and press it into joints at a 45-degree angle, working diagonally across tiles. Make two or three passes over each joint to ensure it's completely filled. Work in 4-foot sections so you can clean before grout hardens on the tile surface.
5. Scrape Excess Before It Sets. Wait 10-15 minutes after grouting each section until grout firms slightly. Hold the float at 90 degrees to the tile and scrape diagonally across joints to remove surface grout without pulling material from the joints themselves. Collect scraped grout and discard — don't reuse it.
6. Polish Joints While Damp. Once grout is firm but not fully hard, wipe tiles with a damp sponge in circular motions to remove the remaining haze. Rinse the sponge frequently and wring it nearly dry — too much water weakens surface grout. Make a final pass with diagonal strokes to smooth joint surfaces. Change water when it becomes cloudy.
7. Remove Final Haze. After grout has cured for 24 hours, a light haze will remain on tiles. Buff it off with a dry microfiber cloth using circular motions. If haze resists, mist tiles lightly with water and buff again immediately.
8. Protect Grout for Years. Wait 72 hours for grout to cure completely, then apply penetrating grout sealer with a small foam brush or applicator bottle. Work it into joints thoroughly and wipe excess from tile faces within 10 minutes. Let sealer cure per manufacturer directions before using the shower.