How to Regrout a Shower Without Removing Old Grout

You can regrout over existing grout by cleaning thoroughly and applying new grout directly on top, though this method works best when the old grout is still structurally sound but just discolored or slightly deteriorated.

1. Strip Away Buildup First. Scrub all grout lines with a stiff brush and grout cleaner to remove soap scum, mold, and loose debris. Pay special attention to corners and areas where water pools. Let the area dry completely for at least 24 hours before proceeding.
2. Check Foundation Before Proceeding. Press firmly on various grout lines to ensure they're solid and not crumbling. If large sections are loose or falling out, you'll need to remove those areas first. Small gaps or hairline cracks are fine to grout over.
3. Prime for Maximum Adhesion. Use a small brush or sponge to apply grout primer to all existing grout lines. This helps the new grout bond properly to the old surface. Allow the primer to dry according to manufacturer instructions, typically 30 minutes to 1 hour.
4. Fill Every Joint Completely. Prepare a small batch of grout according to package directions. Using a rubber float held at a 45-degree angle, press grout firmly into the joints, working diagonally across the tiles. Make sure to fill all gaps completely and create uniform lines.
5. Remove Excess Before It Sets. Within 15 minutes of application, use a damp sponge to wipe diagonally across tiles to remove excess grout from tile surfaces. Rinse the sponge frequently in clean water and avoid dragging grout out of the joints.
6. Seal and Protect Your Work. After grout has set for about 2 hours, do a final cleaning with a clean, damp cloth to remove any grout haze from tile surfaces. Allow grout to cure for 24-48 hours before exposing to water, then apply grout sealer for protection.