How to regrout bathroom tiles (and when to call a pro)

Black, crumbling or cracked grout makes even a clean bathroom look tired, and it lets water get behind the tiles. Regrouting is one of the most satisfying jobs you can do yourself, as long as the tiles underneath are still sound.

What you'll need

• Grout rake or oscillating tool with a grout blade
• Waterproof grout suitable for wet areas
• Rubber grout float and a damp sponge
• Bucket, gloves and a soft dry cloth

Step by step

• Rake out the old grout to at least 2–3mm deep, taking care not to chip tile edges.
• Vacuum the joints and wipe them with a damp sponge.
• Mix the grout to the manufacturer's instructions and press it diagonally into the joints with the float.
• After 10–20 minutes, wipe off the excess with a barely damp sponge, then buff the haze off once dry.
• Leave the shower unused for the curing time on the bag, usually 24 hours.

When to call a professional

If tiles sound hollow when tapped, move when pressed, or there's damp staining on the wall behind, the problem is deeper than grout. That usually means lifting and re-fixing tiles, which is where a tiler is worth it.