Grout Cleaning vs Regrouting

If the grout is solid, complete and only discoloured on the surface, grout cleaning can bring it back. Use a cleaner suitable for the tiles and the grout and a stiff brush, then rinse well. Avoid harsh acids, especially on natural stone, and try any cleaner on a small area first. Once clean, sealing cement grout can help it resist staining.

Grout needs replacing when it's cracked, crumbling, missing from joints, or stained or mouldy right through rather than on the surface. Mould that keeps coming back however often it's cleaned has usually grown into the grout. Damaged grout lets water into the joints, which is worth stopping before it reaches the wall behind.

Regrouting means raking out the old grout to an even depth without chipping the tile edges, cleaning out the dust, then pressing new grout fully into the joints and cleaning it off the tile surface before it hardens. To regrout a shower or regrout a bathroom where the tiles are sound but the joints are tired can refresh the room without removing all the tiles. Cement grout can then be sealed once it has cured: follow the manufacturer's instructions.

Cement-based grout is the most common and is easy to work with. Epoxy grout is harder-wearing and resists stains and water much better, which makes it a good choice in showers and kitchens, but it's more difficult to apply and to clean off the tiles. The choice depends on the area, the tile and how much use it gets.

Grout that keeps cracking along the edge of a bath, shower tray or worktop is a sign that the joint should never have been grouted. These are movement joints, where the bath and wall move slightly, and they need a flexible sanitary silicone instead. The bath and shower resealing page explains how that's done.

Regrouting doesn't fix loose or hollow tiles, and it doesn't fix a shower that leaks because the tanking behind the tiles has failed. If tiles move when pressed or there are signs of water damage, the cause is checked before deciding whether a repair is enough or the area needs retiling.