Remove old shower grout, clean and treat mould, then apply and shape waterproof grout for a fresh, watertight finish.
RG-01Get the room readyOpen a window or use an extractor fan, as grout dust and cleaning fumes need somewhere to go. Lay a towel in the shower tray or bath to protect it, and clear away shampoo bottles and mats. Put on safety glasses and a dust mask before you start scraping.
RG-02Rake out the old groutRun a manual grout rake or an oscillating multi-tool fitted with a grout blade along every joint, going about 2-3mm deep. Keep the tool flat against the joint, not angled onto the tile, so you don't chip the glaze. Do all the horizontal joints first, then the vertical ones.
RG-03Vacuum and check the jointsVacuum out all the dust and loose grout, then wipe each joint with a damp cloth so you can see bare tile edges clearly. Check the backer board or wall behind for softness or staining. Soft, crumbling board behind the tiles usually means water has been getting in and needs sorting before you regrout.
RG-04Treat any mould or mildewSpray a bathroom mould and mildew remover onto any black or pink staining and leave it to work for the time stated on the bottle. Rinse thoroughly with clean water afterwards. Let the whole area dry fully — new grout won't bond properly onto damp tiles.
RG-05Mix the groutUse a waterproof, mould-resistant grout made for wet areas — either an epoxy grout or a cement-based grout with a waterproofing additive. Mix small batches following the pack instructions, so it doesn't start to go off before you've used it. Aim for a smooth, spreadable paste with no dry lumps.
RG-06Apply the groutLoad a rubber grout float and drag it diagonally across the joints at about a 45° angle, pushing grout firmly in as you go. Work in small sections of a few tiles at a time so it doesn't dry out before you can clean it off. Make sure every joint is fully packed, with no gaps or air pockets.
RG-07Clean off the excessAfter about 10-15 minutes, once the grout has firmed up slightly, wipe over the tiles with a damp grout sponge, rinsing it out often in clean water. Wipe diagonally across the joints, not along them, so you don't drag grout back out. Go over the area two or three times as a light haze will keep appearing.
RG-08Shape and smooth the jointsRun a rounded grout shaping tool, or a gloved fingertip, along each joint to leave a neat, slightly concave line. This gives a tidier finish and helps water run off rather than sit in the joint. Wipe away any final haze once the grout has hardened a bit more, using a dry cloth.
RG-09Let the grout cureLeave the grout to cure fully before using the shower — usually 24 to 48 hours, but check the pack for the exact time. Don't run water on it or let it get wet during this time. Avoid touching or knocking the joints while they set.
RG-10Renew the silicone sealantCut out the old silicone along the tray or bath edge and any internal corners with a sharp blade, and peel it away. Clean the gap thoroughly and let it dry, then apply a neat bead of sanitary silicone with a sealant gun. Smooth it with a wet finger for a clean line, then leave it undisturbed to cure as stated on the tube.
RG-11Final clean and tidy upOnce everything has cured, give the tiles a final polish with a dry cloth to remove any last grout haze. Remove any masking tape or protective towels, and check all joints are solid and fully filled. Dispose of leftover grout and silicone tubes as directed on the packaging, and wait the full cure time stated before using the shower normally.
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