Bath & Shower Resealing

A bath or shower tray moves slightly every time it's filled or stood in, and walls and floors move with temperature and the seasons. Grout is rigid, so when it's used in the joint between a bath and the tiles it cracks along the bath edge. That joint is a movement joint and is filled with a flexible sanitary silicone sealant instead. The same applies to internal corners and where tiles meet a worktop or a shower tray.

New silicone doesn't bond properly to old silicone, so siliconing over the top of an old seal usually fails quickly. The old seal is cut out and the remaining residue removed, so the joint is back to clean tile and a clean bath, tray or basin edge.

Soap, limescale and mould in the joint stop new silicone sticking. The joint is cleaned, any mould treated, and the area left to dry fully before resealing. A damp joint is one of the most common reasons new silicone peels away.

A mould-resistant sanitary silicone made for bathrooms and kitchens is applied in a continuous bead and tooled to a neat, smooth finish. Many people fill the bath with water before it's sealed, so the seal is set with the bath at its lowest point and the joint isn't stretched the next time it's used. The silicone needs time to cure before the bath or shower is used: follow the manufacturer's instructions.

Black marks in silicone are usually mould growing on soap residue and moisture. Good ventilation, wiping down after showers and a mould-resistant sanitary silicone all help. Once mould has grown into the silicone it can't be cleaned out properly, so the seal is replaced.

Replacing silicone does not repair failed tanking or hidden leaks. If tiles are loose, grout is crumbling, or there are signs of water damage such as stained ceilings below, swollen boards or a musty smell, the problem may be behind the tiles. Signs of water damage are assessed rather than simply covered over. For loose tiles and regrouting, see Tile, Grout & Seal Repairs.