Re-sealing shower and bathtub

Silicone around the bath, shower tray and basin goes black with mould, peels away from the tiles and lets water behind the bath. Resealing looks like a small job, but if new silicone goes over old, or onto a damp surface, black spots reappear within weeks.

How resealing should be done

• cutting out the old silicone and removing the residue with a silicone remover;
• degreasing and thoroughly drying the joint, plus a fungicide where there is mould;
• for a bath: filling it with water so the joint opens up as it does when the bath is in use;
• applying new sanitary silicone and tooling the bead smooth;
• leaving it to cure as the manufacturer recommends.

Why silicone turns black

Sanitary silicone contains an anti-mould additive, but it does not last forever. Damp, soap and poor ventilation mean that after a few years mould appears on and under the surface. If silicone blackens within a few months, the problem is often deeper: water is getting under the bath or tray, and the bathroom is poorly ventilated. The handyman checks whether the joint moves too much and whether there is damp behind the bath.

Shower, bath, kitchen

The same service covers shower enclosure profiles, the joint between worktop and wall in the kitchen, and the sink. On an enclosure the silicone goes on the outside of the profiles so water can drain back into the tray. Say in the job which areas need sealing and give a rough length in metres.

Common questions