How to Reseal a Shower

Shower silicone needs resealing because it's a movement joint, not a permanent bond — it flexes every time the shower tray, bath or wall shifts slightly, and over years that flexing, plus constant moisture, causes it to shrink, crack or peel away from the tile. Once a gap opens up anywhere along the bead, water gets behind the tile or under the shower tray, which is how small silicone jobs turn into damp, rot or a leak into the ceiling below.

It's a common issue we see across London bathrooms, from period conversions in Islington and Hackney with original tiling to newer ensuites in Canary Wharf flats — the mechanism is the same regardless of the property.

The clearest sign is black or pink staining along the silicone that won't scrub off, followed by any gap, crack, or softness where you can push the bead away from the tile with a fingernail. If water is pooling at the base of the shower after use, or you can see damp or discolouration on a ceiling or wall below the shower, the seal has already failed and water is getting through.

• Black mould staining that won't clean off the silicone itself
• Gaps, cracks or shrinkage along the bead
• Silicone that's gone soft, sticky or lifted away from the tile
• Water pooling on the floor outside the tray after showering
• Damp patches on a ceiling or wall on the other side of the joint

You need five things: a sealant knife or box cutter, a plastic scraper, white spirit or isopropyl alcohol, masking tape, and a tube of sanitary-grade bath sealant with a silicone gun. Choosing the right sealant matters more than most people expect — a dedicated bath sealant with a mould inhibitor holds up far better in a shower than general-purpose or decorator's silicone, which isn't designed for constant moisture.

Resealing a shower yourself is a seven-step job that any competent DIYer can complete in an hour, provided you're patient about cleaning the joint and letting it cure before use.

1. Cut along both edges of the old silicone bead with a sealant knife or box cutter, then peel it away in one piece where possible.
2. Scrape off every trace of old sealant with a plastic scraper, then wipe the joint with white spirit or isopropyl alcohol to remove residue and grease.
3. Leave the joint to air-dry completely, or use a hairdryer, since silicone won't bond to a damp surface.
4. Run masking tape along both sides of the joint, leaving a consistent gap, for a clean, straight edge.
5. Cut the sealant tube nozzle at an angle, load it into a gun, and run a single steady bead along the joint in one continuous pass.
6. Smooth the bead with a wet finger or a silicone tool, then peel away the masking tape immediately while it's still wet.
7. Leave the shower completely dry and unused for 12-24 hours so the sealant cures fully before it gets wet again.

The same method applies almost identically if you're wondering how to reseal a bath or how to seal a bath around taps and the overflow — strip, clean, dry, mask, apply, tool, cure. If mould has already taken hold under the old bead rather than just staining the surface, our guide to replacing shower silicone covers dealing with mould growth specifically.

Call a plumber if the shower tray or bath itself has flexed, cracked, or moved, if water has already got behind the tiles and caused damp or soft plasterboard, or if the leak keeps returning after two or three DIY reseals. Those symptoms point to a structural or waterproofing issue that fresh silicone alone won't fix, and papering over it with more sealant just delays a bigger repair.

RenoPlumb reseals showers and baths across Tower Hamlets, Hackney, Islington, Newham, Southwark and Canary Wharf from our base on Commercial Road in Whitechapel, E1, and we'll check for hidden leaks or tray movement while we're there rather than just replacing the bead. See our shower resealing service for details, or call 07460 824073 for a free quote.

The cost depends on the size of the shower, how much old silicone has to come out, and whether there's any hidden damage behind the tiles that needs fixing first, which is why we don't quote a figure without seeing the job. Every visit comes with a free, no-obligation quote, so it costs nothing to find out. Full detail on how we price jobs is on our pricing page.

Need this fixed by someone local? See our page for a plumber in Islington for borough-specific coverage and response times.