How Often Should Bathroom Sealant Be Replaced?

As a general rule, bathroom silicone sealant lasts anywhere from 1 to 5 years before it needs replacing, though heavily used family bathrooms and areas with poor ventilation tend to need it redone more often — sometimes annually — while a rarely used ensuite might go five years or more.

Signs your sealant needs replacing

• Discolouration or black mould in the sealant line itself, which cleaning products can't shift — mould growing inside the silicone means it needs cutting out, not just cleaning.
• Cracking, splitting or peeling away from the tile or bath edge, which lets water get behind the seal.
• Gaps where the sealant has shrunk or pulled away, particularly common where a bath flexes slightly under weight.
• A musty smell near the seal, even if you can't see obvious mould — this often means moisture is getting through.

Why it matters

Sealant isn't just cosmetic — it's the barrier stopping water getting behind your bath panel, into the floor, or into the wall structure. Failed sealant left unaddressed is a common, avoidable cause of hidden water damage, rot in timber floors, and damp patches appearing on ceilings below bathrooms.

Cost to replace

Re-sealing a bath or shower yourself costs very little — a tube of decent sanitary silicone sealant is typically £5-£10, and the job takes an afternoon including drying time. Hiring a tradesperson to do it (common if you want a genuinely neat finish or have a lot of sealant runs to redo) typically costs £50-£150 depending on how much needs doing.

How to do it yourself

1. Cut out the old sealant carefully with a sealant removal tool or sharp blade, taking care not to scratch the bath or tiles.
2. Clean the gap thoroughly and let it dry completely — any residual moisture or soap scum will stop the new sealant bonding properly.
3. Apply masking tape either side of the gap for a clean line, then apply a continuous, even bead of sanitary silicone.
4. Smooth it with a sealant tool or a soapy finger, remove the tape immediately, and leave it undisturbed (and dry) for the time stated on the tube — usually 24 hours minimum before use.

Common mistakes

• Sealing over old, mouldy sealant instead of removing it — the mould will usually come back through the new layer.
• Using standard silicone instead of sanitary silicone, which often lacks the mould-inhibiting additive.
• Not letting the bath settle before sealing a new installation — sealant applied while a bath is empty can crack once it's used and flexes under weight.

Choosing the right sealant

Not all silicone is equal. Sanitary-grade silicone contains a mould-inhibiting additive that standard bathroom/kitchen silicone often lacks, so it's worth checking the label rather than grabbing whatever's cheapest. Some ranges also offer specific anti-mould formulations aimed at high-humidity rooms, which can be worth the small extra cost in a bathroom with poor ventilation or heavy daily use. Colour choice matters too — white shows dirt and mould more visibly than clear or coloured options, though it's also easiest to keep looking genuinely clean if you stay on top of it.

When it's more than just the sealant

If sealant keeps failing in the same spot within months of being redone, it's worth asking why. A bath that flexes noticeably when you step in — often a sign of inadequate support underneath — will keep breaking the sealant bond no matter how carefully it's applied. Persistent failure in one specific area, rather than general wear over years, is a signal to check for an underlying structural or support issue rather than simply reapplying sealant again.

If you're seeing sealant fail repeatedly in the same spot, it can be a sign of a bigger issue — see our guide to shower tray leaks if the problem is around a shower rather than a bath, and if mould keeps returning across the whole room rather than just the seal, our guide to why your bathroom is growing mould covers the wider ventilation issue.

Tools you'll need

Resealing a bath or shower yourself doesn't need much: a sealant removal tool or a sharp Stanley knife for cutting out the old bead, methylated spirit or a proprietary silicone remover for cleaning residue off the surface, masking tape for a neat line, a sealant gun if you're using a cartridge rather than a squeeze tube, and a smoothing tool (a purpose-made silicone profiling tool gives a neater finish than a fingertip, though both work). Budget £15-£25 in total for a first-time kit if you don't already own a sealant gun, on top of the sealant itself.

How long the job actually takes

Removing old sealant and cleaning the joint properly typically takes 30-60 minutes for a standard bath or shower tray, depending on how stubborn the old sealant is to cut out. Applying the new bead takes only a few minutes once the prep is done, but resist the temptation to use the bath or shower straight away — most sanitary silicones need a minimum of 24 hours, and some longer, before they're fully cured and waterproof.