How to Reseal a Bath or Shower: Replacing Silicone the Right Way
How to remove old silicone, prepare the joint and apply a neat, watertight seal around a bath or shower that lasts.
Mouldy or cracked silicone around a bath or shower is more than unsightly. Once the seal fails, water gets behind it and can damage the floor, walls and the ceiling below. Resealing is one of the most worthwhile jobs you can do, and doing it properly makes the difference between a seal that lasts years and one that fails in months.
The quick answer
- Remove every bit of the old silicone, not just the surface
- Clean and dry the joint completely
- Fill the bath with water before sealing, so it sits at its lowest position
- Use sanitary silicone with a fungicide, not general-purpose sealant
- Keep the joint dry for the period stated by the sealant manufacturer before using the bath or shower
What you need
- Sanitary silicone and a sealant gun
- A silicone removal tool or plastic scraper, and a sharp blade
- Silicone remover gel, if the old sealant is stubborn
- Methylated spirit or isopropyl alcohol and lint-free cloths
- Masking tape
- A smoothing tool, or a finger dipped in soapy water
Step by step
- Cut along both edges of the old silicone with a blade and pull it away
- Scrape off any remaining residue, using remover gel if needed
- Clean the joint with methylated spirit to remove soap and grease
- Let it dry completely, ideally overnight, as silicone will not stick to damp surfaces
- Fill the bath with water, as its weight lowers the bath to its loaded position
- Apply masking tape either side of the joint, leaving a neat gap
- Cut the nozzle at an angle to suit the gap, and apply a steady, continuous bead
- Smooth it in one pass with the tool or a wet finger
- Remove the tape straight away, pulling it away from the bead
- Follow the sealant manufacturer's full curing instructions before using the bath or shower. If the product instructions require the bath to remain loaded while the seal cures, keep it filled for the specified period; drying times vary.
Common mistakes
| Mistake | Result |
| Sealing over old silicone | New seal peels away and mould comes through |
| Sealing a damp joint | Poor adhesion and early failure |
| Gap too wide for silicone alone | Seal splits, so use backing rod or fix the gap first |
| Using the bath too soon | Seal tears or distorts |
| Not filling the bath | Seal stretches and cracks the first time it is used |
Why does mould come back?
Black mould on silicone is usually a ventilation problem. Run the extractor fan during and after showers, wipe the seal dry and keep the room ventilated. Our condensation, damp and mould guide explains more.
When it is more than a seal
If tiles are loose, grout is crumbling, the bath moves when you step in, or there are stains on the ceiling below, the problem may be bigger than the silicone. It is worth getting it checked before resealing.
Frequently asked questions
How often should I reseal my bath?
Every few years, or as soon as the seal cracks, lifts or goes mouldy.
Can I seal over old silicone?
No. New silicone will not bond properly to old silicone. Remove it completely first.
How long does silicone take to dry?
Follow the product label for skin formation, full cure and the earliest permitted water contact. These are different stages, and the times vary between products and conditions; do not assume every sealant is ready after 24 hours.
Related guides
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