Scraping out old silicone and running a fresh bead is a five-minute job, and if the underlying joint is sound, it's genuinely the right repair. The problem is that most repeatedly failing joints aren't sound — there's movement, or moisture, or both, behind the visible bead — and resealing on its own does nothing about either. It just buys another few months before the same crack or blackening appears in the same place.
A repair that actually holds treats the sealant as the last step, not the whole job.
The sequence a proper repair follows
- Check whether the bath or tray moves at all when stepped in or leant on, and if it does, access underneath — via the panel or from below where possible — to support and pack it properly so the movement stops.
- Strip the old joint back completely, removing every trace of old silicone and residue rather than sealing over it, and clean the substrate thoroughly.
- Allow the joint to dry fully — genuinely dry, not just surface-dry — before applying anything new, since trapped moisture under a fresh bead is one of the most common reasons a reseal fails quickly.
- Use a proper sanitary-grade sealant suited to a wet environment, applied in a single continuous bead rather than built up in patches.
- Where the tray or tiling substrate behind the joint shows signs of dampness or damage, that has to be investigated and made good — replacing affected board and checking for water ingress — before the new joint is finished, not after.
What a straightforward reseal misses
Simply scraping out the old bead and running in a new one, without checking for movement or substrate damage, treats the silicone as though it were the point of failure. In most repeatedly failing joints it isn't — it's the last thing to show a problem that's already happening underneath. A fresh bead over an unsupported tray or a damp substrate will crack or blacken again on roughly the same timescale as the last one did.
Interfaces with other trades and finishes
Supporting a bath or tray properly sometimes means adjusting or adding to the frame or feet it sits on, which needs doing before tiling or panelling is closed back up, not as an afterthought. If tiles need to come off to check or replace the substrate behind a persistently wet joint, that reopens the tiling work as part of the job, and it's worth planning for that rather than assuming a surface-level fix will do.
Where a waste or overflow connection turns out to be the actual source of the moisture rather than the joint itself, that's plumbing work that needs resolving before the area is sealed and tiled back up — sealing over an active leak just hides it again.
How you know it's actually fixed
A properly repaired joint stays clean, doesn't discolour, and doesn't split or peel through normal use and cleaning over a reasonable period. If a new joint blackens again within weeks despite decent ventilation and cleaning, that's a sign there's still moisture reaching it from behind, and it's worth going back to check the substrate rather than resealing a third time.
Common questions
How often should bathroom silicone need replacing?+
A properly installed joint on a supported bath or tray, with a suitable sanitary-grade sealant, should last a good number of years under normal cleaning and use — needing it redone every few months is not normal and points to an underlying cause.
Can I support the bath myself without removing tiles?+
Sometimes, if there's access from beneath through a floor void or an adjoining space. Where the only access is through the front panel and tiled upstand, some disturbance to the tiling is often unavoidable to do the job properly.
What sealant should be used in a bathroom?+
A sanitary-grade silicone formulated to resist mould growth in a wet environment, rather than a general-purpose or decorator's caulk, which isn't designed for sustained damp conditions.
Request a written quote
We check for movement and substrate damage before resealing, so the quote covers a repair that's actually likely to hold.