Regrouting a cracked line or running a bead of sealant round the tray edge is quick and sometimes it even stops the visible symptom for a while. But if the cause is a failed waste seal, missing tanking, or tiling fixed to unsuitable board, the water finds another way through soon enough, because the actual barrier that should have been stopping it was never properly there.
A repair that lasts means opening the wet zone up enough to find the real source, then rebuilding it to be genuinely waterproof rather than reliant on grout alone.
The sequence a proper repair follows
- Expose the actual point of failure — this usually means removing tiles in the affected area, or lifting the tray, rather than working from guesswork.
- Replace or properly reseal the tray or waste connection where that's the source, using a correctly specified seal and waste fitting.
- Remove and replace any backing board that's swollen, delaminated or stayed damp — tiling back onto compromised board just repeats the failure.
- Re-tank the whole wet zone with a proper waterproof membrane system before any new tiling goes on, paying particular attention to corners and the tray-to-wall junction where movement is greatest.
- Re-tile onto that tanked, stable background, and finish with correctly specified movement joints rather than continuous rigid grout across every junction.
Why a surface-level patch keeps failing
Grout and sealant are the last line of defence in a wet room, not the actual waterproofing layer — that's what tanking is for. Patching cracked grout or resealing a tray edge without addressing missing tanking or a failed waste means the actual barrier to water is still absent; the patch just delays the moment it becomes visible again, while the damp continues working on whatever's behind the tiles in the meantime.
Interfaces with other trades
Waste and pipework connections are plumbing work, and if the waste itself has failed, that needs resolving as part of the same job rather than treated separately, since re-tiling around a still-faulty waste connection wastes the tiling work.
Where water has reached ceiling joists below, that's a structural timber question — affected joists need inspecting for rot and, where necessary, treating or replacing before the ceiling below is made good, rather than simply replastering over damaged timber.
If the ceiling below needs opening up to assess and repair joist damage, that work has to be coordinated with the bathroom repair above it, since patching the ceiling before confirming the leak source is fixed risks having to reopen it again.
How you know it's genuinely fixed
The test that matters is time and use, not a single check straight after the work: the shower should be used normally over the following weeks with no recurrence of staining on the ceiling below. Because the repair replaces the actual waterproofing rather than patching the surface, there should be nothing left behind the tiles for water to find its way through a second time.
Common questions
Do all the tiles need to come off to fix a shower leak?+
Usually at least the tiles in the immediate wet zone need to come off to properly investigate and re-tank, particularly around the tray and any corners. It's not always the whole bathroom, but it's rarely just a single tile.
How do I know if my shower has proper tanking?+
It's not visible once tiled, so the honest answer is that if the bathroom is older or was tiled directly onto plasterboard without a membrane, it's worth assuming tanking may be missing until checked, particularly if a leak has already occurred.
Will the ceiling below need repairing too?+
If water has reached it, yes — and it's worth checking the joists above that ceiling for damp or rot before simply replastering, since a repaired ceiling over untreated damp timber is only a cosmetic fix.
Get a written quote for the repair
We open up the wet zone to find the actual source before quoting, so the price reflects a repair that stops the leak for good.