Signs your shower is leaking
Most shower membranes fail at 10 to 15 years. How to tell a failed membrane from a grout problem, and why a re grout is not a repair.
A shower membrane has a working life of 10 to 15 years. Past that, the thing most Narre Warren callers notice first has nothing to do with the shower itself: a damp patch on the hallway carpet, or silicone that peels away again three months after it was replaced.
Both of those are late stage symptoms. On the brick veneer belt through Narre Warren proper, now 40 to 50 years old, a failed membrane is the starting assumption rather than a diagnosis. On the Narre Warren South estate homes the original membrane is only now reaching the end of its life, which is why one suburb produces both a clean strip and rebuild and a wall frame that has been wet for a decade. Roughly 55 to 65 per cent of showers in the country are leaking somewhere, so the real question is how far yours has gone.
What are the early signs inside the shower?
These show up first and are easy to dismiss.
- Grout cracking or falling out in the same spot, usually the bottom corner or along the base to wall junction, and coming back within months of being repaired.
- Silicone at the base to wall junction lifting, blackening or peeling away from the tile.
- A tile that sounds hollow when you tap it, or that moves slightly underfoot.
- Grout that stays dark for hours after the shower is used, while the grout higher up the wall dries normally.
- A smell in the room that does not clear with the exhaust fan running.
- Efflorescence, a white powdery deposit, at the base of the tiles or along the grout line.
Signs on the other side of the wall
By the time any of these appear, water has been moving through the wall for a long time.
| Sign | Where to look |
|---|---|
| Damp patch or dark stain on carpet | The hallway or bedroom directly behind the shower wall |
| Skirting board swelling, splitting or lifting paint | The same wall, at floor level |
| Paint bubbling or plaster blistering | Lower third of the wall behind the shower |
| Carpet tack strip rusting, or a musty smell in a wardrobe | A built in robe sharing a wall with the shower |
| A soft or springy floor | Just outside the bathroom door on a subfloor house |
| Stained or sagging cornice, ceiling paint peeling | The room below, on a Narre Warren South double storey |
On the single storey houses the bathroom typically shares a wall with the hallway and a bedroom, so the hallway carpet is where it shows. On the estate homes through Narre Warren South, Berwick Springs, Cypress Hill and Hillsmeade, the main bathroom and ensuite are upstairs, so the first sign is usually a stain on the ceiling of the family room or garage below. That version does more damage before anyone notices, because the water runs along the ceiling framing rather than appearing at your feet.
Is it the grout or the membrane?
Grout is a filler between tiles and was never meant to be waterproof. The waterproof layer is the membrane under the tile bed, and the tiles and grout are a wearing surface over the top. Water passes through grout as a matter of course, which is fine, because the membrane catches it and drains it back to the waste.
That is why the distinction matters.
| Observation | Grout or silicone problem | Membrane failure |
|---|---|---|
| Cracked grout in one spot, fixed once, stays fixed | Likely | Unlikely |
| Same joint fails repeatedly after repair | Unlikely | Likely |
| Any damp outside the bathroom | No | Yes |
| Hollow or moving tiles | Possible | Likely |
| Damage at the base to wall junction of the shower | Possible | Likely |
| House is 20 years or older with an original shower | Unlikely to be the only issue | Assume it |
A useful test: look for damage on the other side of the wall or on a different floor level. Grout failure does not put water in the hallway. Once water is outside the wet area, the membrane has stopped containing it.
Why is a re grout not a repair?
A re grout replaces the filler between the tiles. It does nothing to the membrane, and the membrane is the part that has failed. A re grout on a 40 year old shower looks better for a while and hides the symptom that told you there was a problem, which is the worst outcome available, because the water keeps moving through the wall and the frame keeps rotting while the room looks fine.
Two other repairs are commonly offered and worth understanding. Silicone replacement has the same limitation as a re grout. A liquid overlay, where a membrane is applied over the existing tiles and the shower is re grouted, can work on a young shower with a sound substrate and no structural damage, and it fails quickly on an old one where the frame behind is already wet and moving. On the pre 1990 Narre Warren stock, where the base is usually a 900 by 900 fibreglass tray dropped into the corner with no membrane behind the wall sheeting at all, neither is a fix.
The honest repair for a failed shower here is a strip back to the frame: tiles and sheeting off, the wet bottom plate and studs replaced, new sheeting, a screed to fall, a fresh membrane, then re tiling. The height that membrane has to reach and the standard it is built to are set out in what the law requires. That work is most of a bathroom renovation, which is why most people who call about a shower end up doing the room.
What does waiting cost you?
Water in a wall frame does not stay still. It moves along the bottom plate, into the adjoining wall, and under the floor. On a subfloor house it reaches the joists and the bearers. The longer it runs, the more carpentry is in the job, and carpentry inside a wall is the part of a bathroom that is impossible to quote accurately from a photograph. A shower reported at the damp carpet stage is usually a straightforward strip and rebuild. The same shower two years later has taken the wall frame, the skirting, the carpet and sometimes the bedroom wall next door with it.
Anything built before 1990 gives you a second reason to move early. Wet sheeting breaking up behind your tiles is exactly the material that was used for wet area linings in that era, so it is handled as asbestos and taken out under licence. Testing and removal are covered in the permits and contracts guide.
Getting it looked at
If any of the outside the wall signs are present, get the room opened up rather than resealed. Send a photo of the shower corner and the damp area through the quote form with the age of the house and you get a written fixed price quote for the scope described and a reply within one business day. See shower repairs and waterproofing for the work itself, bathroom renovation cost in Narre Warren for what a full rebuild lands at, and how long a bathroom renovation takes for the timeline.