Waterproofing membranes wear out. Heat, ground movement, and constant water pressure break them down over years. When they go, water gets in and the damage builds fast. Here are six signs your membrane has already failed.
1. Damp patches on walls or ceilings
A damp patch with no obvious plumbing leak points to membrane failure. Water is entering the structure and pushing through to the surface.
The patch is rarely where the problem started. Water travels. A wet patch on a ground floor wall could be coming from a failed membrane on an external retaining wall metres away. Get it inspected before pulling anything apart.
2. Paint that bubbles or blisters
Paint blisters when moisture is trapped behind it. If you see it in bathrooms, laundries, or on walls adjoining an external structure, the membrane behind it has broken down.
The paint is the symptom. The membrane is the problem.
3. White chalky residue on brickwork or concrete
That white powdery crust is called efflorescence. It forms when water moves through brick or concrete and leaves mineral deposits on the surface.
It looks minor. It means water is actively pushing through your structure. Over time it weakens the concrete and corrodes any internal steel reinforcement. If you see it on retaining walls, external brickwork, or a slab edge, the waterproofing behind it has failed.
Residential waterproofing Perth: the wet area failure most people miss
The most common membrane failures in residential waterproofing Perth homes deal with are in showers. Australian Standard AS 3740 sets minimum requirements for wet area waterproofing, but overtime even compliant membranes can fail requiring repairs.
Watch for these signs in your shower:
- Grout that cracks or falls out repeatedly
- Tiles that sound hollow when tapped
- A persistent musty smell that cleaning doesn't fix
- Damp patches or discolouration on the wall or floor of the room next door
A failed shower membrane doesn't just wreck the shower. Water travels quick into wall cavities, concrete slabs, plasterboard and carpets creating an even bigger headache and repair job if not fixed promptly. The resulting rot, mould, and structural damage costs far more to fix than the original waterproofing job ever would have.
4. Cracks in tiles, render, or concrete
Membranes are built to handle minor substrate movement. They're not built for large cracks. Cracking at corners and cracked render on a balcony slab indicate that water movement has gone beyond what the membrane can handle.
Once it cracks, it stops keeping water out. Water enters at the crack and spreads beneath the surface, damaging areas well beyond what you can see.
5. Mould that comes back within days of cleaning
Bathroom mould is common. Mould that regrows days after cleaning is a serious problem.
Mould that returns quickly after cleaning tiles and grout followed by thorough ventilation signals that moisture is present behind the cleaning surface and almost always means a waterproofing membrane has failed. Cleaning the mould without fixing the membrane is a short-term fix that changes nothing.
6. Rust stains bleeding through concrete
Rust stains on a concrete surface mean moisture has reached the steel reinforcement inside. Once steel corrodes it expands, cracking the concrete around it from within. This process is called concrete cancer and it accelerates quickly once it starts.
A rust stain is not cosmetic. It means the slab or wall has lost its waterproof protection and the structural damage is already underway.
What to do next when water damage is present
Take immediate action as water damage gets worse overtime.
Organise a professional inspection as soon as you identify a source of water damage. A licensed contractor can identify where the membrane failed, tell you whether it needs repair or full replacement, and give you a written scope before any work starts.
Antidamp WA has been fixing waterproofing failures across Perth since 1987. If any of the signs above look familiar, the next step is straightforward.
Learn more about our waterproofing services or call 08 6444 1738 to book an obligation-free inspection.