The Situation
Mdm. Wong's terrace house in Skudai had a flat concrete roof slab over the rear extension that had been leaking through two monsoon seasons. Every heavy downpour left brown water stains spreading across the ceiling below, and the plaster had started to flake and bubble. A previous patch job had failed within months.
She called Ace Plumber Johor Bahru to stop the leak properly this time, rather than repeating another short-lived patch.
Our Assessment
Our team inspected both the rooftop slab and the affected ceiling inside to trace exactly where water was entering. Key findings included:
- The existing surface coating had cracked and peeled, leaving bare concrete exposed to rainwater
- Hairline cracks in the slab and a poorly sealed parapet upstand were the main entry points
- Ponding water was sitting on a low spot of the slab long after rain, accelerating seepage
- Internal ceiling damage was limited to staining and surface plaster — no structural concern
Simply painting over a leaking flat roof rarely lasts. Without proper surface preparation, crack treatment, and a continuous membrane carried up the parapet, water finds its way back in through the weakest joint. A full torch-on membrane system bonds to the slab and seals the whole surface as one waterproof layer.
The Solution
We carried out a complete waterproofing system rather than another surface patch:
- Stripped back the failed coating and thoroughly cleaned the slab down to sound concrete
- Routed out and sealed the hairline cracks, then treated the parapet upstand and corners
- Applied a bituminous primer to ensure the membrane bonds tightly to the surface
- Installed a torch-on bituminous membrane across the full slab, lapped at all joints and carried up the parapet to form a continuous waterproof layer
- Re-profiled the low spot to improve fall and ran a flood test to confirm the slab drained and stayed watertight before sign-off
Total job duration: 2 days. The roof passed the flood test with no seepage to the ceiling below.
After the next round of heavy rain, the ceiling stayed completely dry. The torch-on membrane gives Mdm. Wong's roof a durable, seamless waterproof barrier built to handle JB's monsoon downpours for years.
"I had given up after the last repair failed so quickly. This time the team actually found where the water was coming in and sealed the whole roof properly. It has rained hard several times since and the ceiling is bone dry. Worth doing it right."— Mdm. Wong, Skudai
Roof or Ceiling Leaking Every Monsoon?
Ace Plumber Johor Bahru traces the source and waterproofs it properly. Contact us now via WhatsApp.
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