Diagnosis
Concrete roof leak in Mauritius: where the water comes from and how to stop it
A damp patch on the ceiling is rarely below the point where water entered. On a concrete slab, water travels inside the structure before reappearing: treating the stain without finding the entry point fixes nothing. Here are the causes we see most in Mauritius, and how each is treated.
1. Shrinkage and thermal movement cracks
Concrete exposed to Mauritian sun expands by day and contracts at night. The resulting cracks progressively go through the slab. A plain cement patch re-cracks within a season: you need an elastomeric system that moves with the substrate, with reinforced crack bridging.
2. Upstands, parapets and penetrations
Most leaks we diagnose do not come from the flat field but from detail points: upstands that are too short, slab-to-wall junctions, water-heater plinths, pipe penetrations, balustrade feet. Each needs reinforcement fabric embedded in the membrane.
3. Blocked outlets and insufficient falls
Standing water always finds a way in. Leaves, sand, moss: outlets clog fast in the rainy season. Where there is no fall, a screed to falls must be formed, or a system certified for permanent ponding must be used.
4. External tiling laid without waterproofing
Very common on roof terraces and balconies: tiling is not waterproofing. Water passes through the joints, saturates the screed and reappears on the ceiling below. Correct repair means either removal or a waterproofing system approved for application over existing tiles.
5. Our diagnosis method
Full visual inspection of the roof and its detail points, moisture readings, targeted water testing when required, photo report, then a written system and warranty specification before any pricing.
Frequently asked questions
Can a leak be repaired during the rainy season?
A temporary make-safe is possible at any time. Final membrane application requires a dry substrate, so permanent works are scheduled within a favourable weather window.
Does everything have to be demolished to redo the waterproofing?
Rarely. In most cases a liquid system applied to a prepared substrate is enough. Full removal is only required when the old membrane has debonded, is waterlogged, or the screed has failed.
How long does concrete roof waterproofing last?
Depending on the specified system and exposure, warranties range from a few years to over a decade, provided outlets are maintained and the roof is inspected periodically.
Need a diagnosis on your building?
Free inspection anywhere in Mauritius, written specification and warranted works. Call 606 2500.
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