Diagnosis
Flat roof leak: what to do before any works
A flat roof forgives nothing: the smallest discontinuity becomes an entry point. Before having any product applied, identify the real signs and avoid the false fixes that end up costing twice.
Warning signs to act on
These symptoms mean water is already inside the structure, even with no visible drip:
- Rings or paint blisters on ceilings and the top of walls
- White efflorescence, saltpetre, a persistent damp smell
- Exposed reinforcement, concrete spalling, rust runs
- Blisters, wrinkles or debonding on the existing membrane
- Moss, algae or puddles still there 48h after rain
The most expensive mistakes
Painting over a damp area, applying a bituminous product on a saturated substrate, stacking a new layer over a debonded membrane, or sealing the ceiling stain: in all four cases the water stays trapped and deterioration continues, now invisibly.
Immediate make-safe
Clear and clean the outlets, remove debris and vegetation, photograph suspect areas right after rain, and get an inspection before the reinforcement is affected. Corroding rebar turns a waterproofing problem into a structural one.
Choosing the right system
Selection depends on roof use (trafficked or not), fall, UV and salt exposure, and substrate condition. A reinforced liquid membrane suits most roof terraces; a hybrid system with a thermal layer makes sense when overheating under the slab is also an issue.
Frequently asked questions
Can a leak damage the structure?
Yes. Water reaches the reinforcement, which rusts and expands, spalling the concrete. The longer you wait, the heavier and more expensive the repair becomes.
Can I apply a waterproofing product myself?
On a small sound area, possibly. But without substrate preparation, detail treatment and correct film thickness, the product will not hold and no warranty can be issued.
Need a diagnosis on your building?
Free inspection anywhere in Mauritius, written specification and warranted works. Call 606 2500.
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