Flat Roof Waterproofing
Sheet under review by our engineersWhen your roof is flat (an accessible or non-accessible concrete 'slab'), waterproofing is the special layer applied to it to prevent any drop of water from seeping in. It's like a protective membrane that makes the roof completely impermeable to rain.
Why it matters for your home
This is crucial for a flat roof! Without perfect waterproofing, water infiltrates, causing leaks, ceiling stains, mold, and can even damage the concrete structure long-term. It's one of the most sensitive points for this type of roof.
The African context
Very common for slab-built houses. Intense sun and violent rains put materials to the test. Frequent defects include poor quality membranes, inadequate surface preparation, a lack of slope for drainage, or poor sealing at critical points (corners, drains).
Red flags
- ⚠ The contractor doesn't plan for a slope for water drainage (water will stagnate on the roof).
- ⚠ Use of waterproofing products not suitable for tropical climates (sensitive to UV or heat).
- ⚠ The substrate (slab) is not clean, dry, and crack-free before applying the waterproofing.
- ⚠ The waterproofing upstands (where waterproofing is brought up along perimeter walls) are missing or too low.
Questions to ask
- 1. "What type of product or membrane will be used for waterproofing (bitumen, PVC, resin) and what is its warranty?"
- 2. "What slope is planned for water drainage and how many drains are foreseen?"
- 3. "How will sensitive points like corners and pipe penetrations be treated?"
Cost hint (indicative)
The cost is significant and ranges from 8,000 to 25,000 FCFA per square meter, depending on the system (product, number of layers) and installation complexity.
At this stage of your project?
An independent DiasporaBuild inspector can verify on site before you pay.