Roof and slab waterproofing
See also: Oil, Gas and Mining · Lighting, Water and Telecommunications
What it is
Liquid polyurethane waterproofing for slabs and roofs is the application of a continuous, flexible and waterproof membrane on surfaces exposed to weather. The system consists of direct application of a primer, one or more layers of liquid PU (single or bicomponent) applied by roller, brush or spray, and optionally a UV protection layer (aliphatic) or a ceramic finish.
The main advantage of liquid PU over traditional asphaltic membranes is continuity — no joints, no vulnerability points. The PU membrane wraps complex details (drains, pipes, corners) without the need for special accessories. Durability is significantly superior in correct installations: 15 to 25 years versus 5 to 10 years for asphaltic membrane.
Aromatic systems are used in lower layers or applications without direct UV exposure (covered slabs, inter-floor insulation). Aliphatic systems are used on exposed surfaces — more expensive but UV-stable long-term.
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Value proposition
Comparison of waterproofing systems:
| System | Durability | Joints | Trafficability | Relative cost |
|---|---|---|---|---|
| Asphalt membrane | 5–10 years | Yes (vulnerability) | Limited | Low |
| Liquid PU membrane | 15–25 years | No (monolithic) | High (with finish) | Medium-high |
| PVC membrane | 15–25 years | Yes (welded) | Limited | Medium-high |
| TPO | 15–25 years | Yes (welded) | Limited | High |
| Liquid emulsified asphalt | 3–5 years | No | Limited | Low |
Arguments for sales to end customer:
- Life cycle total cost: in residential and commercial slabs, repairing recurring leaks in 10 years costs more than investing in premium PU at construction — verifiable calculation in any real case
- Monolithic continuity: no joints means no vulnerability points — ideal for complex geometries (drains, pipes, corners, shafts)
- Trafficability: aliphatic PU with ceramic finish allows slab use as functional area (rooftop garden, terrace, parking) — building value gain
- Adequacy for sustainable roofs: green roofs and solar panel roofs require premium waterproofing supporting installation and maintenance — liquid PU is dominant solution
- Certifications: ETAG 005 and ABNT NBR 9575 are required in public works and in extended warranty insurance
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