Quick Guide: How to Choose the Right Waterproof Coating
When selecting a waterproof coating, it's not just about meeting the
CNS 8644 standard—you also need to consider the material system and its performance characteristics. Here's a breakdown of common options:
✅
High-Strength Polyurethane (incl. Polyurea)
- Superior tensile and tear strength
- Ideal for bridges, industrial sites, and high mechanical stress applications
- Lower elongation—less suitable for environments with significant movement
✅
High-Elongation Polyurethane (PU)
- Balances flexibility and durability
- Excellent for roofs, seismic structures, and areas with structural movement
✅
Bitumen
- Suitable for static waterproofing (e.g., flat roofs)
- Poor tear resistance—avoid in high-traffic or high-stress zones
✅
Acrylic (incl. elastomeric cement)
- A good choice for exterior wall waterproofing
- Lower chemical resistance may affect long-term durability
⚠️ Installation Considerations
📌 Always ensure the selected material system is certified under
CNS 8644 to prevent mismatches or substandard performance.
📌 Hybrid systems (e.g., combining high-elongation PU with high-strength polyurea) can offer complementary properties and extended service life—just confirm adhesion and compatibility.
📌 Looking for one product that meets all top-tier waterproofing criteria, including
strength, weather resistance, elongation, and thermal stability?
CPU-49-WP101I-A/B is your premium choice.
CNS 8644 Performance Specifications for Roofing Waterproof Coatings
📌 = Highest benchmark in category
✅ = Product meets highest benchmark
CNS 8644 Test Matrix for Roofing Coatings
The CNS 8644 standard outlines specific performance benchmarks for different coating systems. For example, the
tensile strength requirement at 23°C is:
- 10+ N/mm² for high-strength polyurethane
- Only 0.25 N/mm² for bitumen
This reflects the natural differences in material properties and guides appropriate product selection.
Key criteria analyzed include:
- Tensile Strength
- Polyurea shows outstanding performance across all temperatures
- PU provides moderate strength with flexibility
- Bitumen ranks lowest, suitable for non-structural applications
- Elongation at Break
- PU and bitumen demonstrate highest elongation—ideal for structural movement
- Polyurea has lower stretchability but excels in static pressure resistance
- Tear Strength
- Polyurea leads again
- Bitumen is weakest—best reserved for sheltered applications
- Thermal Expansion
- All systems fall within acceptable deformation limits (±1–4%)
- Polyurea, acrylic, and neoprene are most dimensionally stable under heat
- Aging & Durability
- All tested materials retained over 80% tensile strength after heat aging
- Bitumen and neoprene performed well in alkaline aging; acrylic underperformed
- Acid resistance was lowest for bitumen and acrylic systems
- Weathering Under Stress
- All certified products passed crack-free testing under heat, UV, and ozone exposure
Conclusion & Application Tips
- Use high-strength polyurethane/polyurea for high-load environments
- Use high-elongation PU for buildings with structural movement (roofs, seismic designs)
- Use bitumen only in static, low-stress waterproofing
- Use acrylic for basic wall waterproofing, where chemical exposure is minimal
⚠️ Final Notes on Selection
- When a contractor claims CNS 8644 compliance, double-check the material type and certification scope
- Consider combining material systems when appropriate—but always test for adhesion and compliance
- For a solution that meets nearly every highest CNS 8644 benchmark, consider CPU-49-WP101I-A/B
Recommended Reading Topics (Click to explore)
- How to Choose High-Quality Waterproofing Materials
- How CNS 8644 Helps Regulate Waterproofing Material Standards
- Detailed Requirements of CNS 8644 — Roofing & Balcony Applications
- TPUCO’s CNS 8644-Compliant Waterproof Coatings
- Professional Contractors vs. DIY — Which Should You Choose?
- Why You Need Primer, Base Coat, and Top Coat in Waterproofing
- Real-World Waterproofing Case Studies and Success Stories
This content is based on international research, in-house lab data, and practical application experience. Variations from individual manufacturer formulations are not within the scope of this overview.
For premium waterproofing solutions or technical consultations, feel free to contact us:
📞
Phone: +886 2229 91666
📧
Email:
pu@taiwanpu.com
Link to TPUCO products:
Fast drying polyurethane coating:
https://www.taiwanpu.com/en/product/Fast-drying-polyurethane-coating