CNS 8644: Safeguarding Waterproofing Quality

How CNS 8644 Helps Consumers Ensure the Quality of Waterproofing Materials
Choosing high-quality waterproofing materials is crucial to the long-term durability of buildings. Taiwan’s CNS 8644 standard, developed with reference to international regulations and insights from industry experts, provides consumers and government agencies with a reliable benchmark for selecting waterproofing materials. This standard ensures that waterproofing systems can withstand environmental conditions over time, thereby improving overall building protection.

CNS 8644 Classification of Liquid-Applied Waterproofing Materials
CNS 8644 categorizes waterproofing materials based on their application—roofing or exterior walls—and further by material type:

High-elongation polyurethane (PU)
High-strength polyurethane (including polyurea)
Acrylic (including elastomeric cement)
Neoprene
Bitumen
Silicone-based coatings

Each material type must meet key performance indicators to ensure long-term reliability.

Key Performance Criteria for High-Quality Waterproofing Materials

Tensile Strength
- Prevents cracking due to structural shifts (e.g., during earthquakes)
- Indicates the material’s ability to resist physical forces
Elongation
- Allows flexibility with temperature changes and structural movement
- Reduces the risk of cracking and leakage over time
Tear Strength
- Protects against damage during application or regular use
- Higher tear resistance reduces the risk of mechanical failure
Heat Expansion/Contraction
- Ensures dimensional stability under high temperatures
- Ideal for rooftops and buildings in hot climates
Weathering (Aging) Resistance
- Simulates long-term exposure to UV, acid rain, and moisture
- High durability reduces the need for frequent maintenance
Aging Under Tension

Tests stability under mechanical stress
Suitable for high-stress applications (e.g., basements, bridges, high-rise buildings)

Comparison of Common Waterproofing Materials
The most commonly used waterproofing materials include PU (polyurethane), polyurea, acrylic, neoprene, and bitumen—especially in rooftop and balcony applications.

Material Selection Guide
Polyurea

Excellent tensile, tear, and weather resistance
Best for high-stress, long-term protection
Newer aliphatic polyurea (3rd generation) offers better UV resistance and weathering performance
Typical high-performance system: primer + polyurethane/polyurea base + aliphatic polyurea topcoat
Higher cost and more complex to install

Polyurethane (PU)

Flexible and weather-resistant
Easier to apply; suitable for rooftops and exterior walls
Can be blended with polyurea for added strength
Ideal for high-durability applications with a mid-to-high budget

Acrylic

Affordable and easy to use
Suitable for general waterproofing and DIY applications
Less durable than other materials

Installation & Maintenance Considerations

PU and polyurea systems can be exposed or topped with synthetic turf or stone, as they are not suitable for direct tile adhesion.
Exposed waterproof layers are easier to maintain, allowing localized repairs without removing tiles or generating waste.
For tile installation, proper interface treatment is recommended:

Apply primer or bonding coat
While still tacky, broadcast quartz sand to improve roughness and adhesion
Allow to dry completely before tiling

Why CNS 8644 Matters
CNS 8644 provides a comprehensive benchmark for selecting waterproofing materials that offer long-term protection and performance. By understanding the characteristics of each material, you can choose the best solution based on budget, ease of installation, and durability.
To explore full testing methods and detailed specifications, visit CNS Online for the complete version of the CNS 8644 standard.

Recommended Reading Topics (Click to explore)

This article is based on international research, internal lab testing, and practical field experience. Variations due to proprietary formulas or methods by specific manufacturers are not covered here.

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Link to TPUCO products & PU Knowledge:
Fast drying polyurethane coating:
https://www.taiwanpu.com/en/product/Fast-drying-polyurethane-coating
Q27:Key Steps for High-Quality Waterproofing
https://www.taiwanpu.com/en/about/Key-Steps-for-High-Quality-Waterproofing
Q28:How to Choose High-Quality Waterproofing Materials
https://www.taiwanpu.com/en/about/How-to-Choose-High-Quality-Waterproofing-Materials
Q29:CNS 8644: Safeguarding Waterproofing Quality
https://www.taiwanpu.com/en/about/CNS-8644-Safeguarding-Waterproofing-Quality
Q30:CNS 8644 Roofing & Balcony Waterproofing Guide
https://www.taiwanpu.com/en/about/CNS-8644-Roofing-and-Balcony-Waterproofing-Guide
Q31:TPUCO’s CNS 8644-Compliant Waterproof Coatings
https://www.taiwanpu.com/en/about/TPUCO-CNS-8644-Compliant-Waterproof-Coatings
Q32:Team or DIY? Choosing the Right Waterproofing Plan
https://www.taiwanpu.com/en/about/Team-or-DIY-Choosing-the-Right-Waterproofing-Plan
Q33: Why Waterproofing Needs Primer, Mid & Topcoat?
https://www.taiwanpu.com/en/about/Why-Waterproofing-Needs-Primer-Mid-Topcoat
Q34:Waterproofing Project Case Study & Performance Showcase
https://www.taiwanpu.com/en/about/Waterproofing-Project-Case-Study-and-Performance-Showcase

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