Overview

U-STUCCO™ has been independently evaluated in accordance with ASTM C518-10, Standard Test Method for Steady-State Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus. This method measures thermal conductivity (K-value) and thermal resistance (R-value), confirming U-STUCCO™’s superior performance as an insulated stucco system.

Test Methodology

Test Standard:

ASTM C518-10

Testing Period:

September 12, 2014

Specimens:

Three 12” (305 mm) square lightweight stucco insulation panels, 1” (2.54 cm) thick

Apparatus:

Netzsch Inc. Q-Lab Thermal Conductivity Test System

Conditions:

Mean test temperature ~76 °F (24.6 °C), ΔT ~50 °F (27.9 °C)

Results

Average Thermal Conductivity (K):

0.60 Btu·in/ft²·°F·h (imperial)

0.08 W/m·K (metric)

Average Thermal Resistance (R):

R-2.22 per inch (imperial)

0.39 m²·K/W (metric)

Conclusion

ASTM C518 testing confirms that U-STUCCO™ delivers a thermal resistance of R-2.2 per inch, significantly enhancing wall assembly performance by reducing heat transfer through thermal bridges. This sets U-STUCCO™ apart from traditional stucco, which provides negligible insulation value.

What This Means

By combining the durability of cement-based stucco with proven insulation performance, U-STUCCO™:

• Improves energy efficiency of buildings

• Helps meet California Title 24 and IECC codes

• Reduces heating and cooling costs

• Supports sustainable and green building practices

Benefits of ASTM C518 Thermal Resistance

• Provides continuous insulation across wall systems

• Enhances comfort in residential and commercial spaces

• Reduces thermal bridging in wood- and steel-frame construction

• Supports LEED and green building certifications