Issue link: http://cp.revolio.com/i/1121626
Polystyrene Foam Insulation in Long-Term Building Applications – Effective R-values Page 4 A methodology that uses short-term, laboratory- determined R-values along with adjustment factors to account for specific building conditions is warranted when a detailed analysis is needed. The R-value adjustment factor method discussed herein is analogous to the thermal conductivity adjustment method recognized in international standard ISO 10456 8 . Expanded polystyrene (EPS) and extruded polystyrene (XPS) used as insulation in buildings are considered. These products are recognized in the United States by U.S. product standard ASTM C578 9 and in Canada by CAN/ULC S701.1 10 . There are a wide range of EPS and XPS insulation types covered in the North America Standards, but this document focuses on EPS Types II, IX, and XPS Types X, IV per ASTM C578. These are the EPS and XPS types with 15 psi or 25 psi compressive strengths commonly used in building applications. Although not covered here, the methodology provided applies to other EPS and XPS types covered by ASTM C578 and CAN/ULC S701.1. Performance Properties ASTM C578 Material Type EPS XPS II IX X IV Compressive Resistance 1 , psi (kPa) 15 (104) 25 (173) 15 (104) 25 (173) R-value 2 , °F•ft 2 •h/BTU 4.0 4.2 5.0 5.0 RSI 3 , °C•m 2 /W 0.70 0.74 0.88 0.88 Analogous CAN/ULC S701.1 Type 4 2 3 2 4 1 See ASTM C578 for details. 2 Thermal resistance per 1.00 in (25.4mm). See ASTM C578 for details. 3 Thermal resistance per 25.4 mm per ASTM C578. CAN/ULC S701.1 thermal resistance for XPS types 2, 3 and 4 are lower. See standard for complete details. 4 The requirements of ASTM C578 and CAN/ULC are not identical, but they are very similar. Table 1. EPS and XPS Types Commonly Used in Building Applica ons