Dow Styrofoam Insulation Board DOW High Performance Underlayment is an extruded polystyrene foam insulation that is fanfolded into 50-foot lengths. Recommended as underlayment over old siding to provide a solid, level surface for new siding materials. It is heat-bonded between various facers and then pin-perforated for vapor permeance. Facers Available: Plastic/Plastic (P/P). Bonds the insulation between strong plastic film facers. Available in 0.25" and 0.375" thickness. Plastic/Reflective Plastic (P/R). Bonds the insulation between a strong plastic film facer and a metallicized, reflective plastic film facer. Available in 0.25" and 0.375" thickness. Nominal Board Thickness** Product R-Value† Board Size Edge Treatment Min Compressive Strength†† 0.25" 1.0 4' x 50' Square Edge 15 psi 0.375" 1.5 4' x 50' Square Edge 15 psi Building Code Compliance Meets IBC/IRC requirements for foam plastic insulation. See ICBO-ES ER 2257, BOCA-ES RR 21-02, NES NER 699, Und. Lab. Inc.® Classified, see Classification Certificate U589. Maximize Your Energy Savings & Earn Energy Tax Credits As the cost of energy continues to escalate and the environmental impact of energy production becomes an increasing concern, the pressure to conserve energy resources is at an all-time high. In an effort to help promote energy efficiency and conservation, energy tax credits are now available under The 2005 Energy Policy Act for both new construction and existing homes. There has never been a better time to increase the energy efficiency of your home and earn tax credits. Cottage Hill Exteriors uses the top names you trust for your home: Mastic premium vinyl siding, GAF/Elk High definition Architectural shingles, DuPont Tyvek vapor retarder, and Dow Styrofoam insulation. "Cottage Hill Exteriors" is a registered servicemark. Visitors