Certified Insulated Siding Builds Confidence in Energy-Efficient Cladding

Posted by Matt Dobson on June 25, 2013
Certified Insulated Siding Builds Confidence in Energy-Efficient Cladding
Newport Ventures conducted the Insulated Siding Energy Performance Study to determine insulated siding’s effect on the energy performance of five existing single-family homes under real-world conditions.

According to a recent study by Newport Ventures, Inc., a third-party energy consulting firm, insulated siding—vinyl siding with permanently attached foam insulation—can improve a home’s energy efficiency by reducing heat escaping through studs and other framing. While this cladding has been recognized as a continuous insulation option for improving energy performance for many years, now homeowners selecting insulated siding can have the confidence of certification to an ASTM quality standard. [ASTM International was previously called the American Society for Testing and Materials. It's an international consensus-based standards setting organization for all kinds of materials, processes, and installations.]

Through its Product Certification Program, the Vinyl Siding Institute (VSI) has been verifying that vinyl siding meets or exceeds relevant ASTM standards for more than a decade with third-party certification through Architectural Testing, Inc. (ATI), an accredited quality control agency. This June, after ASTM released a new standard for insulated vinyl siding, VSI added insulated siding to the list of products that can be certified through its program.  

All insulated siding certified through VSI’s program is verified to meet or exceed ASTM D7793 through twice yearly, unannounced plant inspections, product testing, and quality review by ATI. ATI’s tests and reviews verify the siding’s weatherability, wind resistance, impact resistance, and color retention, among other performance attributes. Colors that earn certification must also demonstrate the ability to resist major changes over time and exposure to the elements in a variety of climates, as verified by a two-year, outdoor weathering study.

In addition, certified insulated siding is required to demonstrate a minimum thermal resistance R-value, of at least R-2.0 to ensure its energy performance. As you may know, insulated siding is recognized in the 2012 International Energy Conservation Code as continuous insulation that can be used as continuous insulation outside of building framing to provide the required total wall R-value for buildings in the coldest climate zones. It can also help homes qualify under the Energy Star Qualified Homes Program Version 3. (See “Insulated Siding Provides Continuous Insulation,” HE, May/June 2011.)

To identify insulated siding as certified, look for the VSI Product Certification Program mark on cartons or product websites. You can also search VSI’s Official List of Certified Products and Colors, where an “I” connotes insulated siding, at

To learn more about insulated siding, including a guide on the product for energy raters, or the Newport Ventures study on the energy performance of homes retrofit with insulated siding, visit

Matt Dobson is the director of Code & Regulatory Programs for the Vinyl Siding Institute, Inc., in Washington, D.C., the trade association for manufacturers of vinyl and other polymeric siding and suppliers to the industry. VSI sponsors the VSI Product Certification Program and the VSI Certified Installer Program. You can follow VSI on Twitter at

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