In late 2015, NRCA conducted physical property testing on a limited number of samples of new (uninstalled) faced, rigid board polyisocyanurate insulation used as components of low-slope roof systems.
The purpose was to determine the samples' compliances with the U.S. product standard for polyisocyanurate insulation, ASTM C1289, "Standard Specification for Faced Rigid Cellular Polyisocyanurate Thermal Insulation." The results also provide a basis for comparison with previous testing conducted by NRCA in 2002 and 2009.
ASTM C1289 describes methods for testing faced polyisocyanurate insulation's physical properties and R-values and provides consensus-based minimum or maximum values for the properties tested. For example, ASTM C1289's Section 11—Test Methods indicates dimensional stability testing shall be conducted using ASTM D2126, "Test Method for Response of Rigid Cellular Plastics to Thermal and Humid Aging," except each test specimen shall be 12 inches by 12 inches by the full-faced board thickness. ASTM C1289's Table 1-Physical Properties prescribes maximum dimensional stability values of 2 percent linear change in a board's length and width and 4 percent linear change in a board's thickness.