abbr. polyisocyanurate

A closed-cell foam insulation material typically sold in rigid boards (but also available as a liquid, sprayed foam). R-value can range from R-5.6 to R-9, depending on the manufacturer, the age of the foam, and the presence or absence of foil facings. Foil-faced PIC has a greater R-value and is also vapor impermeable (less than 0.1 perm). The use of ozone-depleting substances as blowing agents is being phased out. Most U.S. PIC manufacturers now use pentane.