EnergyGuard™ HD Barrier Polyiso Insulation is made of a premium coated glass-fiber facer (CGF) bonded to a core of isocyanurate foam designed to be used as a cover board for low-slope roof systems. The coated glass-fiber weave is tighter than EnergyGuard™ or EnergyGuard™ Ultra coated glassfiber or paper-faced polyiso, offering increased surface strength for your high-traffic roof.