SecurShield HD polyiso insulation is a rigid roof insulation panel composed of a high-density, closed-cell polyisocyanurate foam core laminated to a premium performance, coated-glass fiber-mat facer. Suited for re-roofing and new construction applications, SecurShield HD is specifically designed for use as a cover board over a variety of substrates. SecurShield HD delivers an R-value of 2.5, which is significantly higher than roof cover boards made with other materials such as wood fiber or gypsum.