SeparatoR® is a 1/2" polyisocyanurate board designed especially for recover and metal-retrofit roof systems. During the installation of these systems, a roof board is often used to separate the old roof from a new mechanically-attached single ply membrane. SeparatoR is the ideal board for this application. Unlike wood fiber boards, SeparatoR's polyiso foam enjoys a R-value of 2.8, nearly double the 1.5 R-value associated with wood fiber.