Atlas Roofing Roofing Corporation is well established in the building materials industry through its ACFoam® family of polyisocyanurate (polyiso) roof insulation board products. Polyiso roof insulation is the most widely used and accepted rigid roof insulation. It is estimated that 60-65% of all commercial new or re-roofing applications nationwide use polyiso. Rigid polyiso is a safe, cost-effective, sustainable and energy efficient construction material. All Atlas polyiso insulation boards are QualityMark™ certified, providing consumers an easy way to identify premium products that meet or exceed listed LTTR-values. All products in the ACFoam® Polyiso Roof Insulation family are closed-cell, rigid foam insulation board…flat or tapered. Polyiso is the only foam plastic roof insulation that can be used without the need for a thermal barrier.