InsulFoam’s HD Composite—closed-cell EPS bonded to high-density polyisocyanurate cover board—has a UL Class-A fire rating and is installed between the roof deck and a built up, modified bitumen, or metal roof system. The 4x8 sheets come 1 1/2 to 6 inches thick and can be installed with mechanical fasteners or EPS-compatible adhesive. Contractor prices range from $1.52 per square foot (R-12) to $1.85 (R-30). InsulFoam, 800.248.5995, insulfoam.com