InsulFoam HD Composite insulation board comprises closed-cell, expanded polystyrene (EPS) foam bonded to a 1/2"-thick high-density polyisocyanurate cover board. Available in 4'-by-8' sheets, the insulation board comes in thicknesses ranging from 1.5" to 7" and R-values between 6.4 and 25, respectively. It can be used on single-ply membrane roof systems, built-up- and modified-bitumen systems, and as an underlayment for metal roofing systems. The 100% recyclable, HCFC- and formaldehyde-free EPS foam is available with compressive strengths from 10 to 60 lbs. per square inch and densities from 1 to 3 lbs. per cubic foot.