RECOMMENDED USESACFoam Composite/FB consists of Atlas closed-cell polyiso bonded to 1⁄2" high density wood fiberboard on the top and a fiber-reinforced felt facer on the bottom.The wood fiberboard top eliminates the need for cover boards or vented base sheets normally recommended over foam insulations. ACFoam Composite/FB may be used with BUR, modified bitumen, and single-ply systems. Consult membrane manufacturer for system details. Available in 4´ x 4´ (1220mm x 1220mm) and 4´ x 8´ (1220mm x 2440mm) panels.