Products / LP FlameBlock Fire-Rated Sheathing

LP FlameBlock Fire-Rated Sheathing is APA-certified OSB with a noncombustible, fiberglass-reinforced Pyrotite cementitious coating factory-bonded to one or both faces, used for wall and roof deck sheathing. The 2025 catalog lists Performance Categories 3/8 through 23/32, with finished panel thicknesses from 7/16 to 25/32 in coated one side and 1/2 to 27/32 in coated both sides. ICC-ES ESR-1365 covers it as roof sheathing for 4 feet on both sides of a fire wall in Type III, IV and V buildings and townhouses (coated side facing the interior), and as roof sheathing on Type I and II buildings with the coating on both sides; the report limits it to nonclassified roof assemblies unless a listing recognizes it in a classified roofing assembly. The panels carry load/span and shear design values equal to untreated PS 1 or PS 2 panels of the same thickness, and the product page also lists ICC-ES ESL-1002 and PMG-1089.