F/G Base Sheet is manufactured from tough inorganic fiberglass mat then coated on both sides with weathering grade coating asphalt and then covered on top with white sand fines to prevent sticking in the roll. Meets ASTM D 4601-04 Type II.
Applied over the flat roofing deck or insulation as a base sheet by mechanical fasteners or hot asphalt before the application of roofing systems. This sheet is suitable for use as a vapor retarder, with a solid mopping of asphaltic material, under roof insulation or between multiple layers of insulation.