DuPont™ ArmorWall™ SP Plus Fire-Rated (FR) Structural Insulated Sheathing (SIS) is an ICC listed, high strength, two-hour fire-resistant exterior wall sheathing product. ArmorWall™ SP Plus FR SIS is unique due to its additional layer of sheathing, made of Magnesium Oxide (MgO), a natural mineral with fire-resistant properties, on the interior face, encompassing the rigid foam insulation. This addition makes ArmorWall™ SP Plus FR SIS a two (2) hour rated assembly, twice that of our standard ArmorWall™ panels. Additionally, ArmorWall™ SP Plus FR SIS offers a factory-applied, air and water-resistive barrier on both the exterior and interior sheathing.. Once seams and fasteners have been sealed the enclosure may be considered “dried-in”, allowing interior construction to commence regardless of final exterior finish status. ArmorWall™ SP Plus FR SIS incorporates five traditional building enclosure elements into a single panel product: structural sheathing, fire-resistance, air barrier, water-resistive barrier, and a high-performance continuous insulation layer. The five-in-one system of ArmorWall™ SP Plus FR SIS can replace several traditional individual components that, on their own, add cost, labor and complexity to a project.