Abstract: Magnesium oxide cement sheathing is laminated to plywood, OSB, wood, steel, other building products or other substrates to enhance fire, structural and sound performance of the substrate to meet new and more stringent fire codes while also providing water, insect, mold and rot protection. Further, the magnesium oxide cement board laminated to a foam core enhances fire performance and mold and rot protection over that of the foam core alone. The magnesium oxide laminate is used in wall, floor and roof assemblies to meet or exceed performance as specified in the building codes.