This specification covers glass fiber reinforced gypsum (GRG) composites suitable for producing GRG parts for non-loading bearings, thin sections, and ornamental shapes for architectural embellishment of interior building construction. Both the neat alpha gypsum cement and the resulting composite materials should conform to the specified physical and mechanical properties such as hardness, flexural strength, impact resistance, coefficient of linear thermal expansion, humidified deflection, surface burning characteristics, and nail pull resistance.