Abstract: Retrofitting a horizontal building roof having a pre-existing, composite-strength concrete roof having a corrugated steel deck with concrete poured over the deck top. Replacing the pre-existing roof with a dry-installed composite-strength roof having a rigid sheet installed over a corrugated steel deck, the rigid sheet attached to the deck by mechanical fasteners extending through the rigid sheet and the upper ribs of the corrugated deck. The newly installed roof restrains the upper ribs against lateral distortion under loading, thus forcing the corrugated deck to maintain shape and operate to composite capacities in excess of predictable flexural load capabilities of its components considered alone.

Abstract: A method of building a roof wherein a horizontally disposed roof deck assembly is formed comprising: a sheet of corrugated steel material, preferably having a symmetrical rib pattern wherein the quantity of steel is equally distributed above and below a neutral axis; a sheet of insulation material; and a sheet of rigid substrate material mechanically fastened together by screws. The screws extend through the rigid substrate and through ridges on the upper side of the corrugated sheet material to restrain the ridges from above against lateral distortion under loading, thus forcing the corrugated sheet to maintain its shape and operate to capacities in excess of its expected or predictable flexural load capabilities. The roof deck assembly is secured to a supporting structure and suitable adhesive material, such as asphalt, is employed for securing a waterproof covering thereover.