The composite joist floor system includes joists supported by supporting members. Corrugated steel decking is positioned over the joists such that the corrugations are substantially perpendicular to the joists. Self-drilling, self-tapping, stand-off screws are spaced along the length of the joist, aligned with the deck corrugations. These stand-off screws provide the required shear transfer between the joist and concrete slab to form a composite floor system. The placed concrete encapsulates the upper non-threaded shank portions of the stand-off screws and the end of the joists. After the concrete has cured, the resultant system comprised of steel joists, steel decking, stand-off screws, and concrete, act together to form a composite system with greater load carrying capacity and less vertical deflection. The stand-off screws connect the joist upper chords to the concrete slab allowing the joist and concrete slab to act as a unit, by transferring shear between the two joined components.