A threaded anchor for concrete metal deck floors includes a hollow plastic sleeve having an internally threaded top portion, a flared top end forming several outwardly-extending fingers, and a bottom end. A threaded bolt has a head end and a shaft with external threads mating with the threads of the hollow plastic sleeve. The shaft of the bolt includes internal threads having at least two different diameters. A nut is threaded to mate with the external threads on the bolt. In use, the assembled insert is punched in place through a hole formed in a metal deck layer. The fingers of the plastic sleeve collapse as the assembly is passed through the hole and expand below the deck. The nut is then tightened against the top of the deck to hold the insert in place.