Abstract: The invention provides a composite metal and wood joist, a joist assembly, and a floor panel incorporating two or more of such joist assemblies connected by plywood floor panels. Each composite joist member consists of a metal channel having a plurality of nailable stiffening members disposed along its length, preferably one at each end and the others spaced uniformly along its length. A joist assembly consists of two spaced parallel joists, the assembly having a plurality of stiffening assemblies along its length, each stiffening assembly consisting of two adjacent stiffening members connected by a cross member.