Abstract: An open web metal structural beam for use in building construction has a generally Z-shaped transverse cross section and is capable of being nested and joined in a lapped position with like beam members. The beam has a top chord defined by an elongate longitudinal angle having an L-shaped transverse cross section, a bottom chord member defined by an elongate longitudinal angle having an L-shaped transverse cross section. The top and bottom chords are secured by an open web member in vertically opposed relation with the vertical leg portions of the L-shapes aligned vertically and horizontal leg portions of the L-shapes in laterally opposed relation and the laterally opposed longitudinal edges of the horizontal leg portions of the L-shapes are bent to form vertically opposed longitudinally extending stiffener lips on the chord members. One or more metal angle members welded vertically between the vertical legs of L-shaped chord members on the side opposite the web increase the rigidity of the structural beam.