Welcome to McMahon Steel Company, Inc., Southern California’s leading fabricator and erector of structural steel and miscellaneous iron.  Founded in 1970, McMahon Steel remains a family owned enterprise. We specialize in the detailing, fabrication and installation of structural and miscellaneous steel for commercial and industrial construction projects throughout the Southwest.  McMahon Steel is AISC and City of Los Angeles certified, and can take care of all your steel needs from the ground up.