First organized in 1903 as the Structural Building Trades Alliance, the Building Trades Department was chartered by the AFL in 1908 in order to strengthen ties between building trades unions, organize local building trades councils, and, it was hoped, resolve ongoing battles over work jurisdiction. Membership was limited to national and international unions affiliated with the AFL whose members were primarily employed in the erection, repair, or alteration of buildings.

Charter members included the Carpenters, Plumbers, Painters, Steam Engineers, Iron Workers, Lathers, and Tile Layers. They were soon joined by the Amalgamated Society of Carpenters, the Asbestos Workers, Cement Workers, Electrical Workers, Elevator Constructors, Granite Cutters, Laborers, Marble Workers, Plasterers, Composition Roofers, Slate and Tile Roofers, Sheet Metal Workers, Steam and Hot Water Fitters, and Stone Cutters.

By the time the Bricklayers joined in 1916, the Department had already helped to unite some rival unions: the Carpenters had absorbed the Amalgamated Carpenters, the Plumbers and Steam Fitters had merged, and the Cement Workers' jurisdiction had been divided between the Plasterers and the Laborers. And while the Bricklayers had absorbed the Marble Workers and Tile Layers, and the two roofers unions had merged, a new union of marble polishers joined the ranks in 1917, leaving the Department with seventeen member unions through 1924.