His first major work in Berlin was under prominent architect Max Taut. Stam was assigned to design a variety of buildings across Germany, notably assisting Taut in the design of the German Trade Union Federation Building, Düsseldorf. During this time, he also worked with Russian avant-garde architect El Lissitzky. The pair's most striking design was the "Wolkenbügel", or cloud iron, a t-shaped skyscraper supported on 3 metal framed columns. Although never built, the building was a vivid contrast to America's vertical building style, as the building only rose up a relatively modest height then expanded horizontally over an intersection so make better use of space. Its three posts were on three different street corners, canvassing the intersection. An illustration of it appeared on the front cover of Adolf Behne's book, "Der Moderne Zweckbau", and articles on it written by Lissitzky appeared in an issue of the Moscow-based architectural review, ASNOVA News (journal of ASNOVA, the Association of New Architects), and in the German art journal "Das Kunstblatt".