The German Union of Building Trades (German: Deutscher Baugewerksbund, DBB) was a trade union representing construction workers in Germany. The union was founded on 1 January 1923, when the German Construction Workers' Union merged with the Central Union of Glaziers, and the Central Union of Potters. Like its predecessors, it affiliated to the General German Trade Union Confederation. In 1924, the Union of Asphalters joined, followed in 1931 by the Central Union of Roofers. In 1924, the union had 435,156 members, making it the third largest union in the country. It was organised in 18 districts.