Pietsch was graduated from the Massachusetts Institute of Technology in 1889 and attended the Ecole des Beaux-Arts in Paris from 1892 to 1898. He was awarded a diploma from the French Government in 1897 and received honorable mention in the Paris Salon of 1898. He was an ardent exponent of the French Renaissance school of architecture throughout his career. He had practiced in Baltimore since 1904, his principal buildings being Eastern High School, Zion Church, the United States Fidelity and Guaranty Company Building, and the Association of Commerce Building. In 1917-18 he served as instructor of French to the officers of the 360th Regiment at Camp Meade, Maryland. He was awarded two medals in architecture at the Ecole des Beaux-Arts and was a member of the Friends of Art in Baltimore.