During the Second World War, Friis was active in the Danish resistance in operations for receiving supplies.
Friis was married on 27 May 1950 in Ringkøbing to Bodil Johanne Andersen.
[2] From 1967 to 1970 he was a professor at the Aarhus School of Architecture and from 1979 to 1989 he operated an architects company in the United States, in collaboration with Jay Robert Larsson, an American Architect.
Friis was a guest professor at the Ball State University, Indiana in 1975, a member of Statens Kunstfond from 1977 and chairman of Dansk Arkitektur Center 1987-89.
[3] Friis has received numerous awards including Træprisen in 1959, Eckersberg Medal in 1967, Møbel- og Betonprisen in 1972, the architecture prize of the Association of German Architects in Bayern 1975, Dagbladet Børsens Diploma for commercial buildings in 1978, IF-prisen Gute Industrieform 1982 and C.F.