Ralph W. Demmon (February 17, 1894 - February 25, 1978) was the second son of Elwood F. and Blanche Demmon. Elwood was a member of the Union High School faculty for 33 years, teaching English. Ralph attended Central High School in Grand Rapids and spent two years at the Michigan Agricultural College (later Michigan State University) before enlisting in the Air Corp. He was a member of Photo Section 2, 91st Aero Squadron Division in France, from 1917 to 1919.

Upon his return, Demmon studied Architecture at the University of Michigan, earning a B.S. Degree in 1923 and becoming a certified architect in 1924. During this time, 1922-1924, he also worked in the state architect's office.

His social life, while at the University of Michigan, included activities with Camelia Alten (November 13, 1898 - April 1999), who was attending Michigan State Normal College (later Eastern Michigan University) at Ypsilanti, Michigan during the same time. Camelia graduated from Central High School in 1917 and Michigan State Normal in 1925. They married July 26, 1924.

Camelia and Ralph had two or three daughters, Gloria Gregory, Dianne, and Betty? (who became Mrs. Gordon B. Boozer). Gloria Gregory's son has been the legal owner of his grandfathers' architectural drawings, which it is now understand will be given to the Public Museum of Grand Rapids.

Camelia Alten was the second daughter of the well known Grand Rapids artist Mathias J. Alten and his wife, Bertha L. Schwind Alten. Her sister, Eleanor (December 1, 1896 - January 1994), married Avery Gilleo, and there is a separate archival collection in the department which documents Avery's correspondence with Eleanor during service in World War I. Viola Alten Gatzweiler was the youngest daughter.

Demmon began his architectural practice in Grand Rapids at the firm of Osgood & Osgood from 1924 to 1927. In 1927 he became self-employed, practicing on his own until his retirement in 1963. Most of his work included homes in the Grand Rapids area, some of which are documented in the Grand Rapids Mirror magazine.

Demmon is also said to have been a jewelry designer, particularly in his later years. He may have learned photography skills from his father, who was self taught.

In retirement, the Demmons lived in Naubinway, Michigan in the Upper Peninsular and in Sarasota, Florida.