He was born in Åsnes as a son of school manager Erland Gudbrandson Grjotheim (1887–1969) and domestic science teacher Kaya Johanne Haarbye (1882–1963).
He finished his secondary education at Hamar Cathedral School in 1940, graduated from the Norwegian Institute of Technology with the siv.ing.
degree on the thesis Contribution to the Theory of the Aluminum Electrolysis, and from 1956 to 1957 he did research at the University of Toronto.
[2] He was a professor at the Norwegian Institute of Technology from 1959 to 1961 and 1969 to 1972, at the Technical College of Denmark from 1961 to 1969 and at the University of Oslo from 1972 to 1989.
He had an honorary degree at the Shenyang University of Technology from 1980, was a guest scholar in several countries and was awarded several medals.