Lauritz Jenssen was born on 23 January 1863 at Strinda in Sør-Trøndelag, Norway.
He was the oldest of seven sons of businessman Lauritz Jenssen (1837–1899) and Jørgine Wilhelmine Darre (1842–1910).
[1] In October 1890, he married Aagot Bødtker (1869–1963), who had worked as an auditor at the technical school in Trondheim in the 1880s, and taken classes in chemistry there.
The couple had a daughter, Margot Dorenfeldt, (1895–1986) who in 1919 became the first woman to graduate as a chemical engineer from the Norwegian Institute of Technology[3] and a son Lauritz Jenssen Dorenfeldt (1909 –1997) who made his career in law.
In the technical sphere, he was a proponent for using pyrite from Norway as well as natrium sulphite in the production of cellulose.