Ludwig Lemmer was born Hermann Ludwig Lemmer on 9 August 1891 in Salemstraße, Remscheid to Ernst Ludwig Alexander Lemmer and his wife Eugenie Adleheid Marcus. He attended the Technische Hochschule in Stuttgart 1911-1913. Following this education, by 1915 he was already in the 19th Jägerbataillon of the German Army. During World War I, he was awarded the Ehrenkreuz des Weltkrieges mit Schwertern. In 1917 he attended the Technische Hochschule in Danzig. Following World War I, he undertook a study trip to Denmark and Sweden before became the Stadtbaurat in Remscheid from 1921 until 1933 when he was removed from his post by the Nazis.
On 3 July 1925 he married Charlotte Betty Zehles in Remscheid.
In 1934 he graduated from the Technische Hochschule in Hannover with a degree in Engineering and passed the state exams in Home Economics and Geography. Thereafter he attended the University of Cologne for three years, but did not complete his study course there. Between World War I and World War II he was awarded the Hungarian Great War campaign medal with swords and the Austrian Great War campaign medal with swords.
He was called up into the Wehrmacht during World War II with his military serial number of 39 4./H.B.A.2 A. He saw service in White Russia, France, Norway and Sweden from 1941-1942 as well as service in Breslau in September 1941. He was posted to Smolensk in 1942 until 1943. On 15 July 1944 he was transferred to the Festungspionierstab 21 in France and in October of that year moved to Bergheim with the Festungs-Pionier-Kommandeur XIX. He was captured by the British as a prisoner-of-war and released by the British Army on 29 June 1945. During World War II he was awarded the German Kriegsverdienstkreuz mit Schwerten and the Iron Cross 2 class.
In 1951 he was awarded his professorship of architecture by the Hochschule für Bildende Künste, Berlin in recognition for his teaching and in that year until 1955 taught at the same institution. During that same time, he was the Senate of Berlin's Director of Build. In 1958 he and his family moved back to Remscheid and in the 1960s he was awarded the Großes Verdienstkreuz of the Federal Republic of Germany. He died on 18 October 1983 in the Fabricius-Klinik, Brüderstraße 65, Remscheid and was buried in the Waldfriedhof Reinshagen.