Heinrich was born on November 11th, 1854 in Kempten. Heinrich's father was Andreas Flach and his mother was Natalie Boda. His paternal grandparents were David Flach and Magdalena Bühelin. He had a brother and a sister, named Eduard and Berta. He was the oldest of the three children. He died at the age of 84 on June 22nd, 1939 in Kempten.