In 1892, his son-in-law, the young architect Professor Max Littmann (1862-1931) joined him, so the construction company of Heilmann & Littmann KG (after 1897 GmbH) came into existence.
Friedrich Gustav Jakob Henle | St. Jakob-Park | Jakob Böhme | Philipp Jakob Cretzschmar | Johann Jakob Engel | Jakob Michael Reinhold Lenz | Mary Heilmann | Johann Jakob Reiske | Jakob von Uexküll | Jakob Nielsen (usability consultant) | Jakob Nielsen | Jakob Heine | Jakob Altaras | Emil Jakob Schindler | Johann Jakob Kaup | Jakob Steiner | Jakob Sporrenberg | Jakob Friedrich Fries | Jakob Erhardt | Jakob Bogdani | Heilmann & Littmann | Hans Jakob Christoffel von Grimmelshausen | Carl Jakob Adolf Christian Gerhardt | Walter Jakob Gehring | Sankt Jakob in Defereggen | Rudolf Jakob Camerarius | portrait of Jakob Muffel | Lutz Heilmann | Johann Jakob von Tschudi | Johann Jakob Moser |
In 1891, he joined the contracting business of his father-in-law Jakob Heilmann, thus transforming it into the Heilmann & Littmann general partnership (later becoming a limited partnership), taking charge of the planning department.