The building that now houses the Zwickau tax office has a long history. Constructed in 1903 as an engineering school, it is characterised by its distinctive barrel-shaped reinforced concrete ceilings. Over time, however, the load-bearing capacity of these historic structures reached its limits: according to current safety standards, strengthening was essential to ensure continued use. In 2008, the listed building underwent comprehensive rehabilitation. Instead of conventional methods such as shotcrete, a solution using textile reinforced concrete was chosen. The challenge lay not only in the structural strengthening, but also in preserving the characteristic appearance and the heritage-protected building fabric. A thin interior layer of fine concrete, only 20 mm thick and reinforced with up to seven layers of carbon textile reinforcement, was applied to strengthen the load-bearing barrel vaults from the inside. The bending load-bearing capacity of the vault shells was additionally verified through two further layers of textile reinforced concrete applied to the upper and lower surfaces. This minimally invasive approach significantly increased the structural capacity without altering the visible appearance or placing undue stress on the historic material. Close collaboration between the specialist designers, Technische Universität Dresden, and the executing specialists led to a solution that preserved the existing structure while meeting modern requirements. The project stands as an impressive example of how modern composite materials such as textile reinforced concrete can open up new perspectives in heritage conservation – resource-efficient, sustainable, and precisely tailored to the specific demands of historic buildings.