Project report on St. Johannis Church in Ellrich
The reconstruction of the bell tower of St. Johannis Church in Ellrich was a technically challenging construction project that combined historical substance with modern construction. The design was based on a contemporary interpretation of the original tower cubature. The engineering firm Smits + Tandler opted for a mixed construction method using in-situ concrete and precast reinforced concrete elements. The main challenge was to develop a concrete mix that matched the existing structure in terms of both color and texture. To this end, various concretes with regional aggregates were examined and tested on sample surfaces. The final choice was a washed concrete surface, as it guaranteed the desired texture and durability.
The precast elements – especially the facade walls – had to meet high requirements in terms of dimensional accuracy and surface quality. The complex geometries of the tower required precise formwork technology and close coordination between the precast plant and the construction site. At the same time, the in-situ concrete core took on the load-bearing functions for the stairwell and elevator. Work began in January 2024 with the construction of the micro-drilled piles. This was followed in the summer of 2024 by the erection of the in-situ concrete core and the subsequent installation of the precast elements. The project involved high logistical requirements, as construction took place in a confined space in a public area. All material transports had to be precisely coordinated, as only limited storage space was available.
The combination of industrial prefabrication and precise in-situ concrete construction resulted in a tower that combined modern construction quality with regional material aesthetics. The project exemplified how historic buildings could be further developed in a contemporary manner using innovative concrete and prefabricated technology.
