<Rötihof extension, Cantonal Administration Centre, Solothurn, 2024

The extension building, Rötihof 2, on Werkhofstrasse is based on the orientation of the existing cantonal administration building, Rötihof 1. Three parallel wings, which are slightly offset from each other, form the urban and landscape framework of the new building. It enables flexible organization and efficient linking of the different uses. The building is also vertically layered over its entire length. A two-storey plinth connects Werkhofstrasse with Rötihofplatz. It houses the new mall. The internal work areas of the offices are located above.

Inside the new building, which hugs the topography, the floor plans reflect the urban design. The counters and reception rooms of the various offices, the publicly accessible facilities such as the state archives and auditorium as well as the café at the head of the square are located in the gallery-shaped mall in the middle of the building, which is naturally lit by skylights. The mall is designed according to the principle of the streets and squares of a city. The interior is reminiscent of market halls or large libraries. The separate decks of the workstations above are lined with walkways in an air space open to the sky for the purpose of interaction and encounters between employees.

The individuality of the offices with their different characteristics can be supported by their communicative front zones documenting the activities or holdings of the offices. The installations interact with meeting points, attractive benches and stairs to structure the mall. The names of the offices adorn the supporting columns that give rhythm to the space. Double-storey interior façades and elegant wooden portals signal the position of the auditorium and café, while a large bridge marks the main entrance near the café. The lettering corresponds to that of the loggia, which marks the public significance of the administrative center in the urban space.

The idea of a correspondence and resonance that links the old and new parts is reflected in the design of the shell. The building, which has a regular rhythm with its single and double-layered timber façades, has a head on Rötihofplatz. It forms one of four reliefs into which the development of the new building is divided on the four sides.

The courtyard space of the Rötihof and its extension will be connected to the courtyard side of the City Council building (the von Roll House) and the City Planning Office on Baselstrasse to create a new sequence of squares that forms the center of the public buildings and strengthens their interplay. Located in front of Rötihof 1 and Rötihof 2, it is perceived as the external entrance to the new building figure. As an efficient access route, it links the cantonal offices very directly with the Bipperlisi station at the Baselstrasse junction, both functionally and in terms of urban space. In addition, the new Rötihofplatz can be reached from the direction of the Werkhofstrasse junction via the intermediate platform of the underpass without any obstacles.

The future square can be put into operation in its function as an attractive entrance even before the transformation of the work yard of the extended planning perimeter. The pedestrian paths and driveways as well as the parking spaces can be maintained during this phase.

In the basic solution, the route to the extension leads via the courtyard area of Rötihof 1 along the parking spaces. The bridging slab, which does not affect the operation of the parking spaces on level -1, could also be built at the same time as the new building. This platform is ideal in terms of urban space, as it provides frontal access to the new building.

The loggias function as a timeless element that integrates the irregular breaks that arise due to the flexible layout of the offices and the changing uses over the short or long term. This is where the mall and counter entrances find a presence in the street space. This is where the offices meet the urban space and, in later phases of operation, the apartments stretching through the entire wing. The loggia also has a cultural significance for the multifunctional extension. As a stylistic element, it lends the timber construction urban gravitas. The new building thus fits into the larger architectural context of Solothurn architecture. Through simple details, the column is used as a motif, repeated many times and varying in scale, to emphasize the entrance façades. These details include the profiling over several storeys and the lettering.

The light and shadow effect of the façade also gives the area along the new access road a striking identity. The loggia creates a harmonious connection between residential and office entrances in the event of a conversion and emphasizes the central and public role of the administrative center on Rötihofplatz, opposite a future residential quarter in the noise-protected reserve zone.

The boulevard of Werkhofstrasse and the loggia visually and functionally reinforce the effect of the main entrance to the west. The direct entrances to the offices lend the façade liveliness and are easy to adapt. The animated front zone of the long building block creates an inviting atmosphere for visitors and helps them find their way to the various entrances to the multifunctional building.