Many buildings experience a change of use in the course of their life span. Due to political uncertainties that effect the governance of this municipality, the flexible reconfiguration of this building was given high priority.
The new town hall in Rosenberg stands in a valley between the incorporated villages of Bronnacker, Hirschlanden, and Sindolsheim. Located just west of where a former hall stood since 1949, the new facility, funded in large part by the State of Baden-Württemberg, was designed and built with the expectation that this municipality could be incorporated into a larger township within the next twenty years. Although the need for a town hall in Rosenberg might not exist in 10 or 15 years, the building was built to last at least five times that long. Flexibility of current use and potential re-use, were therefore paramount in the design of this structure. A reinforced concrete ribbed slab spans the entire building width. Demountable partitions divide these support-free areas and can be easily removed or reconfigured.
Together with an existing school, a baroque church, and an enormous chestnut tree, the new building completes a public square that was only partially evident before the start of construction. From the careful re-working of existing elements, a new town center has been created.
The modular ribbon window facade emphasizes the efforts made toward flexibility. The stairs and all service shafts lie in a central core and so keep the remaining areas variable. Glass of plasterboard partition walls can divide the nearly column-free space at 1-meter increments. Electrical and data cabling is located in armored floor chases and switching is confined to narrow panels located in the cabinetry lining perimeter walls. In-floor heating eliminates the possibility of an unfortunate future location of radiators.
From the onset of the project development, assembly details were designed to ensure the roof of the city council chamber and the main stair could be completed by craftsmen selected through a public bidding process.
A straight run staircase, constructed from a single sheet of 4mm folded steel connects each of the three principal levels of the building. The tubular railing is attached to the upper and lower folds of the steel plate, and in doing so forms a truss that spans the stair opening. The balustrade for the entire stairwell is constructed from a single band of woven stainless steel conveyor belting, suspended from a continuous bracket above, and held in tension from below.
In the roof level is the Council Chamber, which is spanned with a double- curved timber shell. A covered loggia at this level offers a splendid view of the church façade and valley beyond.
The structural member of the roof were milled on a CNC machine. The use of computer-aided milling enabled the manufacture of a single rib type, trapezoidal in section, curved in profile, and twisted through the spanned length. The laminated timber shell spans nine meters in width with a structural depth of seven centimeters. The roof was fabricated and dry –assembled to check for fit in a warehouse prior to its transport to the construction site. Erection of the structural ribbing was accomplished in less than three days, and the entire roof, including decking edge conditions and the curbing necessary for the skylight, was completed by three carpenters in under a single work week.