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BUILDING FUNCTION 83▲ 5.4 Toscana Thermal Pools, Bad Sulza, Germany, Ollertz &Ollertz, 1999. Timber shell structures.▲ 5.5Open structure-free space under the shell roofs.hall is also walled-off to avoid any structural protrusions into the hall. Aswell as its functional suitability, this structure-and-skin combination haswon over critics by its elegance of detail and sheer transparency. Thenightly drama of printing is now highly visible from a nearby road.By their very nature, shell structures are supported at their perimeters.Although any associated structural elements, such as the ribs that mightincrease the strength of a shell are usually constructed inside the exteriorskin, their structural depths are so shallow as to not reduce space usagesignificantly. The Toscana Thermal Pools, Bad Sulza, enclosed by gluelaminatedtimber ribbed-shells, benefit from planning freedom unconstrainedby structure (Figs 5.4 and 5.5). Free-flowing interior spacessurround the main pools. As well as providing openness in plan, the shells’ribbed interior surfaces contribute to the attractive interior ambience.▲ 5.6 Timber Showroom, Hergatz,Germany, Baumschlager-Eberle, 1995.Timber columns project into the showroom.The interior portal frames of the Timber Showroom, Hergatz, are representativeof most interior perimeter structures whose vertical membersintrude into the building plan (Fig. 5.6). Sometimes, floor plan edgezoneswhose widths equal the structural depths can be incorporatedunobtrusively into the overall building function. Take Gothic churches, forexample, where numerous side chapels slot between deep internal buttressesadjacent to the aisles. At Hergatz, it is of little consequence thatstructure does not integrate with an edge-zone function. The gluelaminatedtimber columns are quite shallow, and the exposed frames possessan unusual attractiveness. Here, a conventional engineering system,often relegated to light-industrial buildings, is transformed into one withintrinsic beauty by virtue of its detailing quality. Curves soften the appearanceof the frames and invite new architectural interpretations of their