Déjà Vu

The spiral-shaped wooden structure in Wangen is not the first of its kind, but it is the tallest to date: Based on research by the Cluster of Excellence Integrative Computational Design and Construction for Architecture (IntCDC) program at the University of Stuttgart, the observation tower is made of load-bearing, self-forming wooden components. It is the “big brother” of an earlier structure, Urbach Tower, which stood at the Remstal Garden Show in 2019. It was not possible to ascend the earlier structure, which was a kind of shelter with a small platform at its base. The design idea for the shell remained, but the dimensions grew: instead of being 90 mm (3-1/2") thick and 14 m (46 feet) high, the Wangen shell is 130 mm (5-1/8") thick and 23 m (75 feet) high.

Using computer-based planning methods, the behavior of the materials and the manufacturing conditions were considered from the outset, such that the project participants also call the tower a “permanent research building.” The double-layered panels are each made of a 30 mm (1-1/8") thick "active" layer and a 10 mm (3/8") thin “restrictive” layer glued crosswise. After lamination, the timber builders allowed the flat panels to dry in such a way that the active layer shrank perpendicular to the grain of the boards and the panels bent into the predicted shape. Three of the curved panels were then overlapped and glued together with a thin locking layer, resulting in finished CLT panels just 130 mm (5-1/8") thick.

Thanks to their curvature, which provides additional stiffness to the timber surface, the tower's twelve cross-laminated timber segments were erected in just a few days. The viewing platform is reached via 113 steps, with the staircase column absorbing the vertical traffic loads.