Desired deformation

Since last week there is a unique wooden building in the Remstal near Stuttgart: a tower made of self-formed spruce boards. The method, which has been developed at Empa and ETH Zurich, uses the natural swelling and shrinking of wood under the influence of moisture and thus enables a new and unexpected architecture for the construction with the renewable and sustainable resource of wood. The 14-metre-high tower near Urbach sits enthroned in the middle of the Remstal valley as an exhibit for the Remstal Garden Show 2019. It consists of a total of twelve wooden panels and owes its curved form to a method developed at Empa and ETH Zurich. Curved wooden constructions are not new, but how the individual parts of this building were created is groundbreaking. The two researchers Markus Rüggeberg and Philippe Grönquist from Empa's Cellulose and Wood Materials lab use the natural behaviour of wood and its reaction to humidity. Rüggeberg explains that the team was faced with the challenge of upscaling to meter-sized components, which they have now successfully mastered: "Now we can even predict how strongly such large wood elements bend under the influence of moisture," says Grönquist, who is dedicating his doctoral thesis to this topic.