​By Marianne Burkhalter, Christian Sumi, Yves Schihin, Urs Rinklef, Steffen Sperle, Célia Rodrigues, Unirenova (general contractor), Dr. Lüchinger+Meyer (civil ing.), Hector Egger (timber construction), G. Aerni (pictures), H. Unger (pictures)

The two-story plinth of the building of the railroad switching control room, dating from  the sixties, is retained as a constituent element of the place. On it is raised a prefabricated wooden structure with four levels, with twenty-four home units of different dimensions. The apartments have a double exposition, fully glazed façades and overhung balconies on both sides with the function of prolonging the interior space, protection from weather conditions and screening from the sun. Access to the apartments is directly  from the elevator. The fire escapes are located in two projecting volumes on the north façade. Retaining the scansion of the pre-existing structure (see the longitudinal section), continuous KERTO LVL beams were installed, projecting on both sides of the building. These support the CLT wall elements on each floor while the box elements of the wooden ceilings are attached to them.  The cladding of the ceilings of the interiors ensures the appropriate conditions of acoustic insulation and fire protection. The superimposed volume is unified with the  plinth by means of vertically striped plaster. The new volume can be identified only after careful examination by the unfinished soffits  of the balconies.​

Metsä Wood challenged architects and students around the world to push the boundaries of modern wood building design in the urban environment. Entrants from 40 countries created their Plan B to urbanisation using wood (Kerto® LVL – laminated veneer lumber) as the main material. The task was to design a wooden extension to an existing urban building. The entries were designed to 69 cities worldwide.