Atrium Blumer Lehmann Headquarters "Stammhaus"

The new headquarters of the Swiss timber construction company Blumer Lehmann exemplifies contemporary timber architecture. At its core, a sculptural atrium with a freeform stair—designed by the Institute for Computational Design and Construction (ICD) at the University of Stuttgart—unfolds through the precise arrangement and intersection of curved cross-laminated timber elements. These elements integrate a spiraling staircase, mediate between the building’s levels, frame views, define alcoves, and generate a distinct spatial character. The project synthesizes computational design methods, digital fabrication, and expert craftsmanship into an architectural expression that makes the pioneering potential of timber construction spatially tangible. The overall building, which houses 180 office workspaces, a conference hall, and a cafeteria, was designed by K&L Architekten, St. Gallen. 

The Institute for Computational Design and Construction (ICD) and the timber construction company Blumer Lehmann share a longstanding collaboration across various research and building projects. The design of the atrium for the company's new headquarters builds upon prior insights into curved cross-laminated timber structures, further refining them in response to the project's intricate spatial and structural demands. A freeform staircase connects all five floors of the building, constituting both the vertical circulation core and a communal space that invites interaction. Curved cross-laminated timber elements compose the atrium across the full building height, acting as spatial enclosure and load-bearing structure. Their configuration and interconnection respond directly to architectural and engineering requirements.

In deliberate contrast to the orthogonal grid of the overall building, the atrium’s tapering surfaces articulate two distinct spatial qualities. Outward-facing, the curved timber segments create convex walls with a soft, textile-like appearance. Toward the central void, the precise intersections of the concave elements generate a succession of sweeping ridges, extending vertically through the floors and emerging as a sculptural relief in the shifting daylight. The placement of these timber segments integrates the stairway, orchestrates a dynamic interplay of viewpoints, and carves out alcoves and balconies that establish a spatial dialogue between the atrium and the surrounding office levels.

The curved timber elements serve as both spatial enclosures and integral structural components. Their curvature inherently enhances stiffness, enabling an exceptionally slender wall construction of just 130 mm. Despite this minimal material thickness, the structure efficiently transfers loads across five floors, supporting not only the staircase but also the adjacent floor slabs and the roof above. The use of curved elements with only two distinct radii, combined with the repetition of identical stair modules, further optimizes structural and manufacturing efficiency.

Balancing spatial, structural, and fabrication constraints posed a particular challenge in the design process. Even subtle variations in the inclination of curved timber elements significantly impact their intersection lines, influencing how they behave within the overall composition. To navigate this complexity, an integrative computational design method was employed, which also allows for dynamically adapting to evolving insights and design refinements up to the advanced design stages. Through this synthesis of computational design, digital fabrication, and expert timber craftsmanship, the project demonstrates an integrative approach that translates architectural ambition into a precisely engineered and exquisitely executed timber structure.

For further information on the 'Stammhaus' visit Blumer Lehmann's project webpage.

Institute for Computational Design and Construction (ICD) 
Prof. Achim Menges, Martin Alvarez, Laura Kiesewetter, David Stieler, Dr. Dylan Wood
With support of: Edgar Schefer, Lena Strobel, Alina Turean

Blumer Lehmann AG
Katharina Lehmann, Martin Looser, David Riggenbach, Ursula Frick, Bertie Hipkin, Benedikt Schneider

K&L Architekten AG
Thomas Lehmann, Johanna Deinet

SJB Kempter Fitze AG (Engineers)
Stefan Rick