Project Info
Project Name: Stammhaus
Location: Gossau, Switzerland
Architect: K&L Architekten AG
Atrium Design & Development: Institute for Computational Design and Construction (ICD)
Engineer: SJB Kempter Fitze AG
Client: Blumer Lehmann AG
In Gossau, Switzerland, the new headquarters of Blumer Lehmann stands as both a workplace and a manifesto for the future of timber construction. Designed by K&L Architekten, the five-story building - aptly named Stammhaus (“tree trunk” in German) - brings together over 500 employees in a space that celebrates the company’s legacy while projecting its vision forward.
A Sculptural Heart of Timber
At the center of the building lies its defining feature: a soaring atrium crafted from curved cross-laminated timber, developed in collaboration with the Institute for Computational Design and Construction (ICD) at the University of Stuttgart. Rising like a symbolic trunk, the atrium integrates a spiraling staircase that connects levels, frames dynamic views, and shapes alcoves for gathering. Circulation here is more than movement - it becomes an architectural experience, blending structure, sculpture, and storytelling.
The five-story headquarters by K&L Architekten showcases the possibilities of contemporary timber architecture
Light-filled and sculptural, the atrium connects levels while framing views and alcoves
Blending Tradition with Digital Innovation
Blumer Lehmann has long been recognized for pioneering timber engineering, and Stammhaus embodies this expertise. Straight timber panels are digitally shaped into sweeping curves, demonstrating how computational design and digital fabrication can expand the possibilities of wood. The result is a headquarters that is modern and sculptural, yet deeply rooted in the traditions of Swiss carpentry.
A spiraling staircase weaves through curved cross-laminated timber walls, redefining circulation as experience
Workspaces Rooted in Nature
Inside, the building provides 180 offices, conference rooms, a cafeteria with a terrace, and multipurpose spaces that support collaboration and creativity. Beyond functionality, the design emphasizes well-being:
+ Clay walls regulate heat and improve indoor climate.
+ Wooden acoustic ceilings and natural wool carpets reduce noise for quieter, more comfortable workspaces.
+ Large timber-framed windows open outward, ensuring ventilation and blurring boundaries with the outdoors.
+ A vast 8.5-meter ETFE skylight bathes the atrium in daylight, enhancing the openness of the interior.
Light, air, and timber define the atmosphere of work inside Stammhaus
Large timber-framed windows connect the workspaces with the outdoors, creating a bright, healthy environment
Open-plan offices foster collaboration while honoring Blumer Lehmann’s timber legacy
Natural materials enhance comfort and sustainability throughout the offices
Sustainability as Core Philosophy
As a timber company, Blumer Lehmann demonstrates a holistic commitment to sustainability. Each year, it processes 170,000 m³ of Swiss raw timber, with every byproduct reintegrated into a circular economy - whether as sawdust, carbon-neutral pellets, or renewable energy for power plants. This sustainable ethos extends to its projects, from modular housing solutions to free-form timber structures across Switzerland and beyond.
The building embodies heritage and progress, with a tree trunk at its core as a metaphor for growth
A Headquarters as Identity
More than an office building, Stammhaus embodies the company’s DNA. The atrium’s tree-trunk form symbolizes both heritage and growth, anchoring the firm’s roots while branching into innovation. It is a place where open communication, transparency, and creative energy shape the future of timber construction.
By merging craft, computation, and sustainability, Blumer Lehmann’s new headquarters proves that timber architecture is not only environmentally viable but also expressive, symbolic, and powerfully modern. Stammhaus is more than a workplace - it is a living testament to the enduring possibilities of wood.
Photo Credit: Blumer Lehmann
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