Swiss architect Olin Petzold has completed a minimalist treehouse called Casetta Tessino in the forested Valle Onsernone region of Switzerland. The elevated structure, finished in early 2024, serves as a secluded writing retreat near the village of Loco. Commissioned by a Swiss artist and climate activist, the cabin provides a simple workspace away from the main house. Petzold designed the triangular structure to include only essential elements: a place to sleep, a place to sit, and a place to write. The project draws inspiration from Henry David Thoreau's Walden, emphasizing self-sufficiency and withdrawal from modern distractions.
Local zoning regulations significantly shaped the unique design of Casetta Tessino. Authorities prohibited additions to existing buildings and banned new foundations on the steep, forested property. These restrictions led Petzold to create a suspended structure that hovers among three mature oak trees approximately 100 to 150 meters from the main house. A narrow woodland path provides the only access to the elevated cabin. The support system connects three primary beams to the trees, forming an irregular triangular frame. An equilateral triangle defines the floor plan, rotated to position its corners between the tree trunks and align views along the valley.
The interior space contains a single compact room with deliberately minimal furnishings. A bed sits flush within the floor plane and remains hidden under four wooden panels during the day. Two fixed planks serve as the only other furniture: one functions as a bench while the other acts as a desk. Petzold wanted the space to feel almost empty upon entering, ensuring every element serves a clear purpose. All three facades can open completely, transforming the interior into a sheltered forest platform. When closed, translucent panels filter views while maintaining privacy and protection from weather.
Material selection reflects both environmental conditions and construction constraints. The structural frame and interior elements use lightweight spruce for its workability. Exterior timber components feature durable larch, chosen for its moisture resistance in the shaded, humid forest environment. Translucent polycarbonate panels wrap the building, allowing daylight to penetrate while softening direct views outward. The material also provides passive climate control. In summer, surrounding leaves shade the cabin and reduce heat gain. During winter, bare branches allow low-angle sunlight to warm the interior through the panels.
The remote location required a hand-built construction method without machinery. Petzold designed all components to be carried to the site manually. Joints and assemblies were simplified so workers could execute them without specialized tools or training. "This was conceived as a self-build from the beginning," the architect explains. "The details had to work with what could realistically be done on site." Timber became the primary material through necessity as much as intention, meeting structural, logistical, and economic constraints. All materials are inexpensive, though this economy is largely concealed in the finished work.
The completed treehouse will be shared with other writers and creatives, with occupancy varying by season and user. This collaborative approach reflects the client's desire to support artistic community while maintaining personal retreat. The project contributes to a growing movement of minimalist, nature-integrated architecture that prioritizes experience over excess. Petzold's design demonstrates how strict regulations can inspire innovative solutions that respect both natural environments and human creativity. Casetta Tessino stands as a model for sustainable, low-impact retreat spaces in sensitive landscapes.
