Crafted by Hand and Machine: Human-Robot Fabrication Workflow for the Use of Curved Wood in Construction

Since the 2020s, Switzerland has been improving forest health by increasing species diversity and rejuvenating forest stands. This has led to the harvesting of wood with irregular shapes and diverse species, much of which cannot be processed by conventional sawmills and is typically sold as biomass. This irregular wood is however an untapped resource for the construction industry that could reduce CO₂ emissions, minimize waste, and promote sustainable, biodiverse forests. This study proposes an experimental workflow to incorporate irregular wood into architectural structures by combining advanced fabrication technologies with traditional crafts. A robot manufactures structural connection joints and performs initial guide cuts along beams. Inspired by medieval wood-hewing techniques, a craftsperson uses an axe to remove material between robotic cuts, achieving a cleaved finish that respects the natural fiber orientation. To validate the method, a wooden frame prototype —1.5 meters wide and 3 meters high— was built using curved hardwood beams salvaged from local park maintenance. This prototype demonstrates the viability of curved wood as a high-performance construction material. Interviews and site visits were conducted with key stakeholders in Switzerland, including foresters, sawmills, glulam manufacturers, and artisans, providing a comprehensive understanding of the entire supply chain and the challenges and opportunities of integrating irregular wood into construction. The research highlights the potential of curved wood to address both environmental and industrial challenges. By combining advanced tools with traditional handcraft, this approach reduces waste and extends CO₂ storage in timber, while promoting adaptive construction practices that align with the natural variability of forest resources.