Inspired by the character of Japanese larch forests, students from the College of Environmental Design (CED) at the University of California, Berkeley, designed a timber grid structure for their winning entry, Nest We Grow, in the fourth Lixil International University Architectural Competition. An elegant, recurring moment connection detailed by the team with Kengo Kuma and Associates and Oak Structural Design Office, both in Tokyo, ensure the rigidity of the four-story, 919-square-foot facility.
Led by CED architecture professors Dana Buntrock and Mark Anderson, FAIA, the team used SAP 2000, Rhinoceros, and AutoCAD for conceptual design. Oak Structural Design calculated the building’s anticipated loads with the Rhino model.
Nine larch timber columns anchored in concrete footings provide the building’s primary structural support. The students worked with CED associate architecture professor R. Gary Black to size the columns. To save money, each column is a composite of four 6x6 glulam timbers, held together by nine steel plates and 40 bolts. The resulting 12-inch-square columns rise 29.5 feet, recalling the verticality of Japanese larch forests.
At each floor level, two perpendicular pairs of glulam larch timber beams intersect each column. The beams nest into 3-inch-wide-by-10-inch-deep notches in the columns. “We knew we needed to make a deep enough notch in those columns to fit the beams [and] generate that moment connection,” says Baxter Smith, an M.Arch. candidate and design team member. Classmate Yan Xin Huang adds, “The notches are the size of the beams … so the surface is flush.” The bolts that hold the composite columns together also secure the beams, completing the rigid moment connection, Smith says.
On Nest We Grow’s first and second floor levels, cross-bracing members bolt into tabs of the sandwiched steel plates. This cross-bracing combined with the moment connections and catwalks at the third- and fourth-floor levels provide the necessary lateral resistance against seismic and wind forces.
Hokkaido, Japan–based Takahashi Construction Co. sourced the wood locally for the glulam members, notched the timbers to create the moment connections, and assembled the composite columns in its workshop. Double-decker trailer trucks transported the columns and glulam beams to the project site, five minutes away.
Construction of Nest We Grow began in September 2014. Local craftsmen hoisted the structural members into place using cranes, and then secured the components together by hand. A transparent polycarbonate skin around the structure provides for weatherproofing.
Per the design competition brief, Nest We Grow is intended to bring people and food together at the Lixil JS Foundation’s Memu Meadows research center in Taiki-cho, Hiro-gun, Hokkaido, Japan. Smith says the team hopes the permanent structure, which opened last November, fulfills this goal. “We want to build a sense of community,” he says.
The CED student team also included Hsiu Wei Chang, Fanzheng Dong, and Max Edwards, all of who earned an M.Arch from CED in 2014, and Hsin-Yu Chen, an M.Arch. candidate.