The “aha!” moment at the University of British Columbia’s HiLo Lab came when researchers, intent on bending strips of wood veneer into unusual forms, stepped back to look at their elaborate setup. “We realized we could use the formwork itself as the member,” says Blair Satterfield, UBC department of architecture chair and associate professor.

That breakthrough led to zippered wood, which leverages ordinary construction methods to create extraordinary structures with the humble 2x4. “We thought about the project both formally, in terms of what we can achieve cheaply and quickly with standard studs, and also in a performative way, in terms of efficiency and strength,” says Marc Swackhamer, Assoc. AIA, who chairs the architecture department at University of Colorado, Denver and co-founded HouMinn Practice with Satterfield.

Starting with a cross-cut saw, the team created kerfs along 2×4s, enabling them to bend and twist. Using Grasshopper and the Kangaroo plug-in, they modeled the results and then wrote software protocols to map tooth patterns to specific curvatures. They upgraded to a CNC mill to cut teeth into 2×4s in such a way that two separate pieces of wood would lock or “zipper” only when they are hand-twisted together into the desired position, no wood steaming or soaking required. The mated pieces are clamped and glued to form a curving composite member with the dimensional cross-section of a 2×4. “Anecdotally, these bent and joined members are much stronger than a straight stud,” Satterfield says. "It's unbelievable how much force they can take."

To demonstrate their project’s potential and software's accuracy, the team built and exhibited two full-scale prototypes on the UBC campus in 2019: a common stud wall with a base plate replaced with a curving zippered beam, creating a hyperbolic paraboloid bulge; and a cultural pavilion that uses zippered members, some twisting 135 degrees, to obviate the wall-roof connection.

"Through this analysis of standard sizes and fabrication methods, the team came up with something very sinuous, beautiful, and surprising from a 2x4". 

—Juror Ming Thompson, AIA

The team is further streamlining the fabrication technique by scanning each board and using a script to adjust the design to avoid knots and holes. Most exciting, Swackhamer says, is the “democratizing potential” of a technique that broadens the possibilities of stick-frame construction.

Click here for more information about this award.