Ashen Cabin

This article appeared in the June 2020 issue of ARCHITECT.

In 2018, the 100,000 ash trees in Cornell University’s 4,200-acre Arnot Forest in Ithaca, N.Y., faced an alarming threat: Caretakers detected Agrilus planipennis, commonly known as the Emerald Ash Borer—an invasive beetle that threatens billions of ash trees in 35 U.S. states and several Canadian provinces. The withered trees left in the beetles’ wake are considered a loss by lumber mills. But in Ithaca, Leslie Lok and Sasa Zivkovic, assistant professors at Cornell’s College of Architecture, Art, and Planning and founding partners of local firm Hannah, saw an opportunity.

“People are working on remediation, but a lot of trees will be dying,” Zivkovic says. “We think they are an enormous material resource and should be used for construction.” Intent on finding a use for the castoff trees, the firm began work on a prototype residential project in 2017.

The result is the Ashen Cabin, a compact getaway outside Ithaca. With 3D-printed concrete footings and an envelope made from infested ash wood, it serves as an investigation into how unconventional building materials and technologies can influence the design of residential projects. “You start with the intention of looking at how we can use these materials differently, or to develop novel architectural expression,” Lok says. “It allows us a larger range of tools and materials that we can design with.”

First, Lok and Zivkovic developed the cabin’s concrete foundation, pulling from their research at Cornell’s Robotic Construction Laboratory (RCL). They used a large-format three-axis gantry 3D printer at the RCL to create hollow footings for the cabin’s foundation. When complete, the concrete shells were transported to the site, where a custom rebar cage was added to each void before being filled with poured concrete; blocks of foam in the center of each large footing reduce material use.

In 2019, Lok and Zivkovic worked with Peter Smallidge, the senior extension associate for the Arnot Forest, to hand-select trees that had been killed by the beetle infestation. Although regular sawmills can’t process the damaged trees due to their irregular curvature, Lok and Zivkovic used an iPad-based scanner to generate precise digital models to determine the best way to cut each log, and sent those models to a 5-horsepower band saw, custom-built for the RCL, which sliced boards of varying thicknesses that exaggerate or minimize the wood’s curve. A system of screens and biodegradable foam combine with the low-moisture wood to form an insulated, waterproof envelope.

Windows at varying heights allow natural light into the spare, 100-square-foot interior. Each wall contains a different necessity: a sink and camping pump, a 3D-printed concrete fireplace, and a bench (the only furniture).

“We have demonstrated that this is a viable method to use these infested trees,” Zivkovic says. “Hopefully we’ll get an opportunity to scale this up into a full residential project and then further.”

Project Credits
Project: Ashen Cabin, Ithaca, N.Y.
Client/Architect: Hannah, Ithaca, N.Y. . Leslie Lok and Sasa Zivkovic (principals); Byungchan Ahn, Alexander Terry (wood fabrication/design); Xiaoxue Ma, Alexandre Mecattaf (wood studies); Freddo Daneshvaran, Ramses Gonzalez, Jiaying Wei, Jiayi Xing, Xiaohang Yan, Sarah Bujnowski, Eleanor Krause, Todd Petrie, Isabel Branas, Xiaoxue Ma (wood assembly/documentation); Christopher Battaglia, Jeremy Bilotti, Justin Hazelwood, Mitchie Qiao (concrete); Reuben Chen, Alexandre Mecattaf, Ethan Davis, Russell Southard, Dax Simitch Warke, Ramses Gonzales (concrete assembly/documentation)
Scientific Support: Cornell Robotic Construction Laboratory
Forestry Consultant: Peter Smallidge
Size: 100 square feet
Cost: Withheld