A Tour of Architect Jenna Yu’s Straw Bale ADU in Elmwood

From the outside, architect and designer Jenna Yu’s home on Depew Street may look like any other. Periwinkle with wooden siding and an addition connecting to the original 19th-century home — not unusual for the Elmwood neighborhood.

But unlike most homes in Providence, this addition is non-toxic, environmentally friendly, absorbs carbon, and is constructed of natural materials – namely, panelized straw.

Upon walking into the home, the attention to detail that Yu poured into the space immediately becomes clear. The clay and sand walls were plastered by her family and friends and the light fixtures were handcrafted by her mother and step-father, creating a cozy ambiance that complements the building’s natural materials.

Yu welcomed us for a tour in September, her daughter June Mei snoozing against her chest. With two young children, Yu shared that she was especially focused on creating a space that would be safe for her kids — lead-free and non-toxic.

But beyond being a beautiful space, Yu’s addition also represents an innovative and eco-friendly method of design and construction that has been uncommon thus far in Providence. Insulating homes with straw serves as a sustainable design practice, which has gained traction in places like California and upstate New York.

Yu prioritized moving “away from toxic materials like foam and fiberglass, which create poor indoor environments.” She also explained that in California, where wildfires are more common, firefighters are experiencing negative health effects from the toxins released when the components of traditionally built homes burn. Straw bale, on the other hand, is unlikely to cause as many long-term health effects, as it doesn’t release toxins when burned. Straw bale construction is also exceptionally resistant to fire, as the tightly packed panels leave far less oxygen in the walls than traditional stud construction, and the plaster coating over the straw provides an extra layer of protection.

“There’s the global problem of climate change,” Yu said. “But sometimes people don’t make personal decisions based on what’s best for the climate.”

“The problem with global warming right now is that we’re just putting so much carbon in the atmosphere, and we’re not taking it back down fast enough,” she continued. “So grass and small dimension lumber is pretty good at capturing carbon and then you’re storing it in your walls, and you’re putting it there for… hopefully 200 years.”

She went on to explain that in addition to using biomaterials, she strived to incorporate elements of passive building, a high standard of energy efficiency for built structures, in her design.

Yu studied architecture at RISD and then returned to her home state of California, where she worked in straw bale construction, holding straw bale workshops with the California Straw Building Association (CASBA) for several years. When she returned to Rhode Island, she wanted to bring the design practice with her.

“I had been doing straw bale construction for a few years. People will frame the whole building, and then they’ll get rough straw bales and have to use chainsaws to cut them around the wood,” she said. “And then you have to plaster it.” 

But in Providence, she opted to use panelized straw, a choice she said is gaining traction among those in straw bale construction. “I had just had my first kid, and I wanted this to go up fast.” 

Yu explained that the entire addition — panels and all — arrived in one shipping container from Lithuania. From breaking ground to clearing away construction materials, the project took just over a year to complete.

When the project began in 2019, Yu decided to document the process on Instagram. 

She explained that she didn’t encounter issues with permitting a straw-insulated structure. However, with Providence’s accessory dwelling unit (ADU) laws in flux, she had to adjust her plans for a standalone structure. The zoning regulations at the time instead required the structure be attached to her existing house — essentially creating a duplex.

Once permitting was good to go, they broke ground, creating a massive pit. As previously mentioned, Yu opted for structurally insulated panels (SIPs) to make for quicker assembly and construction. So instead of raw straw bales à la The Three Little Pigs, these panels are comprised of pressed straw, enclosed in wood. Diagonal bracing is used to ensure structural integrity. 

She used EcoCocon, a Lithuanian company to source the straw panels. Yu wrote about the process and floor plans for the addition in-depth for The Last Straw in an article titled Straw Panel Prototype.

 “It’s custom panelized, so it goes up fast, but it’s not exactly prefab,” she said. But EcoCocon helps with the assembly process but creating a 3D model of where each panel should be installed. 

The panels were lifted into place using a forklift, and the trusses were attached. The house was weather-tight within five days. The walls also naturally serve as carbon storage, which Yu said is essential.

Though Yu has heard her share of Three Little Pigs jokes, the building meets rigorous fire standards and is designed to be air-tight, using a building membrane to ensure energy efficiency. The house is designed to be comfortable without relying on mechanical systems, using natural ventilation and thermal mass. Poured concrete floors also help maintain a stable temperature.

Friends and family helped to plaster the walls with clay and sand by hand, and Yu brought in friends who were subcontractors to help with some of the details as well. Yu explained that it was a community driven process, and that the work was made easier with the help of friends.

Yu pointed out that the house has a “truth window,” — a design choice common in straw bale homes — revealing the material behind the plaster.

Though some may be skeptical about the efficacy of natural building materials in a place like Providence, Yu’s own home shows that it can be done — and can serve as a homey, inviting place while also helping to sequester carbon.

She mentioned that EcoCocon may look to open a US-based factory, which would make the process easier. Yu explained that the current options in the U.S. are costlier and take longer.

“This one basically amounted to an equivalent of [building] a custom house,” Yu said, explaining the cost difference between straw bale and typical construction in Providence.

ADUs are on their way to being easier to construct, per municipal guidelines. At its Nov. 4 meeting, the City Council’s Ordinance Committee approved modifying regulations for ADUs so that they won’t have to be attached to the main structure, won’t have to house relatives, and won’t need to be owner-occupied. The change will have to be approved by the full Council.

With zoning changes and easier access to materials in the U.S., biomaterial and straw bale construction could become more commonplace in Providence. Yu mentioned that another straw bale house may go up around Federal Hill in the spring.

But Yu’s home can serve as a model for future homes — it demonstrates that well-designed sustainable construction is already possible here in Providence.

By Katy Pickens / Planning & Preservation Writer / kpickens@ppsri.org

Additional Reporting by Keating Zelenke / Mary A. Gowdey Special Projects Fellow / kzelenke@ppsri.org