UC Berkeley’s mass timber research is impacting the decarbonization of California’s construction industry

With guidance from Assistant Professor Paul Mayencourt and the UC Berkeley Wood Lab. Humboldt County’s Mad River Mass Timber is pioneering the commercial manufacture of dowel-laminated timber (DLT) in the state. The first vertically integrated producer of mass timber in California, MRMT transforms waste wood from our forests into construction-ready building panels.

Unlike traditional construction lumber, DLT panels can be made from a wide variety of wood species. Weak or small-diameter trees that cannot otherwise be used for construction, such as red fir, hemlock, and Ponderosa pine, can be joined together to create strong DLT panels. DLT can also repurpose fire-damaged timber, which until now has not had a commercial use.

The commercialization of this technology promises to lead to the creation of a new sustainable manufacturing sector in California that benefits our forests, the climate, and the economy. DLT, which can be used for rapid, efficient construction, also has the potential to alleviate California’s housing crisis.

This venture demonstrates how the College of Environmental Design’s technical and design expertise can impact, at scale, the state’s transition to greener building practices and a low-carbon future.

Mass timber is a renewable resource that reduces atmospheric carbon

“It’s essential that we reimagine how we build,” says Mayencourt, who holds degrees in architecture and engineering from MIT and the Swiss Federal Institute of Technology in Zurich. He has been working with his Wood Lab colleagues on numerous projects that explore uses for undervalued and underutilized California species, including DLT.

DLT is a kind of mass timber, the industry term for engineered wooden panels prefabricated for construction. Mass timber, unlike steel and concrete, is a renewable resource that locks away carbon for the lifespan of a structure, sequestering it from the atmosphere. By relying on wooden dowels as connectors, DLT avoids chemical adhesives used in other mass timber products and is completely recyclable.

The adoption of mass timber construction could help the industry shift away from concrete and steel, major sources of global greenhouse gas emissions. This is significant given that forty percent of global CO₂ emissions are linked to the construction and operation of buildings. A recent study. published in Building and Environment found that mass timber buildings lowered global warming potential by an estimated range of 39–51% compared to equivalent reinforced concrete buildings and 28–34% compared to buildings made with structural steel. Another study. found that the average embodied energy of mass timber buildings is 23% higher than that of reinforced concrete alternatives.

Until now, builders in California have had to source mass timber from Washington or Canada, and the carbon cost of long-haul trucking mitigated its environmental benefits. MRMT’s locally produced DLT, made from wood sourced from California forests, has the capacity to play a key role in the state’s transition to low-carbon construction methods.

Academia and industry working together to scale production of mass timber in California

“When I learned about mass timber in college, I knew it was something I wanted to pursue,” says fifth-generation sawmill operator and MRMT President George Schmidbauer. “The market was gaining momentum and there was increasing demand for locally sourced materials to address California’s wildfire and forest health issues.

But Schmidbauer found that traditional mass timber production facilities, such as those that produce cross-laminated timber (CLT), require a massive up-front investment. Furthermore, he realized the lumber produced in California was not a good fit for CLT production and would require burdensome modification of local sawmills and, ultimately, a more expensive product. With cost being the biggest metric holding back mass timber adoption, Schmidbauer  wanted to invest in a process that would deliver efficient mass timber products at an achievable price.

After visiting the UC Berkeley Wood Lab and seeing Mayencourt’s experiments with small-scale DLT fabrication, he realized that DLT presented the best opportunity to meet his goals — forest stewardship and low-carbon construction — on a fast timeline.

Schmidbauer and Mayencourt started discussing how to scale the production of DLT to meet the rising demand for locally produced mass timber. “Initially, I acted in a consulting capacity, working to help develop the DLT process,” says Mayencourt. “George and I would have weekly calls, sharing ideas and troubleshooting. With a grant received by the Joint Institute for Wood Products Innovation, my Berkeley Wood Lab research associate Jitske Swagemakers and I were designing projects using DLT in the Tahoe region, and George, with his knowledge of the timber industry and supply chain, was figuring out the manufacturing side in Humboldt.”

To produce at scale, MRMT designed and built a DLT machine from scratch using standard components. Now, the company is producing prefabricated mass timber floors, roofs, walls, and beams for all types of construction. Mayencourt helped write the design guide for MRMT’s DLT products referencing existing building codes.

Sourcing timber for DLT helps protect forests and reduce wildfire risks

MRMT’s use of alternative wood sources, procured from national forests and tribal lands as part of forest health and wildfire mitigation projects, removes biomass from California forests that can fuel intense wildfires. This transforms forest management — a significant expense — into a source of revenue, making wildfire mitigation economically viable.

“With DLT, we can put lower-value wood into panels and engineer around that species’ reduced structural capacity,” says Schmidbauer. “This means we can connect forest restoration and wildfire mitigation to the low-carbon construction economy in more ways than previously possible.”

Transforming wood waste into affordable housing, while boosting rural economies

Drawing on Schmidbauer’s background in affordable housing development and the architectural design skills of Mayencourt and his team, the two are now collaborating on prefabricated DLT kits for the rapid construction of affordable multifamily housing. This promises to bring the benefits of sustainable, carbon-sequestering mass timber into the affordable housing market.

With their first projects already underway, MRMT is seeking additional development partners focused on sustainable development. As it grows, it will boost economic development in Humboldt County, creating jobs in the communities where the timber is harvested and processed. “The entire process is optimized for local economic and environmental benefit,” says Schmidbauer.

“Seeing MRMT scale up the manufacture of DLT is exciting.” say Mayencourt. “With one relatively low-tech innovation, we can tackle forest health, wildfire risk, the housing crisis, and struggling rural economies. We can start to fulfill our commitment to reduce greenhouse gas emissions for the future of our planet.”