Hemp: The Next Disruptor in Construction After Wood?

Blaine Brownell posits that with faster cultivation rates, a higher carbon capture, and advances in processing, hemp could be the next big thing in structural systems after mass timber.

Plantd hemp-based OSB prototype

Concrete, steel, and wood comprise the triumvirate of structural building materials today. Most buildings contain all three in some capacity and employ one as a predominant framing medium. Architects and engineers default to these three materials so regularly that the market seems impenetrable to alternatives. And yet, a fourth option may soon be a reality—and a potentially disruptive technology.

Hemp is growing in popularity as a building product. This nonpsychoactive form of the cannabis plant has been utilized for years to make rope, insulation, bioplastics, and other industrial materials due to its strength and rapid growth. Until recently, hemp has remained a peripheral product—the most familiar of which is Hempcrete—in the construction industry. However, it is becoming an increasingly viable option for more common building elements due to developments related to its similarities to—and differences from—wood.

As is now widely appreciated, wood’s carbon sequestration capabilities—and its resulting favorable carbon footprint compared with concrete and steel—have helped lead to its increased use in building construction. However, the resurgence of interest in engineered lumber has raised renewed concerns about overharvesting and deforestation.

Once the U.S. Farm Bill was amended in 2018 to legalize agricultural hemp, entrepreneurs and product manufacturers began to take note. Like wood, hemp stores carbon. However, hemp’s rapid growth makes for a superior carbon-capture feedstock. Hemp can be cultivated in 90 to 120 days, 100 times faster than oak trees. The plant also sequesters four times more carbon than a similarly sized forest. Hemp absorbs more than 20 metric tons [PDF] of carbon per hectare, and its ability to be harvested biannually effectively doubles this quantity. According to GoodEarth Resources, an Australian eco-energy consultancy, “Industrial hemp has been scientifically proven to absorb more CO₂ per hectare than any forest or commercial crop and is therefore the ideal carbon sink.”