A pile of building bricks made from industrial hemp at a factory in Canada.

Due to its ability to sequester carbon, hemp has landed at the forefront of the natural building conversation.

By Liana DeMasi

The first modern hemp home in the US was built in Asheville, N.C., in 2010. Since then, a handful more have been planned and executed internationally.

Why is this significant? As the latest United Nations’ IPCC report tells us, residents of Earth are on the verge of missing a “rapidly closing window of opportunity to secure a livable and sustainable future for all.” The construction industry accounts for about 11% of annual carbon emissions worldwide – while buildings in general make up 40%.

While most of these buildings are constructed out of more traditional materials like cement, brick, drywall, and plywood, forward-thinking architects and members of the construction industry have increasingly been turning to natural materials as an alternative for the future. Due to its ability to sequester carbon, hemp has landed itself at the forefront of the conversation about natural building.

In 2021, at the U.N. Climate Change Conference, Skidmore Owings and Merrill (SOM) unveiled a prototype for a hemp skyscraper within a larger city, called Urban Sequoia. And they’re not the only ones.

“We’ve made blueprints for hemp villages,” says Jayeson Hendyrsan CEO of Hempcrete Natural Building Ltd., a hemp construction and consulting firm based in Canada. “We want families to live in these carbon neutral homes for generations. While we’re a way off from that being widespread, we’re seeking new ways of doing things. We need to create parallel systems in the building industry.”

Advocates say that hemp can effectively be substituted in for other building materials during the construction process, and there’s evidence to support this. “Hemp and hempcrete [a biocomposite material that can be used in place of concrete] effectively replace the drywall and pink insulation present in typical construction,” says Cameron McIntosh, owner of Americhanvre, a cast-hemp company in Pennsylvania. “Beyond being mold-, mildew- and fire-resistant, a hemp home is also good for the planet. An 8,000 cubic square foot home sequesters about 76 metric tons of carbon.” This means that a house made of Hempcrete can effectively suck carbon out of the air, reducing – if not eliminating – its environmental impact.

Contrary to what recent enthusiasm for the material might suggest, hemp has actually been around for centuries, predating Roman times.

“Some of the first uses of hemp for building were found in China, mixed with limestone and pig’s blood,” says Jayeson. “Everyone became so interested in vinyl, concrete, and modern building materials, but we’ve had the answer right here all along.”

And he’s right. The first use of hemp for building was found to have occurred in China for the caulking of ships in around 200 B.C. In the 6th Century, in what is now France, hemp was found in the pillars of ancient bridges. Throughout history, hemp was – and still is – used in clothing, rope, pottery, and medicine.

With all the benefits of hemp construction, why are there only about 50 hemp homes in the U.S.?

After plywood, pink insulation, cement and drywall became codified in the U.S.’s state and local building codes in the wake of global industrialization, and the criminalization of marijuana in the 1970s and the subsequent villainization of hemp, the agricultural market for the plant was virtually nonexistent, illegal, and unregulated. Now, with further legalization and decriminalization of cannabis, the hemp industry is making up for lost time.

However, “It takes about seven or so years to yield on a hemp farm,” says Cameron, making the supply and demand ratio disproportionate. Americanvre outsources their hemp herd and binder from France as they wait for the American market to catch up.

“The U.S. Hemp Building Association just wrote the International Residential Code index for hempcrete, which is now under secretarial review,” Cameron says. “We’re hoping that this time next year it will be active, which will make it much easier to have discussions with code enforcement. It’ll be recognized for residential construction.”

There’s a disproportionate lack of mainstream knowledge with hempcrete in comparison to cement or drywall, which Cameron thinks can be solved with recognition and regulation. While these current regulatory blocks don't mean hemp is impossible to build with, the loopholes in getting there make it time consuming and more costly. Natural building is already a niche in the industry, limiting the number of firms and companies that have the licensing, equipment and training necessary for hemp construction. Both Cameron and Jayeson’s companies work closely with designers and architectural firms on home design, even recommending and making decisions on the finishing touches. But a build requires someone with expertise in materials, workers, and equipment to be physically present. This means their travel costs get looped in with the cost of labor, and in conjunction with materials, access to equipment, and the local code enforcement paperwork process, a hemp home can run about $60 or more per square foot than a home built traditionally.

“But the payoff on that upfront cost is extreme,” says Cameron. “Beyond the environmental benefits and the overall better safety of the home, you’re also looking at clean, nontoxic air. I compare it to buying organic. It’s going to cost you a bit more up front, but the short and long-term benefits far outweigh what you’re putting in.”

There’s also a possibility for a shift in home ownership through generations. The average American remains in a home for about 13 years before selling it, but Jayeson wonders if that number would increase if homes were built differently. “What would people’s bank accounts look like if they kept their beautiful, solid, low-maintenance, efficient house for, say, five generations?” he says.

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