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The house that hemp built: Fargo developers build hempcrete home to study energy-saving benefits

Justin Berg and Sydney Glup built two identical tiny houses -- one the conventional way, the other with a hemp-derived material called hempcrete -- to help prove hemp's superiority in terms of energy savings, moisture control and air quality.

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Sydney Glup of Grassroots Development is working with Fargo Realtor Justin Berg to build a hempcrete "tiny house," so they can compare its energy efficiency and cost to that of a conventionally built tiny house.
David Samson/The Forum
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FARGO, ND — At first glance, they look like identical houses rising up in the middle of the 300 Block of 10th Street North.

Both are tall, vertical buildings, with matching diagonal roofs, a 12-foot-high ceiling and identical placement of windows and doors.

But step closer, and the difference becomes clear. One house is built the usual way, with a wood frame, fiberglass insulation and white Tyvek house wrap.

The other features nubby, tan-colored walls which look like they’re made of tightly compacted wood mulch. Step inside and you feel like you’ve entered a life-sized sand castle.

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A close-up of the hempcrete during construction. This will be covered with plaster after a six-week curing period.
Contributed / Grassroots Development

Except these aren’t walls of sand or wood chips. These walls are made of hemp. A lumber frame still gives the house its supportive skeleton, but the insulation and walls are molded with hempcrete, a mixture of hurd (the shredded inner core of the industrial hemp plant), a lime binder and water.

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These two structures were built by Justin Berg and Sydney Glup of Grass Roots Development in Fargo as a demonstration project/scientific study. And by “built,” we mean literally.

In late July, Berg, Glup and a small crew constructed the 12-inch-thick walls from the ground up in four days. “Our hands are all over this thing,” Berg says, grinning.

Using a mortar mixer to blend the hurd splinters with a special lime mixture and water, they carried bucket after bucket of the stuff to the frame of the house and hand-packed it between plywood forms, much like those used to shape concrete walls.

“It was almost like chicken salad consistency,” Glup says, explaining how the hemp material felt when mixed with binding agents. “We kept saying, ‘We need more salad over here!’”

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A worker helps hand-pack the shredded inner core of hemp, mixed with lime and water, to form the hempcrete walls of the house, which was built by Grassroots Development of Fargo.
Contributed / Grassroots Development

The hempcrete, which gives off a cloyingly sweet, vaguely hay-like smell, now must be left for six weeks to “cure,” before it is finished with a lime-based plaster.

Meanwhile, sensors embedded in the walls will provide an ongoing stream of information on everything from air quality, temperature and moisture levels to energy consumption, Berg and Glup say.

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The small house on the left is made with traditional construction materials. The house on the right uses the same design, but it is built with "hempcrete," a construction material made from hemp.
Finn Harrison / WDAY News

They are especially interested in how the hempcrete house’s energy usage stacks up against the conventionally built “control” house beside it. In order to keep their findings as pure as possible, the wall material is the only difference between the two houses. Otherwise, the two spaces share the same 299-square-foot footprint, the same layout, the same ceiling height and identical 7-foot-high lofts.

“In conducting good research, we wanted to make sure we had only one major variable, and that being the hempcrete insulation for the wall assembly,” says Glup, sustainability consultant with Grassroots.

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Their hope is that the hempcrete abode will live up to its hype. Their study of other hempcrete structures suggests heating and cooling costs could be 40 to 50% lower than in conventional structures.

Other advantages are expected as well. Hempcrete is an excellent insulator because the limestone helps it store heat, while the airy spaces between the chips of hemp boost its insulating qualities, Glup says.

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Sydney Glup holds the chipped "hurd" from the core of the hemp plant in the hand closest to the camera and the hurd mixed with lime in the other hand.
David Samson/The Forum

At the same time, hempcrete is so permeable that indoor humidity and mold problems are virtually unheard of, they say.

And even though the occasional smarty pants likes to ask Berg if they can “smoke his hemp house,” it’s actually fireproof and smokeproof, he says. Numerous online videos show people aiming blowtorches or heat guns at hempcrete surfaces for hours on end without managing to ignite it.

The hemp-derived substance also has a staying power akin to brick. Hempcrete was discovered in a bridge abutment in France built in the 6th century, says Berg, president of Grassroots Development and a local Realtor.

Finally, because one acre of hemp captures and stores about 11,000 pounds of carbon dioxide during its growth cycle, it is much closer to being carbon-neutral than mineral or glass fibers, according to New Frontier Data.

Once Grassroots collects their 365 days of data, they will share the information with Alex Haynor, research engineer with the Center for Energy and the Environment in Plymouth, Minn. Haynor will transform their data into a 10-page field report, which is shared with the public. The Grassroots team hopes to add weight to the argument that hemp is a worthwhile building material.

The homes will also serve a real purpose, either as rentals or possibly as Air BnB options, they say.

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Hemp havens have long history

Although a hemp building sounds revolutionary to modern ears, the practice of hemp for housing is anything but. “That’s why I have to be careful with the verbiage,” Glup says. “I’m tempted to say traditional (when referring to modern, conventionally built homes) but hempcrete is really more traditional. Hempcrete is thousands of years old,” she adds. ”Because it’s so rudimentary. You don’t need anything. You can mix it in a bucket with your hands.”

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Interior view of the conventionally built tiny home. Both homes are identical in size and layout, with the exception of a different wall material in the hempcrete home.
David Samson/The Forum

Since its renaissance about 30 years ago, hempcrete has seen growing popularity across Europe. Some US builders have also dabbled in it: In 2019, the city of Austin, Texas, built a community of hempcrete tiny houses for parolees and others who would otherwise be homeless.

All of the glowing benefits around this sustainable material could be upstaged by one hard fact: It’s more expensive than current building materials. Berg says the hempcrete house was 25% more expensive than its conventional counterpart.

But he’s quick to add that the energy cost savings over the next few years could make up for that upfront expense. He also points out that the hempcrete house required less lumber ($14,000 for the conventional vs. $11,300 for the hemp building).

And Berg and Glup believe as hemp farming and hemp-processing become more common in North Dakota, hempcrete will get more affordable to produce. More sophisticated hemp building materials—like the hemp panels being manufactured by Homeland Hempcrete in Bismarck —will also make the builds faster and less labor-intensive, they say.

For this project, raw materials were hard to source and needed to be shipped from Kansas and Illinois, he says.

Minnesota has added two new hemp processors and Berg is building a processing facility himself in Wahpeton, which he plans to make operational by late this year.

“In time, it’s how we can align localizing supply and different building methods to help this get into the traditional building industry,” Berg says.

Local processing plant in the works

One factor to consider is that the hemp market is pretty saturated right now. John Mortenson, a plant protection specialist and manager for the hemp program at North Dakota’s Department of Agriculture, says farmers across the country went hemp-wild in 2019 following its legalization by the 2018 Farm Bill and after seeing the popularity of CBD and hemp oil products explode.

So many farmers planted hemp that the market was flooded. Hemp prices tumbled from $4.50 per pound to 20 cents per pound, Mortenson says.

So even as the manufacturers and retailers continue to make money off hemp, producers are finding it so unprofitable that many have switched to planting more conventional crops, like corn and soybeans.

As a result, the state’s total acreage of hemp acres fell from 2,800 a few years ago to just 300 acres this year, Mortenson says.

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John D. Peterson and his business partner Art Weidner grow two varieties of the viney, thirsty hop plant on an 80- by 50-foot plot tucked into the back of Peterson's family farm near Sabin.

Even so, he does believe growing hemp for fiber, including for hempcrete, makes some sense, especially if it can be processed locally. Hemp fiber creates a new market for a plant that is fairly easy to grow, doesn’t need pesticides and is useful for everything from construction materials to biofuels and plastic composites.

Once the hemp market regains its footing, Grassroots Development will be ready. They hope to eventually create a "hive" of Air BnB rentals at their 308 10th Street address, which would include the existing house right on 10th Street and, if possible, the two tiny homes. They would be finished with shared amenities like a garden and a firepit so guests could share a sense of community.

“A lot of people are interested,” Berg says. “I definitely think there are people who will get behind this, as long as we can verify that we can get to their markets and work with their businesses.”

Glup adds that hempcrete creates a healthy, lasting, community-centric option to the typical “TV dinner” home:  “Our goal is to get hempcrete to the point where anyone can choose how they want to build their home. Everyone deserves to live in a health-conscious home that won’t degrade over time. It’s a basic human right.”

Related Topics: AGRICULTUREHOUSINGFARGO
Tammy has been a storyteller most of her life. Before she learned the alphabet, she told stories by drawing pictures and then dictated the narrative to her ever-patient mother. A graduate of North Dakota State University, she has worked as a Dickinson, N.D., bureau reporter, a Bismarck Tribune feature writer/columnist, a Forum feature reporter, columnist and editor, a writer in NDSU's Publications Services, a marketing/social media specialist, an education associate in public broadcasting and a communications specialist at a nonprofit.
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