FARGO, ND – At first glance, they look like identical houses rising in the middle of the 300 block of North 10th Street.
Both are tall, vertical buildings, with matching diagonal roofs, 12-foot-high ceilings, and identical placement of windows and doors.
But come closer and the difference becomes clear. A house is built in the usual way, with a wood frame, fiberglass insulation and a white Tyvek house wrap.
The other features thick beige colored walls that appear to be made of tightly compacted wood mulch. Step inside and you’ll feel like you’ve entered a life-size sandcastle.
Except these aren’t walls of sand or woodchips. These walls are hemp. A timber frame still gives the house its supporting skeleton, but the insulation and walls are cast with hempcrete, a mixture of hurd (the shredded inner core of the industrial hemp plant), a lime binder and water.
These two structures were built by Justin Berg and Sydney Glup of
as a demonstration project/scientific study. And by “built” we mean literally.
In late July, Berg, Glup and a small team built the 12-inch-thick walls from scratch in four days. “Our hands are all over this thing,” Berg says, smiling.
Using a mortar mixer to mix the earth shards with a special mixture of lime and water, they hauled bucket after bucket of the material to the frame of the house and packed it to the hand between plywood forms, much like those used to shape concrete walls.
“It was almost like a chicken salad consistency,” says Glup, explaining how the hemp material felt when mixed with binders. “We kept saying, ‘We need more salad here! “”
The hempcrete, which smells sweet and vaguely hay-like, now needs to be left for six weeks to ‘harden’, before being finished with a lime-based render.
Meanwhile, sensors embedded in the walls will provide a continuous stream of information on everything from air quality, temperature and humidity levels to energy consumption, Berg and Glup say.
They are particularly interested in how the energy consumption of the hempcrete house compares to that of the conventionally built “control” house next door. In order to keep their discoveries as pure as possible, the material of the walls is the only difference between the two houses. Otherwise, both spaces share the same 299-square-foot footprint, same layout, same ceiling height, and identical 7-foot-tall lofts.
“By doing good research, we wanted to make sure we only had one major variable, which was hempcrete insulation for the wall assembly,” says Glup, sustainability consultant at Grassroots.
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 40-50% lower than conventional structures.
Other benefits are also expected. Hempcrete is an excellent insulator because the limestone helps it store heat, while the airy spaces between the hemp chips enhance its insulating qualities, Glup says.
At the same time, hempcrete is so permeable that indoor moisture and mold problems are virtually unheard of, they say.
And while casual smart pants like to ask Berg if they can “smoke his hemp house,” he’s actually flame and smoke resistant, he says. Many videos online show people pointing blowtorches or heat guns at hempcrete surfaces for hours on end, failing to ignite it.
The hemp-derived substance also has brick-like strength. Hempcrete was discovered in a bridge abutment in France built in the 6th century, says Berg, president of
and a local real estate agent.
Finally, because an acre of hemp captures and stores about 11,000 pounds of carbon dioxide during its growth cycle, it’s much closer to carbon neutral than mineral or glass fibers, according to New Frontier Data.
Once Grassroots collects its 365 days of data, it will share the information with Alex Haynor, research engineer at
in Plymouth, Minn. Haynor will turn their data into a 10-page field report, which will be shared with the public. The Grassroots team hopes to add weight to the argument that hemp is a valid building material.
The houses will also serve a real purpose, either as rentals or possibly as Air BnB options, they say.
Hemp havens have a 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 verbiage,” says Glup. “I’m tempted to say traditional (when I’m talking about modern, conventionally built homes), but hempcrete is really more traditional. Hempcrete is thousands of years old,” she adds. “Because it’s so rudimentary. Do you need anything. You can mix it in a bucket with your hands.
Since its revival around 30 years ago, hempcrete has enjoyed growing popularity across Europe. Some American manufacturers have also tried it: In 2019, the city of Austin, Texas,
for parolees and others who would otherwise be homeless.
All of the glowing benefits of this durable material might be overshadowed by one undeniable fact: it is more expensive than current building materials. Berg says the hempcrete house was 25% more expensive than its conventional counterpart.
But he is quick to add that energy savings over the next few years could offset that initial expense. He also points out that the hempcrete house required less wood ($14,000 for the conventional versus $11,300 for the hemp building).
And Berg and Glup believe that as hemp cultivation and processing becomes more common in North Dakota, hempcrete will become more affordable to produce. More sophisticated hemp building materials, such as hemp panels made by
– will also make constructions faster and less labor intensive, they say.
For this project, raw materials were hard to find and had to be shipped from Kansas and Illinois, he says.
Minnesota has added two new hemp processors, and Berg is building a processing facility in Wahpeton himself, which he plans to have operational by the end of this year.
“Over time, that’s how we can align local sourcing and different construction methods to help this enter the traditional construction industry,” says Berg.
Local processing factory in works
One factor to consider is that the hemp market is quite saturated right now. John Mortenson, plant protection specialist and hemp program manager at the North Dakota Department of Agriculture, said farmers across the country went wild on hemp in 2019 after it was legalized by the Farm Bill of 2018 and after seeing the popularity of CBD and hemp oil products. explode.
So many farmers have planted hemp that the
Hemp prices fell from $4.50 a pound to 20 cents a pound, Mortenson says.
So even though manufacturers and retailers continue to make money from hemp, growers find it so unprofitable that many have turned to planting more conventional crops, like corn and soybeans.
As a result, the state’s total hemp acreage has shrunk from 2,800 acres a few years ago to just 300 acres this year, Mortenson says.
Even so, he thinks growing hemp for fiber, including for hempcrete, makes sense, especially if it can be processed locally. Hemp fiber is creating a new market for a fairly easy-to-grow plant that doesn’t need pesticides and is useful for everything from building materials to biofuels and plastic composites.
Once the hemp market recovers, Grassroots Development will be ready. They eventually hope to create a “hive” of Air BnB rentals at their 308 10th Street address, which would include the existing house on 10th Street and, if possible, the two smaller houses. They would be finished with shared amenities like a garden and fire pit so guests could share a sense of community.
“A lot of people are interested,” says Berg. “I really think there are people who will support this, as long as we can verify that we can access their markets and work with their businesses.”
Glup adds that hempcrete creates a healthy, sustainable and community-centric option for the typical “TV dinner” home: “Our goal is to bring hempcrete to the point where everyone can choose how they want to build their Everyone deserves to live in a health-conscious home that won’t deteriorate over time. It’s a basic human right.