WNC leads nation in hempcrete construction
BY JOHN BOYLE • NOVEMBER 29, 2010
When it comes to hemp building, business is booming.
“Western North Carolina essentially is the capital of hempcrete building in the United States right now,” said Gregory Flavall, the co-founder of Hemp Technologies, the Asheville-based company that supplies the hemp-based building material to contractors.
Two hemp-based homes have been completed in Asheville, one in West Asheville and another off Town Mountain Road, and another is going up in Haywood County near Lake Junaluska. Flavall says his company has dozens of projects lined up, both in WNC and throughout the country, including in Texas, Colorado and Hawaii.
Hemp construction undoubtedly got a nice boost, Flavall says, from an article in USA TODAY and a segment on CNN. Over the past six to eight months, interest has picked up domestically, as well as from overseas, with inquiries coming in form the Netherlands and Romania. Hemp Technologies has 38 projects in development, and Flavall said he and his business partner likely will add up to eight employees in the coming year or two to handle demand.
Asheville led the country into modern hemp building, with the Nauhaus Group, a collaborative of local companies, building the West Asheville hemp home at 67 Talmadge St. The other hemp structure, a 3,100-square-foot house on Town Mountain, belongs to former Asheville Mayor Russ Martin and his wife, Karen Corp, and was designed by local company Push Interior/Architectural Design + Build.
Versatile, efficient – but illegal to grow
The case for hemp building is simple — it offers tremendous insulation, pest-resistance, strength and malleability.
But, it’s illegal to grow in the United States. Builders can import industrial hemp products like Tradical Hemcrete, which Flavall’s company sells, but they can’t buy hemp from local growers.
The U.S. Drug Enforcement Agency still considers industrial hemp a “schedule I” illegal drug because it’s a variety of the cannabis sativa plant that marijuana is derived from, a position that dates to a 1937 change in the law. Before that, farmers throughout the U.S. grew hemp for hundreds of products ranging from clothing to rope.
The industrial hemp plant contains very little of the active ingredient that gets people high, and it’s completely impractical to smoke. Still, it’s banned, so that leaves it up to people like Flavall to import it from Europe or Canada for building projects.
Often generically referred to as “hempcrete,” the mixture that’s going into the Haywood County house starts with 55-pound bales of hemp shiv, or ground-up hemp plant stalks.
General contractor Vincent Cioffi and his crew mix it into a standard concrete mixer, four parts hemp, one part lime and one part water. The slurry mixture goes into small containers, and then they pack it between forms to make a wall.
In this house, the walls are 12-inches thick and will take about a day to dry and about two weeks before they’re ready for exterior coatings of lime stucco. Inside, workers are installing magnesium oxide sheathing for walls, a product that breathes and is nontoxic, instead of conventional wall board.
While the hemp material breathes, it doesn’t let water in. It’s also mildew-resistant, and it has a lifespan runs 600-700 years.
“Eventually, if you don’t want the house anymore, you can use the hemp as fertilizer,” Flavall said.
Worth the cost
Homeowner Roger Teuscher, a retired farmer and school superintendent from Florida, said the nonchemical nature of the material and its incredible insulation factor appeal to him. The 3,100-square-foot home has a traditional roof, but all the exterior walls are hemp construction.
“Cost-wise, it’s a little more than regular construction, but not that much,” Teuscher said. “I had been to the other ones under construction in Asheville, and it looked very solid and secure. This material was used in houses in the time of Shakespeare, and most of those houses are still standing. They might’ve been knocked down, but not because the hemp failed.”
Generally, the hempcrete costs 10-15 percent more than traditional construction, but homeowners get that money back in reduced heating and cooling costs, as well as a reduction in homeowners’ insurance because the hempcrete is not flammable.
Flavall and builders also note that the lime in the mixture is constantly taking in carbon, so the product is actually carbon-negative, not just carbon neutral.
A full-sized home requires about two acres worth of hemp.
Cioffi, whose Via Bella Development Inc. is building Teuscher’s home, said he likes working with the product.
“We did have four laborers on this, so it’s a little more labor-intensive compared to the conventional side,” Cioffi said, adding that the product is easier to handle, though.
On this house, Cioffi and his crew will use about 400 bales of hemp and 600 bags of the lime-based binding agent. He and Flavall estimate the cost of the hemp at $56,000.
“It’s been touted as the most green, sustainable and renewable product out there,” Flavall said.