As hemp and cannabis gain cultural currency, a new approach to construction emerges.
Courtesy of D-Kuru / Wikimedia Commons
As state after state slowly moves towards marijuana legalization, it seems like everyone is trying to cash in on the pot-farming boom. But legalization opens the door to a world of innovation and entrepreneurship that’s a lot wider than new, inventive ways to get high, like weed sodas. In “green rush” states like Colorado, farmers are taking advantage of the new legal environment to sow fields of hemp, marijuana’s THC-deficient cousin. Because of its relationship to cannabis, hemp has been illegal in America for over 60 years, despite a consistent chorus of supporters who have touted its use as a natural fiber and food supplement in Canada and Europe. Compared to the economic potential of legalized marijuana, that of pot’s fibrous cousin seems like small potatoes. Yet one use of the plant could revolutionize construction in the U.S., creating a new, lucrative industry for growers: Hempcrete.
Building with Hempcrete. Photo by Steven Craven
Also known as Canobiote, Canosmose, and Isochanvre, Hempcrete is a mixture of the woody cores of hemp (called hurds or shives) and lime. Either cast as blocks and finished with lime stucco or sprayed between walls as a paste, the material does not bear structural weight, but does form well-insulated walls and foundations. While many other materials boast the same qualities, Hempcrete is already beloved for its durability, workability, and cost efficiency: It’s less brittle than concrete and about one-eighth of the weight, nearly one-third the price of lumber, resistant to mold, insects, and fire, and potentially carbon locking (meaning it leaves a negative carbon footprint). As hemp grows to maturity within 14 weeks, often with no need for fertilizer, weed killer, or pesticides, it makes for a supremely easy-to-raise crop, comparable in price to existing materials. Its only major limitations are its lack of load-bearing capacity, long setting time, and relative obscurity, which could lead to property owners misusing or mistreating Hempcrete.
Close-up of Hempcrete
Although rare in America, antique samples of Hempcrete-like material have been found in a French bridge dating back to the 6th century C.E., and more recently, it’s been used in homes and high rises in Belgium, France, Switzerland, and the United Kingdom. It’s common enough that there are DIY books detailing how to work with the material. A few Hempcrete houses have even been erected in America since it was introduced in 2009, but given hemp’s federal illegality it still must be imported under restrained conditions, mainly from Canada and the United Kingdom.
As hemp gains traction alongside cannabis, we’re likely to see the already numerous Hempcrete suppliers multiply and prices decrease. But for now, the difficulties of moving hemp across state borders stall the product’s expansion. As legalization marches forward, though, and the first non-residential Hempcrete building rises in the States, America will likely soon recognize its odd status as the world’s only hemp-hating industrialized nation and embrace a promising new industry.