THE Alternative Building Material

(This appeared in May '10, Merchant Magazine and Building Products Digest)

When I began thinking about this article and the various alternative building materials I could write about, several came to mind. But what counts for “alternative,” anyway? For example, there are products that are greener versions of old standbys like triple-glazed windows or FSC lumber. I could write about Serious Materials’ (www.seriousmaterials.com) innovative EcoRock drywall which they claim is 5 times more environmentally friendly than gypsum drywall, or Eco-Panels’ (www.eco-panels.com) super-efficient and well-designed structural insulated panels (SIPs). And then there are materials and methods that have thousand-year histories but aren’t mainstream, such as cob, which combines clay, sand and straw fibers usually sourced onsite. But these kinds of natural alternatives don’t usually require much of a supply chain. Instead, I’m going to highlight a building material that will blow your mind – hemp.

Industrial hemp used to be one of the most important agricultural products in the United States, but its cultivation has been illegal here for decades. (That may change soon - google Hemp History Week to learn more.) The Puritans brought it with them from Europe, many of our Founding Fathers grew hemp, and as recently as 1942, the government actively encouraged farmers to grow it. In those days, hemp was indispensable for making rope, cordage and sail cloth, and it yielded more usable fiber per acre than cotton or flax. Innovations in more recent times have demonstrated its value as paper and plastic feedstock, nutritive food ingredient, and biofuel. Cultivation can also bring benefits to farming communities as it delivers relatively quick, dependable yields without the use of pesticides or synthetic fertilizers.

Absolutely the coolest thing about hemp is that it’s being used to sequester carbon in an innovative new product called Tradical Hemcrete. It’s a combination of hemp shiv, which is the woody core of the plant, and a hydraulic lime binder. The components are mixed at the jobsite and packed into forms to make thermally efficient, breathable walls that could potentially last for hundreds of years. After its first US installation in the NauHaus, an innovative new home prototype designed by building science think-tank NauHaus Institute, (www.thenauhaus.com), there are now several more homes in the works.

Hemp Technologies, (www.hemp-technologies.com,) based in Ashville, NC, is the North American distributor of the product, importing it from England where it was originally developed. Greg Flavell, co-founder and hemp technology guru, said he discovered the product after searching for the most sustainable building material he could find. “I think this is it – it’s zero waste, non-toxic, breathable, mold resistant, durable, and is carbon negative, sequestering about 238 pounds of carbon per cubic yard,” he told me, adding “it’s also cost competitive.”

There are a few limitations, of course. The product is imported from England, where it was originally developed, because hemp isn’t yet grown domestically, nor are there easily sourced quantities of domestically produced hydraulic lime. The system is sold in two bags, Tradical HF and Tradical HB, which must be mixed at the jobsite by company-trained installers, though any contractor could easily master working with the material. In any case, those factors will slow widespread adoption of the material in the near term. However, Flavell says that they’re working on sourcing a little closer to home and developing a new panel system. Panels could dramatically expand the potential applications and make it easier for distributors and dealers to pick up the product. “We’re hoping to have panels available later this year,” says Flavell. If everything goes according to their plans, hemp could very well become less “alternative” and much more mainstream.