Can I use hemp as a building material and to insulate my house?


Homes that Hemp Can't Build?
Hemcrete is a mixture of dried hemp stems and lime that is poured into thick, concrete-like blocks.
Hemcrete is a mixture of dried hemp stems and lime that is poured into thick, concrete-like blocks.
Lime Technology

Russ Martin, the former mayor of Ashville, North Carolina, likes to joke that if his house burned down, his neighbors could party hearty. Martin built his 3,400-square-foot-home partly out of hemp [source: CNN]. Martin used Hemcrete to build the walls of his house. Hemcrete, made by British company Lime Technology, mixes dried hemp stems with lime. Workers take the moisture-laden "shiv" and pour it into wall forms. The slurry hardens, creating a thick concrete-like wall with a high insulation value. A 12-inch-thick Hemcrete wall has an R-value of R-28 [source: Wilson].

It cost Martin $133 per square foot to build the first hemp house in the United States, well above the 2009 U.S. average of $83.89 [source: CNN]. And in the South, where he lives, he paid nearly twice the average price of $76.77 per square foot [source: National Home Builders Association]. So Martin is in the minority. But there might be more hemp homes, and the prices would likely go down, if the U.S. government legalized the cultivation of industrial hemp. But the federal government classifies all Cannabis sativa as marijuana, even though industrial hemp has much less THC [source Vantreese].

Since it's still illegal to cultivate hemp, many U.S. suppliers are forced to import industrial hemp products. And the price for importing hemp building materials can be staggering, often making the construction of hemp homes too expensive [source: Building Green]. But other countries are way ahead of the United States when it comes to hemp as an industrial green crop. In Canada, for instance, hemp is the new cash crop. In 2007, Canada exported 862 tons (876 metric tons) of industrial hemp, and 59 percent of that went to the United States [source: Hanson].

Just two years later in 2009, U.S. Congressman Ron Paul introduced The Industrial Hemp Farming Act of 2010 that, if passed, would have allowed commercial farming of industrial hemp, and would have given state legislatures the authority to license and regulate the commercial production of hemp as an agricultural commodity [Hemp.org]. Several states, including North Dakota, Montana and Vermont currently have regulations permitting farming of industrial hemp under state law, but those laws can't be implemented without federal approval.

That 2010 federal bill failed to gain approval, which means hemp still has to imported from countries like Canada and Europe, leaving homeowners interested in greener building materials weighing the eco-benefits of hemp against its higher cost.

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Sources

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  • CNN.com. "House made of hemp." Aug., 25, 2010. (Feb., 2011). http://cnn.com/video/?/video/tech/2010/08/25/dnt.nc.hemp.house.wlos
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  • National Home Builder's Association. "Median and Average Price per Square Foot of Floro Area in New Single-Family Houses Sold by Location." (Feb., 2011).http://www.nahb.org/fileUpload_details.aspx?contentID=80055&fromGSA=1
  • North American Industrial Hemp Council. "Hemp Facts." (Feb., 2011). http://naihc.org/hemp_information/hemp_facts.html#scientific
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