The development of hemp in the United States has been ridiculous, because idiot politicians thought it was the same thing as marijuana (it's not) and banned it back in 1970 as a Schedule 1 drug. In actuality, though hemp is a variety of Cannabis sativa, it has less than a 0.3% concentration of THC, the psychoactive ingredient that you need to get stoned. (Marijuana has a 5%-plus concentration.)
Nowadays, thankfully, open-minded materials scientists and builders have discovered hemp's value as an eco-friendly building material. As host of the UK's Grand Designs TV show for nearly two decades, British designer Kevin McCloud has seen his fair share of building techniques and materials. Here he explains why he finds hemp's benefits unmatchable:
Here is how hempcrete can be integrated into established building methods:
While the video above speaks of using recycled plastic forms, the DIY'er can create their own forms out of plain ol' OSB, and you can also see here how easy the stuff is to mix:
Here's LEED Green Associate Joni Lane giving a TED Talk about how hempcrete is a vastly more healthful building material than the conventional alternatives:
And here's Clarke Snell, former managing director of the Nauhaus Institute explaining how walls made of hempcrete deal with water:
By the bye, in the second-to-last presentation above Lane references the illegality of hemp manufacture in the U.S. Thankfully things have begun to change since then; according to the National Conference of State Legislatures, as of August of last year "at least 16 states have legalized industrial hemp production for commercial purposes and 20 states have passed laws allowing research and pilot programs." Next we have to wait for federal law to catch up; the Industrial Hemp Farming Act of 2015, a bill introduced two years ago, appears to have stalled in Washington.
Our President-Elect has stated he'd like to do away with numerous regulations on businesses. Let's hope that hemp shows up on his radar.