Apparently hemp, after the fiber has been extracted, petrifies. Mixed with lime like regular concrete, hempcrete is one-sixth the weight of concrete and solves every building-science problem there is, according to this 2013 video—which has the look of all videos claiming the magic properties of something fringe-ish.
The NauHaus Institute has built a carbon-neutral prototype made from hempcrete and claims it’s the “best wall system in the world.” It’s breathable for water and the Institute says it can take on extra humidity without rotting. It’ll last a long time and improves air quality.
Hempcrete walls don’t seem to require flashing and drainage planes. Also, it is carbon sequestering. In other words, any cellulose material (wood, hemp) takes carbon in during its life cycle, and when it decays, it lets the carbon back into the atmosphere. By building with these materials, it keeps the carbon sequestered in the building.
One builder claims that there is no rot and no termites using hempcrete (hemp isn’t the marijuana plant but instead an industrially farmed cousin of that species).
Another builder calls it an incredibly expedient building method with low embodied energy—this video really does use actual building-science terms anyway—and it can even be grown adjacent to the building site—quickly.
But there could be one problem: It doesn’t require any power tools. Rather only “buckets and barrows and blokes.” No power tools? Wait, what?
