Add hemp fiber to lime and you get a lightweight building material that can be shaped like a cinder block. When fully cured, it floats in water. Buildings up to 10 stories tall have been built from hempcrete in Europe according to Philly.com.
Hempcrete is made using the woody, balsa-like interior of the Cannabis sativa plant (the fiber for textiles comes from the outer portion of the stalk) combined with lime and water. Though it lacks the structural stability its name might suggest, hempcrete does provide natural insulation that is airtight yet breathable and flexible. It is free from toxins, impervious to mold and pests, and virtually fireproof.
Best of all, hempcrete is a sustainable building material because hemp can be grown and replenished relatively quickly. Hemp based building materials could usher in a new era of “green” building products, according to the New York Times.