This week we will provide an overview of another sustainable building material which, while certainly utilized in ancient times, came into modern use in France in the 1980s, later making its way into America. Hempcrete is a strong, durable material which can be used for as walls upon a wooden structural framework, floors, roofs, and insulation.
What is hempcrete?
Hempcrete is made from mixing the hemp hurd with lime and water. Hemp hurd is the soft, woody, absorbent core of the hemp stalk. When the hemp hurd is mixed with the lime binder, the result is a strong, durable material which can be formed into blocks.
How strong is hempcrete?
The compressive strength of hempcrete is one-twentieth that of concrete. Thus, it can't be used for a foundation or in situations where it may be bearing too great of a load.
What are some attributes of hempcrete?
Hempcrete is resistant to cracking during earthquakes, due to its low density. Hempcrete breathes, that is, it allows moisture to evaporate and doesn't mold. It also doesn't give off any gas, is nontoxic, lightweight and termite-resistant. The lightweight nature of hempcrete also allows for easier transport. It is considered fireproof and non-combustible.
How does it insulate?
Traditionally, homes in the United States use fiberglass insulation. Studies have found that 9 out of ten homes are under-insulated. Improving the insulating capacities of homes is an important step in becoming more energy efficient. Hemp hurd mixed with lime is a promising alternative to traditional insulation. It provides good thermal insulation and thermal mass.
Is it sustainable?
Hemp is easy to cultivate. Hemp can also sequester about 18,000 pounds of carbon per acre during its growth cycle. As opposed to construction process of concrete which give off a lot of carbon dioxide, the utilization of hemp can actually sequester carbon.
Sources:
https://www.buildwithrise.com/stories/building-with-hempcrete
https://www.motherearthnews.com/sustainable-living/green-homes/hempcrete-ze0z1602zbay/