Design flexibility - can be used for flooring, roof insulation and walls
50% - 70% energy savings; high thermal insulation
Inherently airtight; breathable walls; low air infiltration: high acoustic performance
Hempcrete® is a mixture of hemp hurds (shives) and lime used as a material for construction and insulation. It is marketed under names like Hempcrete®, Canobiote®, and Canosmose® and is widely available in the UK and Europe. Due to outdated laws, hemp cannot be grown in the United States so this alternative is currently not as cost effective for U.S. builders due to shipping and transport costs.
Like other plant products, the hemp crop absorbs carbon dioxide gas as it grows, retaining the carbon and releasing the oxygen. 165 kg of carbon can be theoretically absorbed and locked up by 1 m3 of Hempcrete® wall during manufacture. This means Hempcrete® actually reduces pollution by pulling carbon out of the air; building material that is exceptionally eco-friendly and goes beyond leaving a "neutral carbon footprint" but actually leaves a negative carbon footprint.
It lacks the brittleness of concrete and consequently does not need expansion joints. A fully cured block of Hempcrete® can float in water yet it is seven times stronger than concrete. Hempcrete® is easier to work with than traditional lime mixes and acts as an insulator and moisture regulator. It is a natural substrate (masonry surface) for plasters and renders (interior and exterior finishes.) The hemp plant is insect resistant and the resulting product of Hempcrete® is also pest resistant, especially and specifically it is termite resistant. In addition, Hempcrete® prevents mold, provides a healthier living environment than chemically processing building materials do and saves money on energy.
The typical compressive strength is around 1 MPa, around 1/20 that of residential grade concrete. Hempcrete® walls must be used together with a frame of another material that supports the vertical load in building construction, as the density is 15% that of traditional concrete. Limecrete, Ltd. (UK) reports a fire resistance rating of 1 hour per British/EU standards. Manufacturers report that the product is 100% recyclable, reducing waste and can even be used for fertilizer once broken down.
From an article on National Hemp Association's website: "One of the recent innovations in the cannabis industry is a Hempcrete® building system by JustBioFiber in Alberta, Canada.
"I was truly impressed: they have devised a building system that solves the problems of making houses out of industrial cannabis (hemp)..."
In visiting the JustBioFiber site, I watched the video directly above. The video at the top of this page shows the building of the first Hempcrete house in the United States and was filmed in 2009. If you watch it, you will note that the method seemed rather slow and laborious...I did. Now, in 2015, JustBioFiber has achieved a new level has in the ease of building with Hempcrete® Lego® style blocks! Hempcrete® is the wave of the future...here now! The more people that know about these amazing new technologies using industrial hemp means the more people to get in the fight against outdated laws against cannabis and industrial hemp in the United States. Get on the band wagon and contact your state and federal representatives! U.S. Senate, U.S. House of Representatives and here is state level contact information.
Graphic at right is an out take from a 2014 Thesis:
"The Potential of Hemp Buildings in Different Climates: A Comparison Between a Common Passive House and the Hempcrete Building System" by Johan Ahlberg, Elza Georges and Mikael Norlén
(click on text or graphic right to view the abstract and download the PDF file; opens in new window.)