In addition to its many other delightful uses, cannabis can also make for a reliable building material. In Ein Hod, Israel, architectural firm Tav Group has created an "ecological house" using all earth-based materials, including one of the dankest substances around: hemp. The building's walls are made of local stone from the site's excavation material, while the upper floor walls are cast in a concrete alternative called hempcrete, made out of hemp mixed with lime.

The cannabis-based building material is an ecologically responsible alternative to typical concrete, which can cause a variety of environmental troubles, particularly in the toxic process of producing it. Hemp, on the other hand, makes for a groovy and natural construction alternative, and it even offers benefits that traditional concrete can't provide.

What are the benefits of using hemp concrete?

1. Environmental responsibility. The process of manufacturing hemp concrete is earth-friendly, avoiding the toxicity of concrete production.
2. Humidity control. In contrast to traditional concrete, hemp concrete is more porous, allowing for better humidity control.
3. Lowered energy costs. Hemp concrete provides excellent insulation, keeping the building cool even in a hot climate, which translates into lowered energy costs for the homeowner.

Take a look at the beautiful pictures of the house that hemp built below. They're strangely . . . relaxing.

More Details

Hemp Concrete 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. 

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 it 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 negativecarbon 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.More Benefits of Hemp Concrete

• Negative carbon footprint; CO2 sequestration
• Prevents mold; healthy living environment
• Termite and fire resistant; waterproof
• No dry rot when used above ground
• No waste, 100% recyclable, zero land fill
• 7 times stronger than concrete
• 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