Benefits of Hempcrete

The Incredible Benefits of Hempcrete


As a society, we are becoming more aware and conscious of the world in which we live and the impact we can make (both negatively and positively) on our environment. The adoption of green construction is growing in popularity to help reduce carbon emissions.

One such method involves building with hemp plants, which has become known as hempcrete.  The resurgence of the hemp industry has opened doors to create innovative ways of building environmentally friendly homes. Additionally, it is extremely cost-effective and one of the best ways to insulate houses and buildings throughout the year.

Hempcrete is a mixture of hemp hurds, lime binder and water.  Hemp holds a high silica content that helps it to bind well with lime. The end result is a lightweight, cementitious and insulating material which weighs only one-eighth to that of concrete. Most importantly, it is able to absorb and store large amounts of carbon dioxide gas, making it a carbon-reducing option.

Know These Facts About Hempcrete

A hempcrete block visualized that also lists allt he facts and benefits of building with hempcrete

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Here are some amazing hempcrete facts that demonstrate its remarkable properties as a building material.

  1. A hempcrete wall of 1m3 can absorb and lock 165 kg of carbon during manufacture. The typical comprehensive strength of a hempcrete wall is around 1 MPa which is around 1/20 that of residential grade concrete.
  2. It acts as a moisture regulator as well as an insulator. It also lacks the brittleness of concrete, so it doesn’t require any expansion joints.
  3. It is non-flammable
  4. It is a non-structural material and is cast around a timber, steel or concrete frame.
  5. It is a bio-composite and cement-like material weighing about 8 times lighter than concrete.
  6. It is earthquake-proof and is 3 times more resistant than regular concrete
  7. It is water-proof and a 100% recyclable material. It is also biodegradable and can be used as a fertilizer once demolished.


Advantages Of Using Hempcrete

Other than being an organic material for construction, hempcrete also has many additional advantages that make it a perfect alternative to traditional means of construction.

1. Hempcrete Sequesters Carbon

A diagram that depicts how hempcrete sequesters carbon

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One of the major advantages of using hempcrete as a building material is that it is “carbon-negative”. A study done in 2003 found that 716.6 pounds of CO2 are stored in 1 ton of dried hemp.

During the process of photosynthesis, the hemp plant absorbs CO2 from the atmosphere during the day (like other plants) and converts the carbon to biomass while exhaling oxygen in the air. When hempcrete is used in construction, the carbon in the plant gets locked away and gives durability to the building. A U.K. construction firm cites a study stating that their hempcrete can sequester 110kgs of Co2 for 1m3 of lime-hemp.

2. Excellent Insulating And Resistant Material

A diagram that depicts how hempcrete is used for wall insulation

Hemp hurds (like other plant fiber insulation materials) can store a great amount of moisture. This is known as its thermal mass property, making it a great source of insulation.

According to Professor Tom Wooley from Rachel Bevan Architects, “The thermal mass properties of the material mean it retains the warmth within the fabric of the building, to a temperature (without heating being used) of around 14-15º – a temperature which is ideal for the food and wine storage industry which is why some have latched on to using hempcrete for their warehouses.”

The hemp hurd has a porous structure. Moisture gets accumulated on the internal surface area of the plant fiber and is absorbed in its cellulose structure. This property makes hemp hurds very potent in absorbing moisture when it exists and releasing moisture when there is a need for it.

Hempcrete’s resistance comes from the properties of the lime binder. Lime is said to have a high pH and is naturally antifungal and antimicrobial. Thus a mix of a lime binder with hemp hurds creates a surface that is resistant to molds, insects and fungus (even when the temperature and humidity allow molds to occur on other insulation materials). This resilience makes hempcrete a unique and desirable material in both hot and cold climates.


3. Hempcrete is Very Strong

Hempcrete is a low-density material that makes it resistant to cracks on movement. The traditional concrete used to build houses produce large cracks during movement which are not able to fill themselves. Hempcrete, on the other hand, produces micro-cracks under movement which bind themselves when moisture comes in contact with free lime.Therefore, it can be considered as an effective material to be used in earthquake-prone areas.

4. Non-Toxic Material

Hempcrete is a mild, eco-friendly material which does not require toxic materials for its growth. Typically, no pesticides, herbicides or chemical fertilizers are used to grow this crop. Furthemore, the harvesting and processing  of hemp takes place without the use of any heat or chemicals.

Once placed in walls and fully dry, the material does not release any toxins.