Hempcrete – the Wonder of the Concrete World

Hemp productionWith 10 states having passed laws allowing hemp to be grown in the past year (*1)  for research purposes and 11 more states that introduced hemp bills this year (*2), hemp seems to be making a major coming back from its glory days. And glory days they were.

 

 

 

Some interesting facts about hemp!
Did you now that

– Hemp farming dates as far back as 5000 years in China.
– For thousands of year over 90% of all ships’ sails and ropes were made out of hemp.
– Prior to 1820s, 80% of all textiles, clothes, drapes, fabrics and most paper for schoolbooks were made of hemp.
– During the 17th and 18th century, you could be put in jail if you had land and refused to grow hemp.
– Henry Ford’s first Model-T was designed to run on hemp gasoline and that the car’s body was made of hemp plastic (which was 10 times stronger than steel!).
– It was in fact America’s first cash crop that yielded over a billion dollar, until the 19th century. Hemp rope
– In 1916, the US Government anticipated that by 1940s, all paper would be made out of hemp, ending once and for all the need to cut trees.

So how did this wonder plant manage to disappear but be banned altogether?

It all started under Hoover’s presidency, when Dupont, the chemical tycoon realized that he could not build his chemical empire and grow his powerful financial and business interests as long as this plant continued to be the main cash crop in America. After all, it required no chemical in order to grow and thrive. So financial interests combined with buying political favors resulted in a massive disinformation campaign, associating hemp with marijuana (a Mexican import) and the creation of the Federal Bureau of Narcotics in 1930, followed by the Marijuana Tax Act in 1937 making hemp the “evil weed”!

SO HOW IS HEMPCRETE MADE?
Simply by taking the inside stem of the hemp plant and mix it with a heated lime base binder to create the building material. Sand and pozzolans or cement can also be added. In terms of finishing, all that is needed for hempcrete walls, is either lime or clay plaster for internal surfaces and lime render for external walls. Stone, timber or brick can also be used as finishing. Lime-based paint should also be used.

WHAT IS HEMPCRETE USED FOR?
Uses include drywall, exterior walls, flooring, roofing and more.
– six-inch layer of Hempcrete can be sprayed on external walls and between the ceiling rafters to make the house more energy efficient.
– Hemp is used for wall insulation. But even better, building hempcrete walls do not require any insulation as they form the wall and insulation in one layer.
– It is an ideal material for restoration of old buildings, to repair infill panels and add insulation to uneven aging walls.
– To build hemp drywalls.
–   Hemp bricks are sold under names such as: Hemcrete, Canobiote, Canosmose, and Isochanvre.

WHAT ARE SOME OF BENEFITS OF HEMPCRETE?

It is flame resistant, water-proof, mildew resistant and rot-proof as long as it’s above ground.

Its thermal qualities are amazing, keeping buildings cooler in the summer and warmer in the colder month. And as a result, could reduce our energy bills in homes by half. Think of the possibilities and the impact when buildings are known to be one of the largest source of greenhouse gases in the US!

Hempcrete has great acoustic properties and is known to absorb noise, making quieter homes on busy streets.

Hempcrete is a hygroscopic material. In other words, when used to builld exterior walls, hempcrete will absorb moisture without rotting or damaging the material. It will then naturally release it during warmer and dryer temperatures. This is ideal for hot, cold and humid regions of the world that struggle with mold damage. Hemp puts an end to this problem.

Hempcrete is one of the best material for people suffering from allergies as it contains no formaldehyde, latex, urethanes or VOCs and is known to clean the air and remove toxins.

Do you live in an earthquake prone region? Foundations made with hempcrete provides 3 times more resistance to earthquake than regular concrete! Unlike cement, known for its brittleness, hempcrete combines strength and flexibility.

Hempcrete is extremely strong. When the lime hardens, it eventually turns into rock and petrifies. This means that hempcrete walls will last thousands of years, instead of 40-100 years for regular concrete. They can also be completely recycled in the ground.

MOST ECO-FRIENDLY ALTERNATIVE:   Hempcrete is Carbon negative

As a tall and super fast growing plant (new plants grow in just a few months), the cultivation of hemp removes more carbon dioxide from the atmosphere (due to its very high cellulose content) than the production and application of hempcrete combined! It is estimated that during its growing phase, it can remove over 15 tons of carbon from the atmosphere. A 1,250 sq. ft hemp house could save about 20,000lbs of carbon and only require 2.5 acres of hemp to be cultivated!

Hempcrete uses the woody stem that was previously thought as waste! Being naturally pest resistant and weed suppressant, its cultivation requires no chemical fertilizers and insecticides. Even better, the simple fact of growing hemp will help deterring insects from the area. Because of its deep root system, hemp cultivation is known to break down pour soil.

Since lime doesn’t need to be heated as much as with regular concrete when it is mixed with hemp, the process uses a lot less energy. Made too much hempcrete? Just use as fertilizer.

ARE THERE ANY ISSUES WITH HEMPCRETE?

Learning curve: As with all new technologies, there is a certain learning curve for using hempcrete and hemp building products. The good news is that there is plenty of information online and case studies available. Time will say how building using hempcrete will live up to their promises in different climates over time.

Pricing: Hemp products may be more expensive at the moment but the advantages outweigh the costs in most cases. With a broader adoption, prices will go down and make it the products of choice for all new construction.

Maintenance: Because of its high breathability, hempcrete requires the use of lime based paint which is more expensive (3 coats are required to achieve the right finish).

As our ancestors discovered, hemp offers one of the most renewable resource for construction, it answers every builder and home owner’s needs. It is in fact nature’s gift to humanity and it is time we give it its proper place in our world.

FURTHER READING

  1. Building with hempcrete
  2. Watch a hemp house being built in this video: Bringing it Home  
  3. Hempcrete Could Change The Way We Build Everything

(*1)States that have passed hemp law: California, Colorado, Kentucky, Maine, Montana, North Dakota, Oregon, Vermont, Washington, and West Virginia
(*2)States that introduced hemp law this year: Hawaii, Indiana, Nebraska, New Jersey, New York, Oklahoma, South Carolina, Tennessee.

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