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How hemp is used as a building material?

How hemp is used as a building material?

Hemp is a particular strain of Cannabis sativa, generally cultivated for industrial use. Unlike its other varieties that are cultivated for marijuana, Cannabis sativa has a very low THC concentration (approximately 0.3 percent), and high concentrations of cannabidiol (CBD). The low concentration of THC makes it an impotent consumable.

A hemp plant can mature in just a few months – requiring less fertilizer than other cash crops like corn, and negative requirements of bug sprays (hemp is highly bug resistant) and chemical fertilizers, thereby, has a huge potential for profit. Unlike consumable hemp, Cannabis Sativa requires a big cultivation area, as they have long roots which are space demanding. The long roots circulate air and improve soil quality- creating yet another advantage for farmers interested in crop rotation.

With many governments declaring the cultivation of industrial hemp, legal, many cultivators have come forward in harnessing its industrial potential. Some of the inventors have come up with ways to convert hemp fiber into stationery like paper, commodities like biodegradable plastics, paint, biofuel, and construction materials like wood, building blocks, and flooring materials.

Hemp produces two different kinds of fiber – the fine bast, and the woody hurds of the inner stem. The fine bast is used to manufacture paper and fabric; the strong woody hurds, also dubbed shives, are sturdy, so are utilized as construction materials.

Hemp has been around for a long time and has been well acknowledged for its durability and supremacy over other commonly used building materials. Recently, a hemp-filled mortar was discovered in a 6th-century bridge connector, in France. Tailing that discovery, contemporary French restorationists formulated a hemp-lime mixture which has been proposed to be employed to replace daub and wattle in restoration projects of medieval timber-framed buildings.

The newly formulated construction materials have shown promising potential as an excellent replacement for Portland cement, which comes with drawbacks like low breathability and is highly prone to moisture accumulation.

In recent times, the most well-recognized hemp-based building materials have been hempcrete and hemp wood.

Hempcrete:

Hempcrete, also known as hemp-lime is bio-composite material, a mixture of lime and hemp hurds (shives). Hemp shives have high contents of silica, which makes them an excellent binding agent.

Hempcrete is also marketed as Canobiote, Isochanvre, and Canosmose.

Hemp shives, when incorporated as a building material (in combination with lime), undergo processing, where the leaves, bast fibers, and seeds are removed by breaking it up into small pieces and the remnants (dust and fiber) are disposed of. The hemp shives should ideally be containing a minimum of fines (small pieces of bast fiber), should be dry, and should be as clean as possible.

Hempcrete has many advantages over conventional lime mixes, and also serves as an insulator. It is not brittle like concrete, thus, it lacks the need for expansion joints, and serves as a flimsy insulating material suitable for many climates. Its adaptability makes it more expensive than traditional building materials, especially if it’s imported, but the long-term return on investment is worth it. Additionally, hempcrete is also resistant to mold and fire.

Marc Faber, builder at a Canadian hempcrete company declared:

“We heat [our material] up to over 1,500 degrees Fahrenheit and it barely has an impact. Very unlikely for this house to catch fire,”

Similar to other plant-based products, hemp absorbs ample CO2 from the atmosphere and retains the carbon while releasing oxygen. Theoretically, 165 kg of carbon can be absorbed and retained by a 1 m3 of hempcrete wall during manufacture.

In the United States, there are currently around 50 homes made from hemp products, in the state of Texas, North Carolina, Virginia, and Hawaii.

Hemp-made houses and commercial buildings can be found in abundance in Canada and Europe, including an eco-house built by Prince Charles.

Hempcrete, also known as hemp-lime is bio-composite material, a mixture of lime and hemp hurds (shives). Hemp shives have high contents of silica, which makes them an excellent binding agent.

Hempcrete is also marketed as Canobiote, Isochanvre, and Canosmose.

Hemp shives, when incorporated as a building material (in combination with lime), undergo processing, where the leaves, bast fibers, and seeds are removed by breaking it up into small pieces and the remnants (dust and fiber) are disposed of. The hemp shives should ideally be containing a minimum of fines (small pieces of bast fiber), should be dry, and should be as clean as possible.

Hempcrete has many advantages over conventional lime mixes, and also serves as an insulator. It is not brittle like concrete, thus, it lacks the need for expansion joints, and serves as a flimsy insulating material suitable for many climates. Its adaptability makes it more expensive than traditional building materials, especially if it’s imported, but the long-term return on investment is worth it. Additionally, hempcrete is also resistant to mold and fire.

Marc Faber, builder at a Canadian hempcrete company declared:

“We heat [our material] up to over 1,500 degrees Fahrenheit and it barely has an impact. Very unlikely for this house to catch fire,”

Similar to other plant-based products, hemp absorbs ample CO2 from the atmosphere and retains the carbon while releasing oxygen. Theoretically, 165 kg of carbon can be absorbed and retained by a 1 m3 of hempcrete wall during manufacture.

In the United States, there are currently around 50 homes made from hemp products, in the state of Texas, North Carolina, Virginia, and Hawaii.

Hemp-made houses and commercial buildings can be found in abundance in Canada and Europe, including an eco-house built by Prince Charles.

Hemp Wood:

Hemp Wood is an impressive example of hemp’s versatility. It was pioneered as a sustainable alternative to hardwoods like oak.

It is very justifiable a choice as a flooring material, for interior face construction, the production of furniture, and the making of consumer products such as skateboards and cutting boards.

The Hemp wood engineers, for 10 long years, have studied, experimented, and improved the hemp wood board which would be made available to consumers by the end of this year.

Hemp wood was the result of the engineering experiment, that deployed an algorithm of an oak tree and then reverse-engineered the tree’s growth cycle to replicate its density, stability, and hardness. The long fibers of hemp added more durability to the product by making it sturdier and lighter than conventional wood products.

Reports have revealed, hemp wood to be 20 percent harder than oak wood. It has a density of 50-55 pounds per cubic foot, and its hardness, on the Jenka scale, is more than 2,000 so its stability, similar to the Brazilian Cherry, is unparalleled.

Industrial hemp has a growth rate that is 100 times speedier than that of an oak tree, and it is also harvestable within a very short time (120 days from seed plantation). The fast growth rate and the short harvest cycle make it an easily renewable building material, and an excellent cash crop.

It is also a very potent candidate in the save-trees campaigns; only 1 acre of hemp can generate the cellulose-fiber-pulp equivalent to the amount of pulp generated by 4 acres of trees, making it a piece of great news for the surviving trees on our planet, endangered by deforestation.

As per reports, Hemp Wood flooring will be available from 2020, with “tongue-in-groove” boards’  prices cited as follows:

$5/ft2: 1 x 6 x 48/72” solid no coating

$6/ft2: ¾ x 5 x 48/72” solid coated

$7/ft2: ¾ x 5 x 48/72” solid stained and coated

Hemp wood would also be available in the form of blocks, and boards for doors.

The organic roots and soy-based cohesive found in hemp wood make it VOC-free, which presents it as a healthier alternative in interior building.

With hemp wood, larger and customizable lumbers than Oak and other timber species can be produced.

Hemp Fiber or Batt Insulation:

Hemp fiber is bound into sheets that can be cut into a variety of shapes and sizes and installed as semi-rigid “batts” in-between structural frames substituting fiberglass and other generally used insulating materials. Hemp fiber insulation has a higher R-Value, which makes its performance superior.

Hemp Oil Wood Finish:

Hemp oil is produced from hemp seeds; the seeds are pressed to produce versatile, durable, and easy-to-use wood coatings.

Product reviews have indicated that hemp-oil-based wood coatings have outperformed the best available commercial products in the context of weathering resistance and the percentage of VOC contains. It has been observed to be a superior alternative to petroleum and synthetic-based polymer coatings.

Despite the difficulties faced by industrial hemp has come a long way in becoming one of the most rapidly adaptive building materials of its time.

China has grown to be one of the largest exporters of hemp products in the world while, Great Britain has taken to offering government subsidies to cultivate these cash crops, and the U.S. in 2018, introduced an amendment to the Farm Bill, which has legalized the cultivation of agricultural hemp, adding fuel to it’s burning popularity in the global market.

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