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Hemp Insulation Is On the Rise

By Tom Saxton Rise Writer
Jun 12, 2021

It's ironic that what might be one of the oldest examples of human industry, dating back to 8,000 BCE in Ancient Mesopotamia, had to deal with some of the most challenging legal constraints in North America from the 1930s until recently. Hemp has long been utilized in many parts of the globe, from China dating back 6,000 years to Europe and the Middle East. 

In North America, this rich history of hemp use was marred in 1937. The United States levied a tax on hemp under the Marijuana Tax Act, eventually banning hemp production altogether. Canada followed in 1938 with the Opium and Narcotics Act. Some attribute this to confusion with its twin within the same species – often referred to as marijuana. But unlike marijuana, hemp is classified as not having psychoactive properties. Some attribute this confusion to propaganda spread by the petroleum-based synthetic textile industry that viewed natural hemp fibers as a significant threat to their rise to dominance. Canada reversed this ban in 1998, and the United States followed in 2018. Hemp's popularity is booming as people begin to re-learn the unparalleled diversity of uses of hemp, including food, rope, textiles, wood-like panelswood oil, and even building insulation. The European Hemp Association has over 10,000 applications for hemp, which proves why our ancestors came to rely on this dynamic plant throughout history.

Table of Contents

  1. What Is Hemp Insulation?
  2. Are There Concerns Related to the Production of Hemp Insulation?
  3. What is the R-Value of Hemp Insulation?
  4. How Thick Should Hemp Insulation Be?
  5. Where Can You Use Hemp Insulation?
  6. How Long Does Hemp Insulation Last?
  7. Is Hemp Insulation Environmentally Friendly?
  8. Is Hemp Insulation Healthy?
  9. How Much does Hemp Insulation Cost?
  10. How Do You Install Hemp Insulation?
  11. How Do You Remove Hemp Insulation?
  12. How Do You Dispose of Hemp Insulation?
  13. What Brands of Hemp Insulation are Best?
  14. What are the Pros of Hemp Insulation?
  15. What Are The Cons of Hemp Insulation?

What Is Hemp Insulation?

Hemp is first grown and cultivated in a wide variety of climatic conditions. It's a plant with a fast yield, reaching maturity in 90-120 days. Hemp insulation comes in the form of batts made from the inner fibrous layer of the hemp plant. The insulation can be intertwined with flax, polyester, or kenaf fibers that help act as a binder. Hemp insulation is a dense type of batting that's not as flexible as sheep and mineral wool.  Another insulation type made from hemp is hempcrete.

Are There Concerns Related to the Production of Hemp Insulation?

How hemp is grown can be a potential concern. Agriculture methods can vary in their environmental impacts and their ability to regenerate soils or degrade them. Generally, though, hemp requires no pesticides or insecticides. It consumes very little water, which results in a lower environmental footprint to cultivate.

HempWool R-20
HempWool R-20 Insulation. Photo Credit: Hempitecture

What is the R-Value of Hemp Insulation?

Hemp insulation is often rated at an R-value of 3.5 per inch. The brand, Hempitecture, claims their bats are R-3.7 per inch. You might think that's low compared to polyiso and XPS rigid foam insulation or even spray foam insulation. But these foams lose significant R-value over time, while hemp stays at R-3.5 for its entire service life while also improving the wall assembly's resilience to moisture damage.

How Thick Should Hemp Insulation Be?

You can install hemp insulation in any thickness you need. The batt sizes come standard to fit 2x4 and 2x6 wall cavities for 16 or 24" stud centers. Typical thicknesses available include 3.5, 5.5, and 8 inches. You can stack these on each other if you want to go even thicker.

Where Can You Use Hemp Insulation?

Hemp insulation can be used in building systems from inner walls, exterior walls, ceilings, and attics. Its higher density allows it to be used as external wall insulation before siding installation. Hemp insulation is not a load-bearing product, so use it accordingly in floor insulation applications. Its vapor permeability is key to its wide array of uses in wall assemblies and adaptability to every type of environment.

HempWool R-13
HempWool R-13 Insulation. Photo Credit: Hempitecture

How Long Does Hemp Insulation Last?

Hemp insulation is a durable and resilient product that can last the life of the building.

Is Hemp Insulation Environmentally Friendly?

Hemp's long history is a testament to its sustainability potential. Hemp's lifecycle is very supportive of a planet-friendly status. It's a renewable resource that builds soil and supports a diversity of life within the earth if grown sustainably. Resilient performance during its long lifespan allows it to be used in a wide array of building systems. At the end of its life, it can, and should, be re-used for another application, recycled, or composted, and allowed to decompose back into the soil.

Hemp Insulation

Is Hemp Insulation Healthy?

Hemp insulation is non-toxic. It is a plant-based product that contains no VOCs, no chemical binders, and does not off-gas. Hemp insulation is hypoallergenic, repellent to mold, pests, and insects. Compare this to petroleum-based foams that can off-gas or itchy and messy fiberglass insulation.

HempWool R-7
HempWool R-7 Insulation. Photo Credit: Hempitecture

How Much does Hemp Insulation Cost?

The cost is usually dependent on the size of the batt. $1.35 to $3.10 per square foot is the current estimated price range.

Installing Hemp Insulation

How Do You Install Hemp Insulation?

Hemp insulation is a DIY-friendly installation material. Since its non-toxic, the necessary PPE is minimal, and it does not itch as fiberglass batting can.

Hemp insulation is very dense. You can't just cut it with a utility knife; use a miter saw, circular table, or hand saw to cut it. When you measure, it's better to measure long than short – add ½" to cavity measurement for a snug, friction fit.

You can use insulation hangers or even rope to keep it supported between the framing members before panel installation for overhangs. If you want to stick with the theme, choose hemp twine for this purpose!

How Do You Remove Hemp Insulation?

Hemp insulation is straightforward to remove after you remove the interior paneling, typically drywall. Even though it's completely non-toxic, it's still recommended to wear essential PPE such as long sleeves, safety glasses, and a dust mask. This step isn't really for the hemp insulation, but for whatever other building material dust could be lurking in an old wall cavity.

Cutting Hemp Insulation

How Do You Dispose of Hemp Insulation?

Don't disrespect the very nature of hemp itself and send this natural material to a landfill! Recycle it or compost it. You can even use it as a vegetation barrier or weed block in your yard or garden, where it will eventually become plant fertilizer as it breaks down. Or you could think of another innovative use of which there are endless options. Hemp deserves to be returned to where it started its life - in the soil, amongst an incredible diversity of microbes, bacteria, and fungi to return to the earth and feed the next generation of lifeforms.

What Brands of Hemp Insulation are Best?

  1. Hempitecture - An exciting company based in Ketchum, Idaho, offers a quality hemp batt.
  2. MEM Inc. - Based in Montreal, Canada, MEM Inc. is among the first companies in North America to produce hemp insulation commercially.
  3. Nature Fibres - Based in Asbestos, Quebec, Canada, Nature Fibres offers batt insulation. This business is a success story of a sustainable product that replaced the toxic asbestos production that the town once relied on.

If possible, source your hemp insulation from the closest manufacturer to reduce the transportation energy footprint.

What are the Pros of Hemp Insulation?

There are so many benefits that it's necessary to form a list. And, don't be fooled to think the list ends here! 

  • Hemp plants are relatively easy to grow and harvest in various climates with a fast yield, typically reaching maturity in 90-120 days. Its ability to be grown in many locations can reduce its transportation footprint.
  • Hemp requires very little water to grow and is grown successfully without pesticides and insecticides.
  • The rapidly growing hemp plant acts as a sponge for CO2 during the growth cycle.
  • It's a rapidly renewable material, recyclable and compostable.
  • It's plant-based, without VOCs or chemical binders. It is non-toxic and doesn't off-gas. 
  • Biobased products like hemp have been proven to improve interior air quality by binding and trapping air pollutants.
  • Hemp insulation is resistant to insects, bacteria, mold, and fungi.
  • It is hypoallergenic.
  • Minimal PPE is required for installation.
  • Hemp has a high fire-resistance rating due to its high silica content.
  • It is vapor permeable. It can allow moisture to pass through it, which is an essential element in every type of wall assembly. Depending on the climate, hemp insulation can be placed in various locations within the wall assembly, from interior to exterior. This adaptability is an integral part of home resiliency.
  • It has good sound deadening properties.
  • Hemp insulation smells great, similar scent to fresh-cut grass.

What Are The Cons of Hemp Insulation?

The biggest drawback to hemp insulation is its current lack of availability. It's not yet widely available locally across North America. As a result, it has a higher cost than other types of insulation. But, Rise is working to help with this problem and help it find a home in more North American households - HempWool from Hempitecture is now available on the Rise Store!

It is still more expensive than mineral wool but is cheaper than sheep's wool. While its long-term performance is promising, its R-value is slightly lower than mineral wool or blown-in sheep's wool insulation.

Nature Fibres Hemp Insulation
Nature Fibres Hemp Insulation. Photo Credit: Nature Fibres Inc

There have been few other plants in history with such a wide array of practical uses that have undergone such limiting legal constraints as industrial hemp. Hemp is an exciting material with so many uses it's almost comical. As building insulation, it rivals its alternatives in overall long-term performance, while it remains at the top of the list in the realm of sustainability. It is just a matter of time before this insulation type is widely available across North America.

Hemp is an excellent example of how sometimes the most novel and exciting building material can be something we discover by looking to the past and learning what our species has been using for millennia. Our ancestors survived; it's wise to learn from them. There are many functional reasons the use of hemp has stood the demanding test of time and has been repeatedly passed down through generations - let's continue the tradition.

Disclaimer: This article does not constitute a product endorsement however Rise does reserve the right to recommend relevant products based on the articles content to provide a more comprehensive experience for the reader.Last Modified: 2022-02-24T12:55:22+0000
Tom Saxton

Article by:

Tom Saxton

Based in Washington State, Tom's education focuses on holistic land management that sustainably grows renewable building materials in a way that replenishes natural systems. His interest is in building systems that combine old techniques and modern science.