I’ve been aware of the value of what is called “hempcrete,” a mixture of lime and hemp hurds (an agricultural byproduct), for several years. But I’ve never learned much about how to prepare it, partly because industrial hemp cultivation has been illegal in the United States for the last eight decades, since it is related to the type of Cannabis famous as marijuana.

Then a few days ago I was asked to write an endorsement for the cover of a book about to be published by New Society Publishing and written by Chris Magwood, about hempcrete. This is what I wrote:

Chris Magwood has combined his deep understanding of building science with some fortuitous hands-on experience of working with hempcrete to craft this timely and detailed guide to the essentials of hempcrete construction. By simply mixing the lightweight core of hemp stalks (an agricultural byproduct) with lime it is possible to make an insulating material that can handle moisture without decomposing, has good structural qualities and thermal performance, is nontoxic and fire resistant, naturally sequesters carbon, and is ultimately completely recyclable. With the successful use of hempcrete in Europe for over a decade, hopefully this book will help usher in a new era of industrial hemp production in North America.

If you would like to find out more about this obviously useful product, here is a link to very detailed article about it: www.thcint.com and when the book is eventually published I can heartily recommend it.

9 thoughts on “Hempcrete”

  1. Hempcrete is a bio-composite mixture of hemp hurds and lime that can be used in the construction industry to build commercial buildings residential hemp houses. Hemp hurds has a great thermal property which makes them an effective insulating product. The lime which is used in the mixture acts as a binder. And if you are looking for construction services to build your dream hempcrete home or commercial building, Hempcrete Direct can help you.

  2. I haven’t read anything anywhere else about pre treating the hemp. How was this done in history? Can you please expound?

  3. The hemp must first be treated with preservatives or it will decay.

    Compression Strength
    Regular concrete is 3 – 4,000 PSI
    Hempcrete is as high as 6,000 PSI

    I believe that the tensile strength is still being determined by the American Concrete Association. It needs a rating.

    It is also 1/3 lighter than concrete

    There is a company trying to get is rated and they call their product Vericrete. They are using Hibiscus stems which grow 3 times faster than hemp!

    • Thanks for your input. By the way, hibiscus grows almost like a weed — virtually no watering, etc. even in poor soil. Save the flowering tops to make delicious tea that tastes like Red Zinger.

    • hi, i tried searching for vericrete and a way to make concrete from hibiscus stems but i couldn’t find it? can you direct me to a link or resource which speaks about this?

      • They were the first to try to get a rating. That was way back in 2008. I think the ACA dragged their feet because of THC, Marijuana, LAW. I think they just gave up. I copied this from Wiki:

        The typical compressive strength is around 1 MPa,[7] around 5% that of residential grade concrete. It is a low density material and resistant to cracking under movement, thus making it suitable for use in earthquake-prone areas.[8] Hempcrete walls must be used together with a frame of another material that supports the vertical load in building construction, as hempcrete’s density is 15% that of traditional concrete. Studies in the UK indicate that the performance gain between 9” (22cm) and 12”( 30cm) walls is insignificant. Hempcrete walls are fireproof, transmit humidity, resist mould, and have excellent acoustic performance.[10] Limecrete, Ltd. (UK) reports a fire resistance rating of 1 hour per British/EU standards.

        In responding to your query, I found that nothing has been standardized and you would need a special permit to use it. If you find out anything. Let me know.

        Claudia Larson


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