Hemp Sweet Home: Learning to Build a Greener Future

“It smells like earth!”

These words came from a masked man, gloved hands nearly elbow deep in a big tub of moistened chopped hurd—the soft inner core of the hemp plant stem. Surrounding him were about 20 others, students at a workshop about the wonders of hempcrete, equally immersed in the mixtures coming together in their tubs. The final product made from a simple combination of hurd, water and powdered limestone is far greater than the sum of its individual parts, as hempcrete provides a durable, economic, eco-friendly building material with a plethora of built-in benefits.

Workshop instructors, internationally known hemp experts Anndrea Hermann and Joy Beckerman of Hemp Technologies, know that the best way to show students just how easy this versatile building material is to work with is to let them actually experience the process of making it. After all, if a group of newbies can make hempcrete blocks in the community room of the Santa Monica public library, imagine how easy using hempcrete will be at an actual construction site.

Which is not to say that building with hempcrete does not come with its own unique challenges. 

It does, starting with the legal and permitting issues that can accompany using material that city officials and building inspectors do not always understand.

“It’s all about education,” Beckerman said.  “And every time a hemp home project is completed, it gets easier for the next person to build theirs, as they have another project to reference.”

One solution to bypass all the red tape is to build in countries without building restrictions, such as Mexico, but Hemp Technologies has worked on a number of successful builds in the U.S. and is eagerly anticipating its newest project in Northern California this year.

Aside from permitting issues, Hermann and Beckerman are also quick to point out that hempcrete will not be the best choice for all builders in all situations. One of the challenges they face in their consulting business is people with “hemp blinders”—those so devoted to the cause that they often overlook practicalities.

Hempcrete: Not What You Think But Still Awesome!

The term "hempcrete" itself is somewhat misleading as it can’t truly be though of as a substitute for concrete in all instances. "Hemp fill" would be a more accurate description, since the material is used to essentially plaster over both sides of a wooden frame, although it can also be used in floors and roofs with the addition of some concrete, which is not necessary for walls.

One of the biggest drawbacks of hempcrete is its inability to bear structural load. Even when it comes to decoration, hempcrete walls can only support about 30 pounds.

Hempcrete is not suitable for anything underground, and it must have a breathable surface on both sides. That’s not a problem when left it its natural state, but those who prefer smooth walls that resemble conventional housing can get around the problem by covering hempcrete surfaces with limestone plaster, or using magnesium oxide boards as a drywall replacement that also function as hempcrete building forms that remain in place after the build is complete.

Judging by sheer visual appearance, you would think that a block of hempcrete would weigh a ton and have a dense texture. In actuality, it is quite lightweight. Students in class are instructed to gently tamp down the edges of the hempcrete blocks, just as hempcrete builders would tamp around the edges of the hempcrete building molds, while leaving the center portions “fluffy.” 

Those who like the aesthetics of natural rough hempcrete will find an adaptable material. Want a specific color for your walls? Just add pigment to the hempcrete mixture for a rainbow of choices. Want to play with sculptural elements? You can easily imbed windows or even recycled materials like glass bottles, right into the structure. Even mistakes and repairs are simple, just slather on more hempcrete.

Benefits For All

Once you understand the limitations of hempcrete, you’ll be astounded by all the things it can do.

Those considering building with hempcrete will find it affordable, about $150.00 a square foot, not including land and ground works costs. You can also expect to save about 28 percent on the lumber costs of framing a traditional home. You won’t need a lot of big heavy-duty equipment either—a paddle mixer is about it. According to Hemp Technologies master builder Greg Flavall, who Skyped into the workshop from New Zealand to answer technical questions, those on a shoestring could build a hempcrete house with little more than “buckets, barrels and blokes.” 

You can expect your hempcrete house to last generations, as hempcrete gets stronger with age. While the hemp portion of hempcrete gets all the press, Hermann and Beckerman say it’s the lime part of the equation that contains the real magic. That’s because over time, the lime “mineralizes” all the cellulose in both the hemp hurd and the house’s wood frame, meaning a hemp house will eventually become a petrified rock!

These ancient dwellings in Ellora, India have been standing for thousands of years due to petrified hemp plaster.

Building with hempcrete can even save you money on health costs! Traditional building materials made from toxic chemicals account for many illnesses and increased medical bills, but all natural hempcrete is completely non-toxic. Hermann spoke of documented evidence from Europe—where they have been building with hempcrete for over 30 years—of a 50 percent drop in employee sick leave and absenteeism.

Economic savings continue even after the hemp house is built. Super insulating, energy efficient hempcrete reduces, and in some cases eliminates, the need for mechanical heating and cooling. It’s also non-combustible, which not only takes away stress, especially when building in high fire zones, it can also result in insurance premium reductions.

We frequently hear the phrase “hemp can heal the planet.” Hermann and Beckerman say this is giving the plant a little too much credit, but it can definitely help, and a hemp home leaves the planet in far better shape than a traditional home. In fact, depending on where you source the hemp and limestone from, hemp homes can actually leave a carbon negative footprint.

For quality control purposes, Hemp Technologies currently sources their hemp hurd from the Netherlands and their lime from France, making them at least carbon neutral. As the U.S. hemp industry expands, they are hoping to eventually be able to source closer to home, and part of the class included ways that grassroots hemp activists can help the cause.

The students who attended the workshop came for a variety of reasons, but they all shared a common belief in the need for sustainable living practices and a strong interest in what hemp can do for the environment. Many were builders and contractors or had some sort of background in construction. Some were real estate developers learning to renovate and flip houses in a more environmentally sound manner. A few were architectural students getting in on the ground floor of what is sure to be the future. 

Some of students were there to check out what hempcrete could offer for a home or small project, while others had grand plans. One couple hopes to build an eco-friendly resort in Mexico, while another ambitious student had plans to develop a hemp inn near Lake Tahoe where people could experience staying in a hemp structure while learning about sustainable and off-the-grid living. A few of the students came based on nothing but curiosity.

Throughout the class, the instructors impressed not only with their passion for the subject but with their array of hemp knowledge that spanned everything from the agricultural to the legal, along with all of hemp’s many practical applications. 

With so much to offer both the individual and the world at large, and as Beckerman said, “Hemp is a no-brainer!”

(Photos by Mitch Mandell)