You’ve probably heard of industrial hemp. Chances are it was in relation to CBD, one of the cannabinoids that is derived from this cannabis family member, known for its copious therapeutic effects. But did you know that hemp can be used (brilliantly, some might say) as building materials? Houses are being made from hemp. In fact, there are currently dozens of houses in the U.S. that were built from hemp materials. The one featured in the photo above is a Hemp House in Maui. Source: American Lime Technology (Builder: George Rixey, Rixey Co.; Photographer: Travis Rowan, Living Maui Media)
Wood, concrete, insulation, chipboard, plaster, and deck stains are all materials that can be made from hemp.
And why is this a thing?
Hemp grows fast and easy, and it’s safe and eco-friendly—as a crop and in all it’s various product forms. And once it doesn’t have to be imported—when U.S. farmers are growing hemp for building materials on home soil—it will be cost-effective for growers, builders, and homeowners alike.
Read on to learn some fascinating facts about hemp in the world of construction and engineering. But first, a little refresher on …
What is Hemp?
Industrial hemp refers to the non-intoxicating (containing .3% THC or less) varieties of Cannabis Sativa L. And it just may be the miracle plant that addresses our emerging health and global sustainability issues. Did you know that over 25,000 products can be made from hemp for modern uses? Check out this article and chart to get an idea of just how versatile the hemp plant is and what it has to offer—that we know of, so far!
Hemp flowers are the part of the plant used the most in producing CBD and other cannabinoids. In its considerable usefulness beyond the medicinal, we turn to different parts of the hemp plant.
Industrial hemp produces two different kinds of fiber: the fine bast, which is used to make products like paper and clothing, and the woody hurds of the inner stem.
When it comes to construction, the hurds are the part of hemp stalk that is strong enough to build with. Additionally, the outer fibrous skin can be used for materials like insulation, and hemp seed oil can be used for treating wood.
Hemp as an Agricultural Commodity
According to a 2018 congressional research report, more than 30 nations grow hemp as an agricultural commodity. They can trade that commodity on the world market. Currently, there is no large-scale commercial production of hemp in the U.S., although it is under way thanks to the 2014 and 2018 Farm Bills.
The world’s population and disposable income are projected to increase dramatically, and, therefore, demand for consumer goods will follow. And yet, we currently do not have the resources to sustain such a demand.
In this article, we’ll look at some of the truly remarkable ways industrial hemp and the materials that can be made from it are changing how we build. With some stunning already-existing hemp houses, you’ll have to see to believe.
Hempcrete is one of the most amazing building products made from the industrial hemp plant. It simply consists of hemp hurds (the core of the stalks), water, and lime. This mixture produces a rigid material that is cast into thermal walls or bricks that are used between or around structural supports.
Cured and finished hempcrete walls have low toxicity and breathe well, while maintaining a high degree of air tightness and good thermal insulation. Hempcrete is also a good insulator against noise.
Using hempcrete is environmentally advantageous. Today we build with materials that are either mined from the earth or harvested from centuries-old forests. Industrial hemp can be grown over and over again, every year. One acre of hemp provides as much paper as 4.1 acres of trees.
Some other advantages of hempcrete include:
- It’s non-toxic
- There’s no off-gassing with hempcrete (Off–gassing (also known as out-gassing) refers to the release of airborne particulates or chemicals—volatile organic compounds (VOCs)—from common household products.)
- It’s solvent-free
- It’s mold resistant
- It has a high vapor permeability
- It controls humidity
- It’s durable
- It’s fire and pest resistance
- It passively self-regulates temperature and humidity
- It’s a great insulator
HempWood is the recent brainchild of Greg Wilson, who owns a Tasmania-based company, SmartOak, that makes “engineered wood”. Wilson, started experimenting with hemp as wood in the U.S. after the 2014 Farm Bill made it possible for him to get his hands on it.
Wilson’s process is to make a fast-growing, eco-friendly plant like hemp denser than oak. This involves adding adhesives to fill the voids of the cell structure in hemp, in order to increase its density. The result is 20% denser than oak.
But here’s what makes it ecologically and economically brilliant: a hemp crop takes 4-6 months to mature; an oak takes 60 years. Okay, mind blown!
A Little Hemp Construction History
Our era is not the first to mix hemp with lime and use it like concrete or plaster. In accent China, hemp was mixed with lime and tung oil and used as caulking on sailing vessels. Hemp’s ability to control moisture made it ideal for the sailing industry.
It’s also been discovered that hemp mortar was used for construction in 6th century France. It was used to reinforce abutments in the Merovingian bridges.
More Hemp Building Materials
Once you start looking, it seems there’s nothing that can’t be made from the hemp plant, which, given its quick growth period and plethora of eco-friendly properties, really begs the question: Why was this non-intoxicating crop ever prohibited in the U.S?
Here are a few more ways hemp contributes to the building process:
Hemp Fiber for Batt Insulation
Hemp fiber is made into sheets that can be cut into a variety of sizes, and then installed as semi-rigid “batts” between structural framing. It’s a welcome alternative to fiberglass and other conventional insulation materials. Hemp fiber insulation also exhibits higher insulation performance.
Hemp Particleboard or Chipboard
Hemp mixed with other fibers such as flax can be pressed into particleboard (also known as chipboard) to create a lighter, stronger and more moisture resistant alternative to its conventional counterpart.
Over the life of the product, the material in standard chipboard will often off-gas, due to the formaldehyde-based adhesives that hold it together.
That makes hemp-based particleboard a safer product that will also play a part in forest conservation.
Deck Stain and Wood Finish
Oil can be pressed from hemp seeds and processed to make an easy-to-apply coating that is both durable and attractive.
According to the product test results, hemp oil-based deck stain can outshine even the best commercial products in the weather-resistant category.
What’s the cherry on top? It contains very low levels of toxic VOCs (volatile organic compounds), making it the perfect alternative to synthetic and petroleum-based polymer coatings.
Apply your hempcrete more thinly, and you have hemp-based plaster. It can be applied as an added insulation or sound-deadening coat to existing walls and can be applied more thickly than conventional lime plasters.
Hemp plaster has an impressive resiliency. In one instance, it has preserved historical caves in India that have been exposed to the elements for 1,500 years.
Modern Architecture Using Hemp
Check out this video from nearly a decade ago that shows how beautifully hemp building materials can be integrated into construction.
The Nature’s Breakthrough educational resource is just one of the ways The Hemp Haus practices its sincere commitment to and passion for educating people about CBD and helping them find the right, high-quality product based on their needs.