A house made of hemp might sound like a hippie idea from the 70ies, but is actually a concept that can build our sustainable future.
In fact, it isn’t as recent and contemporary as it might appear.
The use of hemp as a building material dates back to ancient times. The most famous site is probably a hemp mortar bridge in France from the 6th century, but it’s a lesser known fact that the famous Colosseum had sunscreen awnings made from cotton, flax, and hemp.
In modern times, it was reinvented in France in the late 20th century, when a new technique of using hempcrete was introduced.
In the US, the first hemp house was built in Nashville, North Carolina, in 2010.
The Americans have caught up very quickly, and it’s not unlikely that this is where the hemp building sector will scale up to become a hey material in the future of building, and, in many ways, the material that can build our future.
What Is a Hemp House?
As its name implies, a hemp house is a building made of hemp.
The building sector uses a material known as hempcrete, which is essentially a mix of hemp hurd (the woody essence of the hemp plant), hydraulic lime, and water.
The end result is a natural composite (shiv) that’s put into timber frames afterwards and packed tightly together manually using special tools.
Hempcrete can’t be used to construct the entire house. This is because it isn’t suitable for load-bearing walls, and the foundation structure has to be made out of timber and steel. Nevertheless, everything else can be made out of this biomaterial.
The other option is to use hemp blocks, which are basically prefabricated building blocks. Although they sound more practical, architects are using timber-framed structures more often, probably because it’s a building method backed with more research.
But, this quick explanation of the building process doesn’t begin to explain what a hemp home is.
If we were to put all of its benefits into a single sentence, it would state that hemp is a more sustainable way of building homes, produces a healthier environment to live in, and provides a more energy-efficient option to manage your costs.
Sustainable Future: Carbon Negative Footprint
Among the amazing stats behind hempcrete, is the one that promises genuine awe: the material has the ability to absorb and lock in carbon dioxide, thus reducing our negative impact on the atmosphere.
One cubic meter of hempcrete wall can hold up to 30 kilograms of carbon. That’s 4 times more carbon than trees can process.
On the other hand, cement production alone is responsible for 5% of the entire carbon emission on the planet. Not to mention the energy consumed for the heavy machinery used by the building sector.
The majority of the hemp house making labor is done by human hands and wooden tools that don’t use electricity. With the exception of the motor mixer needed to make hempcrete, the building process doesn’t require any energy-consuming methods.
The eco-friendliness of the process of making a home with your own two hands and the carbon negative footprint that can be left on the planet can make hemp houses an alternative that’s destined to provide future solutions.
They’re also the way the green industry could redeem itself for not being so “green” after all.
Health: A Green Answer to Sick Building Syndrome
According to an EPA report, we spend almost 90% of our time indoors. At the same time, the report notes that “the indoor concentrations of some pollutants have increased in recent decades, due to energy-efficient building construction and increased use of synthetic building materials.” In plain words, sick building syndrome is a real thing.
If we twist our perspective for a moment, our home can start resembling heavy loaded machinery for producing various intoxicants. Listen to Joni Lane for a moment to get a better idea of this concept.
In contrast, hemp houses are often described as breathable structures that provide natural sound and thermal insulation, humidity regulation, and effective protection from the elements.
As an illustration, one cubic meter of hempcrete wall can absorb up to 14 liters of water, which is then released to the ground. This translates to optimal humidity that prevents any mold.
Also, the amazing breathable insulation properties of hemp means that it absorbs and stores any excess heat, which is then slowly brought back indoors.
Essentially, walls made of hemp even out any temperature fluctuations and ensure that the inside is cooled during summer, and heated in the wintertime. In addition, hempcrete is known to be resistant to pests, mold, and insects.
Another famous illustration are the hemp panels of the British Science Museum that are used in an artifact storage unit because the material provides superior control of the environment.
And if we add to the equation that a construction site which uses hemp building material doesn’t require any hazardous protection and that people building a hemp house aren’t exposed to any contaminants, the result is yet another defining benefit of hemp houses: they are a healthier way to build your indoors.
Since hempcrete appears lightweight, some people are concerned about its durability. Yet the concern isn’t necessary. In fact, it can hold up against both fires and earthquakes.
A curious fact can prove the durability of hempcrete: the 6th-century hemp mortar bridge has withstood Viking conquests, multiple world wars, and natural disasters. During World War II, the Germans tried to destroy it twice.
The contemporary builders’ experience confirms what the troubled history of this little bridge tells us: hempcrete tends to harden as it sets down, meaning that time only makes it stronger.
And the beautiful part of its life cycle is that at its end, hempcrete only goes back to nature, leaving no harmful waste behind.
How Much Does a Hemp House Cost?
So, if we know all the benefits of hemp building, why are we not seeing more houses like this?
A part of the answer is the cost. The required amount of building material itself isn’t as much as you would think. In fact, it’s been previously estimated that to build a 1250 square foot house, it would take 2.5 acres of hemp. However, the main obstacle is that it is approximately 20-30% pricier than concrete.
In addition, hemp isn’t your run of the mill building material. You can’t just start using it and expect contractors to be familiar with the material. You would have to take into consideration the additional cost of hiring builders and architects with specialized knowledge.
On the other hand, a hemp house can be a long-term return on investment. Because it holds such effective insulation and self-regulating properties, it can drastically reduce your energy consumption and lead to much affordable living.
Because this building sector is still in its nascent phase, no one actually knows what could happen if the demand for hemp houses would rise.
Will It Go Mainstream?
To get some more answers about the possibility of using hempcrete on a large scale, we sat down with Tommy Gibbons, co-founder of the Hempitecture, who was recently listed (along with its fellow co-founder Matthew Mead) on the Forbes annual “30 Under 30” Class of 2020 for “creating the products, methods, and materials of tomorrow.”
They were also the architects behind America’s first public use hemp building in Ketchum, Idaho.
“I was reintroduced to hemp building at a workshop in Oregon. I recognized hempcrete from a kickstarter launched by my high school friend and classmate [Matthew Mead]. The more he and I spoke, and I learned about the material, I went from wanting to build a tiny home with it to wanting to make this field my career.” said Tommy Gibbons.
He also noted that their company is not only involved in assisting developers in professional installation but that they have builders for clients who come to us for building materials and training.
“We know we cannot be on every hemp building jobsite in the nation. Instead, we want to give others the tools to be able to incorporate hemp building materials into their projects,” Gibbons emphasized.
He explained that a lot needs to be done to make hempcrete a building material on a large scale: “Architects need to be specifying our material. Testing needs to be in place for building inspectors to rely on. A robust and localized supply chain to bring down costs and professional installers who know how to work with these materials. And of course, some public awareness and concern.”
As it usually comes down to economic considerations, Gibbons expressed his hope about hempcrete’s bright future, but added that “we [all] don’t really know how inexpensive hemp building materials could be until we see the full extent of the country’s hemp supply chain.”
It’s tempting to conclude a story about hemp houses with a comment on The Tale of The Three Little Pigs. Perhaps the first two were on to something.
But joking aside, it seems that a story about hempcrete has a similar lesson for us: we need to rethink our tales, endings, and future.
Photos and video source: instagram.com/hempitecture