Why hempcrete is becoming a very popular building material

If you think about the word ‘hemp’ you’d be forgiven for thinking it’s a mere botanical plant used for medicinal and recreational purposes. But the reality is that it’s become so much more.  

Increasingly, hemp – or hempcrete – is being used successfully as an environmentally friendly building material. Here we explore why this material is becoming more popular and ask whether it’s being used locally.  

What is hempcrete?  

Hempcrete is a construction material made up of hemp shives, aggregate, water, and lime sand. It is also used for insulation.  According to Zach Popp, founder, and CEO of Sativa Building Systems, it has a lot of pros such as mold, pest, and rot resistance. It’s also resistant to fires and is non-toxic.  

Popp highlights its versatility too: ‘It can replace multiple conventional materials such as insulation, vapor barrier, sheathing, and gypsum board. It’s breathable and vapor permeable, which helps regulate indoor humidity.’  

It has cost savings too. ‘It has a lot of thermal mass, contributing to HVAC cost savings,’ explains Popp. 

But it’s best ever advantage has to be the fact that it is biodegradable and can be recycled.

Disadvantages of hempcrete 

There are also disadvantages to using the product. ‘If the cast-on-site method is used, it can have a very long drying time of around eight weeks. Depending on hemp hurd supply in the area, it can be more expensive.’  

As it’s a fairly new building material there could also be a lack of familiarity among builders and this could impact its use as a construction material. If you’re entering into new markets it’s important to research if the material has been authorised. ‘ Permitting can be more difficult due to lack of familiarity among code officials, at least in the US,’ says Popp.  

Popp adds that it can also not be used for every stage of the building phase. ‘It cannot be use for below grade constructions, like foundations,’ he explains.
 

How hempcrete is used locally 

There is a good example of hempcrete being used locally in South Africa. The building material has been used to create the tallest hempcrete building which is located in 84 Harrington Street, Cape Town. It’s the result of a partnership between Cape Town-based companies Hemporium and Afrimat Hemp.

Duncan Parker, Hemporium Founding Partner, and CEO said of the project: ‘I bought 84 Harrington in 2016 with the idea being that it would become the flagship Hemporium store, a steak restaurant, and house the Hemp Hotel, a place where people can experience living in a hemp-constructed space. 

‘From a sustainability and eco-construction perspective, we wanted to take hemp construction in South Africa to the next level, while also contributing to the inspiring hemp construction projects being undertaken globally. 

‘We also believed that once licenses for the commercialisation of hemp in South Africa were issued, having innovative examples of what can be achieved with hemp would assist with leading the way for the fledgling hemp industry in South Africa.’ 

The Future of hempcrete 

Building with hemp and hempcrete is still in its infancy in South Africa. Popp, however, believes that there is a good future ahead for building with this eco-friendly material. He says there are several reasons why it will become more popular in the future.  

‘Consumers are demanding products that are both more sustainable and less toxic. Hempcrete helps meet both those demands. Building with hemp will also increasingly become more cost competitive as hemp agriculture grows rapidly and manufacturing processes are refined.  

‘It’s only a matter of time before a homeowner will sacrifice almost nothing and receive many benefits by choosing hemp products.’ 

He believes regulatory pressure will fuel the use of hemp too. ‘In commercial construction, there is an increasing heightened awareness around sustainability and even a regulatory need to replace carbon-intensive materials, like concrete, with more carbon-friendly materials like hempcrete. Even without regulatory pressure, many companies are choosing to emphasise sustainable construction. As hemp agriculture grows, hemp building materials will grow along with it. Bio-composites are proving to be the future of building materials.’