Hemp is a botanical class of cannabis Sativa cultivars grown especially for industrial or medicinal use. It needs special permission to grow, is fast-growing, has long tap roots to help regenerate soil and is better than commercial forestry at sequestering carbon. As a material, it can be carbon-negative, as opposed to other construction materials such as steel or concrete.
We’ve typically heard of the wellness and cosmetic benefits of hemp, not to mention the continued popularity of CBD. However, Steve focused on using hemp as a construction material for the interior and exterior of his home. He explains that the speed at which the crop grew, taking a mere 100 days from seed to harvest, was a huge beneficial factor.
Hempcrete is similar to concrete and is made by wet-mixing hemp hurds with lime-based binder and water. It hardens once dried, serving several construction and insulation purposes. The method has been used in France and has proven to be a good insulator and unlike concrete, is five times lighter. If you add certain structures to it like timber, it can be structural too.
By collaborating with Cambridge University, Steve did something that had never been done before. Commonly when using hemp, you utilise the fibres from the inside, known as the ‘shive’. The fibres from the outside were once used in products like shipping ropes hundreds of years ago – but by mixing it with a resin, Barron was able to create a solid substance in a correlated form on the outside of the house.
There are many challenges that stop us from using hemp in construction for all houses. ‘In the building trade, they’ve done things a certain way for a number of years. It’s very hard to change things and do things slightly differently.’ Steve explains that the crop may not always grow successfully, and he’s previously had a wireworm chew through the roots, destroying one crop – not to mention the drug laws that prevent much of the plant from being processed.
However, he does believe that it is possible to build houses from hemp – even in London. In fact, there is a terrace of houses in Greenwich made of hemp, which even featured on Grand Design a while ago. There may be around five to ten thousand houses around Europe made of hemp.
Since the farm has become organic – they’ve managed to crush the harvest of seed crops into oil, forming balms that are currently sold on The Conran Shop. They’ve also made culinary oil which is used in some restaurants and deli’s in London alongside coasters and trays which they’ve supplied to some hotels too.
Steve’s next steps include building a wind turbine, by working with Cambridge University again, but this time by also using hemp.
Once the next crop is in the ground next year, Margent Farm is accepting visitors too. Check out the website for more information.