The House that Hemp Built – Ordering the materials
From the Archive: 04-11-2010
The House that Hemp Built – Ordering the Materials
Obviously our ultimate goal is to be growing and producing hemp construction materials in South Africa, but we are not there yet.
We are at the commercial trial level, and we are confident that the industry will be ready to launch in the next few years as we move into the commercial production phase. So, in order to showcase the potential, we had to source the hemp materials needed for our hemp house internationally.
We have been working with our Chinese suppliers over a number of years to perfect the hemp chipboard. We aimed to have a completely eco-board and pushed them hard to remove all the formaldehyde from the binder they were using. We finally had a product that we were satisfied with and received our first container a few months ago. The boards are good, but still not as hard as the boards with formaldehyde in, so they are not applicable for wet areas (kitchens or bathroom s) and will not hold heavy duty hinges for long periods. We may have to relent a bit and go back to an E1 binder instead of the E0 we were aiming for, although our suppliers believe they are getting good results from a new soy-based binder they are experimenting with.
The boards are still very good for panelling and walling/shelving, but we aim to perfect them as a multi-use product soon. Ultimately we will be producing these locally, and a chipboard factory alone will provide in excess of 300 jobs and need 6000 hectares of hemp to keep it busy, saving countless trees in the process.
The hemp hurds and binder for the hempcrete and the insulation mats for the internal walls and floors were sourced from a company in France who was able to provide a range of products for us at a competitive price.
We imported 2 types of insulation, 25kgm3 hemp rolls and 45kgm3 hemp mats. They are used in conjunction with each other to catch high and low sound frequencies and have superior thermal properties. There is already technology and machinery in South Africa to make these products when the hemp fibre is available. The products are soft, bio-degradable and a pleasure to work with.
The hemp hurds also come in 2 grades, one for walls and floors and the other is finer for the plaster and render coats on the walls.
The binder for the hempcrete is lime-based. Lime is a naturally occurring mineral that takes a fraction of the amount of energy compared to cement to produce, and we have plenty of it available here in South Africa. There is a part of the hemp/lime binder that we do not have available locally and that is Hydraulic Lime, and we are working with local companies to develop alternatives so that we do not have to import in the future. For now we chose to bring in tried and tested products as we do not want to take any chances with the prototype house.
The French have developed the hemp building industry and have the most experience in the different applications. The UK is fast taking over with the commercialisation of it with the main company there building hemp houses for the British Government on their demo eco-housing estates. The concept is also reaching the States, as seen in this video:
After much investigation and negotiation, our order was placed and the materials arrived in August, just in time for the insulation to be added to the pre-fabricated timber wall panels in the factory.
The hempcrete and plasters will be mixed and applied on site once the frame of the house is constructed.
Everything is coming together nicely…