Building With Hempcrete In The UK
One of the emerging markets within hemp is the building and insulating materials that are made by mixing the hemp hurds (or “hemp shives”) with lime and water. This mixture is known as hempcrete. It is a biocomposite and ecofriendly material that offers great consistency and durability.
In the UK, hempcrete has been used for structure stability. It is poured into wooden shuttering, tampered lightly and dried for days to construct a wall which is cast around a timber frame.
Hempcrete can be considered a natural concrete but with added benefits: It is lightweight, it insulates, resists pests and mold, moderates humidity, and sequesters a large amount of carbon dioxide from the atmosphere. It is claimed that hempcrete can lock up approximately 110 kg of carbon dioxide.
All these qualities make hempcrete perfect for renovation and retrofitting of old and historic buildings to new energy-saving buildings.
Hemp Building Laws In The UK
In order to grow industrial hemp in the UK, you will need a license from the Home Office UK and are required to apply for a controlled drugs domestic license.
Licenses for industrial hemp are valid for one year only. The license only allows for the industrial use of the seed and fiber, which are non-controlled parts of the hemp plant. The license does not allow for the use of the flowers or leaves (‘green’ or controlled materials).
Visit UK government website for more info.
Per sources, cannabis in the United Kingdom is illegal for recreational purposes and is classified as a Class B drug. In 2004, the plant was made a Class C drug with less severe penalties and then was moved back to Class B drugs in 2009. Using cannabis for medical use which is prescribed by a registered specialist doctor was legalized in November 2018.
Still, cannabis has been widely used in the UK in the form of the industrial hemp plant (with low THC ) for over a thousand years for fiber, oil and seeds.
Types of Hempcrete Material In The UK
1. Hempcrete Pre-fab Panels
Due to the higher drying time of hempcrete, the Greencore Construction Group in alliance with the University of Bath, UK, developed a faster-drying mixture of hemp and lime which is mixed with wood fiber to produce a 300mm thick prefabricated panels. One of the major benefits is that they are structural, easy to assemble and also retain the moisture-regulating property of hempcrete.
These pre-fab hemp panels have been used to build a number of residential hemp houses and commercial buildings. Moreover, Greencore Construction has started franchising this technology to small housing developers.
2. Hempcrete Bricks & Blocks
Some manufacturers are producing hemp bricks using hempcrete along with a mix of minerals and pressing them into custom sized blocks.
The resulting hemp bricks are not only insulating but are said to have appealing heat absorption and retention capacity. They may appear to be concrete, but they are much lighter and offer far more benefits for the safety of both the house and the environment.
Notable People & Projects
In 2009, a Hemp Building Symposium was held in Ireland. It was hosted by Irish hemp construction expert Steve Allin and by Canadian hemp building specialist Jayeson Henderson. Another important player in the hemp building scene is Ralph Carpenter, who built a hempcrete extension for his house in Suffolk.
One of the most well known hempcrete building specialist in the United Kingdom has been Ian Pritchett. His projects include 200 residential houses and 50 commercial buildings. Of these, The Triangle Housing is of particular interest.
The Triangle was a joint collaboration between Kevin McCloud’s Happiness Architecture Beauty and GreenSquare, a housing group. Every home built was made with hempcrete. The idea was to produce affordable, flexible and efficient housing that is more durable when compared to traditional spaces of residents. Source.
Hempcrete has also been used to build a Marks and Spencers Supermarket in the United Kingdom. The Science Museum of the UK also has an archive store which is built from the hempcrete.
Hempcrete for sale UK
Hempcrete materials for sale in the UK are based on the size of your project and typically include binder, hemp shiv and other related material such as lime mortar, cork/wood fiber insulation boards, plaster and render.
If you are interested in learning about the industry, you can register for a hempcrete course located in England. This course will provide an introduction to the theory and practices of hemp-lime construction. You will also learn how to use hempcrete in the repair and upgrading of old buildings.
It is a two-day course and open to anyone above 16 years of age. Learn more about it here.