Industrial hemp (from Old English hænep) is a variety of the Cannabis sativa plant species that is grown specifically for a range of commercial purposes including paper, fabric, clothing, biodegradable plastics, paint, insulation, biofuel, food, and animal feed. It is typically found in the northern hemisphere and is one of the fastest growing plants. Its use as a fibre dates back 10,000 years when it was originally spun into textiles.

So why do we choose to build with hemp? Our experience working in the building industry has taught us that hemp combined with lime offers unique and outstanding natural properties that cannot be matched by conventional building materials.

As Kevin McCleod and Joni Lane advocate, hemp is a remarkable plant with outstanding sustainability credentials. Hemp has the ability to absorb substantial levels of carbon dioxide during its rapid growing cycle. When you build with hemp, you are actively capturing and storing carbon for the life of your building.

Hemp displays extraordinary thermal performance. It has the ability to both insulate and store heat, providing you with a more comfortable and constant internal temperature. Combined with a lime or clay plaster finish to internal surfaces, hempcrete provides a passive means of regulating relative humidity thereby reducing your reliance on mechanical heating, cooling and ventilation.

A healthy building means healthy occupants. Numerous studies suggest the level of toxins inside a typical conventional home can be greater than that of outdoor air. Hempcrete contains no harmful chemicals and will not ‘off-gas’ over time. Hempcrete is entirely compatible with non-toxic natural plant-based oil finishes, lime washes and renders. Hemp’s natural ability to control interior humidity levels helps to eliminate the incidence of toxic mould growth.

Building with hempcrete means safer buildings. The composition of the lime binder ensures that every particle of hemp in the hemp and lime mixture is coated. This provides outstanding fire ratings, does not rot and is pest-resistance without the need for treatment with potentially harmful chemicals.

Hemp has been used in building construction for centuries. The Ellora caves in India have remained well preserved from insects, natural conditions and decay due to their hemp composition. In Japan, a home built in 1698 survives today as a testament to the longevity of homes constructed using hemp in an area with one of the highest levels of seismic activity in the world. In contemporary times, hempcrete building underwent an evolution in France in the mid 80’s as building restorers sought a suitable replacement for wattle and daub during the restoration of medieval timber framed buildings. Experimentation with hempcrete exceeded all expectations. The success of this method has led to a revolution in building construction.