What is hempcrete?
Hempcrete is made by mixing hemp shiv (the woody stem of the industrial hemp plant} together with a binder. The binder is usually either pure natural cement (a strongly hydraulic lime), or a formulated hempcrete binder made from lime mixed with a smaller proportion of pozzolans, natural additives or Portland cement.
Hempcrete can be wet-mixed on site and cast around a structural frame, or pre-cast off site to form blocks or panels. Although very hard and self-supporting once set, hempcrete is not load bearing. This is due to the amount of air trapped within the material and the slightly flexible nature of the hemp shiv aggregate.
Hempcrete has a medium density, which means it provides both insulation and thermal mass within the same material. It is vapour-permeable, meaning that water vapour is allowed to pass freely through the wall assembly, rather than being trapped within it, which can cause damp and deterioration to the building’s fabric.