WASHINGTON – Hempcrete, seen as a wood or concrete substitute building material, gets a boost as a building material from advocates for planting and growing the plant this year. The block of Hempcrete will float.
It will be the focus of a series of home building courses during the sixth annual Hemp History Week, set for June 1-7, 2015.
Hempcrete is a bio-composite made of the inner woody core of the hemp plant, which is then mixed with a lime-based binder, according to this description from American Lime Technology, a masonry construction materials consultancy based in Chicago:
The hemp core or “Shiv” has high silica content which allows it to bind well with lime. This property is unique to hemp among all-natural fibers. The result is a lightweight cementitious insulating material weighing about a seventh or an eighth of the weight of concrete.
Fully cured hempcrete blocks float in a bucket of water. It is not used as a structural element, only as insulating infill between the frame members though it does tend to reduce racking. All loads are carried by internal framing. Wood stud framing is most common making it suitable for low-rise construction. Hempcrete buildings ten stories high have been built in Europe.
During Hemp History Week Hemp Industries Associates will organize multi-day courses to cover contemporary construction methods and hands-on practical applications of working with hempcrete, including forming or shuttering, mixing and casting the hempcrete within a framed structure, as well as finishing with plasters and coloring.
Hempcrete is billed as energy-efficient, non-toxic and resistant to mold, insects and fire. HIA claims the product is easily renewable and more sustainable than lumber.
During Hemp History Week more than 1,100 grassroots events will showcase the uses of hemp a variety of industries, including hemp home building and cooking.