Alternative building materials are enjoying a boom in creation, discovery and application. Among traditional ingredients, plant based products have been reintroduced, and one, with its share of controversy, is hemp. A popular use an insulating and structure material is Hempcrete, a bio-composite made of the inner woody core of the hemp plant (shiv) mixed with a lime-based binder.
The hemp core or “Shiv” has a 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.
Hempcrete can be used for everything from roof installation to flooring to wall construction. The creators of the Carson, California-based HempTraders.com, distributors of “fine hemp products”, sell Hempboard, a medium density fiberboard made from 100 percent hemp hurds and can be used to make environmental furniture, counter tops, walls and shelving.
According to American Lime Technology, “Hempcrete was discovered in a bridge abutment in France built in the 6th century. Since its rediscovery it has seen growing use in Europe. Industrial hemp is grown by certified commercial growers so the crop can be certified to be very low in THC. Hemp is not psychoactive. Given it has survived 14 centuries, people expect hempcrete buildings will have a long life.”
HEMP INSULATION – http://www.pacepdh.com/blog/index.cfm/2015/10/26/Hemp-And-Insulation–An-Age-Old-Ingredient
HEMPCRETE WALLS – http://www.hempcretewalls.com/info
Hemp and Building Construction Materials:
BENEFITS OF HEMPCRETE:
- Hemp is a renewable resource.
- Hemp has very good insulation properties.
- Hemp is biodegradable and recyclable
- Hemp is Hygroscopic and provides a degree of humidity control.
- Hemp has a high thermal mass.
- Hemp is lightweight.
- Ability to be dismantles and is reusable.
- Hemp is carbon negative due to the CO2 production during plant growth.
- Hempcrete is Mold and Pest Resistant
HOW TO MAKE HEMPCRETE:
Four parts hemp hurd, one part lime binder, and one part water is all you need to make hempcrete, a durable building material similar to pressboard or adobe. Just fill up the form with hempcrete, tamp it down, and once it’s set, you’re set!
Places to buy hempcrete: