Recently I posted an article about hemp making a comeback as a building material (January 1 2012 post). Today I want to go into a little more detail about hemp building materials and their properties pertaining to their low toxicity and strength.
Let’s start with the foundation. Hemcrete is an excellent component for the foundation of a home. Hemp hurds are mixed with lime, cement, plaster, and water. A chemical reaction between the lime and the hemp hardens the mixture. As time goes on the compound continues to harden. (Archeologists found a bridge in France from the Merovingian period, 500-750 AD, that used this same process, and it is still standing today.) Hemcrete is half as light as traditional concrete foundations, yet 7 times stronger; it is also flexible, which is excellent for earthquake-prone areas.
Hemcrete walls have the same properties as hemcrete foundations and are 3 times more flexible as wood walls. Hemcrete is an excellent insulator as far as temperature is concerned and a sound insulator as well. Hemcrete is insect-, rot-, mold-resistant and does not release deadly toxins into the air; in fact, hemcrete walls will help CLEAN the air inside the home. It is also waterproof and fireproof.
“If hemp were legal in the United States, it would be the cheapest source of raw material for concrete-like foundations. Plus hemp hurds can be processed in existing wood mills without major changes to the equipment. Hemp-foundation homes are ecologically appropriate because they are inexpensive, and can be prepared on site using only a cement mixer, and the material would be cheap and abundant.” (Hemphasis.net)
Washington State University, in Pullman, Washington, developed a hemp fiberboard (similar to plywood). It is 3 times more flexible and twice as strong as traditional wood fiberboard. It has excellent weather and sound proof capabilities, is non-toxic, and is moisture-, mold- and pest-resistant.
Pipes can be made out of hemp fiber (hemp concrete pipes). They are more flexible than plastic pipes and are less prone to cracking.
Hemp insulation comes in many varieties. It has excellent R- value and thermal properties and works just as well as fiberglass insulation and other types of chemical based insulations, without the toxicity. Hemp insulation can be either hemcrete or rolled/mat style insulation, and again, is mold, insect, and rodent repellent.
Hemp homes are carbon neutral, and in some cases carbon negative. With more people being concerned about the carbon footprint they leave behind, hemp IS the perfect choice, for the health of the home inhabitants AND for the environment.