Hemp as a Building Material – What you Need to Know

Hemp as a Building Material – What you Need to Know

Eco-Friendly and renewable, there’s a growing interest in using hemp as a building material – that pun is quite intentional. Hemp has an abundance of uses, including composite wood materials, hempcrete and insulation. Our Axiom team has been looking into the latter in recent months.

NOTE: This story originally appeared in January 2021 and is among our most read post on the Axiom Insights blog.

A big misunderstanding about hemp is that it is a drug. Not so. Though hemp is part of the same species as marijuana – Cannabis sativa –and looks similar, it is a distinctly different strain with a completely different chemical composition. The key is, hemp does not have psychoactive effects on humans. However, the Controlled Substances Act passed in 1970 included hemp, effectively making it illegal to grow in the U.S. without a permit. (Source: BuildingGreen.com)

As far back as 2013, Forbes magazine stated industrial use of hemp is a Win-Win For The Economy and the Environment. Hemp fiber is giving builders an alternative to fiberglass, plastic foams, and other more conventional materials, many of which are derived from non-renewables. As legalization of recreation use grows in the U.S., hemp is becoming more readily available. Here are some answers you might find surprising.

How Eco-friendly is Hemp Insulation?

Hemp insulation is a composite material but is also eco-friendly. According to the Innovative Building Materials blog, most fiberglass batt insulation is made up of 51 percent plant fibers and 49 percent plastics and chemicals. Hemp insulation contains as much as 92 percent hemp and about 8 percent polyester fibers. Non-toxic bonding agents and fire retardant make up the rest of the composite.

Hemp is a rapidly renewable resource. A crop can be ready for harvest in four to six months. Among the reasons Cannabis has been nicknamed “weed”. It’s easily grown in most climates and naturally tolerant to disease, drought, insects, poor soil, and weeds. It needs little water, fertilization, herbicides, or pesticides. The final exclamation: hemp sequesters carbon, which means it captures and stores carbon dioxide, thereby reducing global climate change..

Is Hemp a Good Insulator?

Yes, in fact the U.S. Department of Energy says it’s comparable to other common insulation products. According to the DOE, hemp has an R-value of 3.5 per inch of thickness. It’s renewable, durable and some products also include recycled material. It “breaths”, which helps with humidity control. Hemp has low conductivity and high mass, helping homes stay cool in the Summer, and warm in the Winter. Hemp’s density also helps minimize outside noise.

How Does the Cost of Hemp Compare to Other Products?

Natural, formaldehyde-free materials make eco-friendly insulation products the best choice for green, healthy homes. Unlike fiberglass, insulation materials like wool and cotton are safe to handle and cause no irritation to the skin or cause respiratory issues. Right now, hemp costs about twice that of ordinary fiberglass insulation – approximately $1.20 per square foot, compared to $.64 for fiberglass.

According to sources, that’s more related to production volume than the cost of materials. As hemp material becomes more popular and readily available, cost will go down.

Hemp seems like an ideal material. We’ll be following this interesting, important and environmentally significant subject in the future. Keep following our blog for more information. Stacy Einck, seinck@axiomcom.com.

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