PART 1 WHAT HEMPCRETE IS, AND ISN'T
YOU can’t grow drywall. Or fiberglass. Actually, nothing in today’s house is produced on a farm. With hempcrete, however, builders and buyers are already benefitting rural communities as well as the environment.
Today’s hemp construction industry is motivated by these bigger causes, as it continues to expand into a proper industry. Consumers are responding and a corporate supply chain is forming, but it's still early.
Production home builders are in a good position to take hempcrete to the next level. An excellent pool of talent and resources is available, architects are getting on board, buyers are lining up, First Citizens Bank is ready to finance. This is all because hemp houses are amazing.
What makes them amazing is the functionality of hempcrete. It is primarily an insulating material with excellent thermal and vapor barrier properties, especially in comparison to drywall and fiberglass batting. If you add an outer layer of house wrap, that’s 3 products to make a good wall, while hempcrete simplifies the equation, with better performance overall.
Hemp fiber is essentially two components: bast and hurd. Bast is the long fiber from the outer layers of the plant stem, hurd is the inner core. Hempcrete consists of hurd, mixed with a lime binder and water, to make an oatmeal consistency that can make walls using forms, blocks or panels. The resulting mass is strong, fire and mold-proof, lightweight and attractive, which is why you’ll see some interiors with the smoothed hempcrete left exposed between the studs, its natural tan color a design element that can be covered with panels, as desired, or tinted with a colored lime wash. Drywall? Why would you need it?
Drywall has some serious downsides, environmentally speaking, starting with its capacity to hold moisture, resulting in mold growth. This is not something builders care to discuss, because there is so much that is unknown. Mold ranges from non-toxic to deadly. Allergic reactions from indoor mold can be affecting health without anyone making the connection to the interior environment. Hempcrete does not support mold growth. Its does not hold moisture and the lime binder limits mold as well. It's only when there is paper or organic surfaces, with air/moisture gaps that can support mold.
Other drywall hazards are the dust during installation can be hazardous to workers. It is extremely heavy and is a job only for the young who clamber about on stilts. Cheap drywall can contain harmful chemicals, such as the Chinese drywall debacle of 20-some years ago. Gypsum mines are not that bad, compared to some, but the industry requires massive infrastructure to produce and ship it to site, so the drywall carbon footprint has to be considered. That said, drywall is the standard, it's not going to go away, but the market for alternatives is real, especially if it has the common-sense values of hempcrete.
Hempcrete's other main advantage is the thermal envelope. For more on that and other hemp construction breakthroughs, let's follow up in Part 2 with Zach Popp, Wisconsin owner of Sativa Building Systems and inventor of the Z Panel.
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