Remodeling 101: Hemp May Be the World’s Greenest Building Material

The story of hemp is one of operatic highs and lows. Known for producing the finest and strongest fiber around, it was once considered essential. Hemp seeds sailed on the Mayflower—the stalks were used for making cloth (including the Mayflower’s very sails), rope, paper, and clothing, among other things. George Washington was a hemp farmer as were all the Jamestown settlers (growing hemp was legally required in the colony). Betsy Ross sewed her flag out of it. Then, a century and a half later, hemp all but disappeared.


In the 1930s, marijuana hysteria took hemp down with it and both became illegal to cultivate: though the two are Cannabis sativa, hemp contains only the merest hint of THC and is weed’s benign relative. The fact that it fell out of favor is hard to fathom. Hemp absorbs more CO2 per acre than any other commercial crop making it an ideal carbon sink. Unlike cotton, it requires little water and no pesticides to grow, And, on top of being highly insulating, it’s naturally fire-, pest-, and mold-resistant and serves as an excellent sound barrier.


Only recently legal to farm in the US, Canada, and the UK (France, where it’s been legal since the 1960s, is the European leader in cultivation), hemp and its many uses are again being explored—including as a sustainable, biodegradable building material. If you’re embarking on a home improvement project, you’d be wise to consider hemp insulation and the biocomposite known as hempcrete or hemplime. Here’s a look at these construction materials and how some of today’s eco pioneers are applying them.
Above: A naturally insulating, eco-friendly alternative to concrete, hempcrete is nonstructural and inserted in blocks within building frames. The ones here are from Hempitecture of Jerome, Idaho, a leading US hemp supplier and builder that we featured in Remodelista: The Low-Impact Home.


Hemp Insulation


Above: At Hemptitecture, bales of decorticated industrial hemp fiber await being converted into hemp insulation known as HempWool. The finished product is composed of 90 percent hemp combined with a textile fiber binder.
Above: Installing Hemptitecture’s HempWool in a ceiling. It’s chemical-free, non-allergenic, and has insulating values comparable to fiberglass and other synthetics.
Above: Hemptitecture’s HempWool in an in-progress project in Venice, California. The insulation is safe to touch and smells like hay. It has no VOCs, and ships in bundles wrapped in compostable packaging.


Hempcrete


Above: Belgian designer Axel Vervoodt enlisted Hemptitecture to rebuild and apply HempWool and hempcrete (shown) to a 350-year-old Japanese minka frame in Texas. Hempcrete blocks are composed of hemp hurds (the woody cores of the plant’s stalk) and a lime-based binder—the two materials can be mixed and cast on site. Hempcrete is also sold in pre-made blocks and leftover scraps are biodegradable. Photograph by Lisa Woods.
Above: One of the stars of Remodelista: The Low-Impact Home is Margent Farm in Cambridgeshire, England, where future-minded film and television director Steve Barron grows hemp and makes hemp products. Flat House, his family homestead, was designed by Material Cultures and built using the farm’s first harvest. Photograph by Oskar Proctor from Remodelista: The Low-Impact Home.
Above: Flat House’s framing and exposed hempcrete walls are proudly left visible. They’re finished with a diluted clay paint that prevents the plant fibers from shedding and provides a clean textured look. Photograph by Oskar Proctor from Remodelista: The Low-Impact Home.


Hemp Cladding


Above: Flat House is covered in corrugated panels composed of compressed hemp fiber bound with a resin of farm bio-waste, including sugarcane, corncobs, and oat hulls. Margent Farm developed the cladding and offers it for sale (currently in large quantities only). Photograph by Oskar Proctor from Remodelista: The Low-Impact Home.
Above: The first customer for Margent Farm’s hemp cladding was Common Knowledge in County Clare, Ireland, which used it on the exterior of  its Community-Built Tiny House. The nonprofit teaches sustainable building practices and offers plans for its Tigín, Gaelic for tiny home, for free. Photograph by Shantanu Starick.


For a lively exploration of the history and uses of hemp, listen to the Trace Material podcast produced by the Parsons School of Design Healthy Materials Lab.


Learn more about hemp and other outstanding natural building materials in Remodelista: The Low-Impact Home, and take a look at:




* In with the Old: Hemp House, the First Project of a Young Studio in the Catskills

* Expert Advice: 10 Eco Best Practices from Home Remodeling from Dirty Girl Construction

* Remodeling 101: Everything You Need to Know about Pine Tar

* Modern Plaster Walls, Six Ways






Featured image: Hempcrete walls in the kitchen at Margent Farm. Photograph by Oskar Procktor from Remodelista: The Low-Impact Home. | bit.ly/3XLoEJb


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