By Kevin Curtin

This article originally appeared in the Austin Chronicle

In a serene South Austin neighborhood, where the houses are so small compared to the sprawling oak trees that surround them that it looks like a forest on Google Maps’ aerial view, a crew of builders are constructing a two-story back house. Hammers striking, saws buzzing, and mixers churning are familiar sounds to residents in our growing metropolis, so, from afar, there’s little to suggest this worksite is not your typical build, but actually a first-of-its-kind project in Austin ... until you come closer and see the 400-pound bags of hemp hurd, sacks of lime powder, and a specialized hempcrete mixer.

This will be the city’s first privately owned residence made of hempcrete – a lightweight biocomposite building material that’s both eco-friendly and energy efficient. The dwelling has already been framed up with lumber studs, and now the walls are being cast out of the organic building material, which is handmade on-site by mixing the hemp hurd (the woody inner stalk of a tall-growing industrial hemp variety) with a natural lime binder and water. Meanwhile, the ceiling and floors will be fitted with insulation made from hemp wool, which has a similarly soft texture to the pink fiberglass insulation you’re familiar with – minus the skin irritation.

This hemp house is the pet project of Susan Hays, an attorney, lobbyist, cannabis advocate, and 30-year veteran of Texas politics who ran for agriculture commissioner in 2022. If a Texas Cannabis Hall of Fame existed, Susan Hays would be deserving of entry for her contributions in drafting HB 1325, which effectively legalized hemp in all the various uses we’ve enjoyed since its passage in 2019. At the time, she was on contract as a lobbyist for Village Farms International – a company that operates enormous greenhouses for growing produce in West Texas, but also happens to be a major player in Canada’s cannabis market. Hays worked directly with legislators on the wording of the hemp bill, including oversights that made hemp products more legal and accessible than they intended.

“When the government is trying to regulate something they don’t understand, they fuck it up,” she shrugs cheerfully.

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Hays has long been planning to turn her property’s dilapidated garage into a backhouse that would rise amongst the heritage trees in her backyard, but when the bill passed, she became obsessed with building it out of hempcrete. Luckily, permitting and a campaign for state office delayed it a few years.

“If I’d have built this in 2020, I couldn’t have sourced U.S.-grown hemp, but now you can,” she explains. “So I’m trying to use as many Texas products as I can out of both chauvinism for my state and also greenness – if you’re shipping shit across the world, that’s not green.”

The eco-friendly aspects of hemp architecture are what drew Hays to building a hemp home. While the manufacture of concrete is one of the planet’s largest contributors of the greenhouse gas carbon dioxide, hempcrete is a carbon-negative material. It’s also highly sustainable compared to other building materials, and also hypoallergenic. By now you’ve heard the term “sick buildings,” referring to properties where chemical contaminants in building material, CO2 buildup, and mold cause health issues for those inside them. Hempcrete – which is breathable, mold-averse, and chemical-free – is being viewed as a solution for SBS, or sick building syndrome.

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But Hays is equally excited about hempcrete’s energy-efficient thermal properties. According to her calculations, the dwelling’s extra-thick walls will have an R-value of 30, where conventional walls in the U.S. have a minimum R-value of 13.

The goal is to never turn on the air conditioner,” says Hays, who plans to use the upstairs as an office “with a big-ass closet” since her small adjacent house lacks storage space. The downstairs will have a bedroom, bathroom, laundry, and pantry with a tiny kitchen. As for the aesthetic, it feels like a treehouse – how it rises among the limbs of an ancient oak – but it’ll have a decidedly unfancy vibe she mood-boarded to her architect as “redneck compound.”

Although hempcrete has been a popular building innovation in France since the 1990s, it’s still an emerging market in America and thus Hays calls it an “industry rife with newcomers, scammers, and people whose hearts are pure, but they don’t know what they’re doing.” She feels lucky to have Carl Gradek, who she describes as an “old-school Austin hippie craftsman,” as her contractor. Gradek tells the Chronic he’s been excited to add hempcrete to his portfolio of building techniques and has been going to Hemp Building Association conventions, trainings, and site visits on hemp projects since they started conceiving Hays’ hempcrete house in 2019. Proof of his commitment to hemp building: He even purchased a specialized hempcrete mixer that was made in Switzerland.