The Return of the Banned Supercrop – Why Hemp is the Answer to Australia’s Housing and Climate Crisis
Dedication: To my wife – who is not a hippie but likes her garden.
The Plant that was Criminalised
In 1937, the United States effectively banned industrial hemp. Australia followed suit. A plant that had been cultivated for millennia – used for rope, paper, clothing, building materials, and medicine suddenly became illegal.
The stated reason: hemp was said to be indistinguishable from its psychoactive relative, marijuana. The real reason: hemp threatened the emerging petrochemical empire.
Before the ban, hemp had powered empires. The British Royal Navy relied on hemp ropes and sails. The Spanish, French, and Dutch fleets did the same. The first drafts of the Declaration of Independence were written on hemp paper. Henry Ford built a car from hemp plastic and ran it on hemp ethanol.
Hemp was not banned because it was dangerous. It was banned because it worked.
The Maritime Empire that ran on Hemp
The connection between hemp and imperial power is not incidental. From the 16th to the 19th centuries, European naval supremacy depended on a single crop.
Hemp fibers are among the strongest natural fibers known. They resist rot in seawater, unlike cotton or flax, making them the ideal material for naval rigging, sails, and caulking. The British Crown mandated hemp cultivation in its colonies, including Australia. The First Fleet carried hemp seeds to Sydney Harbour, and convicts were put to work growing it on the shores of Farm Cove.
The Royal Navy’s dominance, and by extension, the British Empire’s, was built on hemp. Every warship required tons of the material. Without it, the empire would have been stranded in port.
The irony is bitter: Australia’s first crop was hemp. And for nearly a century, it was illegal to grow it.
The Demonisation: How a Plant Became a Pariah
The 1937 ban in the United States was driven by a coalition of petrochemical, timber, and newspaper interests. DuPont had just patented synthetic fibres (nylon). Hearst, the newspaper magnate, owned vast timberlands for paper production, and hemp paper would have undercut his profits.
The propaganda campaign was ruthless. Hearst’s newspapers ran sensational stories about “Marijuana: The Assassin of Youth,” deliberately conflating industrial hemp with its psychoactive cousin. The word “marijuana” itself was used to sound foreign and dangerous, obscuring the fact that hemp had been cultivated in America for centuries.
The strategy worked. Industrial hemp was caught in the same net as drug cannabis, and the distinction was deliberately erased. The plant that had been a cornerstone of agriculture was transformed into a symbol of degeneracy.
The Science: What Industrial Hemp Actually Is
Industrial hemp is Cannabis sativa L. with a tetrahydrocannabinol (THC) content of less than 1%. (Psychoactive cannabis typically contains 5–20% THC). You cannot get high from industrial hemp. You cannot smoke it and achieve any meaningful effect.
This distinction is now recognized in law. The 2018 US Farm Bill formally separated industrial hemp from marijuana at the federal level. In Australia, industrial hemp is legal to grow under state-based licensing schemes, with THC limits typically set at 0.35–1.0%.
The psychoactive effects of cannabis are caused by THC, which binds to CB1 receptors in the brain. Industrial hemp contains negligible THC. Its primary non-psychoactive compound, cannabidiol (CBD), does not produce a “high” and has been studied for potential therapeutic applications.
The plant has been deliberately misrepresented. The demonization was never about science. It was about profits.
The Material that Outperforms Concrete
The inner woody core of the hemp stalk, known as the ‘hurd’, can be mixed with a lime-based binder to create a material called ‘hempcrete’. (Despite the name, it is not structural concrete. It is a lightweight, breathable insulation infill.)
The properties are extraordinary:
- Property Hempcrete Performance
- Insulation Up to 15 times better than concrete
- Carbon footprint Carbon-negative: sequesters CO₂ during growth; the lime carbonates over time, locking it in
- Fire resistance Non-combustible: lime content withstands direct flame; certified to the highest Bushfire Attack Level (Flame Zone)
- Moisture management Hygroscopic: absorbs and releases water vapor, prevents mold
- Pest resistance High pH from lime naturally deters termites and insects
- Toxicity Non-toxic: can be crushed and returned to earth at end of life
The lime binder undergoes a chemical process called carbonation, reacting with CO₂ in the air to form calcium carbonate (limestone) over time. The structure literally petrifies, becoming stronger and more durable as it ages.
VIReal-World Proof: The Hester Brook Fire
In 2022, a catastrophic bushfire swept through Hester Brook in Western Australia. A hemp block factory was razed to the ground.
Everything burned.
Except the hempcrete blocks. A stack of fully cured hemp blocks survived the fire intact.
This is not theoretical. Hempcrete has demonstrated non-combustibility in the most extreme conditions Australia can produce. In a country where bushfires are becoming more frequent and intense, building with a material that cannot burn is not a luxury. It is a survival strategy.
The Housing Crisis: 1.2 Million Homes
The Australian government has committed to building 1.2 million new homes over five years. The goal is the centrepiece of the national housing strategy.
But how will these homes be built? With concrete, steel, and petrochemical insulation? Those materials are emissions-intensive, costly, and increasingly subject to supply chain disruptions.
Hempcrete offers a different path. Prefabricated hempcrete blocks and panels can be manufactured offsite and assembled rapidly, reducing construction time and labor costs . The material is lightweight, insulating, and carbon-negative.
The Australian Hemp Council has identified the opportunity: “Hempcrete and other bio-based products can provide insulation, panels, and prefabricated elements suited to rapid, sustainable, modular construction”.
The barriers are not technical. They are regulatory.
The Regulatory Barriers: What is Stopping us?
Industrial hemp cultivation in Australia is legal but heavily restricted. Growers must obtain state-based licenses, comply with strict THC content testing, and navigate a patchwork of regulations that vary by jurisdiction.
Processing infrastructure is inadequate. Decortication facilities – machines that separate the hurd from the outer fibers – are scarce. Most raw hemp must be sent overseas for processing or imported from Europe, adding cost and carbon emissions.
Building codes are catching up. The International Code Council has approved hemp-lime construction for integration into the 2024 International Residential Code. But Australia’s National Construction Code is performance-based, not prescriptive. Hempcrete can be used, but builders must demonstrate compliance through alternative pathways, a costly and uncertain process.
As one Australian homebuilder testified to the Senate Inquiry:
“I want to build my house using hemp blocks… I am having to IMPORT hemp blocks. There is not yet an Australian manufacturer of such blocks, because the hemp industry is too small in Australia. Unfortunately, this makes the blocks more expensive and adds significant CO₂ emissions due to the shipping.”
The solution is not complex: invest in local processing infrastructure, streamline licensing, and update building codes to recognize bio-based materials.
The Senate Inquiry: A Golden Opportunity
In 2025, Australia’s Senate Rural and Regional Affairs and Transport References Committee opened a national inquiry into the development of a hemp industry.
The terms of reference include the role of hemp in:
- Agriculture and regional development
- Construction and housing
- Manufacturing and value-added products
- Environmental sustainability
The Australian Hemp Council has called for:
- A legislated definition of hemp (cannabis with less than 1% THC)
- Removal of hemp from the national poisons schedule
- State-level reforms to open opportunities for the industry
The final report is expected in mid-2026. The recommendations could transform the industry, or be ignored.
The Straits Crisis: A Warning about Supply Chains
The ongoing crisis in the Strait of Hormuz, through which 20% of global oil passes, has exposed the fragility of Australia’s petrochemical supply chains.
Our insulation, our plastics, our synthetic fibres, our construction materials… all depend on oil. When the straits are threatened, prices spike. When prices spike, building costs rise. When building costs rise, the housing crisis deepens.
Hemp offers an alternative. It does not need to be shipped from the Middle East. It can be grown in Tasmania, Queensland, Victoria, South Australia, and New South Wales. It can be processed locally. It can be manufactured into building materials within Australian supply chains.
The question is not whether hemp can replace petrochemicals. The question is when we will decide to do it.
What the Industry needs
The barriers to a thriving hemp construction sector in Australia are well documented:
- Declassify industrial hemp. Remove it from drug legislation to enable full commercial use across multiple sectors.
- Simplify licensing. Eliminate unnecessary requirements to allow broader farming participation.
- Fund regional processing infrastructure. Invest in decortication facilities to shorten supply chains and reduce costs.
- Update building codes. Develop national product standards and certifications for hemp-based construction materials.
- Government procurement. Mandate or prioritize bio-based materials in government-funded housing and infrastructure projects.
- Subsidies for carbon-negative materials. Offer rebates or tax incentives to builders using certified carbon-negative products.
- Training and education. Train architects, builders, and assessors in the use of hempcrete and other natural building systems.
These are not radical proposals. They are basic industrial policy.
Environmental Benefits
The construction sector accounts for nearly 40% of global carbon emissions. Concrete alone produces 8% of global CO₂ – more than aviation.
Hempcrete is carbon negative. The hemp plant absorbs CO₂ during its 90–120-day growth cycle. The lime binder carbonates over time, locking carbon into the building’s structure. A hempcrete wall is a carbon sink.
The environmental benefits extend beyond carbon:
- Reduced water usage: hemp requires less irrigation than cotton or many food crops
- Soil regeneration: hemp’s deep root systems prevent erosion and improve soil structure
- No chemical inputs: the plant grows densely, suppressing weeds naturally
- Biodegradable end-of-life: crushed hempcrete can be returned to the earth or recycled into new material
In a country facing bushfires, droughts, and climate-driven housing pressures, building with a carbon-negative, fireproof, moisture-regulating material is not niche environmentalism. It is common sense.
A Pattern you know well
A technology that works, that is sustainable, local and low-tech, is suppressed for decades. Not because it is inferior. Because it threatens the existing power structure.
The petroleum companies did not just compete with hemp. They criminalised it.
The same pattern appears wherever there is a choke point. Who controls the supply of insulation? Who profits from the current system? Who benefits from keeping the regulatory barriers high?
The questions answer themselves.
The Challenge of Perception
Industrial hemp faces a public perception problem. The deliberate conflation with psychoactive cannabis as engineered by Hearst and DuPont, persists to this day.
Parents worry about children being exposed to “drugs.” Regulators worry about THC limits. Builders worry about what clients will think.
The science is clear: industrial hemp with less than 1% THC has no psychoactive effect. It is a crop — like wheat or barley. The fear is a relic of a propaganda campaign that ended 80 years ago.
The education gap must be closed. Hemp is not marijuana. It is a building material, a textile, a food source, a soil regenerator, and a carbon sink. It has no agenda. It has no politics. It is a plant.
What happens next
The Senate inquiry will report in mid-2026. The government’s response will determine whether Australia seizes the opportunity – or continues to import what it could grow.
For homebuilders, the decision is more immediate. Hemp blocks can be imported now. Hempcrete can be installed now. The material is ready. The supply chain is the constraint.
The international context is shifting. The US has integrated hemp-lime into its residential code. The UK and Europe have active hemp construction sectors. Australia is falling behind. Not because of inferior conditions, but because of regulatory inertia.
Conclusion
The plant that arrived with the First Fleet, that built empires, that was banned for 90 years, is returning.
Not as a countercultural symbol. As a construction material.
Hempcrete offers insulation 15 times better than concrete, fire resistance proven in Australian bushfires, and carbon-negative performance that meets climate targets. It can be grown in a season, processed locally, and assembled into homes that breathe, regulate humidity, and last for centuries.
The barriers are not technical. They are political.
The Housing Crisis. The Climate Crisis. The Supply Chain Crisis.
One plant cannot solve all of them.
But it can help.
And the only thing standing in the way is will.
Andrew Klein
References
- Green Review. (2025, October 30). Hempcrete’s role in fire-resistant building design in 2026.
- Mondaq. (2018, December 13). Growing weeds – Australia’s hemp industry prospers.
- HempToday. (2025, August 21). Australian inquiry spotlights hemp’s promise for housing, farming and climate goals.
- Otetto. (2025, August). Submission to the Senate Inquiry: Opportunities for the Development of a Hemp Industry in Australia.
- Baykova, D. (2025). For and against cannabinoids – biologically active substances in hemp. GPNews, Issue 11/2025.
- Natural Building Australia. (2025, June 13). Why Isn’t Australia Building More With Hemp and Straw?
- Australian Parliament. (2025). Hemp Block Residential Construction in Australia: Submission to the Senate Inquiry.
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@ Andrew Klein: An excellent coverage of a too slow moving policy change in NSW and Australia.
BUILDING WITH HEMPCRETE – There is an unknown organisation that allegedly ”trains” qualified builders on building with Hempcrete blocks. Indeed, I think there may even be an (unknown) Australian small output manufacturer. I know of one Hempcrete house built in outer Armidale during the past five (5) years.
After reading about the merits of Hempcrete I wanted to build my next house in Hempcrete blocks, having used Armidale produced concrete blocks in my first house 50 years ago. The concrete blocks were excellent provided you sealed the local blocks with conventional exterior painting. Sadly, no success with Hempcrete to this date.
Across the road from our former farm there was a high security Hemp farm extracting under licence and employing about 70 persons.
Interestingly, Hemp crops are excluded from CO2 calculations because Hemp sequesters multiples of CO2 compared to any tree species, and even the grass known as Bamboo. Then there is the advantages of double or triple cropping depending on climate at the location. Another Hemp asset deliberately overlooked by government desk jockeys.
Hemp is a tropical C4-pathway tropical plant that has a different reflection spectrum to temperate C6-pathway plants. This allowed a satellite to discover a ”regular red-line” in a 1,000 acre wheat crop in NW NSW about 1985, resulting in the prosecution of the landholder. One run of the planter box had been blocked off/separated from and filled with Hemp seed, hence the regular pattern.
Yes indeedy, the ignorance of mankind never fails an opportunity to parade. Harry Anslinger, the American government’s chief apparatchik doing the dirty work whilst prohibition was in play, found himself at a bureaucratic loose end after repeal, and was a sympathetic ear to the burgeoning petrochemical tsars who were agin’ the use of hemp, wanting, naturally, their synthetics be given a place in the market. Anslinger, seeing a chance at rejuvenation of relevance, jumped at the opportunity and the rest is history… speaking of which, to hell with the fact that hemp and ganja had been part and parcel of some cultures for millennia – first recorded evidence of use was in a Chinese herbal 5,000 years ago.
Ah, America, home of the brave and the deeply stupid, never missing a chance to fuck things up not only for themselves but the rest of planet as well.
The Yanks did not actually ban hemp- there is no constitutional power to do so – but the Marijuana Tax Act 1937, which imposed a tax on licensed producers, of which there were none, had that same effect.
Both varieties should be approved crops in Australia, one for construction/paper/fabric everything you can do the hemp, and the other for medicinal use, regulated like any other medicinal product. There are literally millions of people who could be employed doing this legally !!!
Politics and politicians,,where there’s a will, there’s a won’t.Banning fuckwit politicians, of which there is never a shortage, is a prerequisite to progress.
There were also the 1960-70s ‘Rockefeller Drug Laws’ that criminalised drug use more, especially cannabis.
This was then used to profile, target and harass centrists, liberals, anti-Vietnam protesters, university campuses and ethnic minorities, especially blacks and Latinos.
A query to the gods of the internet furnished the following: The annual spend on the global war on drugs costs at least $100 billion. In the USA, cumulative spending since 1971 has exceeded $1 trillion, with the annual federal budget reaching roughly $39 billion.
And still they come, the poor, the disenfranchised, the maimed and traumatised, the hedonists and thrill-seekers and misguided souls for whom the sweet relief of a high is worth the risk, the cost, the penalty.
Historians in time will record this abject failure of policy as one of the largest examples of clusterfuckery in the modern era.