How hemp bricks could transform SA housing – UJ researchers

Researchers at the University of Johannesburg (UJ) have developed a brick made from hemp that could help solve the country’s housing crisis while fighting climate change.

By Maile Matsimela, digital editor at African Farming

South Africa’s housing crisis extends far beyond statistics. It’s about dignity, climate resilience and the urgent need to build smarter, particularly in rural areas where families still live in poorly insulated homes, exposed to extreme temperatures and unreliable electricity.

“Housing is a major problem in both urban and rural areas. The current informal dwellings are dangerous and unsustainable,” says Professor Michael Rudolph, director of the Centre for Ecological Intelligence (CEI) at UJ. “Many families are still living in poorly insulated homes, exposed to extreme temperatures and unreliable electricity, while the cost of conventional building materials keeps rising.”

The Hemp Revolution

The breakthrough comes from years of advanced research within UJ’s Department of Civil Engineering Technology, where scholars and hemp industry experts are pioneering the transformation of hemp into hempcrete as a sustainable alternative to traditional cement. This work is part of a broader national initiative, in partnership with the Department of Science, Technology and Innovation, exploring advanced materials and innovative building technologies, including UJ’s 3D-printed housing systems.

At the heart of this innovation is the hemp brick prototype, a lightweight, breathable and carbon-negative building material that could redefine how South Africa builds. Developed through collaboration between Canna-B-Africa, CEI and its subdivision, the Hemp Research and Technical Station (HERTS), and UJ’s Sustainable Materials and Construction Technologies Research Centre (SMaCT), the brick represents a science-driven, locally engineered response to the housing crisis.

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More than Sustainability

The benefits extend well beyond environmental impact. “Its benefits go well beyond sustainability,” explains Brenton Abrahams, founder of Canna-B-Africa, UJ’s senior research associate and adviser to HERTS. “The brick offers excellent thermal efficiency, with a porous structure that naturally regulates temperature and humidity, reducing the need for artificial heating and cooling.”

For rural households with limited or costly energy access, this passive climate control could lower monthly expenses and improve living conditions. The brick also delivers strong fire resistance and is naturally resistant to mould and pests, enhancing safety and durability without chemical treatments. Its acoustic performance adds further value by minimising noise transfer and creating healthier indoor environments.

The Science Behind the Solution

The hemp brick is manufactured using the woody core of the hemp plant combined with a natural lime-based binder. Hemp itself is a rapidly renewable crop requiring minimal pesticides and absorbing significant carbon dioxide during growth. When used in construction, that carbon becomes locked into home walls, lowering the overall carbon footprint and supporting South Africa’s transition to greener infrastructure.

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Beyond its technical performance, the innovation carries broader societal impact. Expanded hemp cultivation could stimulate rural agricultural value chains, create new green economy jobs and support local enterprise development linked to sustainable construction.

Rigorous Testing and Presidential Recognition

“UJ scholars have been actively exploring how hemp can be transformed into hempcrete as a sustainable alternative to traditional cement, forming part of broader research into innovative construction technologies, including 3D-printed housing systems,” says Prof. Jeffrey Mahachi, director of SMaCT.

He emphasises the importance of rigorous validation: “The second-generation prototype is undergoing full testing, validation and certification. Our objective is to bring a credible, certified product to market that meets national building requirements while delivering on its sustainability promise.”

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The innovation’s national significance was highlighted at the 2026 Innovative Building Technologies Summit, where the UJ hemp brick prototype drew strong interest from policymakers, industry leaders and President Cyril Ramaphosa. During his engagement with the UJ team, the President acknowledged the brick’s potential to advance sustainable infrastructure development while unlocking economic opportunities within emerging green industries.

Brendan Wood, technical hemp expert at HERTS, noted this presidential recognition as validation of the innovation’s importance.

Building the Future

The hemp brick can also be used for energy storage and bioremediation, both innovative technologies currently being researched at UJ, pointing to even broader applications for this versatile material.

“Rural communities carry the heaviest burden of the housing backlog, which is why we are not simply developing another brick,” says Prof. Rudolph. “We are developing a solution that can accelerate housing delivery in a way that is affordable, energy efficient and environmentally responsible. For rural South Africa, building smarter and more sustainably is not optional, it is essential.”

As Prof. Mahachi says: “As South Africa confronts the interconnected challenges of housing delivery, climate resilience and rural development, the hemp brick represents more than a new building material. It is a locally developed, science-driven solution aligned with national priorities and designed for real-world impact. If adopted at scale, it has the potential to accelerate housing delivery, stimulate rural economies, reduce carbon emissions and redefine sustainable housing in South Africa. The future of construction can quite literally be grown from the ground up.”

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