EDUCATION

We believe that sharing knowledge about integrating healthy materials into our built environment is just as important as building healthy homes. We are passionate about empowering individuals, builders, and designers with the practical skills, technical understanding, and confidence needed to create healthier, more sustainable buildings.

Whether you're looking to explore the benefits of hemp-lime (hempcrete), dive into hands-on learning through our workshops, or expand your knowledge with some free resources and videos, this is the place to get started. Our goal is to make the powerful potential of natural building accessible—giving you the tools and support to bring your own projects to life.

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Why HEMP-LIME?

Hempcrte is one of the most sustainable building materials available, actively reducing environmental impact throughout its entire lifecycle. From cultivation to construction and beyond, hemp-lime offers a regenerative, low-waste, and carbon-negative alternative to many conventional materials.

CLIMATE IMPACT
Hemp is a powerhouse for carbon sequestration. As one of the fastest-growing plants on Earth, it can reach heights of 6–10 feet in just 90 days, producing multiple harvests per year and absorbing up to 15 tons of CO₂ per hectare annually. This rapid growth cycle makes hemp one of the most efficient natural carbon sinks in the agricultural world.

Beyond its carbon capture ability, hemp cultivation is remarkably low-impact. It requires minimal water and thrives without the need for chemical fertilizers, herbicides, fungicides, or pesticides, making it a regenerative crop that enriches the soil rather than depleting it.

When combined with lime to create hemp-lime, this captured carbon is locked away permanently within the walls of a building. Additionally, the process of carbonization—where lime reabsorbs atmospheric CO₂ as it cures—further contributes to hempcrete’s carbon-negative footprint. Unlike conventional materials that rely on synthetic chemicals and high-energy production methods, hemp-lime is composed entirely of natural, non-toxic ingredients. This means it does not release harmful emissions during production, construction, or throughout the life of the building.

Hemp-lime actively offsets emissions even after becoming part of the building envelope, making it a material that not only reduces environmental harm but potentially helps reverse it.

WASTE
Hempcrete’s environmental benefits extend beyond carbon sequestration and reduced emissions. The hemp hurd used in the hemp-lime infill mix is an agricultural byproduct derived primarily from the hemp food and hemp textile agricultural industries. Its production and construction process generates minimal waste, as any leftover hempcrete can be reconstituted and reused. Unlike synthetic materials that persist as landfill waste for centuries, or cause micro-plastics to be spread throughout the environment, hempcrete can be composted at the end of its lifespan, returning to the earth without polluting soil or water systems.

LONGEVITY
Sustainability isn’t just about how a material is made—it’s also about how long it lasts. Hempcrete’s lime binder preserves the hemp hurd and strengthens over time as it carbonizes, essentially turning to stone. If properly designed and maintained hemp-lime walls can last indefinitely, reducing the need for repairs and the environmental costs of material replacement.

By eliminating toxic chemicals, reducing construction waste, and providing a durable, high-performance building envelope, hemp-lime is redefining what it means to build sustainably. Choosing hempcrete isn’t just an investment in a structure—it’s a commitment to a healthier, more regenerative future.

THERMAL INSULATION
Due to the porous nature of hemp hurd, hemp-lime provides superior thermal insulation compared to many other natural materials. Hemp-lime walls can achieve thermal resistance values of up to R-2.1 per inch. While this is lower than some conventional insulation materials, hemp-lime compensates with additional properties—such as thermal mass and humidity regulation—that enhance overall energy efficiency and indoor comfort. In many climates, thicker walls are used to further improve insulation values and maintain stable indoor temperatures.

THERMAL MASS
Hemp-lime’s high thermal mass and specific heat capacity allow it to absorb and store heat, releasing it gradually to help stabilize indoor temperatures. This reduces reliance on active heating and cooling systems by flattening temperature fluctuations throughout the day. When used in conjunction with passive solar design or paired with conductive heating systems like masonry heaters or radiant tube heating, hempcrete enhances energy efficiency by retaining warmth and distributing it steadily over time.

MOISTURE REGULATION

Most modern wall systems rely on vapor and moisture barriers to prevent water infiltration. However, these barriers can also trap water vapor inside a building, especially in high-humidity areas such as bathrooms and kitchens. When condensation forms within a wall cavity, it can go undetected for long periods, leading to mold growth and potential structural damage.

Hemp-lime, by contrast, has a high hygroscopic capacity, meaning it can absorb and release moisture without degrading. It can hold up to 20% of its weight in moisture and gradually release it back into the air, helping to regulate indoor humidity and reduce condensation risks. Similar to the diurnal heat curve, hemp-lime flattens the diurnal humidity curve, improving indoor comfort and preventing moisture-related issues. Additionally, through its ongoing carbonization process, hemp-lime naturally converts excess moisture into limestone, further stabilizing indoor humidity and enhancing overall thermal comfort.

Hemp-lime is immensely adaptable and versatile. It can be used for walls, floors, and roofs, fitting seamlessly into a variety of architectural styles and structural systems. Whether you’re constructing a cozy cottage, a modern office, or a large-scale commercial building, hemp-lime offers design flexibility while maintaining its high-performance properties.

CONSTRUCTION METHODS
Hempcrete walls can be constructed using various techniques, allowing builders to tailor the material to different project goals and construction preferences:
• Cast-in-place: The most common method, where hemp-lime is mixed and packed between temporary formwork.
• Spray-on: Applied pneumatically for faster installation, often onto prefabricated panels or existing walls.
• Blocks & Prefabricated Panels: Pre-made elements that simplify construction and reduce on-site labor.

These methods offer different benefits, from enhanced insulation to increased construction efficiency, making hemp-lime suitable for a broad range of building systems.

STRUCTURAL COMPATIBILITY
Hemp-lime can be integrated into a wide range of framing and structural systems, making it a flexible solution for various building types:
• Concrete & Masonry Structures: Hemp-lime can be applied as an insulating and breathable enclosure around reinforced concrete or masonry walls, improving thermal performance while reducing the carbon footprint of conventional materials. Additionally, some hempcrete blocks are designed to be filled with concrete, similar to standard CMUs (concrete masonry units), offering increased structural strength while maintaining hempcrete’s insulation and breathability.
• Wood Framing Systems: Whether post-and-beam, timber frame, or light wood framing, hemp-lime works seamlessly with wood construction, providing insulation, fire resistance, and durability.
• Metal Framing Systems: Steel and aluminum frames can also be combined with hemp-lime, offering a lightweight, non-combustible solution that enhances thermal and acoustic performance.
With careful design and detailing, hemp-lime can be used in everything from tiny homes to high-rise buildings, as well as for retrofits of historic structures, improving both energy efficiency and indoor air quality.

CUSTOMIZABLE AESTHETIC & FINISHES
Hemp-lime’s aesthetic flexibility is another key advantage. While it is often finished with breathable plasters such as clay, lime, or natural stucco, it can also accommodate exterior cladding options like:
• Masonry veneers (brick, stone, or tile)
• Wood or composite rain screens
• Cement board, metal, and other ventilated facades

This allows designers to create modern, rustic, or traditional aesthetics while maintaining hemp-lime’s breathability and durability.

By combining performance, adaptability, and aesthetic flexibility, hemp-lime stands as a truly modern building material, capable of meeting both today’s architectural demands and tomorrow’s sustainability goals.

SPECIAL CONSIDERATIONS

While hemp-lime is a highly effective and sustainable material, it requires specialized knowledge to ensure proper detailing, structural support, and breathability. Walls must be designed to allow vapor permeability, and framing systems must accommodate the increased wall thickness and weight of the infill material. Proper engineering for vertical and lateral loads is crucial to ensure long-term stability and durability.

Hemp-lime is naturally fire-resistant without the need for chemical additives. Unlike conventional building materials, which can ignite, melt, or release toxic fumes under extreme heat—even when treated with fire retardants—hemp-lime withstands temperatures up to 1,700°C (3,092°F), far exceeding the peak temperatures of a raging bonfire.

Tested under both European and American fire classification standards, hemp-lime has received the highest possible fire rating in the ASTM E84 fire test, achieving a flame spread index of 0 and a smoke development index of 0. In the EN 13501-1 European classification, it earned a Class B-s1,d0 rating, indicating exceptional fire resistance, minimal smoke production, and no flaming droplets.

Unlike wood, which has a high flame spread index, or synthetic insulation that can emit harmful fumes when burned, hemp-lime charres rather than combusts, maintaining its structural integrity far longer under intense heat. Real-world fire simulations conducted by organizations such as the BRE Group (UK) further confirm hemp-lime’s ability to significantly delay fire spread, making it an ideal choice for fire-prone regions and for those prioritizing safer, more resilient homes.

Hemp-lime’s dense composition, alkalinity, and lack of organic nutrients make it naturally resistant to pests. Unlike conventional wall systems, which contain cavities filled with insulation that can become ideal nesting sites for rodents and insects, hemp-lime forms a solid, monolithic structure with no large gaps or voids for pests to inhabit.

Additionally, its alkaline lime binder mineralizes everything it encases, effectively casting it in stone—including the hemp hurd, wood framing, and any other embedded materials—making it unpalatable to pests both large and small. While conventional building materials often rely on fungicides, pesticides, or biocides for pest resistance, hemp-lime offers long-lasting protection with a completely non-toxic solution.

Thanks to its breathable structure and high alkalinity, hemp-lime actively resists mold, mildew, bacteria, viruses, and fungi. With a pH of approximately 12.4, lime creates an environment too alkaline for most microorganisms to survive, naturally preventing their growth without the need for toxic chemicals.

Hemp-lime also boasts a high hygroscopic capacity, allowing it to absorb and release moisture over time without degrading. This unique ability helps maintain stable indoor humidity, preventing the conditions that promote mold growth. Research from the University of Bath found that hemp-lime walls naturally regulate humidity levels between 50-60%—the optimal range for preventing microbial growth. Additionally, a study published in Building and Environment highlighted hemp-lime’s moisture-buffering capabilities, which reduce condensation and associated health risks in indoor spaces.

There are over 80,000 chemicals in consumer products today, yet only about 1% have been tested for safety—let alone for their long-term cumulative effects on human and environmental health. Many of these chemicals are commonly found in standard building materials, and little is being done to mitigate our exposure to them. manufacturers are not required to fully disclose their ingredients, leaving consumers unknowingly exposed to harmful toxins.

From formaldehyde-based glues in particle board to heavy metals in gypsum wallboard, PFAS (forever chemicals) in house wraps, and VOCs such as benzene, ammonia, formaldehyde in paints, conventional materials are often riddled with carcinogens, endocrine disruptors, and respiratory irritants. Insulation products commonly contain fungicides, insecticides, and chemical fire retardants, further compounding indoor air pollution. These toxic substances off-gas over time, continuously degrading indoor air quality and negatively impacting our health—especially in tightly sealed modern buildings.

Hemp-lime is completely non-toxic, free from the dangers of conventional building products. It provides a natural, safe, and healthy alternative for creating spaces where people can truly thrive.

Hemp-lime, also known as Hempcrete, is a breathable, non-toxic, and highly sustainable bio-composite material made from three natural ingredients: the woody core of the hemp plant (called hurd), a lime-based binder, and water. Despite its name, hempcrete is not a substitute for concrete and is not typically load-bearing. Instead, it serves as a high-performance infill for walls, floors, and roofs, offering excellent insulation, remarkable durability, and numerous health benefits.

A hemp-lime wall, finished with lime or clay plaster, replaces several conventional materials—including exterior paint, siding, house wrap, sheathing, insulation, drywall, and interior paint. These materials are often laden with toxic chemicals that off-gas and degrade over time, causing significant environmental harm during manufacturing and compromising indoor air quality for the life of a building. By using hemp-lime, these toxic substances are eliminated from the building envelope, creating a natural building system that enhances air quality, regulates humidity, and stabilizes indoor temperatures.

But the benefits of hemp-lime go far beyond health. It is highly durable, exceptionally energy-efficient, and carbon-negative, actively absorbing CO₂ over its lifespan. It is also extraordinarily fire-resistant, pest-resistant, and mold-resistant, offering long-term resilience with minimal maintenance. While it requires a structural frame for support, hemp-lime seamlessly integrates with most standard building systems and can be customized to meet a wide range of functional and aesthetic goals.

Whether for modern homes or traditional structures, hemp-lime solves many of the challenges conventional construction has ignored. Properly designed and installed it can create buildings that outperform conventional materials in countless ways. Hemp-lime isn’t just another alternative—it’s setting a new standard for the future of sustainable construction.

Hemp-lime naturally filters and purifies indoor air, capturing and neutralizing airborne pollutants such as volatile organic compounds (VOCs) and formaldehyde. A University of Bath study found that hemp-lime walls can reduce airborne VOC concentrations by up to 85%, significantly improving indoor air quality.

Its unique combination of breathability, excellent hygroscopic capacity, desiccant properties, and alkalinity allows hemp-lime to actively regulate indoor humidity, preventing mold, mildew, and bacterial growth—all of which thrive in high-humidity environments. Unlike conventional materials that trap moisture and degrade over time, hemp-lime naturally absorbs and releases moisture while maintaining its integrity, keeping indoor air fresh, stable, and healthy.

For even greater benefits, finishing hemp-lime with clay plaster further enhances its air-purifying properties. Along with regulating humidity, clay naturally emits beneficial negative ions, which can help neutralize airborne pollutants and counteract harmful electromagnetic frequencies from electronic devices and external sources.

By eliminating toxic off-gassing, regulating humidity, and filtering pollutants, hemp-lime creates healthier, more breathable living spaces—making it one of the most holistic and high-performing materials for achieving excellent indoor air quality.

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