Hempcrete and concrete are fundamentally different materials – one is a lightweight, carbon-negative bio-composite, the other is the most widely used building material on earth. Choosing between them is not straightforward, because they don’t do the same job in the same way. This comparison breaks down how they differ across the metrics that matter most: structural performance, thermal properties, cost, carbon footprint, durability and ease of construction.
The short answer: hempcrete is not a direct replacement for concrete. It is not load-bearing in the way concrete is, and it is not suitable for foundations or structural frames. But for wall infill, insulation and interior applications, hempcrete offers significant advantages in thermal performance, indoor air quality, carbon reduction and long-term energy savings that concrete cannot match.
What is Hempcrete?
Hempcrete is a bio-composite building material made from three ingredients: hemp hurds (the woody inner core of the hemp stalk), a lime-based binder, and water. When mixed and cast – either in-situ within formwork or as prefabricated hempcrete blocks – the material cures into a lightweight, breathable solid that provides insulation, thermal mass and moisture regulation in a single layer.
For a deeper introduction to how hempcrete is made and used, see our comprehensive guide to hempcrete construction
Structural Performance
This is the most important distinction to understand: hempcrete is not a structural material. It does not carry load. In hempcrete construction, a separate structural frame – typically timber – supports the building, and hempcrete is cast or placed around it as infill. The hempcrete provides insulation, airtightness and moisture management, while the frame provides structural support.
Concrete, by contrast, is one of the strongest compressive materials available. Reinforced concrete can support multi-storey buildings, bridges and infrastructure. Its compressive strength typically ranges from 20 to 40 MPa for standard mixes, and can exceed 100 MPa in high-performance applications.
Hempcrete’s compressive strength is dramatically lower – typically between 0.5 and 3.5 MPa – which is why it cannot be used as a load-bearing material. Comparing the two on structural strength alone misses the point: they serve different roles within a building assembly.
Where hempcrete does offer a structural advantage is in flexibility. Unlike concrete, which is rigid and prone to cracking from shrinkage and thermal movement, hempcrete has a degree of flex that allows it to absorb minor structural movement without cracking. This can contribute to the longevity of the building envelope over time.
Thermal Performance
Thermal performance is where hempcrete significantly outperforms concrete, and it’s one of the primary reasons builders choose it.
Hempcrete has a thermal conductivity of approximately 0.06 to 0.09 W/mK, depending on density and mix ratio. For context, standard concrete has a thermal conductivity of around 1.0 to 1.8 W/mK – meaning concrete conducts heat roughly 15 to 20 times more readily than hempcrete. Without additional insulation, a concrete wall is a poor thermal barrier.
But hempcrete’s thermal advantage goes beyond simple conductivity. Hempcrete offers superior energy efficiency in part because of its hygrothermal behaviour – it absorbs and releases both heat and moisture dynamically, buffering temperature swings and regulating indoor humidity without mechanical systems. This means a hempcrete wall can perform better in practice than its R-value alone would suggest, because it moderates peaks and troughs rather than simply resisting heat flow.
A 300mm hempcrete wall can provide insulation performance roughly equivalent to a well-insulated conventional wall assembly, while simultaneously managing moisture – something a concrete wall with added insulation and vapour barriers achieves with more layers, more materials and more complexity.
Cost: Is Hempcrete Cheaper Than Concrete?
This is one of the most common questions around hempcrete, and the answer is nuanced.
On raw material cost alone, hempcrete is currently more expensive than concrete. Concrete is one of the cheapest building materials available, with standard ready-mix concrete costing roughly $150–$250 AUD per cubic metre in Australia. Hempcrete materials – hemp hurds and lime binder – typically cost in the range of $300–$600 AUD per cubic metre, though this varies significantly by region, supplier availability, and project scale.
However, a direct material cost comparison is misleading for several reasons.
Hempcrete is a wall system, not just a material. A hempcrete wall combines structure, insulation, airtightness and moisture management in a single layer. A concrete wall requires separate insulation, vapour barriers, and often interior lining to achieve equivalent thermal and moisture performance. When you compare the total cost of a finished wall assembly – not just the raw material – the gap narrows significantly.
Labour costs can favour hempcrete. Hempcrete is lightweight and can be mixed and placed by hand or with simple equipment. It does not require heavy machinery, specialised formwork, or the precision pouring and finishing that concrete demands. In some projects, particularly smaller residential builds, hempcrete walls can be installed by owner-builders or small teams with training, reducing labour costs substantially.
Operational costs favour hempcrete over time. Hempcrete’s thermal performance helps regulate indoor temperatures efficiently, reducing reliance on mechanical heating and cooling. Over a building’s lifespan – typically 50 to 100+ years – the cumulative energy savings can be substantial. In climates with significant heating or cooling loads, these savings can offset the higher initial material cost within 10 to 15 years.
Maintenance costs favour hempcrete. Hempcrete is naturally resistant to pests, mould and fire. It does not require the chemical treatments or regular maintenance interventions that some conventional wall systems need. Concrete structures, while durable, can develop cracking, spalling and water ingress issues that require costly repair over decades.
The honest answer to “is hempcrete cheaper than concrete?” is: the materials cost more upfront, but the total cost of ownership – factoring in the complete wall assembly, energy performance, and maintenance – can be competitive or favourable over the life of the building. For projects where sustainability, indoor air quality and long-term operational cost are priorities, the economics often favour hempcrete.
Carbon Footprint
This is where the comparison is starkest.
Concrete production is one of the most carbon-intensive industrial processes on earth. Cement manufacturing alone accounts for approximately 8% of global CO₂ emissions. Producing one cubic metre of standard concrete releases roughly 100 to 300 kg of CO₂, depending on the cement content and mix design.
Hempcrete, by contrast, is carbon-negative. The hemp plant absorbs significant quantities of CO₂ during its rapid growth cycle — a hemp crop can sequester around 9 to 15 tonnes of CO₂ per hectare. While the lime binder used in hempcrete does produce CO₂ during manufacturing, it reabsorbs CO₂ over time through a process called carbonation. The net result is that a hempcrete wall locks away more carbon than was emitted in its production.
This carbon-negative characteristic makes hempcrete one of the very few building materials that actively reduces the carbon footprint of a building. For projects pursuing carbon-neutral or carbon-positive outcomes, hempcrete is one of the most effective material choices available.
Moisture and Indoor Air Quality
Hempcrete is a hygroscopic material – it naturally absorbs and releases moisture from the surrounding air, helping to regulate indoor humidity levels. This creates a more comfortable and healthier indoor environment, and reduces the risk of condensation, mould growth and the respiratory issues associated with poor indoor air quality.
Concrete is not hygroscopic. In conventional concrete construction, moisture management relies on vapour barriers, mechanical ventilation, and careful detailing to prevent condensation. When these systems fail or are poorly installed, moisture problems can develop within wall cavities – often invisibly – leading to mould, structural degradation and poor air quality.
Hempcrete’s breathability also means it is naturally resistant to mould and fungal growth. The alkaline lime binder creates an inhospitable environment for biological organisms, while the material’s ability to buffer moisture prevents the sustained dampness that mould requires to establish.
Fire Resistance
Hempcrete has good fire resistance properties. The combination of mineral lime binder and the cellular structure of hemp hurds means hempcrete does not easily ignite, does not support flame spread, and does not produce toxic fumes when exposed to fire. Hempcrete walls can achieve fire resistance ratings suitable for residential and many commercial applications.
Concrete also has excellent fire resistance – it is non-combustible and retains its structural integrity at high temperatures for extended periods. On fire performance alone, concrete has a slight edge, particularly in applications requiring extended fire ratings for structural elements.
However, for wall infill and insulation applications – the contexts where hempcrete is typically used – hempcrete’s fire performance is more than adequate and compares favourably with many conventional insulation materials.
Durability and Lifespan
Both materials can last for the life of a building when properly constructed and maintained.
Concrete structures regularly exceed 50 to 100 years of service life, and some Roman concrete structures have survived for over 2,000 years. However, modern reinforced concrete can be vulnerable to carbonation-induced corrosion of steel reinforcement, freeze-thaw damage, and chemical attack – all of which can reduce lifespan if not properly managed.
Hempcrete buildings are relatively new in the modern construction context, but the oldest known modern hempcrete structure – built in France in the early 1990s – remains in excellent condition after more than 30 years. Hempcrete’s flexibility, breathability and resistance to mould and pests all contribute to long-term durability. The lime binder continues to cure and harden over time through carbonation, meaning hempcrete walls actually get stronger as they age.
End of life
At the end of a building’s life, hempcrete can be broken down and composted, returned to agricultural land, or reused as aggregate in new hempcrete mixes. Its biological composition means it does not contribute to construction waste in the way that concrete demolition rubble does.
Concrete demolition generates enormous volumes of waste. While crushed concrete can be recycled as road base or aggregate, the process is energy-intensive and the material cannot be returned to its original form. Concrete waste remains one of the largest contributors to construction and demolition waste streams globally.
The Bottom Line
Hempcrete and concrete are not interchangeable. Concrete remains essential for foundations, structural frames, and load-bearing applications where compressive strength is required. Hempcrete excels as a wall infill, insulation and building envelope material – delivering superior thermal performance, carbon sequestration, moisture regulation and indoor air quality in a single, simple layer.
For anyone building or renovating with sustainability in mind, the question is less “hempcrete or concrete?” and more “where does each material belong in this project?” The most considered approach often uses both – concrete where structural performance demands it, and hempcrete where thermal, environmental and health performance are the priorities.
1. The environmental impacts of the production of hemp and flax textile yarn (2012) | Industrial Crops and Products
2. Carbon-negative hempcrete: a review (2022) | Construction and Building Materials
3. Energy saving potential of hemp-lime external wall insulation (2007) | Energy and Buildings
4. Hygrothermal performance of hempcrete walls (2017) | Building and Environment
