State of the Art Review on Hempcrete as a Sustainable Substitute for Traditional Construction Materials for Home Building

Abstract

Currently, the construction industry relies mainly on non-environmentally sustainable materials such as fired clay brick, concrete, and steel, which significantly contribute to global carbon dioxide generation, leading to environmental degradation. In response to mounting environmental concerns, there is a growing emphasis on developing and utilizing low-impact materials that mitigate the ecological footprint of construction activities. This review offers a detailed overview of current formulations and applications of hempcrete and compares the performance of different types of hempcrete as construction materials. Additionally, this paper seeks to evaluate the potential of hempcrete as a sustainable substitute for traditional construction materials with high energy demands and significant CO₂ emissions based on life cycle assessment (LCA). Furthermore, this study summarizes current challenges and prospects for composite innovations in hempcrete, emphasizing the need for standardized product control and broader industrial acceptance, thus providing useful insights for practitioners and researchers in the field.

1. Introduction

The environmental impact of traditional construction materials has been a growing concern in the construction industry, as highlighted by recent studies [1,2,3,4,5]. Traditional materials such as clay brick, concrete, and steel are associated with significant carbon emissions, resource depletion, and pollution throughout their life cycles. Researchers have been exploring the use of new bio-based composite materials as sustainable alternatives to traditional materials. These alternatives not only aim to reduce environmental impacts but also to enhance the health of building occupants [6,7,8,9]. This demand is encouraging manufacturers to disclose the chemical content of their products [10]. At the same time, there is a growing demand from architects, designers, organizations, and consumers for transparency in the use of construction materials. By identifying harmful substances, researchers can seek better and safer alternatives, promoting healthier and more sustainable building practices.

As made from the inner woody core of the hemp plant (Figure 1) mixed with a lime-based binder, hempcrete has gained attention in the construction industry for its sustainability, thermal properties, and environmental benefits [2,11]. Hempcrete is a natural, healthy, sustainable, and locally sourced mixture, offering low embodied energy compared to traditional construction materials. Its environmentally friendly characteristics have positioned it as a material that is potentially better than zero carbon, meaning it can offset more carbon than it emits throughout its lifecycle [1,3,10,12]. Its use can significantly reduce carbon emissions and waste production, making it an environmentally friendly choice [13]. Furthermore, hempcrete’s ability to improve indoor air quality and its potential for recyclability at the end of its useful life contribute to its status as a preferred material for sustainable construction. As awareness about hempcrete and its adoption in home building continues to grow, it represents a promising path toward achieving more sustainable and resilient built environments.

This paper aims to provide a state-of-the-art review of hempcrete mixture design and its use in sustainable building construction. Initially, the paper provides an overview of the development, composition, and usage of hempcrete as a construction material, assessing its key properties, benefits, and applications in both residential and commercial construction. The paper also offers an analysis of hempcrete’s thermal insulation capabilities, moisture regulation properties, environmental impact, and carbon sequestration potential, which contribute to its growth as a sustainable material. More specifically, the study aims to evaluate the progress made towards enhancing the mechanical strength of hempcrete from the perspective of the effect of formulation adjustment. A summary of life cycle assessment (LCA) is also provided to further discuss the positive environmental effects of hempcrete. Several case studies are also discussed to show the potential of hempcrete in application. This will involve examining advancements in mixture designs, such as variations in hemp–lime ratios, the incorporation of additives, and the use of alternative binders aimed at improving load-bearing capacity and overall structural performance. By analyzing existing research, this paper seeks to identify knowledge gaps and areas requiring further investigation. Ultimately, this review aims to provide a better understanding of the current state of hempcrete technology while highlighting critical areas for future research and innovation.

2. History of Hempcrete

2.1. Timeline of Development of Hempcrete

The use of hemp has a rich history dating back centuries, with evidence of hemp fabrics found in ancient Mesopotamia dating back to 8000 BC. A mixture of hemp hurd, lime, and water, hempcrete has a root that can be found in ancient civilizations, where hemp was utilized for various applications “https://hempco.net.au/ancient-and-modern-uses-of-hempcrete/blog (accessed on 2 December 2024)”. In the UK, hempcrete was used to add thermal performance to traditional and historic buildings, preserving their historic integrity while improving energy efficiency. The modern use of hempcrete can be traced back to France in the 1980s, where it was developed as a method to enhance the thermal performance of medieval timber frame buildings. In Japan, a house built in 1968 using a specific style of Hempcrete still stands today, showcasing the durability and longevity of this material. Overall, the history of hempcrete is a testament to the longevity and sustainability of this material. From ancient civilizations to modern construction practices, hempcrete continues to be a valuable and eco-friendly building material with a rich history and promising future. The use of hempcrete is gaining popularity in the construction industry, with several companies retrofitting homes with this sustainable material [10]. In Pennsylvania, a home insulated with hempcrete has become a demonstration house to showcase the potential of hempcrete to local farmers and builders [14].

2.2. Different Forms of Hempcrete in Construction

Hempcrete is a sustainable building material used widely in construction due to its superior thermal insulation, moisture management, and environmental benefits. The three primary methods of utilizing hempcrete in construction include hempcrete blocks, cast-in situ hempcrete, and spray hempcrete. Each method offers distinct advantages tailored to different construction requirements, allowing flexibility in both design and execution.

2.2.1. Hempcrete Blocks

Hempcrete blocks (Figure 2) are commonly used in wall construction and are typically laid by wetting their surfaces and bedding them with a thin mortar layer of hydraulic lime and sand. The blocks are arranged to minimize thermal bridging along the mortar joints. These units are easily cut with a handsaw, which helps fit them around the structural frame, but designing the frame to match the block size or vice versa improves construction speed and reduces waste. Several companies in Europe and the UK have been producing hempcrete blocks commercially [10,15,16]. While blocks might seem advantageous due to off-site curing and drying, they also present an inefficiency: casting blocks requires a mixer and formwork in the factory, followed by multiple processes to integrate them into the building. Accordingly, casting walls in situ is perhaps more cost-efficient, as the process is quick and requires short on-site labor time [10].

Nonetheless, there is great interest in making precast hempcrete blocks. One specific type of precast hempcrete block is made from hemp shiv and a lime-metakaolin binder (Figure 3), which offers several advantages as a sustainable building material, highlighted by its physical, air permeability, and thermal properties. The study by [17] found that precast hempcrete has a medium density (466 kg/m³) and high porosity (78%), with most of the porosity (76%) being interconnected, which contributes to its excellent insulation and breathability. This material is highly permeable to air, indicating its potential for breathability. Air permeability measurements adopted for hempcrete have revealed that it is a highly permeable material, with significant implications for moisture management and indoor air quality [18].

Hempcrete blocks provide an effective solution for both new and traditional building projects by offering high energy savings and sustainability while maintaining familiar shapes and sizes for construction professionals. These blocks are designed to deliver excellent insulation, which significantly reduces heating and cooling demands, leading to lower energy consumption and costs over time. This aligns with the global emphasis on sustainability and carbon footprint reduction in construction. Preliminary environmental assessments using life cycle assessment (LCA) have demonstrated that hempcrete block walls outperform conventional materials like concrete and brick in terms of environmental impact. LCA studies indicate that hempcrete not only reduces the operational energy requirements of buildings but also lowers the overall environmental impact through carbon sequestration during hemp growth. Research by [7,19,20] supports the introduction of hempcrete as a sustainable construction material, highlighting its advantages over traditional materials for those seeking to balance functional building needs with ecological responsibility.

Figure 2. Hempcrete block [21] (used with permission).

Figure 2. Hempcrete block [21] (used with permission).

2.2.2. Hempcrete In Situ Mixture

Cast-in situ hempcrete (Figure 3) involves mixing hempcrete on-site and casting it into molds made from shuttering or formwork to create walls, floors, or roofs. Shuttering can be temporary or permanent. Since conventionally used hempcrete is non-load bearing, it is always cast around a structural frame, typically timber, which bears the building’s load. In new constructions, a simple softwood studwork frame is usually placed within the hempcrete wall. The hemp shiv and binder are mixed with water using various mechanical mixers, depending on the project’s needs. The mixed hempcrete is placed or sprayed into the shuttering void, allowed to set initially, then the temporary shuttering is removed, and the hempcrete dries over a few weeks before finishing touches are applied [10]. Variations in mixture composition and compaction during in situ casting can affect performance, especially with do-it-yourself (DIY) projects. Additionally, the drying process of lime impacts its thermal conductivity; that is, thicker layers could slow this process further. Future research will explore the drying times and thermal comfort in lime hemp walls to optimize their use and improve energy performance metrics [22].

Figure 3. Hempcrete mixture from UK Hemp [23] (used with permission).

Figure 3. Hempcrete mixture from UK Hemp [23] (used with permission).

2.2.3. Hempcrete Spray

Spray-applied hempcrete (Figure 4), popular in France, has been introduced to the UK by Myles and Louisa Yallop of The Limecrete Company. They have promoted sustainable construction, transitioning from hand-placed to spray-applied hempcrete. Their spray machines, operational since 2012, are the first in the UK. In the U.S., Americhanvre (https://americhanvre.com, accessed on 10 May 2025) has introduced spray-applied hempcrete and has been using this technique in constructing homes. This method has both pros and cons, with continuous advancements in techniques and equipment. The spray-applied method is like hand-placed hempcrete but uses mechanized delivery and requires slight modifications to the structural frame [10]. While sprayed hempcrete shares similarities with molded hempcrete, differences at high relative humidities may occur in hempcrete after spraying due to variations in pore size distribution [24].

To summarize, the attributes of the three forms of hempcrete application are listed in

Table 1. Comparison of different forms of hempcrete.

Feature	Hempcrete Block	Hempcrete In Situ	Hempcrete Spray
Form	Precast Blocks	Wet-mixed, cast in formwork	Mechanically sprayed wet mix
Common Applications	Wall infill, internal partitions	Wall systems, floors	Walls, roofs (fast build)
Installation Method	Laid with lime mortar	Hand placed into shuttering	Sprayed using machine onto form
Mixture Composition	Hemp shiv + Lim binder + water + (additives)	Hemp shiv + Lime binder + Water	Hemp shiv + Lime binder + Water
Construction Speed	Moderate	Slow (curing needed)	Fast (depending on the thickness)
On-site Equipment Needed	Basic tools, cutting saw	Mixer, formwork, hand tools	Spray machine + trained operator
Customization	Moderate (cut to fit on site)	High (adjustable mix)	Low (factory-mixed)
Labor Intensity	Moderate	High	High

.

3. Different Formulation of Hempcrete

3.1. Types of Binder Used in Hempcrete

A hempcrete binder must meet the following requirements [10]:

• Initial Strength: It should provide an initial set with sufficient strength to support the weight of the drying hempcrete wall, requiring a strong hydraulic set.
• Vapor Permeability: It must allow water to continue drying out of the hemp shiv after the initial set, ensuring vapor permeability.
• Long-term Strength: It should offer long-term structural strength, providing a full set over time.

• Lime

Lime-based binder is the most used type of binder in hempcrete mixture. Lime plays a crucial role in the composition of hempcrete, serving as a binding agent that enhances the material’s structural and environmental properties. When combined with hemp shiv, lime creates a natural composite that is both strong and lightweight. Its primary function is to bind the hemp shiv, providing structural integrity while maintaining flexibility. Lime contributes to hempcrete’s high vapor permeability, allowing moisture to evaporate, which helps prevent mold growth and maintains a healthy indoor environment. Additionally, lime’s natural alkalinity provides anti-fungal properties, enhancing the durability and longevity of hempcrete structures [10,22,26,27,28,29].

Besides the basic lime used in hempcrete mixture, research also shows the potential of using local materials as a binder together with lime in hempcrete, such as clay or metakaolin (https://www.greenbuildermedia.com/blog/insulation-alternative-hempcrete, accessed on 10 May 2025). The study developed a binder using local raw materials, specifically pumice sand and calcic lime CL90, to explore its potential in plant-based aggregates in concrete applications. The mechanical performance of this lime-pozzolan binder was evaluated, demonstrating that a mixture with a pumice-to-lime ratio of 90% to 10% by weight achieved a compressive strength exceeding 8 MPa after 28 days, which is comparable to lime-based binders currently used in plant concrete. This finding underscores the potential of pumice lime as a viable alternative to conventional concrete for construction, particularly when combined with plant aggregates. However, the presence of crystalline silica in pumice sand may limit its use to precast products due to potential health and safety concerns. Hempcrete’s properties, tested across densities from 190 to 540 kg/m³, demonstrate significant dependence on binder content and density. Higher-density hempcrete was shown to provide enhanced microbiological stability due to its high pH, even under humid conditions. These results underscore hempcrete’s potential as a bio-based alternative to traditional materials, meeting stricter standards for energy efficiency and indoor environmental quality [30]. The study suggests that future research should focus on optimizing binder formulations to enhance compatibility with plant-based aggregate concrete and address any potential interface issues [4].

• Starch

An experimental investigation examined the mechanical performance of starch-hemp composite materials, which are made from 100% natural fibers and are durable. The optimization of the binder solution was based on dynamic viscosity and surface tension. Specimens with five different hemp/starch ratios (6, 8, 10, 12, and 14) were created using the optimal binder. During the 30 to 40 days drying process, the specimen density decreased rapidly down to a range from an average of 170.8 kg/m³ to 158.9 kg/m³, resulting in a material lighter than lime hemp concrete with the average density of 350 kg/m³ to 465 kg/m³ [16,31,32]. The tensile strength of the specimens ranged from 0.03 to 0.08 MPa, the elasticity modulus ranged from 1.47 to 2.16 MPa, and the Poisson ratio ranged from 0.08 to 0.12, as the hemp/starch ratio increased from 6 to 14. Since the bio-composite in the study is deformable, the failure mode of such material is based on the appearance and propagation of cracks [31].

• Magnesium Oxide (MgO)

The use of magnesium oxide (MgO) as an alternative binder introduces another variable due to its unique hydration process and lower calcination temperature compared to lime, potentially contributing to both environmental and mechanical benefits. The study by [33] emphasizes the sustainable production of magnesium oxide (MgO) from reject brine as an alternative to traditional materials like lime (CaO). However, unlike lime, which is typically produced from limestone at higher calcination temperatures (~900–1000 °C), MgO in this study was successfully synthesized at a lower calcination temperature of 700 °C. The resulting MgO demonstrated high reactivity and a large surface area (58.01 m²/g), suggesting superior performance for applications requiring rapid hydration and chemical interaction. Moreover, while lime production relies on mining and thermal decomposition of calcium carbonate—processes that are energy-intensive and emit significant CO₂—this method of MgO production uses waste reject brine, offering a resource-efficient and low-carbon pathway. The life cycle assessment (LCA) further supports the environmental advantages of MgO over lime, showing reduced ecological impact due to brine valorization and material circularity.

Additionally, hempcrete composites utilizing magnesium binders exhibit approximately twice the compressive strength of those with lime binders while maintaining similar density and thermal conductivity. These findings suggest that magnesium-based binders not only improve the mechanical properties of hempcrete but also offer substantial environmental benefits, positioning them as a promising alternative in sustainable construction practices [20]. Thus, MgO not only offers technical benefits such as higher reactivity and lower production temperature but also delivers environmental advantages over conventional lime, aligning with sustainable development goals in construction materials.

Table 2. Comparison of lime and MgO as binder in hempcrete [33].

Aspect	Lime (CaO)	Magnesium Oxide (MgO)
Raw Material	Limestone (CaCO3)	Reject brine (Mg2+ from desalination)
Calcination Reaction	CaCO3 → CaO + CO2	MgCO3 or Mg precursors → MgO + CO2
Calcination Temperature	~900–1000 °C	~700 °C
Energy Consumption	High	Lower
CO2 Emissions	High (from carbonate breakdown and fuel)	Lower (especially when sourced from waste brine)
Reactivity	Moderate	High (58.01 m2/g surface area)
Hydration Behavior	Slower and more controlled	Faster, with high surface area and fast dissolution
Source Sustainability	Finite, mined mineral	Derived from industrial waste (brine valorization)
Environmental Impact	Higher due to mining and emissions	Lower due to waste recycling and energy efficiency
Suitability for Hempcrete	Traditional binder	Promising alternative with enhanced reactivity and greenness

summarizes the attributes of lime and MgO binders for hempcrete.

Reference [34] investigated various strategies to improve this property, including alternative binders like magnesium oxide (MgO), additives such as metakaolin, fly ash, and nanosilica, and finding the best mixture proportions for increasing the strength. Incorporating sand as a fine aggregate was also evaluated. The experimental results showed significant improvements, with compressive strength increasing from 58 psi to 655 psi depending on the mixture design. Specimen 2LS60, with 45% MgO, 5% hemp of total weight, with an additive 60% sand of total weight, and 4% nanosilica of binder weight (for 100 g 2LS60 mixture, we will need 27.8 g MgO, 3.1 g hemp, 30.9 g water, 37.1 g sand, and 1.1 g nanosilica), achieved the highest strength of 655 psi, a 2,126% increase over the original strength of 29.43 psi [34]. The study concluded that determining the right binder content, particularly using MgO, and reducing hemp hurd content, along with synergistic pozzolanic additives and sand, substantially enhances hempcrete’s mechanical properties. These findings support the development of high-performance hempcrete mixtures suitable for load-bearing applications, contributing to sustainable construction practices by offering a viable, eco-friendly alternative to conventional concrete [11].

3.2. Additional Add-Ons in Hempcrete

• Sands

Incorporating sand as a fine aggregate into hempcrete to enhance its load-bearing property is investigated in several studies [11,34,35]. Adding sand to hempcrete can significantly influence the material’s mechanical properties and performance. Sand acts as an aggregate that enhances the density and compressive strength of hempcrete, making it more robust and durable for load-bearing applications. By incorporating sand, the mixture achieves a better compaction, which can lead to improved load-bearing capabilities while still maintaining the lightweight nature of hempcrete. Moreover, sand can help control the material’s thermal conductivity, potentially improving its insulation properties by filling in voids and reducing air pockets. However, it is important to balance the amount of sand added, as excessive sand can compromise hempcrete’s desirable qualities [36]. Adding sand into hempcrete composite, together with finding the most appropriate binder content, particularly using MgO, and reducing hemp hurd content, along with synergistic pozzolanic additives, substantially enhances hempcrete’s mechanical properties [34].

• Metakaolin

A study by [37] demonstrated that incorporating metakaolin into air–lime binder significantly enhances its mechanical properties, with a 20% replacement resulting in a 41% increase in compressive strength and 14% in flexural strength (from the load deflection curve for flexural test) due to the pozzolanic reaction forming C-S-H hydrates. For hemp concrete, adding 20% metakaolin improved compressive strength by 80%, despite a 20% reduction in dry density, while maintaining ductile behavior that improves structural safety by delaying the failure phase. These findings highlight metakaolin’s role in strengthening air–lime binder, consuming free Ca²⁺ ions, and reducing the vulnerability of embedded hemp particles.

• Fly Ash

The incorporation of modified fly ash in cementitious materials significantly enhances compressive strength (66 MPa) [38]. Such findings suggest that perhaps the use of fly ash may be suitable for use in crop fibers such as hemp fibers in construction materials. According to [39], incorporating low-calcium fly ash-based geopolymer as a binder in hempcrete offers environmental benefits and maintains structural integrity under magnesium sulfate exposure. However, attention should be given to potential sodium leaching, which can affect long-term durability, especially in sulfate-rich environments. Reference [40] shows that adding fly ash to hempcrete improves its compressive strength and durability by enhancing the binder matrix through pozzolanic reactions and better particle packing. Typically used as a partial cement or lime replacement (10–30%), fly ash reduces porosity, increases long-term strength, and contributes to improved workability and environmental performance.

• Silica Fume

The study reported by [41] reveals that adding silica fume to concrete mixture enhances concrete’s compressive, tensile, and flexural strengths and flexural aspects (such as deflection of beam), while Manila hemp fibers improve toughness and crack resistance but slightly reduce these strength metrics. Workability decreases with the inclusion of silica fume and fibers, as evidenced by reduced slump and compaction values, with Mix M14 (25% silica fume, 1.5% fibers) showing the lowest workability but superior stiffness. Despite minor strength reductions, Mix M14 demonstrated the best load-bearing capacity, highlighting the effective reinforcement of silica fume and Manila hemp fibers for improved structural performance.

• Gum Arabic

The study reported by [42] reveals that adding gum arabic to lime-metakaolin mixtures significantly affects their properties, increasing total porosity and pore diameter while reducing specific pore surface area. Despite higher porosity, gum arabic admixtures (3% and 5%) enhanced flexural strength by a factor of three and improved compressive strength by 25–60% in pastes and by 53–92% in hemp–lime composites, while also decreasing water absorption. However, water immersion reduced the compressive strength of hemp–lime composites by 45–63%, with greater reductions observed for higher gum arabic content, though strength recovery upon re-drying remained partial.

• Bamboo

Bamboo is noted for its flexibility and strength, making it an excellent choice for resisting tensile loads or stresses, which is crucial for structural integrity. Unlike other woody materials, bamboo’s extreme flexibility allows it to be bent and used in curved structures, such as archways, making it particularly suitable for dome-shaped structures. Reference [36] highlights the potential of bamboo as a sustainable construction material, particularly in the context of 3D-printed hempcrete houses. Bamboo reinforcement is ideal for 3D-printed dome houses, where its tensile strength complements the compressive strength of materials like concrete and hempcrete. These materials, when used in combination, can enhance the structural performance of 3D-printed buildings, providing environmentally friendly and cost-effective solutions. The paper suggests that the integration of bamboo with other green materials in 3D printing could lead to innovative, sustainable building practices that reduce the environmental impact of construction.

Table 3. Comparison of different additives used in hempcrete mixture.

Additive	Purpose/Effect	Notable Results	References
Sand	Enhances density and compressive strength; improves compaction; optimizes thermal conductivity	Requires balance; excessive use may reduce hempcrete benefits	[11,34,35]
Metakaolin	Improves compressive and flexural strength; enhances pozzolanic reaction; maintains ductility	20% metakaolin → 80% strength gain; 14% flexural strength increase	[37]
Fly Ash	Increases compressive strength; suitable for sulfate exposure; may leach sodium	66 MPa for cementitious mix; benefits in geopolymer binder	[38,39]
Silica Fume	Enhances all strength types; increases stiffness; reduces workability	Mix M14 with 25% silica fume showed highest stiffness but low workability	[41]
Gum Arabic	Increases porosity and flexural strength; reduces water absorption; partial strength recovery after re-drying	3–5% of gum arabic addition improved compressive strength by 25–60%; water immersion reduced strength by 45–63%	[42]
Bamboo	Provides tensile strength; ideal for 3D-printed dome structures; sustainable reinforcement	Suitable for tensile resistance in curved and dome-shaped structures	[36]
New Materials	Improves hygrothermal properties and compressive strength; uses recycled brick and MPCMs; supports insulation	0.09–0.57 MPa strength; 0.087–0.10 W/m·K conductivity; 2.78 gm/m2 RH% moisture buffering	[27]

summarizes the attributes of different additives for hempcrete.

• New Material Addition

Reference [27] shows that mixtures with a 1:1 binder-to-hemp ratio and densities of 300–400 kg/m³ exhibit hygrothermal and mechanical properties suitable for insulating in-fill wall applications. These properties include compressive strengths of 0.09–0.57 MPa (again, compare to conventional concrete with 21 MPa compressive strength), thermal conductivities of 0.087–0.10 W/m·K, and specific heat capacities of 1250–1557 J/kg·K. Additionally, the samples demonstrated excellent moisture buffering capacity, with an average value of 2.78 (gm/m² RH%). Recycled crushed brick pozzolan significantly enhances performance, with 10% crushed brick (as an aggregate) producing the lowest thermal conductivity and highest moisture buffer capacity among the samples. Moreover, binder formulas combining hydrated lime and crushed brick achieve mechanical properties comparable to those using metakaolin and hydraulic lime. These findings highlight the potential for sustainable and high-performing hemp–lime composites in construction. The integration of microencapsulated phase change materials (MPCMs) into hempcrete also presents a promising advancement in enhancing its thermal properties for construction applications. However, increasing the proportion of MPCMs beyond certain levels can diminish energy savings, highlighting the need for careful consideration of the material’s composition and its application in building envelopes.

3.3. Pre-Treatment of Hemp

Pre-treatment innovation suggests potential for substantial energy savings, especially in heating and cooling, while also requiring adjustments in building systems to optimize performance [43]. Reference [44] shows that increased water absorption from adding hemp fibers can weaken mortar strength over time. This underscores the potential of hemp pre-treatment—by reducing water uptake, it can improve fiber–matrix bonding and enhance the mechanical strength of hempcrete. A simple one-step dip-coating process has been employed to impart hydrophobic properties to hemp shiv. This was achieved through topological alteration and chemical modification using silica-based sol-gel coatings. The treated hemp shiv demonstrated several improved characteristics compared to its untreated counterpart, including stable water repellence with contact angles maintained for over 60 s, controlled surface wettability, a uniform and crack-free coating, and increased surface roughness with contact angles reaching up to 118°. These enhancements suggest that water-based sol–gel coatings with low HDTMS precursor loading are advantageous for the bio-based building industry, offering benefits such as hygroscopic properties, long shelf life, cost reduction, and lower environmental impact, making them a viable option for improving the durability and performance of bio-based construction materials [45].

Additionally, according to reference [46], linseed oil pre-treatment is hypothesized to reduce water absorption by the hemp shiv, thereby stabilizing the matrix and improving durability under compressive stress. Linseed oil pre-treatment improved compressive strength and elastic modulus and reduced water absorption, making it a valuable long-term enhancement despite a slight increase in thermal conductivity.

Table 4. Hempcrete mixture design and properties based on different studies.

Study	Hemp/ Lime Ratio	Hemp	Lime	Water	Addons	Density (kg/m3)	Thermal Conductivity (W/mK)	Compressive Strength (MPa)
[47]	0.75	25%	33%	42%	NA	330	0.27	NA
[16]	1.6	32%	20%	48%	NA	275	NA	NA
[30]	0.25	12%	49%	39%	NA	540 ± 19	0.120 ± 0.011	0.562 ± 0.051
[30]	0.38	16%	42%	42%	NA	385 ± 5	0.086 ± 0.007	0.163 ± 0.036
[30]	0.83	24%	29%	47%	NA	265 ± 14	0.071 ± 0.007	0.071 ± 0.033
[30]	1.94	33%	17%	50%	NA	190 ± 11	0.061 ± 0.003	NA
[27]	2.00	20%	10%	60%	Metakaolin10%	365	0.0910	0.33
[27]	1.43	20%	14%	60%	Natural hydraulic lime	324	0.0912	0.30
[48]	1.3	17%	13%	67%	Slag 3%	200	_	0.11
[48]	1.9	19%	10%	69%	Slag 2%	170	_	0.072
[48]	2.9	20%	7%	71%	Slag 2%	140	_	0.033
[49]	0.5	19%	37%	44%	Microorganisms 1%	_	_	_

summarizes the mixture design and properties based on the reviewed literature.

4. Applications of Hempcrete in Structures

Hempcrete is increasingly applied in sustainable home construction in the form of blocks, spray-applied mixtures, and in situ cast mixtures. Hempcrete is applied to modern residential buildings due to its compatibility with existing timber framing systems. Currently, both hempcrete blocks and spray-applied hempcrete are used as the wall insulation, while in other cases, in situ cast hempcrete is used to construct wall and floor systems. All three of these forms are made from hemp shiv mixed with lime-based binders, sometimes modified with additives like fly ash or metakaolin to enhance performance. These hempcrete products are known for their low density (250–500 kg/m³), desirable thermal properties, and excellent moisture regulation properties, making hempcrete ideal for energy-efficient, breathable, and environmentally responsible housing.

4.1. Wall System

Hempcrete is widely used in wall systems, offering a sustainable and protective solution for building structures, and is particularly beneficial for walls because of its breathable nature and lime binder. This combination helps protect both the hemp aggregate and the timber frame from moisture-related issues, allowing untreated softwood to be used within the hempcrete without additional moisture protection measures. Hempcrete blocks are modular units placed with thin lime-based mortar joints to form non-load-bearing wall infill. Spray-applied hempcrete and cast-in-place hempcrete are commonly used for thermal insulation purposes. Although specific research on the longevity of untreated softwood in hempcrete is lacking, industry practice in the UK supports its effectiveness, with many existing hempcrete buildings reporting no adverse effects [10]. Hempcrete is especially ideal for insulating exterior walls in most low-rise buildings when it has a density ranging from 250 to 350 kg/m³. This type of insulation can be used as infill within the structural frame of the wall, such as between studs, or it can be applied to the outer or inner surfaces of the frame [11]. Similarly, reference [17] has shown that precast blocks composed of hemp shiv and lime-metakaolin binders exhibit medium density (466 kg/m³), high porosity, and significant air permeability—contributing to indoor air quality and thermal efficiency.

4.2. Flooring

Although hempcrete alone is not sufficient for a floor without an impractically thick layer, it adds thermal mass and helps the floor act as a heat storage. It also allows for a continuous insulation layer with hempcrete walls, reducing thermal bridging. To maintain the benefits of a hempcrete floor (Figure 5), it is crucial to use breathable finishes that prevent moisture buildup in the hempcrete layer, which could lead to deterioration or failure. This approach is unsuitable for areas requiring a radon barrier, where a non-breathable floor slab is necessary [10]. Hempcrete can be used as an insulating, vapor-permeable floor slab, offering a natural, non-toxic alternative to conventional floor construction methods. Traditional floors typically involve synthetic insulation products, combined with concrete, a plastic damp-proof membrane (DPM), and a cement screed, resulting in non-vapor-permeable floors. These synthetic materials have high embodied energy and can off-gas toxic chemicals [1].

4.3. Roof

Using hempcrete in roofing applications offers several advantages, particularly in terms of sustainability and thermal performance. Hempcrete is a natural insulating material, making it ideal for roofs where addressing thermal regulation is crucial. Its high thermal mass also helps maintain a stable indoor temperature by absorbing and slowly releasing heat, which can lead to energy savings in both heating and cooling. Additionally, hempcrete’s breathability allows moisture to escape, reducing the risk of condensation and mold growth in the roof structure. Incorporating hempcrete in roofs can also enhance sound insulation, providing a quieter indoor environment. The lightweight nature of hempcrete reduces the load on supporting structures, making it suitable for various architectural designs. Moreover, hempcrete’s natural resistance to pests and fire adds an extra layer of protection to roofing systems.

In a pitched roof design, the roof timbers typically form a separate structure that rests on and is fixed to the wall structure. This can be accomplished in various ways, such as using prefabricated trusses delivered to the site or constructing the roof with single timbers on-site. Single-pitch or flat roofs are usually built with engineered joists. For hempcrete buildings, roof design options generally mirror those used in conventional wood-frame construction. The primary difference is often the inclusion of a long roof overhang at the eaves to provide additional rain protection. This can be achieved with longer rafters or additional bolt-on rafter ends [10].

Table 5. Comparison of compressive strength of hempcrete and other materials.

Material/Standard	Compressive Strength (MPa)	Notes and References
Typical Hempcrete Block (Lab-tested)	0.3–3.5 MPa	Varies with binder, curing, additives [50]
Clay Brick Masonry (ASTM C1314)	3–10 MPa (prism)	Typical bonded wall values [51]
Concrete Masonry Unit (CMU)	3–9 MPa (prism)	Non-reinforced wall assemblies [51]
Normal Structural Concrete	20–40 MPa	Structural applications [52]

summarizes the compressive strength of hempcrete and other materials for construction. Hempcrete, with a compressive strength range of 0.3 to 3.5 MPa [50], is notably weaker than traditional masonry materials such as clay brick and concrete masonry units (CMUs), which typically range from 3 to 10 MPa [51]. In contrast, structural concrete exhibits the highest compressive strength, ranging from 20 to 40 MPa [52], making it suitable for heavy-load-bearing applications. While hempcrete offers environmental and insulation benefits, its relatively low strength limits its structural use compared to conventional materials.

5. Advantages of Using Hempcrete in Construction

5.1. Sustainability

Given that over 95% of buildings are residential dwellings, for any meaningful global impact on CO₂ reduction, locally sourced materials and easy-to-construct methods are needed for energy-efficient and low-carbon residential buildings. One such promising material is industrial hemp [53]. To reiterate the advantages and attributes, hempcrete, a plant-based biomaterial, is lightweight yet dense, and it can be cultivated in small areas with minimal pesticide use. It is fire-resistant, durable, acts as a carbon dioxide sink, is recyclable, energy-efficient, non-toxic, and insect-resistant due to its lack of protein content, making it both environmentally and construction friendly [6,7,8,11]. Hempcrete can be used in walls, floors, and roofs and is available in blocks and panels that reduce construction time and cost [13]. Hempcrete has been shown to have potential in residential construction applications to improve thermal resistance of masonry walls, reduce consumption of carbon-intensive concrete, and reduce the weight of cement-based structures. Reference [54] highlights a state-of-the-art review of hempcrete for affordable and sustainable home building and describes key research needed for this composite material to be a successful alternative to conventional wood-frame residential building construction.

5.2. Thermal Insulation

Hempcrete is a medium-density material that is relatively lightweight compared to other walling materials like stone, brick, or concrete due to its high air content. In a finished hempcrete wall, air is trapped within the microscopic pore structure of the hemp shiv and the air channels and pockets formed by the interlocking particles of hemp shiv. This trapped air gives hempcrete walls superior insulation compared to other general walling materials. However, compared to specific insulation products such as very lightweight fiber insulations like wood fiber or sheep’s wool, hempcrete performs less effectively at an equivalent thickness. Despite this, hempcrete is much cheaper than processed insulation materials and, due to its medium density, is often used to create the entire thickness of a monolithic wall. By pouring hempcrete into formworks or spraying it, builders create seamless walls that combine structure, insulation, and thermal mass in a single layer, typically 300 to 400 mm (12–16 inches) thick. This method is cost-effective because hempcrete production is less energy-intensive than traditional insulation materials like fiberglass, and it eliminates the need for additional layers like vapor barriers. This wall typically includes only thin render and plaster finishes or cladding on the exterior and interior surfaces. The thickness of cast hempcrete insulation is usually between 300 mm and 400 mm, achieving typical U-values around 0.12–0.30 W/m²·K depending on density and binder composition, and providing a very high standard of insulation [10]. For instance, a study by [55] highlighted that the cost of producing hempcrete walls, including raw materials and processing, is around 30–50% lower than synthetic insulation materials. Additionally, hempcrete’s medium density (typically around 275–500 kg/m³) makes it suitable for constructing monolithic walls of full thickness, eliminating the need for additional structural or insulation layers. This dual functionality further reduces overall construction costs.

5.3. Fire Resistance

Hempcrete exhibits remarkable fire resistance due to its composition and physical properties, making it a safe choice for construction. Unlike many conventional building materials, hempcrete is non-combustible, meaning it does not ignite easily or contribute to fire spread. The lime-based binder in hempcrete creates a fire-resistant barrier that helps protect the hemp fibers from ignition. When exposed to fire, hempcrete can withstand high temperatures without losing structural integrity for extended periods. Its ability to resist flames and limit heat transfer can delay the progression of a fire, providing occupants with more time to evacuate and reducing overall fire damage. Additionally, hempcrete does not release toxic fumes when exposed to heat, which further enhances its safety profile. These fire-resistant qualities make hempcrete an attractive option for sustainable construction projects where safety is a priority [10].

5.4. Moisture Regulation

Hempcrete is highly effective in moisture management due to its porous structure and vapor permeability. Its ability to absorb and release moisture helps maintain a stable indoor humidity level, creating a healthier living environment. The natural hygroscopic properties of hemp fibers allow hempcrete to absorb excess moisture from the air when humidity levels are high and release it when the air is dry. This capability prevents the buildup of moisture within walls, reducing the risk of mold and mildew growth, which can be harmful to both the structure and the occupants’ health. Furthermore, the lime binder in hempcrete contributes to its moisture-regulating properties by facilitating breathability, allowing moisture to pass through without compromising structural integrity. This moisture management capability enhances the durability and longevity of hempcrete buildings while contributing to energy efficiency by reducing the need for mechanical ventilation systems. Overall, hempcrete’s natural moisture-related attributes make it an ideal material for sustainable construction, promoting comfort and well-being in living spaces [1,2,10,13].

6. Case Study of Hempcrete Structures or Buildings

Hempcrete is increasingly utilized in construction for its sustainability, versatility, and efficiency. It can be used in walls, floors, and roofs and is available in blocks and panels that can potentially reduce construction time and cost. It is commonly used in large-scale projects, including commercial and public buildings [13].

6.1. The Hempcrete Museum Store [HMS], Wroughton

The innovative hempcrete storage facility building of the science museum, made from hemp and lime, won the Sustainability Award at the Museums and Heritage Awards, outperforming competitors like the BP Showcase Pavilion at the Olympic Park and the Museum of Surfing. The hempcrete facility was created as a cutting-edge solution to protect sensitive objects, such as horse-drawn carriages, fine art, wooden ship models, and paper archives, from climate conditions, e.g., light, heat, and moisture. The building’s zero-carbon design, using natural materials that buffer temperature and humidity, ensures the preservation of the museum’s collections for future generations. Hempcrete is a sustainable material composed of hemp fiber and lime mortar, formed into hemp-clad panels, commonly used in housing and industrial buildings. Beyond preserving objects, the Hempcrete facility helps the museum reduce carbon emissions and achieve significant energy savings. The Hempcrete Museum Store represents a sustainable approach to museum storage. Although construction costs were 10% higher than traditional methods, operational costs are less than half of similarly sized climate-controlled spaces. Made from bio-based materials like hemp–lime, the building reduces carbon footprint, stabilizes environmental conditions, and locks in CO₂ over time. Its hygroscopic properties maintain stable humidity and temperature, even during air handling [56,57].

6.2. Pennsylvania Hempcrete Home

The PA Hemp Home (Figure 6) is a pilot project located in New Castle, Pennsylvania, aimed at researching, testing, and applying hemp–lime insulation in the renovation of a small, affordable, and sustainable home. Led by DON Enterprise and supported by the Pennsylvania Department of Agriculture, the project focuses on creating healthy, affordable, and visitable housing. Initially, there was no acceptable building code for hemp–lime insulation, but the PA Hemp Home was used to support the proposed hemp–lime construction appendix for the International Residential Code (ICC 2024) [58]. The project received accolades, being named an honoree in the 2021 Fast Co. Innovation by Design Awards for the Materials Category and listed as one of the Top 10 Design Innovations in the United States on the television series America by Design from ByDesignTV. The project involves collaboration with expert hemp–lime builders Cameron McIntosh from Americhanvre in Pennsylvania and Alex Sparrow from UK Hempcrete in England. The Pennsylvania Housing Research Center at Penn State University conducted energy and performance testing, with findings shared with Pennsylvania businesses and residents, while the Healthy Materials Lab at Parsons managed the house renovation design and indoor air quality monitoring and testing (https://healthymaterialslab.org/projects/pa-hemp-home, accessed on 10 May 2025). This project shows the potential of using hempcrete in residential structures.

6.3. A Long-Term Case Study of Hygrothermal Performance of a Hemp–Lime Concrete Building

The study by [59] presents a four-year evaluation of a hemp–lime concrete (HLC) building (Figure 7) located in southwestern France, highlighting the material’s excellent hygrothermal performance in real climatic conditions. The 30 cm thick sprayed HLC walls significantly dampened external temperature fluctuations—up to 90%—and delayed peak effects by approximately 12 h, ensuring consistent indoor comfort throughout the seasons. Indoor temperatures remained within thermal comfort zones defined by EN 15251 standards [60], with relative humidity levels between 40 and 60%, demonstrating the material’s moisture buffering capability. In-depth wall monitoring showed that HLC responded effectively to outdoor variations, with gradual internal moisture stabilization over time. Numerical simulations (WUFI (Pro 5.1) and MATLAB (Ver. 9.4) -based models) were compared to measured data, revealing good agreement, particularly when temperature-dependent sorption processes were considered. This confirms the effectiveness of HLC as a high-performance, sustainable envelope material for regulating indoor climate with minimal energy demand.

6.4. Hemp–Lime Buildings Case Study in North and South Italy

Two case studies [61] in Northern and Southern Italy have evaluated the performance of hemp–lime buildings (Figure 8) through in situ monitoring, demonstrating that prefabricated hemp–lime blocks provide stable indoor temperatures and effective humidity regulation under both cold and warm Mediterranean climates. Despite limited or no HVAC use, internal conditions remained comfortable, with minimal fluctuation in temperature and relative humidity. The material’s high porosity and hygroscopicity allowed it to buffer external climate variations effectively. Numerical simulations using WUFI^® (Pro 6.3) closely matched experimental results, validating the material’s passive insulation capabilities. These findings confirm hemp–lime’s suitability for sustainable construction, supporting its role in energy-efficient, low-impact building design.

7. Life Cycle Assessment (LAC) of Hempcrete

Life cycle assessment (LCA) is a critical tool for evaluating the environmental impacts of building materials throughout their entire life span—from raw material extraction to end-of-life disposal. Hempcrete, being a bio-based composite made from hemp shiv and a lime-based binder, shows promising results in LCA studies due to its renewable content, low embodied energy, and carbon sequestration potential.

Several studies have highlighted hempcrete’s sustainability advantages. Reference [62] uses a cradle-to-gate system boundary (pre-farm for urea/fertilizer production, on-farm for hemp cultivation, and post-farm for bio-binder production and board manufacturing) and a functional unit of 1 m² of hemp-based board in Western Australia. This results in a net carbon footprint of −2.302 kg CO₂ eq. Urea production contributes to 14% of total emissions, while electricity for bio-binder production (from the public grid) accounts for 26% (and grid electricity overall makes up 45% of emissions). If all grid electricity is replaced by solar power, the carbon footprint decreases to −6.07 kg CO₂ eq, a 164% reduction compared to the base case. References [49,63] conducted an LCA study comparing hempcrete walls with varying thicknesses and coatings, demonstrating that even with additional lime coatings, hempcrete maintained a significantly lower environmental impact compared to traditional concrete or brick systems. The CO₂ sequestration during hemp cultivation plays a vital role, with estimates showing that hempcrete can absorb more carbon than it emits during production, effectively acting as a carbon-negative material in certain configurations. Reference [63] also emphasized that factors like binder formulation, transportation distances, and application method (spray, cast-in-place, or block) influence the LCA results. For instance, cast-in-place systems often reduce emissions due to less transportation and on-site formwork reuse. Reference [49] evaluates the environmental performance of non-load-bearing walls constructed with hempcrete blocks using LCA methodology. It finds that hempcrete blocks can act as a net carbon sink due to CO₂ uptake during hemp cultivation and carbonation of the lime binder, with experimental verification via X-ray diffraction. Although lime binder production and raw material transportation contribute significantly to environmental impacts, the overall energy demand and global warming potential are substantially lower than those of conventional materials. The results confirm that prefabricated hempcrete blocks are a sustainable building alternative, especially when optimized for carbon sequestration and energy efficiency.

The study by [20] evaluates the environmental performance of magnesium-based binders as compared to traditional lime binders in hempcrete. The research reveals that magnesium binders can significantly reduce the global warming potential of hempcrete, primarily due to lower CO₂ emissions during production and enhanced carbon sequestration through carbonation.

Table 6. LCA comparison of hempcrete and conventional concrete.

Property/Metric	Hempcrete	Conventional Concrete	LCA Boundary	Reference(s)
Global warming potential (GWP)	–1.03 to –2.30 kg CO2 eq per m2 (0.25 m-thick wall) [after carbonation] −40 to −80 kg CO2 eq per m3 (varies by binder mix)	+300 to +400 kg CO2 eq per m3 (OPC concrete) +50 to +90 kg CO2 eq per m2 (masonry wall; 0.20–0.25 m thick)	Cradle-to-Gate (includes raw material extraction, binder production, transport, and manufacturing)	[63,64,65]
Transport sensitivity	Transport within ~50–200 km adds 5–15% to total GWP; >200 km increases impacts	Cement and aggregates often transported >100 km; transport can contribute 10–20% of OPC GWP	Included in Cradle-to-Gate	[64,66]
Electricity source impact	Grid electricity for bio-binder production contributes up to 45% of hempcrete GWP; 100% solar reduces net CF by ~164%	Cement production energy (kiln fuel + electricity) >80% of OPC CF	Included in Cradle-to-Gate	[65,66]
Functional unit (for LCA)	1 m2 hempcrete wall (0.25 m thick, U-value ≈ 0.27 W/m2·K) or 1 m3 hempcrete mix	1 m2 concrete/masonry wall (0.20–0.25 m thick) or 1 m3 concrete mix	Cradle-to-Gate (some studies extend to Cradle-to-Grave)	[63,64,66]

shows a comparison between hempcrete and conventional concrete in terms of life cycle assessment (LCA) with cradle-to-gate and cradle-to-operation boundaries, covering material extraction, transport, production, and, in some studies, operational phases. Hempcrete demonstrates a significant environmental advantage with a net negative global warming potential (GWP) ranging from −1.0 to −2.3 kg CO₂ eq per m² (or approximately −40 to −80 kg CO₂ eq per m³), primarily due to biogenic carbon sequestration during hemp growth and carbonation of lime binders. In contrast, conventional concrete walls (0.20–0.25 m thick) exhibit a positive GWP of around +50 to +90 kg CO₂ eq per m² (or +300 to +400 kg CO₂ eq per m³ for Ordinary Portland Cement-based mixes). Additionally, hempcrete has superior insulation properties, with lower density (300–600 kg/m³) and thermal conductivity (0.05–0.15 W/m·K) compared to concrete (2200–2400 kg/m³ density and 1.7–2.0 W/m·K thermal conductivity). However, hempcrete is generally non-load bearing (compressive strength of 1–3 MPa) compared to concrete’s structural capacity (20–40 MPa). Electricity used in hempcrete binder production significantly impacts its carbon footprint (up to 45% of emissions), but this can be markedly reduced by utilizing renewable energy sources. Conversely, cement production energy constitutes over 80% of concrete’s total embodied carbon [63,64,65].

Overall, the LCA study of hempcrete confirms its alignment with sustainable building practices, contributing not only to reduced energy consumption and emissions during use but also to improved end-of-life performance through biodegradability and low-toxicity disposal.

8. Discussion

8.1. Compare Hempcrete Mechanical Properties from Different Hempcrete Formulars

The mechanical properties of hempcrete are largely dependent on the formulation and specific components used in its creation. Traditional hempcrete, made from a mixture of hemp hurds, lime, and water, is valued for its excellent thermal insulation and vapor permeability properties but is typically not suitable for load-bearing structures due to its relatively low compressive strength. Recent studies have explored various modifications to enhance its mechanical properties. For instance, the introduction of alternative binders such as magnesium oxide (MgO) has been shown to significantly improve compressive strength, as demonstrated by [34], where compressive strength increased from 58 psi to 655 psi with specific formulations. The inclusion of pozzolanic additives such as nano silica and metakaolin further enhances the composite’s structural integrity by facilitating stronger chemical bonds within the matrix.

Furthermore, the incorporation of sand as a fine aggregate contributes to the overall density and strength of the hempcrete, making it more suitable for a broader range of applications. Despite these advancements, hempcrete still falls short compared to conventional building materials like concrete and steel in terms of load-bearing capacity. However, it excels in other areas such as environmental impact, insulation properties, and ease of use. Continued exploration into the optimization of these formulations is necessary to balance strength and sustainability, potentially paving the way for more structural applications of hempcrete.

8.2. Water Absorption Problem for Hempcrete

Hempcrete faces challenges primarily related to its water absorption and drying times. Traditional mixing methods are unsuitable because hemp shives absorb significant amounts of water, leading to long setting and drying periods. It usually takes around 6–8 weeks to dry, which also depends on the climate/weather and the wall thickness [10]. Although a new projection process addresses this by adding only the necessary amount of water to slake the lime, thereby accelerating setting and reducing drying times, it introduces other complexities. This method enhances particle compaction, resulting in higher density, but density variations can occur within block sections. The projection distance influences density, affecting thermal and mechanical properties, such as thermal conductivity, Young’s modulus, and strength. Manufacturers must balance these properties, as hempcrete’s mechanical performance is generally lower than that of traditional load-bearing materials, limiting its use in structural applications. Additionally, while denser blocks offer greater strength, they compromise on insulation properties, necessitating a trade-off between thermal insulation and mechanical strength depending on the construction type [28].

8.3. Load-Bearing Issue in Hempcrete

Despite its many construction and environmental benefits, hempcrete has drawbacks, such as poor mechanical performance, which makes it unsuitable for load-bearing structures, and a high capacity for absorbing and retaining water, which can reduce its durability [13]. Hempcrete’s inherent limitations as a non-load-bearing material are a significant barrier to its widespread adoption in structural applications. The current necessity of integrating hempcrete with structural frames, such as wood-frame or light-gauge steel studs, adds complexity and cost to construction projects. Although advancements in binder technology and material composition have increased hempcrete’s compressive strength, reaching the thresholds required for standalone load-bearing applications remains challenging. One promising avenue is the development of hybrid construction techniques that pair hempcrete with other structural materials. For example, using bamboo, known for its high tensile strength and sustainability, as reinforcement within hempcrete structures could provide the necessary support while maintaining ecological benefits. Engineered timber, with its compatibility and shared eco-friendly properties, also presents a viable option for reinforcing hempcrete walls. Such innovations could potentially transform hempcrete into a more versatile material capable of serving a wider array of architectural functions. Hempcrete is not yet being fully incorporated into the building code yet. However, it is currently part of an appendix, in the 2024 edition of International Residential Code (IRC) [58]. The code provides guidelines on hempcrete construction with detailed drawings available. However, hempcrete is defined as a non-load bearing construction material in the code, which limits the applications of hempcrete in construction for right now.

8.4. Economic and Market Potentials for Hempcrete

The economic potential of hempcrete is closely tied to the growing global emphasis on sustainable and low-impact building materials. As more countries adopt stringent environmental regulations and carbon reduction targets, hempcrete’s appeal as a sustainable building solution is likely to increase. Its ability to act as a carbon sink, combined with its thermal, fire-resistant, and moisture-regulating properties, positions hempcrete as an attractive option for residential and commercial buildings aiming to achieve high energy efficiency standards. Successfully integrating hempcrete into residential building practices could create a new market demand for hemp and hempcrete as construction materials. Moreover, replacing traditional industrial materials with those of agricultural origin in certain applications for reinforced concrete structures can enhance sustainability. This shift would benefit society by offering positive economic opportunities for farmers and promoting environmental sustainability [54].

However, the widespread adoption of hempcrete faces several economic challenges. The initial cost of hempcrete can be higher than traditional materials due to the need for specialized production processes and skilled labor. Furthermore, the scalability of hempcrete production is currently limited by factors such as hemp cultivation regulations and the availability of processing facilities. Overcoming these barriers requires strategic investment in supply chain infrastructure and policy support to facilitate the growth of the hempcrete industry. The development and implementation of industry standards and building codes, such as the proposed Hemp-lime Construction appendix for the International Residential Code (ICC 2024), are crucial for gaining regulatory acceptance and fostering residential builder confidence [58]. The code explains the terminology, property, and construction details related to hempcrete. Additionally, increasing awareness and education about the benefits of hempcrete among architects, builders, and homeowners will play a pivotal role in driving demand and expanding the market.

9. Conclusions

Hempcrete offers numerous advantages as a sustainable construction material. Its low carbon emission, coupled with excellent insulating, fire-resistant, soundproofing, and moisture-regulating properties, make it an attractive substitution for traditional construction materials for environmentally conscious builders and architects. Additionally, its recyclability, non-toxic composition, and resistance to pests and mold further enhance its appeal in sustainable construction. Hempcrete’s ability to reduce carbon emissions throughout its lifecycle contributes to reducing the environmental impact of buildings, positioning it as a valuable tool in achieving high energy efficiency standards.

However, despite these benefits, hempcrete faces challenges, especially in load-bearing applications. Its relatively low compressive strength and high-water absorption attributes make it unsuitable for use as a standalone structural material. These limitations require the integration of supportive structural frames, such as timber or steel studs, adding complexity and cost to construction. Additionally, the longer drying times and higher initial costs compared to traditional materials present economic hurdles that need to be addressed to facilitate wider adoption.

To fully realize the potential of hempcrete, ongoing research is essential to improve its structural properties and address its limitations. Hybrid construction techniques, combining hempcrete with materials such as bamboo or engineered timber, offer promising solutions to overcome its mechanical weaknesses. Furthermore, establishing clear regulatory standards and fostering market demand through education and policy support will be key in integrating hempcrete into mainstream construction. As the global demand for sustainable building materials grows, hempcrete is well positioned to become a leading player in the green building movement, contributing to a more sustainable future for the built environment.