Desk Research & Primary Findings

Issued on:30th August 2023

1. Background

1.1 Overview of Hemp

Hemp is widely regarded as one of the most versatile plants on the planet, with a wealth of potential applications that make it a highly valuable resource. The hemp plant stem has numerous applications, with a long history of use as a building material. Its history in the construction of homes and bridges dates over 2,000 years (Assaf 2023; Roberts 2021). Historic structures made from hemp, such as the house in Nagano shown in Figure 1.1. and Figure 1.2 displays hemp stalks.

Moreover, over the last few years in South Africa, Afrimat played a vital role in the development of Africa’s initial hemp dwelling in 2011 (refer to Fig 2.1), which was chosen as a World Design Capital 2014 initiative. Subsequently, they erected an additional five structures made of hemp, including the world’s tallest building constructed with hempcrete and boasting 12 floors (refer to Fig. 2.2).

The utilization of hempcrete as a building material is not well-known among the general public and policymakers in Lesotho. Yet there is widespread growth of hemp ranging from medical cannabis cultivated legally. But, more prominently, illegally grown for traditional medicinal purposes and as a recreational drug. The literature review does not indicate any local exploration in the construction field. Because there is a local and world reassessment of the regulation of hemp plants, we need research ahead of any deregulation to prepare the industry. We have researched information on the accessibility, legal guidelines, durability, carbon footprint, resource cost, and the necessary knowledge and techniques for hemp application as it has proven to be a successful building material in South Africa (Duvall, 2019).

1.2. Characteristics of Hempcrete

Hempcrete is a type of biocomposite made from a mixture of hemp shiv, lime binder, and water. Compared to concrete, it is lightweight, weighing only around one-eighth of the concrete’s weight. According to Isaacs and Bedliva (2014), hempcrete can be sprayed to construct walls, floors, and roofs. Additionally, the lime component contains air lime, which accelerates the setting process. The coarse parts of hemp that stick to the fiber after it is split can be sourced from hemp stalks, as suggested by Tradical (2022). As a result, the combination of lime and hemp produces a natural concrete material that is lightweight, with the possibility of ultra-lightweight under specific applications.

1.3. Uses of Hemp as a Building Material

Hempcrete has limitations in load-bearing applications or as a foundation material due to its lower compressive strength compared to concrete. Roberts (2021) reported that hempcrete has a compressive strength of 1 MPa,[1]  which is 1/20th that of concrete. However, according to Hempitecture (2021), hemp can also be utilized in the form of fiberboard and bricks. Hemp panels are suitable for insulation purposes, while hemp bricks can be used as non-load-bearing infill in partitions and exterior walls for both new construction and renovation projects.

Hempitecture (2021) outlines two main methods for constructing buildings with Hemp Lime composites: Cast-in-place and Hemp Blocks. For Cast in Place, hempcrete walls can be built on-site using two techniques: pouring the mixture into temporary formwork and manually tamping it (as shown in Figure 3.1), or spraying the material onto the target area using the projection method (as depicted in Figure 3.2) (Lupu et al 2022).

2. Advantages of Hempcrete Blocks

Tradical (2022) states that the combination of lime and hemp creates a natural lightweight or ultra-lightweight concrete. The material is known to regulate indoor temperatures and remove fungi, fine dust, and bacteria from the air, creating a pleasant odor due to its ionizing effect (Hahmed, Mahmud, Sarker & Islam, 2022). 

The environmental benefits of using hempcrete in the building industry are observed in every stage of the production and use of the material (Tradical, 2022). Since it is made from the stalks of the hemp plant, hempcrete carries the inherent advantage of promoting the farming of plants that have a restorative effect on the environment. Secondly, hempcrete is produced in a simple, low-resource process that promotes reuse and recycling of waste materials which can be used to further the interests of companies in the waste management space. Lastly, the excellent thermal properties of hempcrete benefit homeowners and the environment by lowering the need for temperature control. Additionally, hempcrete is a sturdy material that does not require the use of harmful chemicals for pest and parasite control (Tradical, 2022).

Hempcrete is also carbon-negative and sequesters carbon dioxide from the atmosphere throughout its life cycle. It is resistant to mold, pesticides, and pests, and has a two-hour burn rating. The material filters particulates and provides a thermal mass barrier to regulate interior temperatures, making it disaster-resistant and an ideal option for earthquake-prone areas (Roberts, 2021). Hempcrete has high thermal capacity and vapor permeability properties, resulting in high-performance buildings that meet current and future thermal regulations (Tradical, 2022). Additionally, it is grown without the use of harmful chemicals, requires minimal irrigation, and contributes to soil regeneration (Tradical, 2022).

3. Disadvantages of Hempcrete Blocks

Although hempcrete is a promising and innovative building material, it currently remains relatively expensive compared to more conventional options, according to Lynch (2020). Estimates suggest that it may cost at least three times as much as regular concrete. Additionally, hempcrete can be difficult to obtain, as the production of hemp can be seasonal, and the material needs to be dried for eight weeks, which is affected by changes in weather conditions.

Furthermore, according to Lynch (2020), the maximum compressive strength of hempcrete is 3.5 megapascals (MPa), which is significantly lower than the lowest compressive strength of regular concrete at around 17 MPa.

4. Primary Explorative Research  Findings

4.1. Research Methodology

To collect primary data, the stratified and snowballing sampling techniques were convenient for this study, because it was imperative to select respondents based on their qualifications and expertise, ensuring they have the necessary background to provide valuable insights. This chapter presents the findings from the one face-to-face, three calls, and six Zoom interviews that each lasted between 45 minutes to an hour held in January and February 2023, with professionals and experts who have worked or are working with Hempcrete. A set of questions (see Annex 3 questionnaires for hemp), which included open-ended questions, had been prepared with the aim of gathering information about some specific topics such as availability and accessibility, cost, durability, knowledge, and techniques around hempcrete.

4.1.1. Availability of Hempcrete Blocks

The aim was to ascertain whether hemp is locally grown and its intended applications. Additionally, to grasp the impact of regulations and laws on hemp production feasibility in Lesotho. As a result, One respondent (from the Ministry of Health) showed that a few hemp plants are already available in the country. The Respondent mentioned that hemp grows well and is primarily cultivated for medicinal purposes, following guiding laws to ensure legal compliance. Additionally, the Respondent noted that hemp has potential applications like creating hempcrete blocks. However, the policy lacks clarity as it primarily concentrates on medical uses.

Nine Respondents explained that Lesotho doesn’t cultivate hemp mainly because the policy focuses on medicinal cannabis production and doesn’t adequately cover hemp’s various uses.

4.1.2. Cost of Hempcrete Blocks

Another aspect evaluated included the cost of obtaining a cannabis cultivation license in the country, along with establishing the purchase price and production cost of hempcrete blocks from South Africa. Eight Respondents revealed that the license fee is substantial, amounting to M500,000 (EUR 25,000) for the operation of a cannabis plant in Lesotho. Additionally, companies must adhere to international guidelines, including GACP (Good Agricultural and Collection Practices), which increases licensing costs to M600,000 (EUR 30,000). However, a Ministry of Health representative mentioned that if companies only require the hemp plant’s stalks, an operator’s license is not necessary. The official also pointed out that the Ministry of Health can request hemp-cultivating companies to supply stalks. This way, the Ministry could provide these stalks to entrepreneurs for free.

Regarding the purchasing cost of the material, two Respondents mentioned that buying hempcrete blocks can be expensive compared to conventional bricks. Furthermore, the Respondents pointed out that the requirement for skilled foreign manufacturers to educate entrepreneurs in hempcrete production and construction contributes to increased labor expenses. Nonetheless, Hempcrete blocks offer long-term thermal advantages resulting in cost savings towards heating costs.

4.1.3. Durability of Hempcrete Blocks

Additionally, the study aimed to evaluate the durability of hempcrete blocks compared to traditional bricks. Four Respondents highlighted that the lime and silicone binding agents gain strength over time, enhancing the resilience of hempcrete blocks in contrast to concrete blocks.

4.1.4. Environmental Impact of Hempcrete Blocks

Understanding the carbon emissions linked to hempcrete’s usage emerged as a crucial aspect. The analysis acknowledges that hempcrete, primarily a biological byproduct, has a lower embodied carbon than conventional bricks. Throughout its lifespan, it absorbs carbon dioxide from the atmosphere. Furthermore, two respondents emphasized that hempcrete blocks can also sequester carbon, helping reduce greenhouse gas emissions

5. Feasibility of Hempcrete blocks

Lesotho, as the pioneering African nation to legalize and permit the cultivation of medicinal cannabis for international export, boasts favorable conditions for cannabis cultivation. The country benefits from ample available land on the outskirts of its towns, attracting significant attention from international enterprises interested in investing in medicinal cannabis production. However, the high costs associated with operating licenses present a significant barrier for Basotho farmers seeking to cultivate hemp. Hemp is currently categorized alongside the highly profitable medicinal cannabis plant, amplifying these challenges. To fully leverage the potential of cannabis, it’s imperative to integrate its diverse applications into the national policy framework. Presently, existing cannabis companies face limitations in utilizing byproducts like stalks, which are often discarded, due to stringent regulatory constraints. These companies are constrained from selling or even donating these byproducts due to the stringent legal protocols they must adhere to.

Avans University Masters research

In partnership with Rise International (2022), a team of Master’s students from Avans University in the Netherlands conducted a study to assess the practicality of employing hemp as a construction material in Lesotho. Their findings emphasize that crafting hempcrete is a straightforward procedure achievable with standard farming equipment or even by manual means. Furthermore, they highlight its efficiency, noting that a single acre of hemp yields four times more fibers than a forest, with a rapid 100-day harvesting cycle. The researchers affirm that hemp thrives in Lesotho’s soil conditions, and its three-month growth cycle positions it as a swiftly renewable resource (Houtbouwbeurs, S. D, as cited in Avans University 2022). This dynamic suggests a consistent and substantial output from hemp farms. The researchers concluded that affecting this transformation necessitates a reclassification of the Cannabis sativa plant, which contains higher CBD and minimal THC—constituents that give rise to hemp—distinct from the Cannabis sativa plant employed in medicinal cannabis production, characterized by elevated THC levels. Such differentiation would exempt hemp production from the currently prohibitive licensing costs. For more insight, refer to the Avans student’s accompanying video here

6. Distribution

Currently, there are limited instances of hempcrete structures in Lesotho, except for a private residence underway in Morija, approximately 40 minutes from the capital city, Maseru. However, the expenses involved are substantial due to the importation of hempcrete blocks from South Africa. This is further compounded by increased logistical and labor-related expenditures. The scarcity of expertise in hempcrete construction is also a notable challenge, as only a small number of individuals have received training in this specialized technique.

7. Unmet needs of Hempcrete

Lack of public knowledge about the opportunities for the production of hemp is the greatest hindrance to development. It would be an advantage for Lesotho to use hemp as a building material as it can be produced quickly and efficiently on a small and large scale. Ultimately, a local hempcrete industry would also stimulate the economy and reduce the reliance of Lesotho on South Africa’s construction material industry. The emergence of a new industry would also introduce new job opportunities for Basotho.

8. Conclusion

Hemp can be used as a building material, and it has also been confirmed by experts (Director of Pharmaceutical, and Afrimat Managing Director), and it has a massive potential market in Lesotho. This is because not only does Lesotho have a favourable climate and vast lands to start the industrial production of hemp, it already has a policy directing the production of cannabis. However, the Drug Abuse Policy fails to incorporate and advocate for other uses of other types of cannabis such as hemp as it only shows support for the production of medicinal cannabis. Additional factors that hinder the use of hemp in construction are high licensing costs and the necessity of imports for creating hempcrete. These imports include lime and skilled labour for the production and construction of hempcrete blocks.

9. Recommendations

The first consideration is the economic implications of using hemp as a building material. Hempcrete, made from hemp plant stalks, not only extends the plant’s lifespan and value but also multiplies its benefits. We recommend further research to support policy changes promoting hemp farming in Lesotho. Hemp is a global billion-dollar economic sector, covering medical, recreational, and various other applications. Lesotho’s inherent advantage in hemp growth offers a significant economic opportunity. This holds implications for construction development, including skills advancement, job generation, business prospects, and exports. However, the high licensing costs must be reevaluated for a more inclusive industry.

This paper identifies diverse sociopolitical implications for the hempcrete industry, primarily linked to the Drug Abuse Policy. The recommendation put forth in this paper suggests a revision of this policy to encompass the advantages of hempcrete production and usage. Firstly, the policy’s blanket classification of all hemp plants is criticized, stemming from the negative associations with a few strains used for recreational drug abuse. Secondly, neighboring South Africa’s legalization framework stands as a viable model for adoption in Lesotho. Given that multiple African nations are currently moving towards hemp deregulation, creating regional competition, prompt action is essential. If current and future hemp producers, primarily focused on oil extraction, find hemp cultivation financially unviable, it could result in the loss of a cost-effective and dependable material for our construction industry.

10. Appendices

Appendix A: Key Respondent List

Respondents #CompanyYears of ExperienceProfession/ Qualifying Criteria
Respondent 1Afrimat14 yearsSales Manager & Managing Director Hemp constructor
Respondent 2Owner of the first hemp building in Lesotho 50 years Customer perspective First Hemp Homeowner in Lesotho
Respondent 3 Individual Entrepreneur4 yearsBuilder of the first hemp builder in Lesotho
Respondent 4Ministry of Health24 yearsDirector Pharmaceutical
Respondent 5Medi grow8 yearsEnvironmental Spet
Respondent 6WeGrow5 yearsAgricultural spet
Respondent 7Hemp Africa6 yearsAgricultural Spet Africa
Respondent 8Ignited Unlimited21 yearsAgronomist (knowledge of Cannabis)
Respondent 9Constructed the first Hemp building17 yearsConstruction manager on the first building of hemp in Lesotho
Respondent 10Organica13 yearsEnvironmental Spet


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