Hempcrete is a material that is constructed on-site, referred to as a “cast in place” material. Once the building frame is in place, a wooden framework is added.
The hempcrete is manually poured into the framework and compressed. Typically, a lime plaster finish is applied to the hempcrete surface.
Despite its current widespread use, hempcrete insulation has been in use since the 1990s in France. Growing environmental sustainability awareness has increased interest in sustainable alternatives like hempcrete.
Materials and Tools Required for Making Hempcrete
Hemp Hurds
Hemp hurds, the inner core of the hemp stalks, is the primary ingredient in hempcrete. These can be obtained from hemp farming or processing operations. Therefore, it is crucial to ensure that the hemp hurds is clean, dry, and free from dust, debris, and large plant matter for optimal performance in the hempcrete.
Binder
The binder is a crucial component that binds the hemp hurds together. The most commonly used binder for hempcrete is hydrated lime, which acts as an adhesive agent. Other lime-based binders or natural hydraulic lime (NHL) can also be used. The binder should be mixed with water according to the manufacturer’s instructions to achieve a uniform consistency.
Water
Water is necessary for activating the binder and creating the hempcrete mixture. The amount of water needed may vary depending on factors such as the type of binder and desired consistency of the hempcrete mixture.
Mixing Equipment
To effectively mix the hempcrete ingredients, you will need suitable mixing equipment. A cement mixer is commonly used for larger-scale projects, while a large tub or trough can be used for smaller batches. Ensure that the mixing equipment is clean and free from any contaminants that may affect the quality of the hempcrete.
Formwork or Molds
Formwork or molds are essential for molding and containing the hempcrete during installation. These can be made of various materials, such as wood, metal, or plastic. The formwork should be sturdy and properly secured to prevent any leaks or deformations during the casting of the hempcrete.
Basic Construction Tools
You will need basic construction tools such as shovels, buckets, trowels, and a level to install the hempcrete. These tools will aid in mixing the ingredients, filling the formwork, and achieving a level and even surface.
Step-by-Step Guide to Making Hempcrete
a. Preparing the Hemp Hurds
Thoroughly clean the hemp hurds by removing dust, debris, or large plant matter. This can be done through sieving or using specific cleaning equipment.
Ensure the hemp hurds are completely dry before mixing them with the binder. Moisture in the hurds can affect the binding process and the overall performance of the hempcrete.
b. Mixing the Binder
Follow the instructions provided by the binder manufacturer to mix the binder with water. This typically involves adding the appropriate amount of water to the binder and mixing until a uniform consistency is achieved. This mixture will serve as the adhesive agent for the hempcrete.
c. Combining the Hemp Hurds and Binder
Gradually add the binder mixture to the hemp hurds, ensuring even distribution and proper coating. Mixing can be done manually using shovels or mechanically using a cement mixer. Thorough mixing is essential to ensure the binder fully coats the hemp hurds.
d. Forming the Hempcrete Mixture
Adjust the water content or binder ratio as needed to achieve the desired consistency, which is typically similar to wet sand. The hempcrete mixture should be cohesive and easily moldable while retaining its shape.
e. Installing or Casting the Hempcrete
Pour or pack the hempcrete mixture into the desired formwork or onto the construction surface. Use tools such as shovels and trowels to fill the formwork evenly, ensuring that all gaps are filled, and the mixture is compacted.
f. Curing Process
Allow the hempcrete to cure and dry for several weeks. During this time, the lime binder undergoes carbonation, reacting with carbon dioxide from the air to harden the mixture and form a solid structure.
g. Finishing Touches
Once the hempcrete is fully cured, it can be finished with lime plaster or other suitable coatings to enhance its appearance and protect it from external elements. Lime plaster is commonly used, allowing for breathability and compatibility with the hempcrete material.
Remember to adjust the details based on your specific requirements and to adhere to any local regulations or guidelines for hempcrete construction.
How Long Does Hempcrete Typically Last?
According to various sources, the durability of hempcrete ranges from hundreds to thousands of years, making it a durable option.
In addition to its durability, hempcrete is also an economical and non-toxic material once it has fully cured. However, it is crucial to protect the hemp blocks with a suitable finish to prevent degradation.
What is Hempcrete’s Strength?
Hempcrete’s compressive strength typically ranges from 1-3.5MPa, with a more common strength of around 1MPa, making it unsuitable for foundations or footings due to its low strength compared to concrete.
However, since the primary use of hempcrete is insulation, this is generally not a significant concern. Moreover, its low density contributes to its ability to resist cracking.
Building Hempcrete Wall With A Low Carbon Footprint
In recent years, an increasing interest in environmentally sustainable building materials has led to a shift away from traditional construction materials.
Hemp concrete walls offer superior thermal performance, as the material provides thermal mass that helps regulate indoor temperatures, making it an energy-efficient option.
Hempcrete is also fire-resistant, which adds an extra level of safety and security to any building project.
The material’s low carbon footprint is a bonus, as hemp absorbs carbon dioxide during its growth, making it carbon negative.
Hempcrete is lightweight and easy to form, which simplifies construction projects. However, it’s worth noting that hempcrete can be more expensive than traditional building materials due to its limited use and production.
Regardless, the many benefits of hempcrete make it an attractive option for environmentally-conscious builders and architects.
Hempcrete is created by mixing four parts hemp hard with one part lime binder, which can be either hydraulic or air lime. Hydrated lime is added to the mixture to enhance the material’s durability and strength.
One of the unique features of hempcrete is that it can be recycled. Once a building reaches the end of its useful life, hempcrete can be broken down and repurposed or used as a soil amendment. The use of hempcrete can also create foundations that are more stable and resilient to movement.
Hempcrete provides an eco-friendly, durable, and energy-efficient alternative to traditional building materials. While it may be more expensive than conventional materials, the many benefits of hempcrete make it a wise investment in the long run.
Using hempcrete in building projects contributes to a more sustainable future and a greener planet for future generations.
Is Hemp Suitable For Home Construction?
While possible, constructing a house entirely from hemp might not be financially feasible for the average homebuyer. The Dun Agro Hemp Group successfully built a fully hemp-based house 250km from Amsterdam.
Hempcrete played a significant role in the creation of the structure, and the material was naturally dried for three months.
The Dun Agro Hemp Group stated that the hemp-based house is earthquake-resistant, presenting significant opportunities in regions where earthquakes occur more frequently.
What Makes Hempcrete So Unique?
Hempcrete products, such as hemp blocks, can benefit areas that face technical challenges using traditional construction materials.
Hempcrete offers numerous benefits, including:
Thermal Regulation
Hemp blocks or hempcrete bricks have a natural ability to regulate temperature, enabling efficient dissipation of accumulated heat.
This makes them ideal for containing heat during winter and evenly distributing it during summer to avoid overheating.
Humidity Regulation
Hemp is a highly effective material for maintaining a healthy indoor environment. Homes constructed using hempcrete ensure a consistent and healthy climate for the occupants, particularly in areas with high humidity.
Additionally, hempcrete can be an effective solution for renovating old buildings that suffer from dampness and preventing future condensation issues, ultimately preserving the state of the building.
Fire Resistance
The fire resistance of hempcrete and hemp blocks varies depending on the finish and thickness of the material used. However, it can provide up to two hours of fire resistance, making it a reliable option regarding fire safety.
Acoustic Insulation
Hemp is an excellent sound insulator, capable of trapping and dampening sound waves to protect against noise pollution.
This makes it a reliable solution for soundproofing. Additionally, hemp insulation can allow individuals to play loud music without disturbing neighbors.
What Are the Disadvantages of Working With Hempcrete?
Hempcrete has a compressive strength of approximately 1-3.5MPa, which is considerably lower than concrete. Consequently, it is not recommended for heavy load-bearing applications.
Due to its limited usage, not all builders and architects possess experience working with hempcrete. In addition, unlike concrete, hemp can be challenging to acquire, making it less commonly used.
Hempcrete walls are generally thicker than standard walls, resulting in less available space within a home. Additionally, hempcrete is unsuitable for foundations and footings due to its high moisture absorption rate, making it unfit for load-bearing applications.
Is it Pricey to Use Hempcrete?
Although hempcrete has the potential to be a cost-effective alternative, it is not currently a cheaper option. The main issue is that hemp-based construction materials are not yet widely available, so the cost is often higher than traditional materials.
However, many experts argue that the cost may be lower in the long term due to hemp’s durability and energy-efficient properties.
When Should You Consider Using Hempcrete?
Hempcrete possesses excellent resistance to cracking and functions as a reliable moisture regulator and insulator. As a result, the material is suitable for use in earthquake-prone areas, despite having lower compressive strength than typical residential concrete.
However, it is robust enough for small building projects and highly durable. Therefore, Hempcrete is suitable for constructing fences, walls, tiny homes, sheds, and other similar structures.
Additionally, hempcrete is entirely recyclable, meaning that at the end of a building’s useful life, it can be broken down, repurposed, or used as a soil amendment.
More bricks can be produced by cultivating additional hemp, creating a sustainable cycle.
Final Thoughts
In conclusion, hempcrete turns weed into a unique and innovative building material, gradually gaining recognition for its many advantages. Hempcrete offers several benefits: thermal performance, fire resistance, carbon-negative, and recyclability.
While it may be more expensive than traditional building materials, hempcrete’s long-term benefits and eco-friendliness make it a smart investment.
Using hempcrete in building projects contributes to a sustainable future and a greener planet for future generations. As more people become aware of the many benefits of hempcrete, it will likely gain wider acceptance and usage in the construction industry.
It’s incredible how weed has health benefits and can also be beneficial in different forms. For example, you can take it as edibles for convenience or use it as a construction material for eco-friendly reasons.
With its versatility and durability, hempcrete has the potential to change the way we build and pave the way for a sustainable and greener future.
