What is Hempcrete used for

The Many Uses of Hempcrete

An A Frame roof that shows how hempcrete can be insulated along the outside of the roof

Of the multiple varieties of cannabis, the industrial hemp plant is of particular interest and rising popularity due to its 25,000 applications. Other than being incorporated into thousands of products like health foods, organic body care, and clothing, this versatile plant is growing in popularity within the construction industry. The product is known as hempcrete and is made simply from mixing hemp hurds (or “hemp shives”), lime binder and water. In this article, we discuss the various uses of hemp lime within construction.

Hempcrete is an incredible material which is being used for both building and insulation purposes. This is because it is toxin-free, carbon-negative, breathable and airtight. It is resistant to molds, pests, fungus and completely fireproof. All these properties make it a remarkable option to construct a building or a hemp house.


What Can It Be Used For?

Hempcrete was first developed in France during the mid-1980s and has been extensively used by various construction companies in France to build houses ever since. It replaces the traditional means of construction and offers an eco-friendly option to construct homes, buildings and structures. It is considered eco-friendly due to its ability to retain hundreds of kilograms of carbon dioxide from the atmosphere and exhale oxygen. This material can be used in many ways such as:

1. Building Hempcrete Walls

A hempcrete wall being constructed that shows the inner hempcrete layer of insulation

One of the most common uses of hemp lime is in building walls. It cannot be used to build foundations but can be installed in a cavity within the wall or can be added as an extra layer in the build-up. It forms the walls and the insulation structure in one piece, with other materials being used as structural frames such as timber, steel or concrete frame. It is a great source of insulation and is more lightweight than traditional concrete.

2. Floors And Roofs

Hempcrete can also be used to build floors and roofs in combination with other materials to provide an insulating layer. It can also be used to build infill panels, which are non-load bearing panels installed between the floors of a building’s primary structural frame. Traditional infill panels are built from materials like concrete or masonry but hemp lime has proved a worthy adversarial alternative.


3. Building Retrofit Infill Panels

During the restoration of historic and traditional buildings, hempcrete is frequently used to repair or replace the infill panels used on the timber frame buildings. It is also used to add insulation to concrete walls in old buildings. This is because it’s a vapor-permeable property and can mold itself precisely to unevenly shaped walls (something common in older buildings).


4. Building outside tables and seating

Hempcrete has the potential to absorb and store a large amount of carbon dioxide from the atmosphere. Using hemp lime in outside tables, benches or seating can provide us with an innovative and eco-friendly means to conserve energy. Moreover, it is durable and waterproof (two important benefits for outdoor structures).


5. Building Roads

A thesis studied the possibility of hemp-lime composite noise barrier walls in highways for acoustic testing according to the European Union Standards EN ISO 717-1 and ISO 10140-2 for airborne sound insulation.

PDF: Hempcrete_Noise_Barrier_Walls_KC

The thesis concluded that a hemp lime wall can provide effective highway noise insulation along with other environmental benefits. Thus, it can be effectively used in constructing noise barriers on roads.

Methods Of Constructing a Hempcrete Building

Hempcrete itself is not a load-bearing material and normally requires the use of casting it to timbers. There are three basic methods used in casting hemp lime. These include:

1. Tamping

The tamping process of building houses and buildings with hempcrete

This method involves temporarily attached boards, usually plywood sheets that act as a mold and then filled with hempcrete. The mix requires tamping either with hands or using a simple device such as a wooden stave. Tamping is done in order to avoid large air voids in the material so that it has effective insulation properties. However, it is very important to have a balanced tamping pressure which should be neither too hard nor too low in order to avoid air voids.

2. Spraying

The phase of making hempcrete that involves spraying the hempcrete

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Spraying is usually adopted when looking to save time during the project. Plywood sheets are sprayed with hemp lime mix evenly with the help of pipe pressure. The hemp-lime mix attaches to the plywood or the frame used. The hemp and binder slurry are combined together at the nozzle of the sprayer. Due to the pressure with which it is projected out of the nozzle, spray-applied hempcrete sticks firmly to the surface onto which it is sprayed.

3. Hempcrete blocks

A close up view of hempcrete blocks that have recently been formed and still need to dry

Hempcrete blocks require a load-bearing framework which is usually of timber. These blocks are placed on the framework and required corrections are made before installing the wall plate. These blocks are produced by pressing, aging and packing of hemp lime with the help of appropriate machinery.