Earth Bag Construction
My introduction to this type of construction was to use it for war and environmentally ravaged locations as a worthwhile housing option.
Earthbag construction is a building method that uses polypropylene bags filled with soil or other materials to create walls. The bags are stacked and tamped down to create a solid structure. This method is often used for building homes, retaining walls, and other structures in areas where traditional building materials are not readily available or are too expensive. It is also considered as an eco-friendly and sustainable building method as it utilizes natural materials and reduces the carbon footprint.
Earthbag structures are created by filling polypropylene bags with a mixture of soil, clay, or other natural materials. The bags are then stacked on top of each other to create walls. The bags can be filled by hand or with the use of a machine. Once the bags are stacked, they are tamped down to compress the material inside and create a solid structure. After the walls are built, they are typically reinforced with barbed wire or mesh and then plastered over with a mixture of clay, lime or cement to waterproof and protect the walls.
The process of building earthbag structures typically starts with the excavation of the foundation and the installation of a base course of bags. The walls are then built up in layers, with each layer consisting of several courses of bags. The bags are usually filled with a mixture of soil and a small amount of cement, which helps to bind the soil particles together and increase the strength of the walls.
Earthbag structures can be used for a variety of building types, such as houses, sheds, barns, and retaining walls. They are considered as eco-friendly and sustainable building method as it utilizes natural materials and reduces the carbon footprint. It is also relatively inexpensive and easy to construct, which makes it an attractive option for people looking for an alternative to traditional building methods.
Earthbag Soil Recipe
The recipe for an earthbag soil mix can vary depending on the specific application, but a common mixture is:
3 parts soil: This should be a well-draining, subsoil that is free of organic matter, rocks, and debris.
1 part clay: This should be a plastic clay that is high in clay content and free of sand and silt. The clay helps to bind the soil particles together and increase the strength of the walls.
1 part Portland cement: This helps to harden the soil mixture, increase the walls resistance to water penetration and improve fire resistance.
Water: Enough to moisten the mix so that it can be tamped and compacted easily without falling apart.
It is important to note that the soil used should be tested to ensure that it has the right properties for building with earthbags. The soil should have a low plasticity index and a high compaction rate. It's also important to be aware that using a high amount of cement can decrease the ability of the walls to breathe and could cause moisture problems.
It is also important to note that this is a basic recipe and the mixture can be adjusted to suit the specific needs of the project and the availability of local materials. For example, some builders may use a mixture of sand and gravel instead of soil, or use lime instead of cement. Additionally, some builders also add a small amount of lime to the mix to help with curing and to reduce cracking.
It is recommended to consult with a professional or an expert in earthbag construction for the specific recipe of the soil mix for your project.
What Are the Size Constraints of Earthbag Construction?
Earthbag construction is a flexible building method, and there are no specific size constraints for earthbag structures. However, there are some factors that can affect the size of an earthbag structure:
Foundation: Earthbag structures require a solid foundation, such as a concrete slab or a stone foundation, to support the weight of the walls. The size of the foundation will determine the size of the structure that can be built on top of it.
Wall height: The height of the walls is limited by the weight of the bags and the material inside them. Taller walls will require more reinforcement and may be more difficult to construct.
Roofing: The roof of an earthbag structure needs to be designed to handle the weight of the walls and the materials used in the walls. A larger structure will require a stronger and more robust roofing system.
Wind and seismic loads: The size of the structure will affect the wind and seismic loads that it needs to be able to withstand. Larger structures will require more reinforcement and may need to be anchored to the foundation to resist these forces.
Building codes: Different regions and countries may have specific building codes and regulations that dictate the maximum size of a structure that can be built using earthbags.
These are some of the main factors that can affect the size of an earthbag structure, but as long as the structure is properly designed and constructed, it can be built to any size.
How Much Barbed Wire is Required?
The amount of barbed wire required for an earthbag structure will depend on a number of factors, including the size and height of the walls, the type of soil used in the bags, and the intended use of the structure.
Typically, barbed wire is used to reinforce the walls of earthbag structures by providing additional tensile strength. The barbed wire is layered between the courses of bags, typically three layers of barbed wire is used, one at the bottom, middle and top of the wall. This helps to prevent the bags from shifting or bulging and also helps to distribute the load of the structure evenly across the bags.
A general rule of thumb is to use one roll of barbed wire for every 50-75 linear feet of wall. However, the actual amount of barbed wire required will depend on the specific characteristics of the project, such as the height and width of the walls, the type of soil used, and the intended use of the structure.
It is also important to note that the use of barbed wire is not the only way to reinforce earthbag structures, other ways such as using mesh or chicken wire, or steel reinforcement bars can be used. It's recommended to consult with a professional or an expert in earthbag construction for the specific requirements of reinforcement for your project.
Finishes
Earthbag structures can be finished in a variety of ways, depending on the intended use of the space and the desired aesthetic. Some common methods of finishing earthbag walls include:
Plastering: A layer of plaster, typically a mixture of cement, sand, and water, is applied to the surface of the earthbag walls to create a smooth, finished surface. Plastering can also help to seal the walls and protect them from moisture.
Stucco: A layer of stucco, typically made from a mixture of cement, sand, and lime, is applied to the surface of the earthbag walls to create a finished surface. Stucco is also a good option for protecting the walls from moisture.
Render: A layer of render, typically made from a mixture of cement, sand, and lime, is applied to the surface of the earthbag walls to create a finished surface. Render can also help to protect the walls from moisture.
Lime wash: A layer of lime wash, typically made from a mixture of lime and water, is applied to the surface of the earthbag walls to create a finished surface. Lime wash is also a good option for protecting the walls from moisture.
Painting: The surface of the earthbag walls can be painted with a variety of paint types and colors to create a finished surface.
Natural finishes: The earthbag walls can be left as they are and used as a natural finish.
It's important to note that the walls should be allowed to dry completely before applying any finish. Additionally, it's also important to consult with a professional or an expert in earthbag construction and finishes before proceeding with any finishes as different finishes may have different effects on the walls and its longevity. The attachment of the finish is the important note. Attachment must be secure without puncturing the bag and releasing the contents
Type of Bags Required?
Earthbag construction typically uses bags made from woven polypropylene, which is a type of plastic that is strong, durable, and resistant to moisture. These bags are often used to transport goods such as grain, fertilizer, and other materials, and are readily available from suppliers of construction and agricultural materials.
When choosing polypropylene bags for earthbag construction, it's important to consider the following factors:
Size: The bags should be large enough to hold the amount of soil or other fill material required for each course of the wall, typically around 20-40 pounds per bag.
Material: The bags should be made of woven polypropylene, which is strong, durable, and resistant to moisture. Avoid bags made of woven polyethylene or other types of plastic, as they may not be as strong or durable.
UV protection: The bags should be UV resistant as it will help to prevent the bags from breaking down under the sun.
Color: The bags should be a light color to reflect sunlight and prevent the bags from overheating.
Quality: The bags should be of good quality and free of holes or tears.
It's important to note that when using bags for earthbag construction, only new bags should be used as used bags can contain contaminants or be damaged. Additionally, it's also important to check with your local building code to see if using polypropylene bags is allowed and if there are any specific requirements that need to be met.