Image courtesy of Homedit.com.
Earthbag homes are more eco-friendly than traditionally built homes that use less sustainable building materials. The walls of earthbag homes are made from heavy-duty bags filled with subsoil and stacked in rows.
Compared to concrete, which is among the most common building materials, it’s a much more sustainable option because manufacturing a ton of cement emits about 0.9 pounds (0.41 kg) of carbon dioxide.
Contrast this with earthbags filled with subsoil excavated on-site and you can easily see the benefits from a sustainability point of view.
This is why many eco-conscious builders and homeowners are turning toward sustainable building materials like earthbags in preference to more traditional, less environmentally friendly approaches.
An earthbag home is a home whose walls have been built with earthbags filled with sand, gravel, clay, and other organic materials found mainly on the site. The bags are then layered in the desired shape, tamped, and held together with barbed wire to create sturdy walls.
In the rest of this article, I’ll discuss the pros and cons of building an earthbag home to help you decide whether an earthbag home is right for you.
Before diving into the pros and cons of building an earthbag home, it’s essential to understand the basics of building one.
Earthbag construction was originally developed by architect Nader Khalili of the Cal-Earth Institute in California. The intention was to help people build strong, long-lasting, cost-effective, and eco-friendly homes.
Here are the basics of building an earthbag home:
- Gathering the tools and materials: The primary materials and tools needed include polypropylene bags, barbed wire, buckets, tamper, and fill materials.
- Filling the bags: The bags are filled with sand, gravel, and clay. A rule of thumb is to have a balance of the three fill materials. Therefore, the same number of buckets are used for each bag before sewing or stitching.
- Digging the foundation: Before laying the foundation course, a trench, 6 to 12 inches (15 to 30 cm) deep, is dug and filled with gravel for efficient drainage.
- Laying the lower course: The filled bags are layered from the corner toward the center and butted against each other. They’re aligned to a string line and tamped for stability.
- Securing the bags: Barbed wire is used to secure the bags, ensuring no gaps between them. The above process is repeated while adding the doors and windows until the wall attains the desired height. Finally, a protective plaster is applied for a more attractive and hard-wearing finish.
- Roofing: Flat or skillion roofs are the most common for earthbag homes. The roof is erected with horizontal joists covering the building’s length to pull the structure together and provide lateral support for the walls.
Now that you know the basics of building an earthbag home, let’s dive into the pros of these sustainable structures.
The main reason engineers, architects, builders, and homeowners are shifting toward earthbag homes is because they’re very environment-friendly.
It’s worth noting that conventional building materials like concrete affect the environment throughout their life cycle — from extraction and construction to use and disposal. This explains why the construction industry is responsible for up to 50 percent of climate change.
Earthbag building is an eco-friendly technique that facilitates green building in the following ways:
- Less transportation required: The primary materials – sand, gravel, and clay – are readily available on most sites. Therefore, there is no need to transport them from far-flung quarries, generating greenhouse gases.
- Less embodied energy: Embodied energy is the amount of energy consumed during the production, manufacture, transportation, and use of building materials. Earthbags are filled with on-site materials and don’t require much energy to manufacture or transport, resulting in low embodied energy.
- Lower carbon footprint: Carbon footprint refers to the overall amount of carbon dioxide released into the atmosphere by a building. Earthbag buildings have a low carbon footprint since they don’t require materials to be transported over long distances. They also don’t require heavy machinery like bulldozers for construction.
Earthbag homes are highly durable if constructed correctly.
Earthbag construction results in robust and long-lasting structures in the following ways:
- Sandbag materials: Polypropylene is the main material for making earthbags. Since it’s impervious to water, polypropylene makes water-resistant earthbags that don’t rot or decay. The material is also flame-retardant.
- Layering technique: The bags are placed side-by-side, like bricks. This method reinforces the structure’s integrity, making it more durable.
- Barbed wire: This holds the bags together, preventing them from shifting or sliding. The wire further reinforces the earthbag home’s durability.
- The foundation: Digging the foundation prevents the subsoil from spreading due to the structure’s weight. Spreading subsoil creates unequal settlement, affecting the building’s structural integrity.
Earthbag houses are ideal for seismic zones due to their strength and durability. For instance, 55 earthbag structures survived a 7.8 magnitude earthquake in 2015 in Nepal. Therefore, it’s an ideal option in an earthquake-prone zone.
Construction is one of the most expensive one-off investments most people make.
Earthbag construction is a cost-effective option since the primary materials are readily available on site. You don’t have to transport them from afar and incur transportation costs.
In addition, if you obtain the fill materials from the construction site, they are essentially free of charge, except for the labor costs associated with handling them.
Building an earthbag home is DIY-friendly. The work involved is not highly skilled and with a little research or training, anyone can learn to fill the sandbags correctly, layer, and tamp them to attain the desired height.
Going the DIY route saves you the money on hiring a contractor.
To put this cost efficiency into perspective, while building a concrete home costs between $100 and $250 per square foot, earthbag construction costs between $7 and $15 per square foot. Therefore, earthbag building is a good option if you’re on a tight budget.
Earthbag walls have a high thermal mass thanks to their thickness and density.
Most earthbag walls are about 38 cm (15 inches) thick. Thicker walls have high thermal mass that helps capture and store solar energy.
High thermal mass materials like earthbags are excellent at absorbing, storing, and releasing heat, evening out temperature fluctuations.
These materials absorb heat during the day to keep the indoors cool, and release the absorbed heat at night to warm the internal space. This phenomenon lowers the demand for central heating and cooling, conserving energy.
Adding thermal insulation will help further mitigate the effects of a hot or cold climate, keeping your home at a comfortable temperature.
Earthbag homes require minimal maintenance — a welcome relief for homeowners with busy schedules.
Earthbags don’t require regular maintenance procedures, unlike other building materials that need painting, re-varnishing, and other maintenance work every few years. All you need to do is apply the protective plaster, which keeps water from penetrating the walls.
Also, earthbag homes are insect-proof and mold-proof, thanks to the polypropylene material, so you don’t have to worry about regular repairs due to pest damage.
While earthbag homes offer numerous benefits, there are a few drawbacks you must consider before building one. They include:
Building an earthbag home is labor-intensive and takes a long time.
Filling the sandbags is the most labor-intensive and time-consuming part of the process. From excavating fill materials and putting them in buckets to filling the bags, the process requires a lot of time and labor.
Therefore, you should only go the DIY route if you have sufficient time and energy for the work. Otherwise, consider hiring professionals, which will add to the overall cost.
Layering, leveling, and tamping earthbags requires specialized skills to ensure the structure is built correctly. These skills are not difficult to pick up but it’s important that you set aside time to learn them properly to avoid re-work or other problems down the line.
If you don’t know what you’re doing, you could end up with an unevenly leveled earthbag home, which could affect the structure’s stability and integrity.
So, take the time to learn the process and consider hiring a professional to supervise the work if it’s your first time building such a house.
Earthbag homes have thicker walls and, while this is a plus for energy efficiency, it makes plumbing and electrical installations more difficult.
Electricians and plumbers must drill the walls to install pipes, wires, and other hardware. The thick walls make this process time-consuming and cumbersome. It requires professionals for safe electrical wiring and plumbing connections.
Some professionals use trenching to run piping behind the walls, while others create a chase wall for electrical wires.
Another approach is to install Romex wire as you build the wall by placing it along the top of a course of bags before placing the next course. You can incorporate wooden anchors into the wall as you go to allow easy fitting of electrical boxes.
Earthbag homes are energy-efficient, low maintenance, and durable, making them ideal for those looking to reduce their bills and lower their environmental footprint while building a sturdy structure.
However, plumbing and electrical installations can sometimes prove challenging due to the thick earthbag walls.
Building an earthbag home is also labor-intensive and requires specialized skills. So, take the time to learn how to build with this technique correctly or hire skilled labor to help you.