Methods, Technique, Pros and Cons
"Earthbag construction is an inexpensive method to create structures which are both strong and can be quickly built. It is a natural building technique that evolved from historic military bunker construction techniques and temporary flood-control dike building methods." -reply from Google search: "what is earthbag?"
The practice of building with mixtures of earthen materials like sand and clay are as old as human history. Two of the oldest types of earthen construction are rammed earth and adobe. Both of these methods involve the use wooden forms and molds to create bricks or long layers of material which are stacked upon each other, creating walls . If you are familiar with the process of building with adobe or rammed earth then you already understand the basics of the earthbag construction method.
When building with earthbags the material that is used is usually a mix of sand and/or gravel, clay with a small amount of water and sometimes a bit of cement added to stabilize the mixture for greater strength (a technique of most benefit in areas threatened by earthquakes). This mixture is used to fill some type of woven plastic or mesh bag. Most often used are woven polypropylene bags like the type found in grocery stores holding 50 pounds of rice. Woven polypropylene also comes in mile long tubes which are wound onto large spools. These spools of plastic tubing are used in an earthbag technique called superadobe.
When the bags are nearly full, the ends are folded over, sewn closed with wire or pinned with nails and then set into rows just like bricks. In the case of superadobe where the bag is one continuous tube, the tube is layed down in the shape desired and then sealed at the end. On top of each row of bags lines of barbwire are laid out over the entire course of the wall, held in place with small weights and then the next row of bags or tubes is laid down over the barbwire so that the barbs grasp each layer of bags. This line of barbwire acts as a kind of mortar adding a great deal of tensile strength to the wall. When combined with the final layers of plaster, these elements create a solid monolithic structure able to withstand great shearing forces. Sometimes to add even more structural integrity, rods of rebar are pounded vertically through the bags at specific intervals. When properly constructed to suit the demands of the specific location and climate earthbag construction can create structures easily meeting or surpassing the integral strength of any other building method and can be formed into a nearly endless variety of shapes and size while greatly reducing or eliminating the need for environmentally costly materials like timber, concrete and plastic insulation.
Perhaps one of the greatest advantages of building with earthbag is its affordability. Because the majority of construction material is literally right under your feet, material cost can be almost nothing. In the worst case scenario the greatest expense for materials will be from the excavation costs. In very rare situations the earth on site will not be suitable for use in construction and dirt will have to be imported from elsewhere but this is incredibly unlikely to be the case. One of the great wonders of this method is that with proper amendments almost any soil types can be used.
Contrasting this benefit is one of the greatest disadvantages to earthbag which is labor! Earthbag construction is very labor intensive. However, depending on your outlook this may not be a bad thing. It is also important to keep in mind that relative to more traditional building methods the amount of time and effort spent erecting earthbag walls is not necessarily significantly greater. The crucial difference is that with earthbags all time and effort is compressed into one phase of building, namely filling and stacking the bags. Whereas in other more traditional methods the manpower is spread out over many different stages of wood framing, insulation, siding, trimming, etc etc.
Compensating for the above disadvantage of increased labor in the main building stage is that the earthbag method is incredibly low tech. This means anyone can do it and can do it easily! Many homes have been built with nothing more than the study of a couple books and youtube videos perhaps supplemented with a workshop/seminar or a visit from an experienced consultant.
Why Are Earthbags Important?
There many many reasons to utilize the Earthbag construction method but I think there are 4 key aspects to the process which really set it apart as uniquely advantageous.
1. plentiful local materials. When Building with Earthbags the majority of the building materials needed happens to be the most plentiful, easily accessible material on the planet: DIRT! Thats why the practice of building with mixtures of earthen materials is as old as human history and as much as it is a physical practicality it is also psychologically healthy. Building with the earth brings a deep satisfaction in feeling connected to the place that gives you life.
2. sustainability. Earthbags also play a role in environmental health by taking plastic out of the waste stream. Bags can be found as misprints or salvage from local businesses but even buying them new has environmental benefit. This is because the Polypropylene used in making the bags is a byproduct of oil refineries and needs to be utilized in some way whether it is disposed of or turned into something useable. Turning them into bags for building walls with indefinite lifse spans is a great way to not only negate their environmental impact but also creates a new market which can open the door to even more sustainably derived resin products like those made from hemp oils. If you really can not bring yourself to love the plastic then consider burlap bags or canvas! anything that will hold the dirt can work. Ultimately, earthbags can do a lot for moving construction methods a lot further down the sustainability spectrum.
3. Low Tech! Of all the great features that Earthbag building has to offer the one that resonates the most with me is that anyone can quickly and easily learn how to do it with only the most minimal training. In a few hours you can learn all the basic steps which will allow you to build nearly limitless shapes and forms. Because this skill can so readily be put within reach of any person it can be a tool to offer strength and empowerment to those who can not qualify for entry into the debt financing system.
4. affordability. Because the materials are so cheap and easy to access nothing can compare to the cost effectiveness of building with earthbags. Depending on how much DIY you are willing to invest into your project its not unheard of for cost per square foot to be as low as 10$. Of course that is building at its most basic and simplistic but as a starting point you can see how much room there is to expand and embellish your projects before you get close to what traditional methods will cost you.
I am not a rich person and odds are you aren't either. Building a durable, strong, safe home in an environmentally conscious way using any of the more traditional methods will be beyond the reach of most people. The modern way of obtaining shelter in the west is to rent or to enter into the convoluted and dangerous systems of debt created by governments and financial institutions. I believe that earthbag building offers a way out of the debt trap while providing strong, earth-friendly, beautiful shelter.
If you are at all interested in earthbag building there is one book you MUST have. It is called "Erathbag building: the tools, tricks and techniques. Its by Donald kiffmyere and Kaki Hunter and it is your new bible!
Dr Owen Geiger is one of the leading experts on natural building materials. He is the founder of the Geiger Research Institute of Sustainable Building and authors for many websites that host large volumes of information on earthbag building and other natural building methdods.
Nadir Kahlili pioneered the use of earthbags in the superadobe technique. Founding the California Institute of Earth and Architecture in 1991 Kahlili designed the first earthbag homes to pass the highly stringent California seismic codes. After Kahlili's passing in 2008 the Institute continues to carry on as a non-profit research and educational organization
Scott Howard started Earthen hand to increase awareness and education for earthen building mediums. He provides workshops all over the world covering many aspects of natural building materials from earthen plaster to cob ovens to full home construction projects and everything in between. He is a highly regarded and valuable asset to the natural building community offering consultation services and help with all aspects of design and construction.
A very exciting innovation in earthbag building is a new technology called the Earth Home Builder which allows a VERY efficient method of filling and laying the bags which is very similar to 3D printing. The average rate of filling and laying bags by hand is about 30-40 ft per hour. The Earth Home Builder being operated by a competent crew can lay about 400 feet an hour. This technology is being pioneered by a new company called United Earth Builders, a highly knowledgeable group of people looking to bring earthbag building closer to the mainstream and opening it to non-profits building affordable housing for those who really need it.
Click here to see the Earth Home Builder in action CLICK
Precision Structural Engineering is one of the very few (if not the only) firms employing engineers qualified to render technical drawings that will meet building codes in 23 states.