Imagine building your own environmentally friendly home out of dirt, barbed wire, and bags, using nothing but a shovel and some sweat. Intrigued? The name for that alternative building method is “earthbag building.” While not nearly as popular these days as straw bale building, the earthbag home movement has been steadily building steam as a means to build a low-impact, low-cost, eco-friendly house that requires minimal external energy whether it’s winter or summer.
Building homes with earthbags (also called sandbags) is a relatively new technique, but its roots are old. People have been using sandbags for a long time to create formidable protective barriers for both flood control and protection (think military or civil emergencies). The resulting sandbag walls are resistant to severe weather and natural disasters such as floods, hurricanes, and earthquakes, and can be built with materials at hand.
Transferring those qualities to a house is a desirable thing, so about 30 years ago the Research Laboratory for Experimental Building at Kassel Polytechnic College in Germany began examining the feasibility of using this method of natural building with earthen materials for homes, without resorting to concrete or other binders mixed with the sand. The researchers found that woven bags packed with earthen materials created a stable and desirable building method. Their original structures were built using pumice, a light material with great insulating qualities.
An early prototype of an earthbag house was then built in Guatemala in 1978, using cotton bags filled with earth, stabilized with bamboo poles, with wire to tie them together. The bags were soaked in a lime-wash beforehand to protect the cotton from decay and insects.
Since then, earthbag building pioneers have
refined the method to be sustainable, long lasting, and low-cost. Because cotton and other natural fibers like burlap break down with moisture and simply aren’t as strong as some other materials, innovators in earthbag building began using woven polypropylene bags as the forms for holding the materials. The polypropylene bags can also break down from exposure to sunlight, so the structures are covered with a plaster or cob-like surface to preserve the bags’ integrity s and to make them more aesthetically pleasing.
The advantages of building with earthbags are many: • The bags can be filled with local materials, lowering the amount of embodied energy from manufacturing and transporting conventional building materials. In many areas, the best fill-dirt is literally right under the builder’s feet.
• The materials used to pack the bags (dirt, pumice, vermiculite, and other such materials) do not decompose, don’t attract rodents or insects, and are not flammable.
• Because earthbags are filled with non-toxic materials, they will not off-gas any toxic fumes or chemicals, a common problem with conventional housing.
• Building with earthbags isn’t a highly skilled task, although there are best practices for constructing dwellings. When compared to conventional building techniques, the skill level needed is much lower but the labor, or sweat level, is much higher. This means people with more time and energy than money can build an earthbag home and not have to hire a builder or contractor.
• Earthbags don’t have to be stacked in square or rectangle patterns and earthbag homes can be built in a large variety of shapes, such as domes and arches. Because of this, earthbag homes can be built without the need for a separate roof, as the walls can be corbelled inward to form the roof. No wooden or steel materials are necessary in the roof structure, saving both trees and the energy needed for manufacturing the steel or lumber.
• Earthbag homes can be built to provide either insulation or thermal mass, depending on the fill material. If the bags are filled with lighter materials, the walls are highly insulating. When filled with heavier materials, such as earth, the walls become thermal mass to store and dissipate heat for the house.
• The foundation of the building can also be built with earthbags filled with gravel, providing a non-wicking base for the structure in wet areas.
• Earthbag homes can be dirt cheap to build. The polypropylene bags are often available to purchase at a low price as misprints from the manufacturer, and even when purchased new they are quite a bit cheaper than other common building materials. Barbed wire and other necessary materials are readily available and low-cost.
The basics of earthbag building are quite simple. The polypropylene bags or tubes are filled with pre-moistened earth and laid up in a running bond (similar to bricklaying). The bags can be filled in place on the wall to eliminate most of the heavy lifting, and once the whole row has been laid, the bags are compacted with heavy tampers. Strands of 4-point barbed wire are then laid in between each course of earthbags, which holds the bags in place, in a kind of Velcro effect. The barbed wire adds strength to the walls, and allows the bags to be corbelled (stepped in) to form a dome. The doorways and window openings can be built around removable forms, enabling arches to be used for a strong structure.
Earthbag Building Innovators:
• An architect named Nader Khalili has been integral in popularizing the concept of building permanent structures with bags,
mixing the idea of adobe domes found in his country, Iran, with the earthbag building method. He refined the earthbag concept further by using strands of barbed wire between the layers of bags, which ties them together for stability. At first, Khalili filled his bags with desert sand, but then conceived the idea of the “superadobe”: bags or tubes of polypropylene filled with a moistened adobe-type earth that dries into a form of adobe bricks. Khalili’s institute in California, Cal-Earth, The California Institute of Earth Art and Architecture, is a non-profit foundation now leading the world in earth architecture technology.
• Paulina Wojciechowska was a Khalili apprentice, and authored Building with Earth: A Guide to Flexible-Form Earthbag Construction, as well as establishing a non-profit called Earth Hands and Houses. The foundation supports building projects empowering indigenous peoples to build their own shelters using locally available natural materials, and it teaches workshops on natural building techniques.
• Other innovators in the earthbag movement are Kaki Hunter and Donald Kiffmeyer, who together wrote the exhaustiveEarthbag Building book. This is a valuable resource for earthbag builders, full of tips and tricks for learning the skills needed to create a structure using the earthbag technique. Kelly and Rosana Hart, ofGreen Home Building have also taken the technique and refined it with their own techniques, such as using crushed volcanic rock for the fill, and applying a papercrete finish to the exterior.
One major barrier to earthbag building is the strict regulations inherent in local building codes. Not enough earthbag buildings have been built to clear the way for other owners/builders, even though Khalili’s earthbag structures have been proven safer than many other building types. His buildings have passed tests for California’s high seismic building codes so they are resistant to earthquakes as well as fire, flood, and other natural disasters.
If you’re interested in building your own green home, I highly recommend investigating the earthbag building method. This technique results in a low-cost, long lasting, environmentally friendly home that can be built without highly skilled labor. Earthbag homes are extraordinary structures, which showcase the use of appropriate technology and intelligent design: good for the Earth, good for your wallet, and good for you.
Derek Markham is a father, writer, and social media butterfly who enjoys bikes, bouldering, and slacklining. He can usually be found on Twitter, Natural Papa,Twilight Earth, Blue Living Ideas, and Green Living Ideas, as well as dropping random goodness intoDerekMarkham.com. Connect with him on Facebook.
http://www.youtube.com/watch?v=WMNzoWkXTtc&feature=player_embedded
Source:
http://greenlifestylemagazine.net/issue-2/earthbag-building.php
http://www.youtube.com/watch?v=WMNzoWkXTtc&feature=player_embedded
Source:
http://greenlifestylemagazine.net/issue-2/earthbag-building.php
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