Earthbag Construction

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Earthen architecture endures. If we can build one ecologically friendly house in our lifetime that is habitable for 500 years, we will have contributed to a sustainable society.

Adapted from Earthbag Building, a Mother Earth News “Book for Wiser Living,” by New Society Publishers. Authors Kaki Hunter and Donald Kiffmeyer have been involved in the natural building movement for 12 years and specialize in environmentally friendly and affordable building methods. To order, see Page 126 or go to www.MotherEarthShopping.com.

You can share your earth-building experiences by going to our new Green Homes and Renewable Energy Directory at www.MotherEarthForums.com/greenhomes.

Advantages of Earthbag Building

We love earthen construction in all its forms. The sheer joy of mixing and plopping cob into a sculptural masterpiece is unequaled. But for the first-time owner/builder, there are some distinct advantages to earthbag construction. Here are the advantages we think it gives to the do-it-yourselfer as compared to other types of earth building.

Adobe is one of the oldest-known forms of earthen building. It is probably one of the best examples of the durability and longevity of earthen construction.

Adobe is made using a clay-rich mixture with enough sand to provide compressive strength and reduce cracking. The mix is liquid enough to be poured into forms and then left until it’s firm enough to be removed from the forms to dry in the sun. Adobe bricks cannot be used for wall building until they have completely cured. While this is probably the least expensive form of earthen building, it takes more time and effort. Earthbag building, on the other hand, does not require as much time and attention as adobe. Because the bags act as a form, the dirt mix is put directly into the bags and immediately placed on the walls. They also don’t need as much moisture as adobe — earthbags cure in place on the wall, eliminating the time spent waiting for the individual adobe bricks to dry.

Rammed earth is another form of earth building that has been around for centuries and is used worldwide. Many miles of the Great Wall of China were made using rammed earth.

Rammed earth involves the construction of temporary forms into which earth is compacted. These forms must be built strong enough to resist the pressure exerted on them from ramming (compacting) the earth into them. The soil also must be a specific ratio of clay to sand with about 10-percent moisture by weight added to the mix.

In most modern rammed-earth construction, a percentage of cement or asphalt emulsion is added to the earthen mix to help stabilize it, increasing cohesion and compressive strength and decreasing the chance of erosion once the rammed-earth wall is exposed.

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