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Earthbag building

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Revision as of 21:10, 25 February 2017 by Moribund (talk | Contributions) (tidy further reading section, adding some items)
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History

The notion of building walls with sandbags or earthbags has been around at least 100 years. Originally and into modern times these have tended to be burlap (hessian) fabric bags forming temporary structures acting as flood barriers or as military fortifications. Building permanent structures such as homes using earthbags is a more recent development.[1]

The earliest record of such construction methods appears to have occurred in Germany in the 1970s. Gernot Minke and others at the Research Laboratory for Experimental Building at Kassel Polytechnic College were investigating ways of building earthquake resistant structures without cement. They used polyester and burlap tubes filled with pumice to make domed structures. With the Francisco Marroquin University in Guatemala and the Centro de Estudios Mesoamericano Sobre Tecnologia Apropiada (CEMAT) a structure was built in Guatemala in 1978 out of lime soaked cotton fabric bags filled with pumice sand.[2]

The Earthbag building method was popularized by Persian Architect Nader Khalili who eventually developed a building technique he termed Superadobe, where polypropylene bags or tubes filled with moistened adobe soil were used to form often domed structures. Khalili went on to publish 6 books and found the non profit organization Cal-Earth Institute (California Institute of Earth Architecture) in 1981.[3] He has been criticized for attempting to capitalize on this technique at the same time as claiming it was "freely put at the service of humanity and the environment" when he tried to patent the technique of using bags made from any material filled with any material in 1991.[4]

The Earthbag or "Superadobe" Building Method

Many people may be familiar with earthen building methods such as adobe and rammed earth. In Earthbag building, these methods are coupled with the time tested method of building with sand bags. Sand bags have often been used as durable barriers to absorb shock and have proven extremely flood resistant. Earthbags are sacks of earth or insulation that are arranged one row on top of the other to create extremely resilient, often domed, structures. The basic structure looks much like an upturned coiled clay pot.

The Materials

  • Bags
  • Earth (most types-clay, sand, etc)
  • Barbed Wire
  • Gravel (optional)

The Tools

  • Shovels
  • Tamping tool
  • Bricks/weights
  • Nails/wire
  • Buckets
  • Hose
  • Sheetmetal Slider
  • Pliers
  • Ladder

As some of these tools may not be needed in your particular earthbag project, some may also become necessary. A leveling board, hoes for digging and other materials like rubber mallets may come in useful.

Building Tips

The bags: Often used are Polypropelene rice or feed bags. These are durable and readily available. However they will eventually rot off. This is natural and shouldn't be a problem since, according to Nader Khalili, the contents of the bags settles into its permanent form within 3 days.

Procedure

The following is an excerpt from Earthbag Building: The Tools, Tricks and Techniques.

"Earthbag Building utilizes the ancient technique of rammed earth in conjunction with woven bags and tubes as a flexible form. The basic procedure is simple. The bags or tubes are filled on the wall using a suitable pre-moistened earth laid in a mason style running bond. After a row has been laid, it is thoroughly compacted with hand tampers. Two strands of 4-point barbed wire are laid in between every row, which act as a “velcro mortar” cinching the bags in place. This provides exceptional tensile strength while allowing the rows to be stepped in to create corbelled domes and other unusual shapes."

References

Further reading

Books

Websites

Videos

  • Case Study presentation by Frank Morris Matovu at the 4th Quarterly Roundtable Discussion Meeting on Appropriate Building (Low-tech Construction) at The African Heritage House, Kenya (2 parts available to view on YouTube by searching "Flexible Form Rammed Earth Construction (Earthbag Construction)"