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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 Earthbag building method was developed into its current state by Persian Architect Nader Khalili
- Earth (most types-clay, sand, etc)
- Barbed Wire
- Gravel (optional)
- Tamping tool
- Sheetmetal Slider
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.
The bags: Often used are Polypropelene rice or feed bags. These are durable, readily available and have a high UV resistance. The thing about the bags, though, is that no matter what 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.
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."
The California Institute of Earth Art and Architecture. Founded by Nader Khalili, this non-profit foundation has a great website spanning technical innovations published by NASA for lunar and Martian construction, to housing design and development for the world's homeless for the United Nations.
A well documented example of building with earthbags, especially helpful in detailing materials and tools.
Hunter, Kaki; Kiffmeyer, Donald. Earthbag Building : The Tools, Tricks and Techniques. Gabriola Island, BC, CAN: New Society Publishers, 2004. p 17. http://site.ebrary.com/lib/hsulib/Doc?id=10089797&ppg=17 Copyright © 2004. New Society Publishers. All rights reserved.
See Superadobe as well and maybe join these pages.