Simplicity
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 premoisted suitable earth laid in a mason style running bond. After a row is laid, it is thoroughly compacted with hand tampers. Two strands of barbed wire are laid in between every row and act as a “velcro mortar” cinching the bags into place. This provides exceptional tensile strength while allowing the rows to be stepped in to create a corbelled dome. The walls cure to a durable cement-like hardness.
Earth Not Trees
Earthbag domes can eliminate 95% of the lumber currently used to build the average framed house. Conventional wood roof systems eat up a lot of trees. Why cut and haul lumber when the most abundant, energy efficient, versitile, cost effective, termite, rot, and fire proof construction material is available right beneath our feet? Earth is currently and has been the most used building material for thousands of years, and we have yet to run out.
Earthbag Performance
Under static load testing conditions simulating seismic, wind, and snow loads, non-stabilized earthag domes exceed 1991 Uniform Building Code requirements by 200 percent. (Californial Institute of Earth Art and Architecute under the supervision of International Conference of Building Officials). No surface deflections were observed, and the simulated live load testing continued beyond the agreed limits until the testing apparatus began to fail. The earthbag system has been proven to withstand the ravages of fire, flooding, hurricanes, termites, and two natural earthquakes measuring over six and seven on the Richter scale.
Thermal
Earthen walls function as an absorbent mass that is able to store warmth and re-radiate it back into the living space as the mass cools. This effect is a 12-our delay in energy transfer from exterior to interior. This means that at the hottest time of the day the inside of an earthbag structure is at its coolest, while at the coolest time of the day the interior is at its warmest. This performance is regulated by many factors including placement of windows and doors, wall orientation, wall thickness, and wall color. Bermed structures provide assisted protection from the elements. Berming on the north side of a dome provides additional insulation helping to keep it warm in winter months. Earth is the most reliable temperature regulator.
Cost Effectiveness
Materials for earthbag construction are in most cases inexpensive, abundant, and accessible. Grain bags and barbed wire are available throughout most of the world and can be obtained for a fraction of the cost of cement, steel, and lumber. Dirt can be harvest on site or hauled in for the cost of trucking.Sustainability
Earthen architecture endures. That which endures sustains. Examples of early Pueblo earthen construction practices dating from 1250-1300 AD is evident throughout the Southwestern United States. In the rainy climate of Wales, the thick earthen cob-walled cottages protected under their thatched reed roofs boast some 300-500 years of continual use. If we can build one ecologically friendly house in our lifetime that is habitable for 500 years we will have contributed towards a sustainable society.