I just posted the recent news about gaining engineering approval for earthbag construction through PSE, Nabil Taha’s engineering firm in Oregon. He is licensed in 27 states and has developed an earthbag building system to meet international building codes. This is a major step forward for gaining widespread acceptance of earthbag building and we are very appreciative of his leading role and support.
The following engineering guidelines are quoted from the PSE website:
– Earthbag building utilizes the ancient technique of rammed earth in conjunction with bags and tubes as a flexible form. Earthbag construction does not require as much time, attention, or forms as adobe or rammed earth construction requires.
– The fill can be on-site soil or other local materials. Depending on the needs and uses of the completed project, certain materials are selected for either insulation or providing thermal mass. Generally, the fill is of a mineral composition and not subject to decay.
– Because these structures can take an endless variety of shapes, the need for traditional building materials, such as wood or steel, is negated. This saves both energy and precious natural resources.
– When construction is performed in the right way, earthbag buildings have been proven to withstand the ravages of fire, floods, hurricanes, termites, and earthquakes.
– Earthbags can be stacked for a number of different building types and shapes.
– Round is sound, round or circular shaped earthbag homes/buildings are very strong, and can resist the wind and seismic forces better than rectangular buildings.
– Earthbag buildings do not have to be round, circular or curved.
– The earthbag system, in conjunction with the design of monolithic shapes is the key to the earthbag structural integrity.
– Different materials have been successfully used for earthbag construction such as sand, dirt, crushed volcanic rock (scoria), etc.
– A good mix is approximately 70% sand and 30% clay.
– To prevent the earthbags from sliding relative to each other, barbed wire is always used between earthbag courses.
– Masonry equations can be used for earthbag wall designs.
– The Building Code requires a minimum amount of reinforcement to be used for earthbag construction. The following amount/area of steel can be included in the Code minimum requirement amount of steel: steel mesh in the plaster/stucco, steel bars in the bond beam, barbed wire or the joint reinforcement used between the courses/rows of earthbags.
– At the top of the earthbag wall, providing a concrete bond beam with 2- # 5 bars is recommended.
– Earthbag wall thickness should be 16 inches or more.
– Building codes do not allow generic prescriptive designs that can be applied to all earthbag structures. (Each structure must be analyzed on a case-by-case basis.)
– The best information we have found about bags for earthbag building is on Kelly Hart’s website under “Frequently Asked Questions.”