In Part I and Part II of this series we examined the use of cob and straw-bale as a sustainable and possibly regenerative building
material for housing. Both show some promising potential and remain as viable options. As we continue our search, we’ll take a look at building with earthbags, also known as superadobe.
Earthbag/Superadobe: Very similar to the cob and straw-bale models, earthbag buildings use sandbags filled with earth gathered on location as building blocks, secured with barbed wire as mortar and sealed with an earth plaster for weatherproofing.
FREEDOM/INDEPENDENCE: Another building material and method that boasts great flexibility in design and an organic feel to the architecture. I really like that the primary materials are gathered on site and that the durability of structure is independent of the quality of the dirt being used to fill the bags. This is a nearly ideal situation for self reliance in that a very small proportion of the building materials needed would have to be purchased and hauled. The resourceful person can potentially gather the necessary manufactured elements without spending any money by simply recycling used materials.
ENVIRONMENTAL FOOTPRINT: Like cob, the thermal mass makes this very energy efficient. The use of local and recycled materials brings the environmental footprint of an earthbag building to nearly zero.
ADAPTABILITY: Much like cob and straw-bale, the imagination is the only limitation here. In some cases, superadobe is combined with cob, straw-bale and conventional building methods.
SECURITY: Earthbag construction has proven itself to provide a secure shelter and can be made to resist extreme conditions such as earthquakes, floods and hurricanes. This type of building, however, seems to be susceptible to moisture retention and may not be suitable in humid or rainy climates.
STABILITY: Earthen construction is naturally stable, and although this is a relatively new and modern building technology, results show a lot of promise. The overall feel of such a structure is grounding, stable, and enduring.
COMFORT: On the surface, the idea of living in a house made of sandbags and barbed wire does not sound very comfortable, but keeping things in perspective, these base materials are simply providing a solid foundation and framework much like bricks and mortar or wood and nails would provide for a more conventional building. In the end, when combined with ingenuity and technology, earthbag buildings can offer the same level of comfort as any house.
BOTTOM LINE: Earthbag buildings provide a promising alternative to cob and straw-bale that is not dependent on the availability of resources. Unlike cob which requires clay with specific properties, and straw-bale which requires an abundant and local supply of straw bales, Superadobe building techniques can be employed regardless of the available local resources.
Additionally, family homes have already been built in Southern California and blueprints are available that meet all the pertinent building codes. Although plans would have to be verified with local codes, this makes Earthbag construction an even more attractive option for people living in areas, such as California, where building codes are known to be rigid.
Earthbag construction does require the use of manufactured materials such as sand bags, barbed wire, and a waterproof plaster material as a lining. Although not the necessarily the ultimate solution, Earthbag structures add another valuable option and further insight into the perfect EarthSky People dwelling.