The following is an excerpt from our May 2015 newsletter Force of Nature
In April 2015 Nepal was hit with an 8 magnitude earthquake, causing incredible damage across many communities. The destruction of buildings was extremely wide spread. For example in the rural village of Sangachok some 90% of buildings were destroyed. One notable exception was an earthbag building completed just days before the earthquake. "The real kicker is that it can wobble a little bit, and so you've got a bit of earthquake resistance as opposed to sheer mud walls, mud brick walls, or most of the buildings are done out of the Kathmandu brick, which is terribly bad for the environment," said Cameron Court, of the construction company that helped to build it. (Click on the image below to see video about the earthbag building in Sangachok.)
Earthbag building is a low-tech, low impact approach to building. So how does it work? Kaki Hunter and Donald Kiffmeyer literally wrote the book on earthbag building and give a great description of the process in an article on why they love earthbag building:
"The Earthbag System is a contemporary form of earthen construction that uses modern woven polypropylene feedbags (usually misprints) or long tubes as a flexible textile container (or what we call a flexible form) preferably filled with dampened soil. The bags or tubes are filled in place on the wall being built so there is no heavy lifting. After a whole row is laid, the bags are compacted from above with hand tampers. The compacted earth later cures to a cement-like hardness. Two strands of four-point barbed wire are laid in between every row that act as a "Velcro" hook-and-latch mortar, cinching the bags together while providing continuous built-in tensile strength. Tensile strength inhibits the walls from being pulled apart during stressful conditions like earthquakes, floods, hurricanes, and load-bearing and lateral forces."
Earthbag building began in the military as a way to quickly make durable, bullet-proof shelters. They have come a long way, including specially designed bags for earthbag construction. Advantages of earthbag construction include the ability to use a very wide range of soils (locally sourced), no delay for curing, no need to build a foundation, no need for hi-tech tools. Their very design is disaster resistant. One disadvantage is that if you use basic soil you will not get strong R values. However, earthbag buildings can have high R values (high 20s+) if filled with specific soils (such as pumice, perlite, rice hulls).
There are commercial earthbag buildings including a school, an orphanage and a spiritual temple. The building in Nepal was designed as a teaching centre for teachers, though now it is reportedly being used as a community hub as it is one of the few buildings standing.