It is not hard to imagine that the first real homes must have been earthen structures, because earth happens to be the most abundant and handy material available to man. They might have been nothing more than tiny huts originally, but they started the history of constructed houses.
Eventually, though, technology took over, spawning modern building materials and technologies. They have, no doubt, helped house the burgeoning population of earth in great comfort. But at the same time, being high on energy consumption and use of non-renewable resources and polluting substances, they wreak havoc on our ecosystem. Moreover, the high cost of modern construction has rendered about 100 million people around the world homeless.
A search for more ecologically sound and socially responsible housing has brought earthen houses back into focus. Several ancient cultures had extensive villages of earthen houses built with locally available materials. Examples include cob, rammed earth, and adobe houses of South American and West Asian countries. Sometimes dried blocks of earth called adobe bricks were also used in place of formless earth.
Though made of earth, these structures are not as crumbly as one might imagine. Many of them have stood the test of time, remaining unscathed for several hundred to a few thousand years. The Fujian Tulou and the Great Wall of China are just a few of the ancient earth structures still in use.
The German professor Gernot Minke, who experimented with earthen architecture, came up with a technique of building walls using bags filled with pumice. But it was when Nader Khalili, a Californian architect, put forward the idea of using bags filled with moon dust for constructing structures on the moon that this technique received attention. This was in 1984.
Khalili further developed this technique as a means of building shelters cheaply and rapidly for disaster-stricken areas. Taking a page from the building techniques of his native land Iran, he used earth from the building site as a filling material. He also got it certified as an earthquake-resistant building design. Since Khalili considered the earthbags as an improvement on the sundried adobe mud bricks, at least with respect to the ease and speed of preparation, he called this method “super-adobe.”
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Many of his contemporaries and students have developed similar techniques for their own purposes. One such innovation is the hyper-adobe developed by the Brazilian architect Fernando Pacheo.
The basics of earthbag homes
The materials used in the construction of the walls include bags, fillers and barbed wire. The bags are usually made of polypropylene for strength and durability. The bags filled with earth are stacked layer by layer. Since earth-filled bags are heavy, they are first placed in the right spot before filling in the earth with a bucket. This precludes the need for heavy machinery. Each layer, called a course, is completed before placing the next layer on top.
For the foundation
One or two feet of top soil is removed from the building site and spread with a layer of rubble. The foundation layers consist of double bags for extra strength and protection against moisture. They are filled with rubble and gravel and arranged in a single line along the periphery of the excavated area. The bags are tamped down to a smooth surface. The next layer is stacked with the bags overlapping the joints of the previous layer. The foundation is built until it is level with the surrounding ground.
For the walls
Originally Khalili used desert sand inside the bags, but later moved on to dampened sub soil from the construction site. The moist mud will eventually dry into adobe-like blocks within the bags, increasing its strength as time passes.
For structural stability
As each layer is finished, two long pieces of barbed wire are kept on it so that when the next layer comes on top, there’ll be better adhesion between the layers. This is the secret of the excellent structural stability of the structure that helps it to withstand even strong earthquakes.
Strong wooden frames are used to provide doors and windows for the houses, the only requirement of wood in the construction.
Structures with domed roof are made by stacking the bags in concentric circles of ever-decreasing radius. Flat roofing can be constructed in the conventional way using the walls as support for the beams.
For plastering the walls
A mixture of earth and lime is used to finish the walls. In places with heavy rain, several coats of liquid bitumen may be used as a sealant.
Functional advantages of earthbag building
Internal climate control
The filling material of the bag can be changed to suit the climatic conditions of the region. The walls can provide either excellent thermal mass or a great degree of insulation, depending on the fillers used.
Sound insulation is an advantage of the thick and dense walls of a super-adobe structure. Compared to a wood-frame house, this offers greater privacy. Urban housing of this type can protect dwellers from noise pollution, too.
The high flexibility of the building material makes it ideal for constructing organic structures that are aesthetically appealing and compatible to natural surroundings.
Earthquake resistance of earthbag structures has been proven. They are fire-resistant, too. The mud walls can offer a greater degree of protection against microwaves and other harmful electromagnetic radiations.
There is not a construction material more eco-friendly than plain earth. Excessive use of wood has already laid waste to thousands of acres of natural forests. Cement and steel are manufactured with highly polluting industrial processes.
Easy on resources
The cost of producing synthetic building materials and transporting them to the construction sites is a major burden on resources. Earthbags are made on site with materials available right there. It’s almost as simple as building with Lego blocks!
Easy to recycle
Earth being the main component of these structures, it can be easily reused when they are dismantled, a great advantage with temporary housing.
Affordable housing for all
Of all the advantages of earthbag structure, its potential to provide affordable housing for the poor and for those who are rendered homeless by natural disasters is the most commendable. However, many people desiring to live in an earth-friendly manner are also building with earth. Since the structures require very little input other than locally available materials and human labor, the costs are minimal.
If you desire to construct a home made of earth, it is best to do as much research as possible. You can even attend a workshop where you can learn in a “hands-on” manner. Once you have the technique down, building in this manner is not difficult and can be a very rewarding experience.
Do you have experience with earthbag homes? Share your tips in the section below: