Earthbag Construction

Clean the site and start digging the earth. Once you dig the top layer, remove it and should not be used in the filling of Earthbags. After enough earth material is extracted, mix it with little water so that the mixture should be damped. Properly mix earth material and water. Now start filling the polypropylene bags with the mixture. The most common mixing ratio of the materials:

• Clay 25% – 30%
• Sandy Soil 70% – 75%
• Moisture 10%

• • Square Structure

    This type of structure consists of placing the earthbags in a square or rectangular pattern and then installing a wooden roof over it. This type of structure requires a special type of care in the foundation. This type of structure consists of a trench foundation, Earthbags walls, wooden beams and lintels, and a lightweight roof (Preferably timber but can be steel).

    The step by step guide of construction of a square earthbag room or house is given below

    1. Foundation for Square structures:
       This type of structure requires a special type of care in the foundation. This type of structure consists of a trench foundation, Earthbags walls, wooden beams and lintels, and a lightweight roof (Preferably timber but can be steel). The complete building process can be seen from this video from start to end. For a square foundation, Dig the earth wider than the earthbag wall (15”) and 3 ft deep. On the bottom of it, place the polythene sheet and then place the drainage pipes on it. Then add aggregates or rubble or until the 6” below the ground level. Compact it and then add a layer of gravel filled in a double polypropylene bag till the finished level of the ground. Add the barbed wire and add a second layer of 6” gravel-filled bags. This is how the foundation of the square foundation is done. The typical cross-section of this type of foundation is:
       • Step 1: Dig the earth and provide drainage
         For the foundations, Dig the earth wider than the earthbag wall (15”) and 3 ft deep and place the polythene sheet at the bottom of the foundation. Provide pipes to allow the footing to drain after heavy rain. Also, provide a drain to keep the surface water and groundwater away from the building site.
       • Step 2: Add the first layer of Aggregates
         Add coarse aggregates or rubble (Rubble is broken stone, of irregular size, shape, and texture. Rubble naturally found in the soil) until level about 6” below finished grade. Tamp the aggregates or rubble until it’s even and solid. There should be minimum voids between particles.
         
       • Step 3: Add the second layer of aggregates
         Fill the gravel in double polypropylene bags. Place bags on a level gravel bed 6” lower than the finished soil level. The bags should be aligned.
         
       • Step 4: Add the barbed wire and second layer of aggregates
         Place the barbed wire on top of the first layer of gravel and then add the second layer of gravel bags. Its top height should be almost 6” above the ground level to control the moisture effect. Always place the bags in overlap to the below bags. The general rule of overlays is discussed in the figure.
         
    2. Walls of Square Structure
       The walls are made of earthbags with the mixture discussed earlier. Always place the bags in overlap to the below bags. The general rule of overlays is discussed in the figure.
       
    3. The roof of square structure
       The walls are made of earthbags with the mixture discussed earlier. Always place the bags in overlap to the below bags. The general rule of overlays is discussed in the figure.
       
    4. Plastering
       Plastering of earthbags structures can be done by lime plaster or mud straw plaster. Since there is a spacing between the two layers of earthbags which are placed vertically, it is important to fill those spaces with plaster. The earthbags alone cannot withstand the extreme rainy conditions so plastering should be done as it provides weather resistance as well as structural strength also.

• Dome Structure

  Dome structures are also called superadobe structures and were introduced by Nadir Khalili in the 1980s.In this structure, a separate wooden or steel roof is not required and the roof is built in the form of a dome.

  1. Foundations for Dome structures
     Perhaps the most integral part of any structure is its foundations. If foundations aren’t laid accurately the whole building can collapse. Make a trench in the ground of the height of two earthbags and then simply place two layers of earthbags bonded together with the barbed wire. Cover these two layers in a plastic sheet to stop any water from coming into the foundations.
  2. Walls, Doorway, Windows, and Roof
     The walls of dome structures are not vertical. The earthbags are placed in a circular shape following the lancet arch. There is no need for a special roof for this type of structure. The geometry and placement of earthbags in the case of dome structures are of great importance. Every earthbag should be laid following the principles of superadobe structures. The dome structures follow an arch shape at every layer of earthbags.
  3. Plastering of Dome Structures
     Perhaps Plastering of earthbags structures can be done by lime plaster or mud straw plaster. Since there is a spacing between the two layers of earthbags which are placed vertically, it is important to fill those spaces with plaster. The earthbags alone cannot withstand the extreme rainy conditions so plastering should be done as it provides weather resistance as well as structural strength also.
  4. Flooring
     Nobody wants to lay their feet on the uneven surface. The floor of unfinished cob rooms or buildings is just as same as the floor outside the building. So, we need to provide some kind of finishing to give it a proper surface. The ground is compacted a little bit and then plaster is applied on the ground. This plaster is done with a mixture of fine clay and water. After plastering, the surface is coated with linseed oil.