Ithaka Institute - Building

Guidelines to build earthbag houses in Nepal

The construction with earthbags is the cheapest and most simple way to build rapidly safe houses with natural materials. However, some principle rules of statics and earthquake resisitant building have to be respected. The following guidlines try to give an easy to understand outline of the main principles to follow in order to be safely housed in your new building.

1. Site selection

For the first house, select as far as possible a flat space that should be at least 10m large. We await many people coming to visit and participate in the construction therefore a larger place is to be preferred. If the site is on a slope, make sure that the backside wall is far enough from the slope.

2. Form: Roundhouse

Round houses have the best static and are safest in an earthquake. Old Newari houses were built round exactly for this reason. We propose an outer diameter of 6m. Use a rope to demarcate the circle for the foundation:

2.1 Form: Rectangular House

If for any reason you cannot be convinced to build a round house, please let you convince to building a house with a square shape and not a rectangular. If, however, you decide for a rectangular shape, you have imperatively to add every 3-meter a buttress. Never build a straight wall for more than 4 m without a buttress (see chapter 3 how to build and intercalate a buttress). If you build with square or round shape the corner have to be build as buttress and the walls have look out at each edge (see chapter x on corners).

3. Foundation

Dig the foundation trench 50 cm wide and 30 – 40 cm deep. Ramp the soil in the foundation trench. If the soil is hard and not sandy a depth of 25 cm is sufficient. Take of the grasses, roots and organic top soil layer in the middle of the circle which will be floor of the house.

Round or rectangular foundation: Dig the foundation also for each buttress, for the corner-buttresses and the angle-brackets at the door openings. In a rectangular shape, put two doors vis-à-vis in case of emergency.

4. Filling of the foundation

Try to get gravel stones of 20 to 50 mm (should be possible to get with a tip lorry, take one lorry load which should be enough for 3 – 5 house foundations). Fill the gravel in the 45cm x 90cm PP bags and place three layers in the foundation trench. You will need 25 bags per layer. Each layer should be tamped/rammed a bit so that a fairly equal and flat surface will occur.

Hammer through every meter a 6 – 8 mm and 50 cm long iron rod through the three layers but not into the soil. 10 cm of the rods should look out.

The first 1,5 layers of gravel sacs should be in the soil, while the second 1,5 layers gravel sacs are above soils and serve as plinth that protects the base against erosion from rain (see image):

Foundation of 1 to 2 bags , depending on soil quality, add than 1,5 to 2 bags with ravel as plinth which makes at total of 3 gravel bags half under the soil and half above to protect against eroding rain water. Place only then the clay-soil filled bags. Place the iron rod like in the image through all three bags but not into the soil.

If you cannot obtain gravel, use small stones from crushed buildings. You can also mix gravel and small stones. Makes sure no clay is mixed with the stones otherwise water would be soaked into the wall that would keep always wet and not stable!
If you have no gravel you might also put the stones directly into the trench without the sacs. However, the gravel bags have the advantage to make a floating foundation that make the house more resistant in the case of earthquakes.

5. Filling the bags with clay soil

To read the complete guidelines please download the PDF document here