The earthbag clinic and school buildings in Leogane have unfortunately experienced cost overruns. Obviously this is a very important topic, and doubly so when building in developing countries where budgets are very tight. One problem has been the unusually high cost of materials, which can be much higher than in the US. The main expense has been cement plaster. Uneven walls have taken more cement than anticipated. Here are a few suggestions for minimizing plaster expenses for earthbag construction.
– Use earthen plaster whenever possible. Be sure to use adequate sized roof overhangs to protect the walls from moisture damage.
– Use cement or lime plaster only where necessary – for example, on lower exterior walls where driving rain will hit.
– Lime plaster is preferable. Unlike cement plaster, lime plaster can be applied over an earthen base coat that fills all the large recesses.
– Flatten wall surfaces with a tamper after every few courses as the walls are built. Do this before the soil dries too much. This simple step can cut plaster work and plastering materials in half. Note: this method requires adequate clay content in the fill material.
– Tubes create smoother walls than bags, and can help minimize plaster work.
– Tuck or pin bag corners out of the way, or turn bags inside out to avoid protruding corners.
– Minimize plaster work with good workmanship. Get in the habit of sighting down walls and checking your work from various angles to catch any errors right away.