With increased global climate change, most regions worldwide are experiencing strong floods, flash floods, and even earthquakes. The massive destruction of property and buildings rises with every natural calamity. While houses are the safest haven for people, conventional building elements relied upon in most regions have proven futile in the advent of such natural disasters. However, ancient methods of construction such as earthbag technology are now emerging as a suitable alternative building method in earthquake-prone areas.
After a devastating earthquake in 2015, it was noted that all of Nepal’s 55 Earthbag structures survived a 7.8 magnitude earthquake with no structural damage. Currently, village builders and professional engineers alike now embrace this technique.
Earthbag technology is an inexpensive, simple, and sustainable method for building structures. The model can be traced back to the 16th century where the technique was used by the military as a system that deals temporarily with flood control.
How an Earthbag Structure SafeGuards Against Climate Change
This type of construction relies on the use of sturdy sacks, which are filled with organically available material on the site.
The standard materials infilled in the sacks are either subsoils that contain high levels of clay soil to become cohesive, water-resistant gravel or even crushed volcanic rocks. Other types of earthen material used include road base, engineered fills, or the local subsoils. Soil stabilization techniques may be used to allow the clay soil to become more stable through
The construction process for earthbag houses initially begins with dug-out trenches in an undisturbed subsoil surface, partly filled with gravel or stones to form a rubble trench foundation.
In regions that experience high seismic attacks, the foundation for such houses is usually a reinforced concrete footing or a reinforced beam. Moreover, earthbag houses can also be constructed on concrete slabs, a more costly construction method. Each layer of stack sacs has two high-end strands of barbed wire on top to attach the bags and prevent their slippage by preventing any outward expansion of the walls. The types of sacs used are the woven mesh bags commonly used to transport grains or rice.
Designs for earthbag houses vary from circular models to other shapes; however, the construction relies on the experience of the laborers to come up with improvised forms. Earthbag houses are primarily suitable for earthquake-prone regions, hot and dry regions, and even roundhouses.
The homes are pretty useful since they can be relied on to safeguard a building against flash floods, which is very beneficial for residents in flooding areas. It is also a fast construction method since the bags incorporated with barbed wire offer the house a robust support system. It also has excellent thermal mass capacities, which make it favorable in various climatic regions.
Openings for the structure are made from timber molds or scrap wood. The roof can be made from common roofing materials such as timber slats with a grass thatched roof cover. However, the interior finishes for the house, such as plastering, take a long duration since they require a specialized skill set.
The technology is cost-effective since rammed earth is the main building component. Often, very little wood or industrial materials are needed, so the buildings are environmentally sustainable. Aso, because earthbag structures are made from predominantly natural materials, the structure adds zero carbon footprint thereby reducing the impact on climate change. Earthbag construction is particularly advantageous in regions that have limited trees as it eliminates the need for wood resources in the walls and roof.
Earthbag walls are usually rather thick and heavy, which does limit some of their possible uses. For instance, they may not be the best choice for interior walls, where space may be limited.
Cover Image courtesy of A4 architects