site walls | sustainable neighborhoods nicaragua

Spring 2012 | Constructed January 2013
Location: Nagarote, Nicaragua
Parnternship: SosteNica
Cornell University Sustainable Design

Cornell University Sustainable Design (CUSD) teamed up with SosteNica to design and construct a model home that embodies the values of healthy, beauty, sustainability and cultural continuity, while also addressing affordability. In efforts to respect tradition, use less embodied energy, and protect building inhabitants from the woes of tropical heat, CUSD designed the model home using local building materials. As part of the Site Walls Analysis team, it was our responsibility to determine the best facade material - in this case, Earthen Adobe Walls. 

Model Home Design. 2012 Design Credit: Cornell University Sustainable Design

facade design

After site analysis, research, and consideration of Bamboo, Rammed Earth, and Compressed Earth Blocks facades, we decided that the most structurally sound building material in this case would be compressed earth blocks, using a combination of the site's soil, hay, other earthen materials, and water. In Nicaragua, it was important that we considered large seismic activity and erosion complications when choosing our construction method. Using an adobe block machine allowed us to create more stable, stronger adobe blocks to prevent damage from threatening earthquakes or monstrous monsoons. The facilitation of the adobe block machine also created opportunity to educate the local community on how to use it to create a consistent earthen "brick" to be used for the remainder of their homes modeled after our design. 

the process

When building with compressed earth blocks, the primary design and specification considerations had to deal with the control of moisture and the prevention of erosion. In areas like Nagarote, Nicaragua, the heavy rainy seasons could easily destroy the earthen structure, so in order to prevent such a catastrophe the structure was sited on higher ground, and away from poorly drained areas or areas where pools of standing water are likely to appear. All drainage systems were directed away from the building, including irrigation systems, which should be located far enough away in case of leaks or malfunctions.

Because of the compressed earth blocks basic composition, the adobe blocks were only used in low retaining walls - height no more than eight times their width.

The process of creating the compressed earth blocks involved a brick-forming machine, which on estimate created 300-400 bricks per day for a crew of two, untrained persons with the smallest equipment available on the market. The adobe bricks cured for less than 10 days, and were protected from water during the entire drying process. In this case, the adobe bricks were laid on well-compacted gravel and san trench foundations.

When laying the walls, the community applied mortar to the full surface of the adobe blocks. Once all the bricks were laid, both unstabilized and stable blocks required an additional layer of mud and plaster as the finish. This plaster requires a periodic reapplication of about every 1-3 years.