Globalized cultures, imaginaries, and economies are often matched to the standardization of building approaches. However, solutions that are not tailored for a specific context tend to entail environmental, economic, and social issues. Throughout human history, vernacular wisdom has produced interesting low-energy and climate-responsive architectures all around the globe: These can be seen as interesting examples in an era of global warming and overall uncertainty; at the same time, they represent accessible sustainable solutions in deprived areas of the world as well as in wealthier areas. The experience of participatory design and building process is here presented, carried on in a rural area of El Salvador, Central America. A sanitary facility for a school is designed and realized after the collectively desired recovery and improvement of one of the fruits of local vernacular wisdom in building design, i.e., the adobe earth brick. Some potentials and limits of such experience as well as of the used technology are reviewed in the perspective of affordable and ecologically sustainable housing and settlements in the area.