My major project at Cal-Earth was to build a 10-foot lancet dome with a 1.5ft spring line. We constructed the dome with unstabilized earth (i.e. without adding cement or lime) except in the sections exposed the most to the elements. Namely, the dome was stabilized around openings.
The plaster will serve to protect the dome from the elements. We included a dome mushroom cap in the design, the main purpose of which is to shed water away from the structure. The dome was completed by mid-December 2012 in less than two weeks of work. However, due to time constraints, we entrusted future apprentices to place the protective mushroom cap on the dome. The Cal-Earth staff considers the cap idea one of their R&D successes. My fellow apprentices and I are thankful for them for providing us with the resources and space to experiment and develop new construction techniques.