Experts warn that public confidence in concrete construction is misleading. “Do not believe for a second that concrete won’t be impacted in an earthquake,” says Jharna Joshi, an architect and professor at Kathmandu University. Even a slightly longer or more intense earthquake could have also brought down concrete structures in 2015.
According to Survant, current building codes limit rammed earth structures to two and a half stories, making them less popular in a dense, city environment that builds upwards even though rammed earth buildings can go up to three stories.
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Building codes require adjacent residential buildings, even in concrete, to not exceed three stories, but contractors often add additional floors on top of existing structures. “There is a building code, but people do not follow the rules. And since land is very expensive, some build six stories to not lose any value.”
Acharya says his rammed earth structures did not crack in the last earthquake. Earth buildings are used internationally and historically, with structures found in Chile, India, Nepal, and Iran. “Earth structures have been part of vernacular for millenia, and they have tested it,” says Survant, explaining that rammed earth structures use reinforced ring beams, steel bars, and up to 10% concrete that interlock the earth walls.
“The concrete and rebar is providing the same support, but with far far less concrete and using local materials,” he adds.