With all the videos I’ve done on earth buildings (like the tiny cob cottage in North Carolina or the mudbrick home in Melbourne, Australia) one of the most common questions I’ve gotten is what happens if it rains? So I asked natural building expert Michael G. Smith to address just this issue.

His basic response: it’s not all that different from building with wood. “Basically you need to put a roof over any earthen structure, just as you would a wooden structure. The problems show up a lot more quickly with earthen structures than with wooden structures, but it’s all the same forces acting on both of them. You don’t want to build a wooden house with no roof or it’s going to rot.”

In this video, he talks about how long-lasting earth structures can be as long as they have a roof, a foundation (to protect from ground moisture), and possibly a protective plaster (“if you live in a place with wind-driven rain that comes in horizontally”).