The basis for the design of log supported underground home came for the Navaho hogan. In these structures logs rest on footings of stone to form the roof as well. A mixture of pumice and earth cover the house. Asphalt paint is used as a vapor barrier, while stucco protects the logs from moisture. One of the draw backs of underground homes is the cave like atmosphere.
Most people prefer lots of windows and sunlight.
Another problem is keeping the erosion of the earth covering the house in check. This is easily done by planting grass and shrubs that keep the soil stable. Underground homes must be stable enough to bear a heavy load of earth pressing down on the structure. This has cause many people to shy away due to their concerns about cave ins. Also, extra effort must be made to keep underground homes dry.