The design and layout of the underground Hobbit House was influenced by the site conditions; bedrock, trees, slope of hill, depth of water table and equipment I had available to excavate. It was decided early that the structure should be as underground as possible and to accomplish the load carrying needs of the structure a simple dome concept was chosen. Bringing light into an underground house is an important design concideration. By creating a central light core in the center of the dome, natural light from the outside becomes plentiful. As excavation started, bed rock was encountered causing the structure to be situated less deep into the hill side . As the rock was exposed it was decided to create multiple levels following the level of the rock. Having multiple levels added greatly to the interior character. Almost every surface except the floors are curved. To keep the feeling of spaciousness in such a small footprint the ceiling height was maximized. In the lower level, the entrance level, the ceiling height is 10 feet and in the upper level which is a little cozier a 7.5 ft ceiling height was used.
With varying radi and height of the dome the only construction method to accomplish the building of the dome was a customized wooden form to create the unique geometry of the interior space. Given a uniform dome other simplier methods may have been available such as an inflatable membrane covered in insulation and shotcrete.