Fisher House (Hatboro, Pennsylvania)
The foundation of the home is built entirely of stone in, for Kahn, a traditional style of building. The stone foundation was necessary due to the home’s placement on a slope and its need for a solid anchoring into the ground of the site. The exterior and interior portions of the home are made from the same cedar wood sourced from the local Pennsylvania area. This was done to keep down costs. The woodwork of the Fisher house is often viewed as the most comprehensive of any of his woodwork during the period. Later projects were said to lack the continuity of the Fisher House, often smaller details such as interior doors were left unadorned in a way that left the project feeling incomplete to viewers. It was best in the end that Kahn was not allowed to build from all stone, because if he had the home would have been lacking in much of the great detail work that makes it so famous. The use of cedar wood throughout the interior and exterior of the home compelled Kahn to create amazing details in the building simply by folding windows into the building envelope to provide new habitable space on both the interior and exterior of the building. Had Kahn been left to build the Fisher House entirely from stone on the exterior then the details he created from windows never would have come into existence.
Earth shelter
In some low budget earth shelters, insulation may not be applied to the walls. These methods rely on the U factor or thermal heat storage capacity of the earth itself below the frost layer. These designs are the exception however and risk frost heave damage in colder climates. The theory behind no insulation designs relies on using the thermal mass of the earth to store heat, rather than relying on a heavy masonry or cement inner structures that exist in a typical passive solar house. This is the exception to the rule and cold temperatures may extend down into the earth above the frost line making insulation necessary for higher efficiencies.