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.
Glaspaleis
Peter Schunck compared the structure of the building with a ship, floating on uncertain ground. The foundation is basically a concrete trough, that can 'give a little' if any mining shafts were to be dug under it. This 'ship' would then never be able to capsize. During construction, the moat of the old Roman settlement Coriovallum was uncovered, which was the reason to lay the foundation deeper than originally planned. Inside the old walls the subsoil was firm, but outside them it was very bad. Building such a structure on such ground in a mining area was deemed too risky and the ground was cleared until a single layer of equal overall weakness was encountered, a 12 m thick sand layer. This sand is generally considered a bad foundation soil, but in a mining area it is a good choice because it flows and 'gives' evenly in case of a cave-in in a mine below it. Still, Peutz decided that the soil pressure should not exceed 1 kgf/cm² (100 kPa). So for the foundation he used a reinforced concrete slab extending under the whole building. This 50 cm thick beamless foundation slab is mushroom-shaped.