Structural engineering concerns itself with the provision of necessary and sufficient man-made or altered natural materials to resist and counteract external forces and the continuous tendency of inanimate matter to disintegrate. The resistances provided against gravitational pulls and lateral forces, as well as against internal disintegration stresses, must be sufficient. Any omission below the requirements of sufficiency will result in a failure of designed or expected performance. Failures occur in all types of structures, whether framed or wall bearing, whether of timber, steel or concrete frame. Foundation failures are so common, taking as the definition of failure the non-compliance of the structure with design expectations, that a structure which behaves as anticipated is hailed as an engineering triumph. A common cause of failure is insufficient resistance to resist exterior forces. An example is concrete retaining wall failures where someone underestimated the lateral pressure to be resisted. Another problem is the change of pressures to be sustained when fine-grained backfill becomes liquid when saturated such as what happened to a housing development in Connecticut. Walls also must be given freedom to move when backfilled and also when localized overpressures occur with well designed expansion joints. Lateral distortion of the entire structure from unbalanced pressures can also cause concrete wall failures. This was the case in a garage floor of a house built into a hill. Pressure against the lower story wall was pushing the footings downhill and tore away the lower floors. Another cause of failure is sloppy drawn plans and lack of experienced supervision. A draftsman in Manhasset, New York misread the print on the plan and instead installed reinforcing wire that was to small.