Foundation (engineering)
A foundation is the element of a structure which connects it to the ground, and transfers loads from the structure to the ground. Foundations are generally considered either shallow or deep. Foundation engineering is the application of soil mechanics and rock mechanics (Geotechnical engineering) in the design of foundation elements of structures.
Richmond District, San Francisco
To lure home buyers with promises of large houses while keeping prices low, homes were built with large basements (basements are an unusual feature in California because its weather permits shallower foundations) with the intention that the buyers could convert the basements into living space at their own volition. This essentially marketed a house as two stories, with the first story (basement) unfinished. This decision would prove to be ingenious as the 20th century evolved, as many basements were converted to garages. Some were converted with garages in the front and in-law units in the back.