The split-level house is an architectural form that experienced its greatest popularity in
America, especially its northern and eastern regions, from the mid-
1950s to the mid-
1970s.
A split-level house is comprised of two sections - one two-story high segment adjoined to a staggered single story, creating three distinct interior areas separated by two half-flights of stairs (see figure 1, below). These segments are usually arranged side-by-side so that all three are visible from the front of the house. The main entrance opens onto either the "first" or "second" floor, while the garage is invariably located on the lower level. This three-level style can be seen as an intermediate stage between the single-story, Prairie Style and similar Bauhaus and International-influenced layouts that featured prominently in America's postwar suburbanization and the later resurgence of multilevel suburban housing.
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| Third floor +-------------------+
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+-------------------+ Second floor |
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| First floor +-------------------+
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Figure 1 - Frontal view of typical split-level house
There are few limits on the external appearance of split-level houses. Many early models cribbed heavily from the "Modern" styles they supplanted, but split-level houses can and have been built with a variety of exterior styles, from modern and traditional to postmodern and neotraditional. The primary factor setting this architectural style apart is its interior, and its principal selling point was the manner in which it allowed the house to be easily divided by function. The upper level was conceptualized as a peaceful, private space, primarily composed of bedrooms. The central level was an intermediate space, housing the kitchen and semipublic spaces like living and dining rooms. The lower level, usually partially subterranian, was conceptualized as a louder, less refined, more functional space. It played host to the garage, recreation rooms, storage space, and infrastructural appliances like furnaces, water heaters, and clothes washers.
Closely related is the "split-entry" style, in which the areas which in split-level houses would be the second and third floors become a single upper story, with the front entrance opening onto a landing around the midway point of the stairs between upper and lower levels.