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There are many differences -- or variations -- which occur in construction as a direct result of the region, or part of the country, in which the building is located.
Many of these differences evolve directly and naturally from the particular conditions of climate, moisture, kinds of materials available, etc. which exist in the particular region, and can therefore be considered truly indigenous, functional differences. A good example of this is the use of sun-dried mud adobe in the southwestern United States. In this region there is readily available the particular adobe clay soil which was long ago discovered to be easily made into usable and inexpensive building blocks. This region also experiences significantly less rainfall, which would otherwise contribute to an accelerated deterioration of the relatively unstable adobe mud blocks. Another significant difference can be pointed out in those areas of the country where frost and freezing conditions penetrate into the soil, necessitating that footings and foundations be set into the ground to a depth below that which frost penetrates, so as to avoid the upheaval and movement which can take place from freeze-thaw action. This can require footing depths of 3 to 4 feet, and more, below ground surfaces. See ( ill. 1).
A regional by-product of the need for deeper foundations is the tendency for residences in those colder areas to have below-grade basements, or cellars, because they are logical extensions of the deeper excavation process. Added space is thereby gained, at not- too-significant added cost. See ( ill. 2).
Basements are often not without problems, however, because those regions usually have higher ground water levels which result in a tendency for basements to have water leaks and higher humidity conditions. Many methods and details for treatment of the water/moisture problem have resulted, including application of waterproofing to interior and exterior surfaces of basement walls, under-floor drainage systems, underfloor waterproofing membranes, sump pump systems, etc.
ill. 2: Section Through a Basement, Comparing Cold Climate Footing Depths
In contrast to the deep foundations of cold regions, the warmer southern and southwestern areas of the country usually are devoid of frost penetration into the soil, and so footing depths can be quite shallow—a common minimum depth being as little as one foot below natural ground level to bottom of the footing ( ill. 3). Therefore, in these areas there is much less incentive to create deep excavations for below-grade basements, and so they are infrequent. Further, the main floor is usually a concrete slab placed directly at grade on prepared soil bases, since there is no excavated area below, and therefore no need to form a structural system capable of spanning open excavated areas. Contrast this with the usual joist and beam system commonly used over excavated basement spaces ( ill. 2).
In colder regions, on occasions when basement-less slab-on-grade construction is used, it’s not common practice to pour the floor slab integrally with the foundation wall, as is often done in the southern regions (ill. 4).
ill. 4: Integral Floor, Stem Wall and Footing In Warn Climates
ill. 5: Floor Slab Insulated At Edges in Cold Climates
Rather, it’s desirable -- in fact necessary -- to isolate the floor slab from the exterior wall via an insulated separation, in order to minimize heat loss from the warm interior to the cold exterior ground thru the perimeter edge of the slab and foundation ( ill. 5).
Another indigenous difference is the widespread use of stucco as an exterior finish in the south and southwest; a material only infrequently found in the colder regions of the country. The reason for this is that stucco is highly susceptible to damage from penetration of moisture due to frequent wetting, then being subject to freeze-thaw cycles which deteriorate it, cause it to loosen from its base, crack and spall (fall off).
Many regional differences in building features exist simply because of design or appearance characteristics which have developed and become widely accepted in particular regions. These features contribute to the special uniqueness and character of that region and often provide a desirable identity or traditional quality. Examples of these are: the Cape God designs found frequently in the northeast; the Santa Fe style of the southwest, the Raised Ranch of the east and mid west, the use of clay tile are in the south and southwest, the design features attributed to the California Ranch style of the west coast, etc. Some of these design or appearance characteristics result from functional requirements as well. An example is the widespread use of steeper-pitched gable roofs in the cold and rainy areas of the country, in order to more quickly shed the frequent rains, and to minimize large build-ups of snow and ice. Contrast these with the frequent use of so-called flat roofs of the Santa Fe style or other southwestern territorial style houses, where those climatic requirements are greatly diminished.