Why do some houses have basements, and what are the different kinds of basements?
In the simplest of terms, a basement is part of the foundation that supports the house and the “need” for a basement is usually the result of where the house is located. In coastal regions like the Gulf South, there are very few basements because they expensive to build and have the potential to flood with heavy rains. In the northern, colder parts of the country, basements are the practical solution to the issue of frost heave. Frost heave is where the moisture in the ground freezes and pushes on the house foundation (usually upward). This can cause serious structural problems. The depth to which the ground water freezes is known as the frost line. One solution is to build the foundation deeper than the frost line, which results in a room that is partially or fully underground. The depth can vary, but most are deep enough to create extra living or storage space.
On sloping sites, basements can be constructed where on the uphill side, the basement may be completely hidden within the ground, and open on the downhill side. This creates what is typically referred to as a “walk out basement”, because you can walk out the downhill side onto the lawn or patio. The overall size of the basement may vary, based on personal preference and how the space may be used.
Beyond the obvious structural concerns (the basement must be capable of supporting the house above) there are other design considerations when building basements. These include conditioning the space (heating and/or cooling), insulation, waterproofing, and drainage around the perimeter of the basement/foundation. Like any other part of the house, basements offer opportunities to improve the function and use of the home, but must be thought out, designed, built, and maintained properly to avoid costly repairs in the future. Consultation with your architect or plan designer is strongly encouraged to accommodate the function of your basement.