Options for Building Foundations

• The type of foundation of a building is dependent on the soil under the building and the characteristics of the building itself. In some areas where expansive soils occur, such as Houston, Texas, foundation systems are broken down into two groups: shallow support systems and deep support systems. Smaller structures without basements, such as summer cabins, have foundations that are not quite so complex.
  
  

Shallow Support Foundation Systems

• According to the Foundation Design Options website, a foundation that has shallow components that do not go below the soil's moisture active zone is the definition of a shallow support foundation. Shallow support foundations are more subject to vertical movements than deep support systems because of the expansive soils. The key advantage of this system is the shortened length of the beams, which need only extend a minimum of 6 inches past the compacted fill and into the natural soils. Between the grade beams and under the stiffened structural slab, the fill is compacted enough to support the concrete beams as they are put in place.
  
  

Deep Support Foundation Systems

• In a deep support foundation system, as opposed to the shallow version, the piles extend way beyond the moisture zone of the soils. In so doing, they limit the building's vertical movement by providing solid support not affected by moisture fluctuations. Deep support systems are constructed in a few different configurations, according to the foundationperformance.org website. There are two ways to create an isolated structural system with deep foundations: the void space with a structural slab or the crawl space with a structural floor. Stiffened structural or nonstructural slabs are another aspect in conjunction with deep foundations. The advantage of the deep support foundation is the stability of the piles extending beyond the moisture zone.
  
  

Smaller Structure Foundation Options

• The floors on smaller buildings are generally supported by different types of materials from complex concrete footings to something as simple as cinder blocks and patio stone. The easiest way to create a foundation for a small cabin-type dwelling is using patio stones and cinder blocks. Lay a level foundation of patio blocks and set the cinder blocks directly on the patio stones positioned at the corners of the structure. Any type of decorative skirting may be used to conceal the cinder blocks and prevent animals from gaining access under the building. Use concrete footings when a more solid foundation is required or the structure needs to be at a certain distance off the ground. A concrete pad is ideal for pool houses or garages where a wood floor would be impractical. Concrete footings and pad are more elaborate and costly but provide more stability to your building.