Can a Stem Wall Be a Crawl Space Foundation?

Crawl spaces

• A crawl space foundation consists of supports that elevate a home off the ground. Height elevations typically range around 2 feet. This type of foundation appears on homes located in areas where frequent rainfall and moisture prevails. In effect, a crawl space foundation helps protect the structure of the home from the effects of water and moisture. In some homes, the crawl space also provides an area for plumbing, heating and cooling ducts, and electrical lines.

Foundations

• The materials used to make a home’s foundation can vary depending on when the home was built. Some materials used in the making of a foundation include concrete block, brick, poured concrete and stone. The foundation provides support for the weight of a home and gives it a level plane to rest on. A foundation separates a home’s wooden structure from the soil and helps prevent wood rot from taking hold. Homes constructed with stem walls typically have the walls lining the perimeter of the foundation. This layout provides additional support for the home structure.

Stem Walls

• While crawl spaces separate a home’s structural framework from the earth below the home, a stem wall helps to brace a home’s framework in place. It does this by extending into the ground past the frost level so ground freeze-and-thaws can’t shift the base of the wall. The bottom of a stem wall sits on top of a footer section or ledge that runs the perimeter of the wall. The footer consists of concrete and steel materials. The top of a stem wall sits at least 6 inches above ground level. In effect, the crawl space exists inside the stem wall enclosure, with the main floor of the house sitting on top of the stem wall section.

Effects

• The use of stem wall and crawl space foundations in wet regions provides an added layer of protection against the potential for high water levels. As rising groundwater levels and strong winds can cause a foundation slab to shift, the built-in ledge feature created by stem walls works to anchor a home’s foundation to the ground. When groundwater levels rise, the potential for moisture to invade a home’s foundation increases as water levels move closer to the actual structure. The additional height provided by stem walls places some distance between a home’s structural framework and potential flooding or moisture vapor effects.