06/11/2014

Slab on Grade vs. Pier and Beam

There are two basic types foundations in residential construction.

Slab on Grade

The first, and perhaps most common, foundation type is a slab on grade foundation.  A slab on grade is, essentially, a slab of concrete poured into a form that rests on the ground.  There are two basic types of slab foundations: Monolithic foundations and stem wall foundations (or chain wall foundations – depending on which part of the country you’re from).  The primary difference between these two slab foundation types is the way in which the concrete is poured.  A monolithic foundation is poured all at once, a seamless slab anywhere from 4 – 12 inches thick.  Monolithic slabs with a uniform thickness are often used for patios or carports.  For more robust construction projects (like that of a residence), concrete grade beams are integrated into the foundation.  A stem wall foundation is poured in sections.  The outside edge (about 12 inches wide and just deeper than the frost line) is poured first.  Once the stem wall has cured, a 4-6 inch slab of concrete is poured on top of it to complete the slab foundation.

Pier and Beam

The second foundation type is a pier and beam style foundation.  A pier and beam foundation is made up of piers, or short columns, and beams which span the distance between the piers.  Historically, piers were built to rest atop the ground with little or no support driven beneath them.  This is largely why older homes in and around New Orleans are prone to sink.  Construction practices have evolved and, today, piers usually sit atop wooden, metal or concrete pilings.  Piers can be constructed of wood, metal or concrete and are often clad in a decorative finish.

 

Which foundation type do you have?

If you have a basement or a crawl space beneath your home, you have a pier and beam style foundation.  If you walk up stairs to go inside your home, chances are, you have a pier and beam style house.  Conversely, if you cannot see a void beneath your house and you have no stairs to traverse, you are, more than likely, living in a home with a slab on grade foundation.

“If you have any more questions about slab on grade foundation types or pier and beam style foundations, please feel free to reach out to us.  We have been serving the greater New Orleans area for nearly 175 years.  We take pride in our ability to provide answers to your questions.  We look forward to hearing from you.” – Greg Abry