Two foundation types that are routinely use home builders are monolithic slabs and stem-walls, both of which are vastly different in the way they’re built and installed. Here is a look at their characteristics and how they are different from each other.
Monolithic slabs are made from a single pour of concrete. Monolithic slabs typically are 4 inches deep, and have thickened perimeter edges and hefty portions under the load bearing walls. Built over compacted soil, it is essential that the slabs are placed at least 6 inches above the ground.
Monolithic slabs are can be used for most types of buildings in warm and tropical areas. In cold climates, however, they’re used only in separate external constructions like garages and barns. The main advantages of using monolithic slabs are as follows:
- The slabs can be very sturdy, especially after the addition of steel and fiber mesh.
- They can be constructed in a shorter time, compared to other foundations.
- With the addition of Post-Tensioning, they can be used in grounds containing poor quality or loose or expansive (clay) soil.
- They can be used easily on hard ground without the need of digging out the soil first.
- The slabs are somewhat consistent and have uniform stability.
Stem-walls (preferred by Cogdill Builders of Florida)
Stem-walls are structures that are used to connect the foundation of a building to its walls. Predominantly constructed concrete footings with masonry walls, they rise above the ground level to provide a raised platform for placing the building slab.. The structures require three components for their construction – a poured slab, a foundation wall, and a spread footing.
To construct a stem-wall, the first step is to clear the site. Then we compact the subgrade, dig and pour the footing, and then install the masonry foundation wall. The foundation is then filled with structural sand fill and compacted. Then the building slab is poured into the foundation wall and compacted interior filled area. The advantages of this type of foundation are:
- Stem-walls are appropriate for sloped lots because they can be built in different heights to accommodate varying site ground elevations.
- They can give your home a taller look as the free-board distance between the slab and the surrounding ground can be increased or decreased as desired.
- The slab can be increased in elevation to allow any septic systems to drain by gravity flow instead of by mechanical lift station.