What Is the Typical Concrete Basement Wall Thickness?

Considerations

• The taller the wall, the thicker it must be. The loads putting pressure on the wall, such as the structure it supports and lateral pressure compressing it from the sides, affect the determination of the appropriate thickness. Soil can exert a strong force on basement walls; thicker concrete does a better job of resisting the lateral stresses.

Thickness

• In general, poured concrete basement walls that are 8 feet tall or less and have no more than 7 feet of soil pressing against them from the outside function well at a thickness of 8 inches. When a taller wall or a higher level of soil or both come into play, the thickness should increase to 10 inches. These figures can vary due to differences in local building codes.

Exception

• Although a thickness of 8 inches is typical for a home with 8-foot-high concrete foundation walls, an important exception exists. The 8-inch thickness works well for homes with most types of siding, but does not provide adequate support for a home with brick veneer siding. The veneer must rest on a ledge at the base the foundation, which necessitates increasing the thickness of the concrete to 10 to 12 inches.

Reinforced Concrete

• Reinforced concrete -- concrete to which steel bars, or rebar, is added -- offer more resistance to external stresses than concrete with no reinforcement. The rebar increases the wall's strength without expanding its thickness. In some situations, the rebar is critical to the structural integrity of the wall. For example, a hillside home that receives significant pressure from the soil could fail unless rebar is added to the concrete.