What is the minimum width and thickness of concrete footings with cast-in-place concrete for a two-story slab-on-grade?

The minimum width and thickness of concrete footings, particularly for a two-story slab-on-grade application, is critical for ensuring adequate support and stability of the structure. Choosing a footing size that is too small can lead to structural failures or inadequate load-bearing capacity.

The correct dimensions of 16 inches in width and 6 inches in thickness provide a robust foundation capable of distributing the load from the two-story structure evenly across the ground. These measurements take into account various factors including the weight of the building, the soil type, and local building codes which often recommend larger footings for multi-story structures to resist settlement and lateral forces.

In contrast, other options present widths and thicknesses that may not provide adequate support. For instance, a width of 10 inches or less could lead to insufficient bearing capacity under the weight of a two-story structure. Similarly, thicknesses less than 6 inches may not provide enough depth for reinforcement or may not be in compliance with local codes governing foundational elements for buildings of this height.

Thus, the selected dimensions ensure compliance with safety standards and provide the requisite strength and stability for the building.