In light-frame construction, what is the minimum width of a footing that supports two floors?

In light-frame construction, the minimum width of a footing that supports two floors should be 15 inches. This dimension is crucial because the footing must adequately distribute the load from the structure above to prevent settlement and ensure stability.

Footings must be deep and wide enough to bear the weight of the building materials and the loads imposed on them, which include permanent loads like the weight of the structure and temporary loads such as occupants and furniture.

The choice of 15 inches takes into account typical load-bearing requirements, soil conditions, and the structural design of light-frame buildings. It is a common standard to ensure the footing provides sufficient support for the additional load that comes from two floors, as compared to single-floor support requirements, which might have a smaller footing width.

The other measurements would likely not offer the necessary stability and load distribution for a two-story structure, potentially leading to issues like foundation settlement or structural failure over time. Hence, 15 inches is established as a safe minimum to ensure durability and compliance with building codes in light-frame construction.