What is the minimum width of the footing for a 2-story house?

• A. 12 inches
• B. 15 inches
• C. 18 inches
• D. 20 inches

Answer: (B)

Footings must provide enough bearing area to safely transfer the building’s weight into the soil. A two-story house carries more load than a single-story, so the footing needs to be wider to keep the soil bearing pressure within what the soil can safely support. Fifteen inches is the minimum width commonly used for this scenario because it offers a practical balance: it gives enough bearing area for typical soils and loads while remaining straightforward to form and reinforce. A narrower width, like twelve inches, could overload the soil in many conditions and lead to settlement. Wider widths, such as eighteen or twenty inches, are chosen only when soils are weaker or loads are higher; they’re not the minimum. Always refer to local codes and a soil report, since soil conditions can change the required width.