California Residential Inspector Practice Exam

What is the minimum required width of a concrete footing for a two-story dwelling with a crawl space in an area where the soil's load-bearing value is 1,500 psf and the snow load is 20 psf?

1. 18 inches

2. 20 inches

3. 24 inches

4. 30 inches

The correct answer is: 20 inches

To determine the minimum required width of a concrete footing for a two-story dwelling with a crawl space, it's essential to consider both the load-bearing value of the soil and the loads acting on the structure, including live loads, dead loads, and any environmental factors such as snow load. In this scenario, the load-bearing value of the soil is specified as 1,500 pounds per square foot (psf). This value indicates how much load the soil can safely support without risking failure or settlement. On top of this, there's a snow load of 20 psf that will also apply to the structure in winter months. When designing the concrete footing, engineers will take the total loads from the building above, which combines the weight of the structure (including floors, walls, roof, and environmental loads) and divides it by the load-bearing capacity of the soil to ensure the footing is adequate to distribute this load without exceeding the soil's capacity. The width of the footing is crucial, as a wider footing distributes the load over a greater area, thereby decreasing the pressure on the soil beneath. The dimension of 20 inches correctly accounts for a conservative approach to ensure that the loads imposed by a two-story structure, combined with the specified snow load, can be