What is the maximum allowable slope for the bottom surface of footings?

The maximum allowable slope for the bottom surface of footings is 1:10. This means that for every 10 units of horizontal distance, the vertical change can be up to 1 unit. A slope of this proportion is significant because it provides sufficient bearing capacity while ensuring proper drainage and stability of the footing.

In construction, footings are critical since they transfer the load of the structure to the ground. A steeper slope could compromise the structural integrity by risking excessive lateral forces acting on the footing, potentially leading to failure. On the other hand, a slope that is too flat (like those represented by the other choices) may not provide the necessary drainage needed to prevent water accumulation and erosion that could undermine the footing.

Understanding the appropriate slope helps in designing footings that support structures effectively while considering local soil conditions and water management practices.