The bottom surface of footings in a shallow foundation is permitted to have a maximum slope of what?

The maximum slope allowed for the bottom surface of footings in a shallow foundation is 1:10. This means that for every 10 units of horizontal distance, the slope can rise or fall by only 1 unit. This relatively gentle slope helps ensure stability and proper load distribution, preventing excessive lateral pressures that could compromise the integrity of the foundation. A slope that is too steep may lead to uneven settlement or failure, particularly in soils that are not cohesive or that have low load-bearing capacity.

In general, more gradual slopes are safer for footings, as they maintain greater contact area with the soil, which can enhance the structural support. Steeper slopes, like those represented in the other options, increase the risk of potential foundation instability, making the 1:10 slope the safest and most widely accepted practice in foundation design. This guideline is crucial for preserving the overall durability and performance of the building.