What is the maximum allowable slope for trenches installed parallel to footings that do not extend below the bearing plane?

The maximum allowable slope for trenches installed parallel to footings that do not extend below the bearing plane is 45 degrees. This slope is significant as it helps maintain the stability of the soil and the integrity of the foundation. A slope of 45 degrees indicates that for every unit of vertical distance, there is a corresponding unit of horizontal distance, which creates a balance that is generally safe for such applications.

In practice, allowing a slope less steep than 45 degrees can aid in preventing erosion or collapse of the trench walls while maintaining accessibility for plumbing work or inspections. Safety regulations often dictate maximum slopes to mitigate risks associated with soil movement. Therefore, a 45-degree slope is seen as a standard that effectively combines safety with practicality when working near footings. Slopes that are steeper (like 60 or 90 degrees) would pose significant risks and are generally not permissible. A slope of 22.5 degrees, while safer, is generally very conservative and may not be necessary unless specified by particular site conditions or soil types.