Trenches installed parallel to footings must not extend below what specific structure-related measure?

When considering the placement of trenches in relation to footings, maintaining the integrity of the structure is crucial. The 45-degree bearing plane is significant because it establishes a safe boundary for excavation depth relative to the footing. This angle effectively represents the maximum extent downward that a trench parallel to the footing can be dug without compromising the stability of the footing.

If trenches were to extend deeper than this 45-degree angle from the bottom of the footing, it could lead to soil failure or insufficient support for the existing structure, which can compromise the overall structural integrity. This concept is fundamental in construction and plumbing, as it ensures that all excavations are managed in a way that promotes safety and stability for any structures above.

Other measures like the footing depth itself, a 40-degree angle of inclination, or a cement base level do not provide the same clear guideline as the 45-degree bearing plane, which is specifically designed to prevent undermining the footing's support.