CSLB Class B General Contractor's License Practice Exam

When trenching for a sewer line running parallel to a footing, how far away must the trench be from the footing?

1. 1 foot away from the wall

2. 2 feet away from the wall

3. 3 feet away from the wall

4. 4 feet away from the wall

The correct answer is: 3 feet away from the wall

The correct answer is that the trench must be at least 3 feet away from the footing when trenching for a sewer line running parallel to it. This requirement is primarily based on the need to maintain the structural integrity of the footing and the surrounding soil. When a trench is excavated close to a foundation, it can disturb the soil that supports the footing, potentially leading to settlement or even failure of the structure above. By maintaining a minimum distance of 3 feet, the trenching minimizes the risk of undermining the footing, as this distance allows the soil to better support the load of the structure while reducing the lateral pressures that could affect the footing’s stability. Following these guidelines not only ensures safety but also complies with building codes and best practices in construction, which often recognize the importance of adequate separation between excavations and structural foundations. Observing this precaution helps prevent future structural issues and is critical in responsible construction management.