California Residential Inspector Practice Exam

What is the minimum required nominal wall thickness for a plain masonry foundation wall 6 feet high when the soil classification is GM?

1. 6 inches

2. 8 inches

3. 10 inches

4. 12 inches

The correct answer is: 8 inches

The minimum required nominal wall thickness for a plain masonry foundation wall is determined based on factors such as wall height and the soil classification, which affects the lateral loads the wall must resist. In this case, a soil classification of GM indicates that the soil is gravelly, which is one of the more favorable soil types in terms of bearing capacity and stability. For a plain masonry foundation wall with a height of 6 feet, local building codes or relevant standards outline specific thickness requirements to ensure structural integrity and safety. Researching the applicable codes, such as the California Building Code, reveals that for 6-foot walls in favorable soil conditions, a nominal thickness of 8 inches is typically mandated. This thickness provides adequate support against the lateral pressures exerted by the surrounding soil. It also addresses other factors such as potential cracking, durability, and stability of the foundation over time. Thus, the choice of 8 inches reflects compliance with structural standards for masonry foundation walls in this specific condition.