Retaining walls less than what height require a construction supervisor license?

A construction supervisor license is typically required for overseeing the construction and installation of retaining walls that exceed a certain height due to the potential structural and safety implications of these structures. Retaining walls are designed to hold back soil and can experience significant lateral forces, especially when they are taller.

In many jurisdictions, a retaining wall that is regulated typically has a threshold height — in this case, 10 feet — that determines when an experienced supervisor is needed to ensure compliance with safety standards, proper design, and construction practices. A wall built below this height may still pose risks, but the construction codes often consider such smaller walls to be manageable by less specialized contractors. Thus, a construction supervisor license is required for retaining walls that are 10 feet or higher, making this option the correct answer.