What is a requirement for a guard rail on a mezzanine?

The requirement for guard rails on a mezzanine is established to ensure the safety of individuals working or moving in elevated areas. The correct choice includes a 4-inch toe board and a 42-inch top rail, which are standards set by various safety regulations, including the Occupational Safety and Health Administration (OSHA).

The top rail height of 42 inches is crucial as it provides a sufficient barrier to prevent workers from falling over the edge of the mezzanine. This height is optimal for deterring accidents and ensuring that the guard rail is effective in its function. Additionally, the presence of 4-inch toe boards is necessary as they help prevent tools, materials, or objects from falling off the edge, thereby further safeguarding anyone working below.

The other options either suggest inadequate rail height or the absence of foundational elements like toe boards, which do not align with established safety practices. A fall from a mezzanine can result in serious injuries or fatalities, so adhering to these specific measurements is essential for maintaining a safe working environment.