For an automatic fire alarm to be required in an R-2 apartment building, which condition must be met?

In the context of an R-2 apartment building, the requirement for an automatic fire alarm system is primarily influenced by the number of dwelling units within the structure. Building codes typically stipulate that when a certain threshold of units is reached, an automatic fire alarm system becomes necessary to ensure the safety of residents. This requirement is aimed at providing early detection and alerting occupants in case of a fire, thus facilitating evacuations and enhancing overall fire safety.

While the type of construction, presence of gas lines, and local jurisdiction regulations can certainly influence overall fire safety measures and may impose additional requirements, it is primarily the number of units that dictates whether an automatic fire alarm system must be installed in compliance with national fire codes and standards. This ensures that larger apartment buildings, which house more residents, are adequately protected.