How is ordinary construction defined in relation to its exterior walls?

Ordinary construction is defined by its use of materials and methods that create a balance between fire resistance and structural integrity. In this context, Type III construction is characterized by exterior walls made of non-combustible materials, such as masonry, while allowing for combustible interior elements. This combination is significant because the exterior walls provide a degree of fire resistance, while the use of wood framing or other combustible materials for interior construction presents different challenges and risks during a fire event.

Type III masonry exterior walls serve as a protective barrier against the spread of fire from one building to another, as they do not ignite easily and maintain their structural performance under adverse conditions. This characteristic is crucial for firefighting operations and building safety. Therefore, choosing masonry as the material for exterior walls places this construction method firmly within the definition of ordinary construction.

In contrast, the other options reflect construction types that involve different materials, resulting in different fire risks and characteristics. For instance, Types I and II involve steel and aluminum, which are non-combustible materials primarily used in high-rise and commercial buildings, while Type IV (heavy timber) has unique properties related to large wooden elements. These distinctions are what set Type III ordinary construction apart and define its utility in fire service operations.