What is the primary concern with Type III construction?

Type III construction, often referred to as "ordinary" construction, is characterized by exterior walls made of non-combustible materials (such as brick or concrete) while the interior walls, floors, and roofs are primarily made of wood. The primary concern with this type of construction pertains to the concealed void spaces that can exist within the structure, which can significantly affect fire behavior and firefighting tactics.

These void spaces—whether in the floors, ceiling joists, or studs—can facilitate the rapid spread of fire, as they act as channels that allow flames and heat to move between different areas of the building without immediate visual warning. This hidden nature of void spaces means that fire may spread unnoticed, and the integrity of structural components can be compromised before a fire is detected.

Understanding these concerns is crucial for firefighters and building inspectors to assess structural fire risks effectively and to develop appropriate suppression and safety strategies. Since all the mentioned areas—floors, ceiling joists, and studs—can have concealed voids, recognizing that the primary concern encompasses all of these spaces is key in Type III construction.