The primary concern with Type III construction is concealed void spaces in __.

In Type III construction, which is often referred to as "ordinary construction," the primary concern revolves around the presence of concealed void spaces that can be found in various structural components. These concealed spaces, particularly in floors, ceiling joists, and studs, can harbor fire and smoke, allowing them to spread rapidly throughout the building, often unnoticed.

Floors create horizontal voids that can trap heat and allow fire to advance. Similarly, ceiling joists and studs can conceal spaces that facilitate the movement of fire from one area to another, enabling it to bypass fire suppression measures that might be in place. This interconnected framework essentially acts as a conduit for fire and smoke, complicating firefighting efforts and increasing the risk to both occupants and firefighters.

Thus, the correct answer encompasses all these components—floors, ceiling joists, and studs—highlighting the need for firefighters to be acutely aware of these void spaces when working in Type III construction. Understanding where these spaces are located and how they function within the structure can significantly influence fire attack strategies and overall safety during operations.