What do fire enclosures primarily protect?

Fire enclosures are specifically designed to protect interior vertical openings, such as stairwells or elevator shafts. These enclosures serve a critical role in containing smoke and heat during a fire, thereby providing a safe route for evacuation and access for firefighting operations. By creating barriers that restrict the movement of fire and smoke, fire enclosures help to maintain the integrity of escape routes and protect the structure's occupants, ultimately enhancing overall safety during fire incidents.

In contrast, open spaces in a building are not the primary focus of fire enclosures, as they are intended to facilitate movement rather than contain flames or smoke. Nonfire rated walls do not provide the same level of protection and are not usually part of an enclosure's function. Lastly, while electrical systems must be protected from fire, this is not the primary function of fire enclosures, which concentrate on safeguarding designated vertical openings within the building structure.