What specific fire-resistance rating (in hours) is typically required for hoistway enclosures in high-rise buildings?

In high-rise buildings, hoistway enclosures are typically required to have a fire-resistance rating of at least two hours. This means the walls and doors of the elevator shaft must be constructed of materials that can withstand exposure to fire for a minimum of two hours without structural failure or allowing the passage of flames or excessive heat. The purpose of this fire-resistance rating is to prevent the rapid spread of fire and smoke throughout the building via the elevator shaft. The hoistway acts like a vertical chimney, and without proper fire protection, it can quickly become a conduit for fire to spread to upper floors. The two-hour fire-resistance rating is a common requirement based on building codes and standards, like those established by the International Building Code (IBC) in the United States. Some jurisdictions may require even higher fire-resistance ratings for hoistways in particularly tall or complex buildings. The fire-resistance rating applies not only to the hoistway walls but also to the elevator doors, which must be fire-rated and self-closing to prevent the spread of fire and smoke into the elevator car or onto other floors. Furthermore, any penetrations in the hoistway walls, such as for wiring or ventilation ducts, must be properly fire-stopped to maintain the fire-resistance rating of the enclosure. Fire-stopping involves sealing the openings with fire-resistant materials to prevent the passage of flames and smoke. Maintaining the fire-resistance of the hoistway enclosure is crucial for ensuring the safety of building occupants during a fire, allowing them time to evacuate and preventing the rapid spread of fire to other parts of the building.