What is the highest rating class for fire doors?

The highest rating class for fire doors is three hours, which indicates their ability to withstand fire and prevent its spread for an extended duration. Fire-rated doors are crucial components of a building's safety system, serving to compartmentalize fires and protect egress routes. A three-hour rated fire door can effectively contain a fire for a significant period, allowing occupants to evacuate safely and giving firefighters enough time to address the incident.

This rating is essential in high-rise buildings, assembly occupancies, and other structures where extended fire resistance is necessary to ensure safety. Ratings less than three hours, such as half-hour, one hour, and one and a half hours, provide less protection and are suited for different applications where the risks and approval criteria may allow for a shorter period of fire resistance.