What is the minimum fire resistance rating of an exit door in buildings of three stories or less?

The minimum fire resistance rating of an exit door in buildings of three stories or less is indeed 1 hour. This requirement is established to ensure that exit doors provide adequate protection in the event of a fire, allowing occupants to safely evacuate the building. A one-hour fire resistance rating means that the door can withstand fire exposure for that duration, helping to contain the spread of flames and smoke, and protecting the escape routes.

This standard is based on building codes that address life safety and property protection, recognizing the importance of maintaining a safe egress path during emergencies. The one-hour rating reflects a balance of safety needs for smaller buildings, where the risk and fire exposure may be more manageable than in larger structures, which typically require higher ratings. This level of fire resistance is sufficient to provide a reasonable degree of safety for occupants escaping from a fire.