In the event of a fire, a fire door works to slow the spread of flames and smoke throughout the building so that the people within can escape safely. Fire doors are typically used in commercial locations that require these stronger, fire-resistant doors to meet building codes. These doors have a fire-resistance rating that is given by building and fire code inspectors to determine how long the door will hold up in a fire.
Fire door requirements are determined by the National Fire Protection Association (NFPA) and are centered around the timeframe that the doors can withstand the spread of fire. For instance, a door with a 90-minute rating is expected to resist flames and smoke for 90 minutes. Most doors’ rating also takes into consideration the rating of the surrounding walls; in fact, the wall rating is absorbed into the door rating, usually by about 75 percent. This means that a wall that has a 2-hour rating will usually have doors with 90-minute ratings. Rating requirements for particular locations are set by building codes or local fire marshals.
All fire doors must be clearly labeled that all requirements have been met by a certified testing agency, and they must also show what their rating is. For wooden fire doors, there are specific requirements that must be included to pass certification. For example, the door must have a solid wood core, and there should be no more than ¾-inch clearance between the bottom of the door and the floor. There should be no holes greater than 1-inch in diameter drilled in the door, and hardware preps must be done by the manufacturer to ensure certification. The frame must consist of steel and should also be prepped by the manufacturer.
Hardware is another factor that is considered in certification. Fire doors must be able to close and latch on their own; if a fire occurs, they require no manual intervention to close and latch. The doors should also never be propped open, unless it is by a magnetic hold that is attached to the fire alarm so it is released if the alarm sounds. If locks are used, they must be fail-safe to ensure that the door is automatically unlocked in the event of a fire.