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Fire Doors 101

January 20, 2014

Fire ProtectionIn an effort to get my creative brain flowing, I asked a coworker to give me a topic. Being fire safety geeks (yes, we both shopped off the Christmas list), she suggested fire doors. A paltry challenge, I hoped.

Oddly enough, I was vaguely aware of fire doors before ever working at WSRB. The retail store I worked for in college frequently got penalized by the local fire department for removing the fire doors in our backroom or blocking them open; getting shipments stacked up somewhere before we could unload it was much more important to us than protecting ourselves from a potential fire.

Only after starting here at the Bureau did I become aware of what a fire door does: contain a fire within one part of the building to help keep it from spreading to another. Essentially, rooms within buildings are built as a sort of compartment. Each compartment is protected, via different structural elements, to help keep a fire from spreading into another compartment. Sprinkler systems designed for property safety (NFPA 13 systems) also use the compartment concept: how much water does a system need to provide to put out a fire within a compartment, given the structural elements, hazards within the compartment, and various other considerations. Fire doors must provide at least 30 minutes of protection, meaning that in the event of a fire, they should be able to withstand the heat for at least 30 minutes. In the right situations, three-hour fire doors (meaning they should withstand the heat of the fire for at least three hours) can be used to separate a building into two fire divisions (we have an upcoming article about fire divisions, keep your eyes out!).

How is protection determined?

  • The surface temperature does not exceed 250 degrees F after a certain time period
  • It must maintain its shape
  • It must maintain its integrity (it cannot collapse)
  • It must be able to absorb other collapsing materials

If a door can do these things for at least one hour, then it is a one hour fire door.

Fire doors are also used to help provide a protected area to exit the building. Generally, fire doors are located at each level of a stairwell, where the well opens to the floor. Keeping stairwells safe allows occupants to exit the building without (hopefully) having to go past or through a fire.

These doors are internal doors within the building, whereas fire exit doors are used as exits to the exterior of the building. Many fire exit doors  have a panic bar which sets off an alarm when pushed.

How do you know when you’re looking at a fire door? In commercial buildings and apartment complexes, the doors at the tops of stairwells are most likely fire doors. You can generally spot the door’s listing on a small placard along one of the sides of the door or along the top. They aren’t always there though (when I went to take a picture of the placard on a fire door in our building, it wasn’t there!). According to the NFPA, if a label isn’t found, your local AHJ (authority having jurisdiction) may have guidelines to provide acceptable proof of the rating, including inspections or documentation (NFPA 80 is the mandate for inspection and testing of fire doors, if you’re ever looking for some light reading).

A few more quick notes about fire doors:

–          The door isn’t the only part of the entire protection that must be rated in order to be a fire door; the entire framing assembly must also be rated.

–          Fire doors should be left closed at all times. There are some instances where a door may be left open, but it must be wired into the fire alarm system so it will automatically close when the alarm goes off. This is generally done using an electromagnetic system that keeps the door open, and the magnetic coil is de-energized when the alarm goes off.

–          If a window is present in a fire door, there are material types and thickness requirements, and a wired glass or safety ceramic is preferred (individual AHJs may have adopted different IBC [International Building Code] or NFPA requirements. Check with your local jurisdiction to find out more).

–          No holes or breaks can exist between the door and the frame while the door is closed.

Lastly, on those fire exit doors I mentioned before? They should open to the outside on commercial buildings. There are numerous deadly fires in US history where many lives could have been saved had the exit doors opened to the outside of the building.

4 Comments leave one →
  1. January 30, 2014 11:30 am

    Great overview. Thanks for the info.

Trackbacks

  1. Risk Analysis …. About Fire Doors | SOFI Blog

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