Feb 28, 2022 8:00:00 AM / by LSS

Fire Door Gap Mishaps Blog Image

Gaps around a fire door may seem like a small inspection point however, they can make the biggest impact in the event of a fire. Fire door gaps have a required measurement per the NFPA which should be routinely inspected to ensure compliance. I know, as a facility manager, asking you to add one more thing to your already long to-do list is not ideal. Nevertheless, don’t let such a minor deficiency result in a major fire mishap.

Fire needs a consistent oxygen supply in order to burn. Large gaps around the fire door can create negative pressure during an active fire. This negative pressure will suck oxygen into the area of fire, providing more ammunition to grow stronger. This results in positive pressure that allows smoke and toxins to escape the area of fire and travel into areas of the building that are supposed to be fire-restricted areas. Not only does this put any occupants trying to evacuate in danger but the hot air and smoke being released could ignite combustibles on the other side of the door.

Properly sealed fire-resistant gaps around fire doors will ensure there is no oxygen supply feeding the active fire. Compliant fire door gaps will encourage the fire to burn smaller faster with the potential of it dyeing out on its own due to the lack of oxygen. In addition to the sealed gaps, fire doors are required to have a built-in active latch. This piece of hardware would prevent the door from flying open due to positive pressure being built up.


NFPA 80, Section

Swinging Doors with Builders Hardware

Wood Doors:

  • Clearance for under the bottom of the door maximum is 3/4”
  • Clearance between door and frame is 1/8”
  • Clearance for meeting edges for a pair of doors is 1/8”

Steel Doors:

  • Clearance for under the bottom of the door maximum is 3/4”
  • Clearance between door and frame is 1/8”, +/- 1/16”
  • Clearance for meeting edges for a pair of doors is 1/8”, +/- 1/16”

NFPA 80, Section 10.3 – Vertically Sliding Fire Doors

  • Clearance between the door and the wall when the door is closed is 3/8 in.


Fire Door Deficiencies

Fire doors prevent the spread of fire and smoke from spreading throughout the building which is why they play such a critical role in a facilities fire safety system. Overtime deficiencies can occur, so it’s important for facility managers to keep a close eye on the overall condition of doors to ensure compliance. Due to their complexity, annual inspections are required by a knowledgeable professional in the field. Below is a list of common deficiencies found during routine fire door inspections.

If any of the below are detected within your facility, repairs must take place as soon as possible.

  • Painted or missing fire door labels
  • Poor clearance dimensions around the perimeter of the door in the closed position
  • Kick down door holders
  • Auxiliary hardware items that interfere with the intended function of door (barrel & dead bolts)
  • Area surrounding the fire door assembly blocked by furniture, equipment and/or boxes
  • Broken, defective or missing hardware items (latch bolts, strike plates, closer arms, cover plates)
  • Fire exit hardware installed on doors that are not labeled for use with fire exit hardware
  • Missing or incorrect fasteners
  • Bottom flush bolts that do not project 1/2″ into the strike


Fire door mishaps are preventable if proper steps are taken. In the event of a fire, lives are at stake so don’t delay in getting the deficiencies within your facility repaired. Contact our team of professionals today at (888)675-4519. You’re Safe with Us.

Tags: Fire Door Inspection, fire door gaps, fire door repairs


Written by LSS

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