They identify a door as a rated fire door. Communicate the rules that apply to it; most commonly, that it must be kept closed, must not be propped open, and must not be blocked or obstructed. Fire doors are a part of a building's passive fire protection system, and they only work when they are actually closed.

Because people prop them open, every day in every kind of building, fire doors get propped open with wedges, boxes, chairs, and whatever else is handy. A posted Fire Door sign reminds building occupants why that door is there and why leaving it open defeats the purpose. In some cases, it also communicates a requirement that facility managers need workers and visitors to follow.

A fire-rated door slows the spread of fire and smoke from one part of a building to another by maintaining a barrier for a specified time: 20, 45, 60, or 90 minutes, depending on the rating. That time window is what allows occupants to evacuate and firefighters to respond. A propped-open fire door provides none of that protection.

Yes. NFPA 80, the standard for fire doors and other opening protectives, requires that fire doors be identified as fire-rated and that their required operating condition be maintained. IFC (International Fire Code) Section 703 requires that fire door assemblies be maintained in their required condition. Local building codes and fire marshals enforce these requirements during inspections.

The common messages are "Fire Door: Keep Closed," "Fire Door: Do Not Block or Prop Open," and "Fire Door: Keep Clear at All Times." Some signs combine the identification of the door as fire-rated with the rule in one label. Direct and simple language works best since the message needs to land with everyone from employees to contractors and visitors who may have no prior knowledge of the building's layout.

For doors that are approached from both directions, posting a sign on each side ensures the message reaches anyone who interacts with the door regardless of which way they are coming from. This is particularly important for doors connecting high-traffic corridors or separating production areas from common spaces.

Yes. Stairwell enclosure doors, corridor fire doors, and horizontal exit doors are all applications for fire door signs. Any door that has a fire rating and a behavioral requirement that building occupants need to follow warrants a sign.