Fire Strategy: Does This Door Actually Need to Be a Fire Door?

There is something I have seen for years that still bothers me. Someone buys a “Fire Door Keep Shut” sign, puts it on a door and suddenly everyone starts calling the door a fire door. Unfortunately, sometimes it isn't. A sign does not make a fire door. Before I start looking at hinges, gaps, intumescent seals, closers and locks, I want to understand why that door is there and what the building is actually trying to achieve. Because sometimes the problem isn't the door. Sometimes the problem is the building around the door. Start with the building, not the door When I am looking at an existing building, I don't want to walk straight up to a door and decide whether it is a fire door based on what it looks like. I want to know: What is the building…