This is the 7th post in a series about fire doors and the results of a recent (unscientific) survey.
The real answer to this question is “it depends.” Stair doors are almost always fire doors, main entrance doors – almost never. Offices, bathrooms – rarely. Storage, corridors – sometimes. You get the picture. As a couple of people pointed out, there’s no way to answer this question without more information about the floor plan and the applicable code.
My point in asking the question was to show that fire doors are difficult to spot and that’s one of the reasons that they are modified improperly or suffer from lack of maintenance. I think the data supports that theory. So if you want to know how to tell if a door is a fire door, just refer back to the post about Question 3.