Local building codes will often dictate the number of fire exits required for a building of a given size and we need the number of exit sign as its many. This may include specifying the number of stairs. For any building bigger than a private house, modern codes invariably specify at least two sets of stairs. Furthermore, such stairs must be completely separate from each other. Some architects meet this requirement by housing two stairs in a “double helix” configuration where two stairs occupy the same floor space, intertwined. It may make no functional sense to have two stairs so close to each other, but it meets the requirements of the building codes.

Fire fighters have cited overzealous guards who told people during a fire that they are not allowed to use emergency exits. The practice is actually quite common in the absence of fires, as well. Some skyscrapers have stairwells with standard emergency exit signs on each door, which then lock upon closing. Users of these stairwells are trapped, whether they know or do not know that the only door that opens from the inside is the one on the ground floor. A further problem becoming very common in the USA (2005) is that retail stores at night close one of their main entrance/exits through makeshift heavy metal barriers, exit signs, paper notes, or junk placed in front of the exits. Some actually lock their exits. A large array of exit signs and mechanical exit systems have also been devised, including EXIT SIGNS that says contradictorily, “This is not an exit,” “Do not use this exit,” or warning users that a heavy penalty will be assessed for non-emergency use. Some systems do not allow the exit to be opened until the exit signs‘ signals the intention to exit (through a button or lever) for some amount of time, such as 20 seconds. It is also common for these exits to remain completely locked until somebody tests them.