Traffic Flow and Safety

Openings in walls and partitions must be sized for their primary function of providing entry and exit to or from a building or its interior spaces, and doors must be sized and capable of operating so as to prevent or permit such passage, as required by the occupants of the building. In addition, openings must be adequately sized to serve as an exit under emergency conditions. (See Art. 3.5.10.) In all cases, traffic must be able to flow smoothly through the openings.
To serve these needs, doors must be properly selected for the use to which they are to be put, and properly arranged for maximum efficiency. In addition, they must be equipped with suitable hardware for the application. (See also Arts. 11.65 to 11.67 and Art. 11.55.)
Safety. Exit doors and doors leading to exit passageways should be so designed and arranged as to be clearly recognizable as such and to be readily accessible at all times. A door from a room to an exit or to an exit passageway should be the swinging type, installed to swing in the direction of travel to the exit.
Code Limitations on Door Sizes. To ensure smooth, safe traffic flow, building codes generally place maximum and minimum limits on door sizes. Typical restrictions are as follows:
No single leaf in an exit door should be less than 28 in wide or more than 48 in wide. Minimum nominal width of opening should be at least:
36 in for single corridor or exit doors
32 in for each of a pair of corridor or exit doors with central mullion
48 in for a pair of doors with no central mullion
32 in for doors to all occupiable and habitable rooms
44 in for doors to rooms used by bedridden patients and single doors used by patients in such buildings as hospitals, sanitariums, and nursing homes 32 in for toilet-room doors
Jambs, stops, and door thickness when the door is open should not restrict the required width of opening by more than 3 in for each 22 in of width.
Nominal opening height for exit and corridor doors should be at least 6 ft 8 in.
Jambs, stops, sills, and closures should not reduce the clear opening to less than 6  ft 6 in.
For a specific type of occupancy, the number of exit doors required in each story of a multistory building and the minimum width permitted for each door can be determined from the maximum capacity listed in Art. 3.5.10. The maximum sizes of openings permitted in fire barriers are given in Table 11.19, p. 11.119.
Safety at Entrances. Because of the heavy flow of traffic at building entrances, safety provisions at entrance doors are an important design consideration. Account must be taken of the location of such doors in the building faces, flow of outdoor traffic, and type and volume of traffic generated by the building. Following are some design recommendations:
Arc of a door swing should exceed 90.
An entrance should always be set back from the building face.

Hinge jambs of swinging doors should be located at least 6 in from a wall perpendicular to the building face.
If hinge jambs for two doors have to be placed close together, there should be enough distance between them to permit the doors to swing through an arc of 110.
If several doors swinging in the same direction are placed close together in the same plane, they should be separated by center lights and should also have sidelights, to enable the doors to swing through 110 arcs.
If doors hung on center pivots are arranged in pairs, they should be hinged at the side jambs and not at the central mullion.
The floor on both sides of an exit door should be substantially level for a distance on each side equal to at least the width of the widest single leaf of the door. If, however, the exit discharges to the outside, the level outside the door may be one step lower than inside, but not more than 71⁄2% in lower.