All doors on an accessible route, or within employee circulation paths (unless exempt by 206.2.8), are required to comply with 404 Doors.

The code calls for doors with vision lights, viewing panels, peep holes, windows, etc., to have the bottom edge measuring 43” maximum above the finished floor.

It should be taken into consideration that most doors are located ½”-1” above the finished floor because of either a raised threshold or the undercut of the door. Therefore, if a door is designed to have the bottom edge of the viewing panel to measure 43” from the bottom of the door, but the door is installed over a ½” raised threshold, the viewing panel will be too high.

It is required that vision lights be located relative to the finished floor, not the bottom of the door.