I’ve written before about the vision light location required by the accessibility standards. In a nutshell, a door is not required to have a vision light or sidelight, but if either of those exists in a particular door opening, the bottom of at least one light has to be no more than 43 inches above the floor (there is an exception for lights above 66 inches AFF).
Although the standards don’t specifically address how this is measured – it is normally measured to the “visible glass” – the lowest part of the light that you can actually see through. The purpose of this requirement is to allow someone in a wheelchair to be able to use the vision light.
The question I received a few days ago was about a 24-inch-diameter round vision light. If the bottom of the circle is at 43 inches above the floor, only a very small part of the glazing is in that area of the door – less than if the light was a rectangle.
Should the mounting location for a round light be at 43 inches above the floor? Or lower to allow more viewing area? WWYD?
For more information about the required locations of vision lights and viewers, refer to this Decoded article.