R310.3.1

Section R310.3.1 is titled 'Minimum door opening size' and covers requirements for doors being utilized as emergency escape and rescue openings. A cross-reference to another section of this code for the minimum height of emergency escape and rescue opening doors is established. The purpose of this section is to require emergency escape and rescue opening doors to have certain minimum dimensions so occupants and emergency responders can readily pass through the door.

The model shows a below grade emergency escape and rescue opening door which leads to an area well, with a translucent overlay which is the minimum height and area required per the cross-referenced section. What is the width measurement of this overlay?