Hey Karl,

Code Question:

I have a residential home with a bedroom on the ground floor. The window sill height is less than 44 inches off the interior floor but is 60 inches off the exterior grade. Does the window opening need to be 5.7 square feet or 5.0 square feet?


The answer is 5.7 square feet and is found by looking at two locations. Section R310.1.1 and the definition of “Grade Floor Level” !

R310.1 Emergency Escape and Rescue Required
All emergency escape and rescue openings shall have a minimum net clear opening of 5.7 square feet (0.530 m2).
Exception: Grade floor openings shall have a minimum net clear opening of 5 square feet (0.465 m2).

GRADE FLOOR OPENING. A window or other opening located such that the sill height of the opening is not more than 44 inches (1118 mm) above or below the finished ground level adjacent to the opening.

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