I thought i might add a bit as i noticed 2 things missing in the discussion that might be of use to somebody. I referenced this from
the MICHIGAN 2015 and should be close to the IRC.
1) grade floor or below is 5.0 sq ft
2) sill height above floor 44"
R310.2.1 Minimum opening area. Emergency and
escape rescue openings shall have a net clear opening of
not less than 5.7 square feet (0.530 m2). The net clear
opening dimensions required by this section shall be
obtained by the normal operation of the emergency escape
and rescue opening from the inside. The net clear height
opening shall be not less than 24 inches (610 mm) and the
net clear width shall be not less than 20 inches (508 mm).
Exception: Grade floor or below grade openings shall
have a net clear opening of not less than 5 square feet
R310.2.2 Window sill height. Where a window is provided
as the emergency escape and rescue opening, it shall
have a sill height of not more than 44 inches (1118 mm)
above the floor; where the sill height is below grade, it
shall be provided with a window well in accordance with