From the 2018 International Residential Code unless otherwise indicated.
Basements, habitable attics and every sleeping room shall have not less than one operable emergency escape and rescue opening. Where basements contain one or more sleeping rooms, an emergency escape and rescue opening shall be required in each sleeping room.
Emergency and escape rescue openings shall have a net clear opening of not less than 5.7 square feet. The net clear height opening shall be not less than 24 inches and the net clear width shall be not less than 20 inches.
The horizontal area of the window well shall be not less than 9 square feet, with a horizontal projection and width of not less than 36 inches. The area of the window well shall allow the emergency escape and rescue opening to be fully opened.
Window wells with a vertical depth greater than 44 inches shall be equipped with a permanently affixed ladder or steps usable with the window in the fully open position.
An emergency escape and rescue opening is not required where existing basements undergo alterations or repairs.
Exception: New sleeping rooms created in and existing basement shall be provided with emergency escape and rescue openings in accordance with Section R310.1.