Egress windows are required in every room used for sleeping purposes (bedrooms) on any floor and in basements with habitable space. If you are constructing a new home, the code requires that you put an egress window in each bedroom. It also requires an egress window in the basement if habitable rooms will be finished in the basement. If you install a basement bedroom or bedrooms, an egress window is required in each bedroom. If you have an existing home and you add a sleeping room in an unfinished basement, the code requires that you install an egress window in the sleeping room or rooms.
WHAT ABOUT A LADDER?
R310.2.3.1 Ladder and steps.
Window wells with a vertical depth greater than 44 inches (1118 mm) shall be equipped with a permanently
affixed ladder or steps usable with the window in the fully open position. Ladders or steps required by this section
shall not be required to comply with Sections R311.7 and R311.8, Ladders or rungs shall have an inside width of
not less than 12 inches (305 mm), shall project not less than 3 inches (76 mm) from the wall and shall be spaced
not more than 18 inches (457 mm) on center vertically for the full height of the window well.
This basement bedroom window (shown in the photo below) in this Parker Colorado home did not feature a ladder attached to the window well so this was noted as a deficiency in the Home Inspection Report performed by Denver's Best Home Inspection. 
