A dormer is a window structure that projects out from a pitched roof to provide more light and space in an attic area. Adding dormer windows is a popular way to make an attic area more useful, either for storage or an additional bedroom. In fact, the word dormer comes from the French word “dormer,” which means “sleeping room.” If you’re planning to add a bedroom in your attic, most building codes specify minimum sizes for windows to allow for egress in emergencies.