Many residential designers pay too little attention to roof overhangs. Roof overhangs have several important functions: they can protect exterior doors, windows, and siding from rain; they can shade windows when solar heat gainIncrease in the amount of heat in a space, including heat transferred from outside (in the form of solar radiation) and heat generated within by people, lights, mechanical systems, and other sources. See heat loss. is undesirable; and they can help keep basements and crawl spaces dry. A house with improper overhangs can overheat in the summer, can suffer from water entry problems at windows and doors, and can have premature siding rot.
The most common design error is to make roof overhangs too stingy. It’s also possible (although much rarer) for roof overhangs to be too wide.