National Building Code for Window Opening

Code

• Before 1994, window installers contended with at least three different national building codes, depending on location. In that year, the organizations responsible for the codes created the International Code Council, whose purpose was consolidating existing regulations and eliminating duplication. It created the International Residential Code and other building rules. The IRC acted as the foundation for all local and state codes, as well as federal versions, such as for the National Park Service and the State Department.

Basics

• All basements, habitable attics and sleeping rooms require at least one operable window that is used as an emergency escape. If a basement has one or more sleeping rooms, each room needs an escape. The windowsill must not be more than 44 inches from the finished floor’s bottom. If the finished sill is below the adjacent ground level, such as in a basement, a window well is needed helping with the exit. The window must open directly onto a public way, yard or court accessible to a public way. Basements less than 700 square feet and used only for mechanical equipment do not need windows.1)

Well

• A window well is an enclosure with a fitted cover and a bottom preventing weed growth. The device’s primary purpose is keeping leaves, debris and moisture out of the home, as well as providing emergency exits. The well’s minimum horizontal area is at least 9 square feet with a minimum horizontal projection and width of 3 feet. The well must have enough clearance that allows the window to be opened. A ladder or steps can use up to 6 inches of space inside the window well.

Windows

• Windows acting as emergency openings need a minimum area of 5.7 square feet, although openings on a grade floor require only 5 square feet. The height must be at least 24 inches and the width at least 20 inches. Occupants must be able to operate the window from the room’s inside without using keys, tools or special procedures. If a window is located under a deck or porch, the deck or porch must allow the window to be fully opened. It must also provide a path at least 3-feet wide leading to a yard, court or public way.