How Far From the Floor Is the Average Windowsill?

Traditional Windowsill Height

• The distance from floor to windowsill has varied widely historically to harmonize with the style of the house and to take advantage of local geography. A window sill 3 feet from the floor has traditionally been considered ideal, primarily because it allows furniture to be placed beneath the window without blocking light or air. In some homes, some windowsills if not all of them are set closer to the floor, particularly if they're showcase windows.

Building Codes

• Every municipality has a building code describing requirements for new construction and renovation. Usually local building codes are based on the International Residential Code (IRC) and/or the International Building Code (IBC). Codes are updated regularly, though many towns use older versions of building codes. It is important to check local code requirements before deciding on windowsill height.

Codes for Windowsill Heights

• Both the IRC and the IBC have new windowsill height requirements in their 2012 codes. Operable windows that are more than 72 inches above the ground must have windowsills that are 36 inches above the interior floor, according to the IBC, and 24 inches above the floor according to the IRC. If the windows do not open more than 4 inches or are protected by window guards, both standards allow the windowsill to sit closer to the floor.

Emergency Escape

• Adequate openings for emergency escape and rescue are required in bedrooms and basements by both the IRC and the IBC. Usually this requirement is met by operable windows, although skylights and roof windows also suffice in cases. The IRC requires a minimum window opening of 5 square feet for rooms on the ground floor and 5.7 square feet for rooms on other floors. If skylights or roof windows are used for emergency escape, the bottom of the window opening must be within 44 inches of the floor.

Replacement Windows and Windowsills

• In general, building codes require that replacement windows meet current code requirements. When updating old houses, you may have to make window openings larger and change windowsill placement. Always check local building code requirements when updating windows.