Window Sill Height Specs for 2012 IRC

Minimum sill height for windows according to the 2012 International Residential Code. This building code provides a safety factor for small children.

Code for Window Sill Height

Section R312.2.1 of the 2012 International Residential Code located on page 91 explains that the lowest part of the actual window opening shall be no less than two feet above the finished floor when the sill is more than six feet above the ground. There is some confusion that has arisen among inspectors, builders, and writers alike concerning where the code says this height should be. Even though section R312.2.1 begins with “Window sills”, the wording of the building code explains plainly that the actual window opening closest to the bottom is going to be where the measurement is to be taken.

There is a clause in the code that explains that the window may be reinforced with fall proofing (bars on the window). In extreme cases when brick or whatever has been finished around the unit, it may be plausible to implement such a system. Just remember, if it is an egress unit, then such a system will no work.

2012 International Residential Code Page 91

R312.2 Window fall protection. Window fall protection shall be provided in accordance with Sections R312.2.1 and R312.2.2.

R312.2.1 Window sills. In dwelling units, where the opening of an operable window is located more than 72 inches (1829 mm) above the finished grade or surface below, the lowest part of the clear opening of the window shall be a minimum of 24 inches (610 mm) above the fininshed floor of the room in which the window is located. Operable sections of windows shall not permit openings that allow passage of a 4-inch-diameter (102 mm) sphere where such openings are located within 24 inches (610 mm) of the finished floor.