Minimum Window Sill Height Second Floor. Just FYI for anyone who wants to know minimum floor-to-window-sill height its 18 for first floor and 24 for 2nd or 3rd stories any window sills above 72 of the outside ground --this is according to the California Building Code and IRC. Minimum Window Sill Heights According to the 2018 IRC all windows that are more than 6 feet above the grade outside the window must have a bottom opening a minimum of 24 inches above the rooms interior floor.
For windows where the fall height from floor to ground is 4 m or greater there shall be no window openings greater than 125 mm within 865 mm of the floor. Window wells serving an egress window shall not be less than 9 square feet in area with. However if the window extends to within 18 inches of the floor it must either be safety-glazed or have a bar or other physical barrier to prevent someone from falling into the glazing.
Unless the code has been recently updated anything within 20 of the floor has to be tempered but there is no minimum sill height requirement above the floor the window can go all the way to the floor.
The 2012 IBC International Building Code and the IRC International Residential Code requires the bottom sill of operable windows to be a minimum height above the interior floor when they are 72 inches or more above the grade outside the window. I believe it is 18 from the floor height to the actual glassIf there is glass below that height it must be tempered. An exception is given however for windows that do not open more than 4 inches or that are equipped with window guards or window opening control devices that comply with ASTM F2090-10. Section 1015 requires the bottom of openings created by these windows to be a minimum of 36 inches above the adjacent interior floor when they are 72 inches or more above grade.
