Building codes mandate the size of basement windows. This allows for a quick exit in an emergency. According to the International Residential Code, basement windows must have:
An opening width of at least 20 inches.
An opening height of at least 24 inches.
A net clear opening of at least 821 square inches—or 5.7 square feet.
A sill no more than 44 inches off the floor.
Not sure if your existing basement windows meet today’s requirements? All you need is a tape measure. Open the window as wide as possible. Measure the width and height of the opening. Multiply the width by the height. Is your measurement equivalent to the required 821 square inches—or 5.7 square feet? If not, you will need to have larger windows installed to meet requirements.