In USA, Some township may require a 5 square feet egress regulations for single / double hung windows, so how do we know the minimum size for the windows? Here is the calculation.
1 square foot = 144 square inches
5 square feet = 720 square inches!
The single hung window can only open up or down unit so the length of window is cut into half.
Assuming we have a 36 inch wide window, so 5 square feet egress regulations for single / double hung window is (36 x 20 )inches = 720 square inches . The min requirement of full window size is 36 “ x 40” !
Assuming we have a 32 inches wide window, then we need a full window size 32 “x 45 “!