A staircase is a functional part of a home, but it can also serve as a decorative element. Whether you're building a home from the ground up or remodeling an existing one, it's important to understand the basics of straight stair design, including how much room a staircase will take up. The size of a staircase depends on how many people use it, and how long it is. If you want to know how much space is needed for a metal staircase, you first need to work out the length of the staircase in feet. You then need to calculate how much space is needed for each of the two sets of stairs. This will give you an idea of how much space you need. You need to think about where the conventional stairs are going to go in the room and how much space is available. The average width of a stair tread is 12 inches, although this can range from 10 to 14. The average height of a stair step is between 7 and 8 inches. You can calculate how much space is needed for a stairway.