This is a currency note from the Bank of the United States and is not an obligation of the United States government. The Treasury Department did not issue notes intended for circulation as currency until 1862.
The grommet panel must be a minimum of 70 inches wide, between the side hem seams, to provide just slightly more than 1.5 times fullness on the 40-inch space.
The building code requires a minimum of 5 feet, 2 inches because of the tread width minimum of 26 inches. If we add the width of two 26-inch steps, a center column and a handrail, we find that a 62-inch diameter is a minimum for any spiral staircase. I chose a 70-inch diameter to make the stairway easier to walk.he center column and two treads make a total diameter of 68 inches. The circumference of the stairway is the diameter in inches multiplied by 3.1416. So, 68 inches x 3.1416 = 210 inches (rounded to the nearest inch). Since we will make 14 steps, 210Ã·14=15 inches.