While not new, since the concept was already described by Christopher Alexander in its architectural theories, it only gathered some traction in programming due to the publication of Design Patterns: Elements of Reusable Object-Oriented Software book in October 1994 by Erich Gamma, Richard Helm, Ralph Johnson and John Vlissides, known as the Gang of Four (GoF), that identifies and describes 23 classic software design patterns.
Use a calculator to calculate the stair riser length or the number of steps you'll need. Divide the height from the first floor to the top of the second floor by a predetermined height of your choice for the riser. The typical height of a riser is 6 or 7 inches (15 to 17.5 cm).
A standard number of treads in a stair between first and second floors is 14. One hundred-five divided by 14 equals 7 1/2 . That means the distance from the top of each step to the top of the next step will be 7 1/2 inches. With a riser height of 7 1/2 inches, tread width (run) should be at least 9 inches. Ten inches is a more comfortable run; when you multiply 7 1/2 inches by 10 inches, you get 75 -- within the conventional ratio of 72 to 75 inches. With 14 10-inch treads, the total run of the stair will be 140 inches.