A flight of stairs is comprised of the steps, railing and stringer. When designing and building stairs, it is critical to understand how to cut accurate stringers to get level and safe stairs. The stringers are what shapes the stairs and acts as a frame for the entire stairway. Understanding the function of a stringer is necessary before trying to design or build a set of stairs.
Stringers are the frames that hold the stairs in place. When you look at a stringer without steps installed on it, the appearance is that of a jagged-edge knife. Stringers are cut from a single piece of 2-inch thick by 12-inch tall piece of wood. It is a single piece of wood because it must be able to support the weight placed on the staircase. Avoid using wood with large knots or cracks in it. The steps that are placed on the horizontal parts of the stringer are called treads and the vertical pieces that provide a solid back to each step are referred to as risers.
The most common depth of a single step on a stringer is 10 inches. Each tread usually hangs over the stringer by 1 inch. When you cut treads, you need to keep in mind that the riser in the back of the step will be approximately 1 inch thick. That means that the treads are 11 inches thick to allow for a one inch overhang. Risers can run anywhere from 7 to 8 inches tall. The difference depends on your preference and tall you want your steps to be. Taller steps can sometimes be difficult for small children and older adults to use.
The top step in a stringer is usually approximately 1 inch narrower than the other steps and can be used in one of two ways. The stringers can be attached to the frame of the stairway using metal brackets and the top stringer step becomes the first step of the stairway. The other use for the top step of the stringer is to attach it to the frame of the stairway for additional strength and support. Longer stairways will often use the first step as a connecting point rather than a place to install the top tread.
Determining the Steps
There is a simple way to determine how many steps you need to cut when making your stringers. The rise in a stairway is the distance from the floor to the landing of the stairway using a vertical line. When you have measured the rise, you divide it by the height of your steps to find out how many steps your stairway will need. For example, If the distance from the landing to the floor is 10 feet, or 120 inches, and your want your stair risers to be 7 inches high, you would divide the rise by the riser height to get 17 steps.
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