Your staircase's stringers serve fundamentally as the structure's skeleton and support structure. When constructing stairs, the stringers should always be made out of pressure-treated 2x12s that are straight and of high quality. Be certain that the wood has a RET level of .60 if you are going to lay the stringer down on the ground. You want the side of the board that has the crown to be facing down on the cut side.
You will need to lay out one of your 2x12s on saw horses in order to prepare the stringers and use a framing square and clamps to trace the contour of the stair on the 2x12. You will be able to determine the precise angle at which your steps should be cut if you begin by lining up the riser height and tread depth on the framing square. Next, align the framing square with the stringer. It is necessary to repeat this operation all the way along the stringer.
You will notice that it is too short by the height of one thread since the lowest step will be the ground. This is because the ground will be the bottom step. Immediately following the marking of the stringers, you will need to make an adjustment. You can adjust for landing on the ground by cutting off the thickness of one tread before dropping the stringer. It's possible that you'll need to make an additional adjustment in order to keep the design of the stairs uniform, and this will depend on how you're going to connect the top step.
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Calculating Your Measurements
Calculate the total rise required for the stairs. Your total rise is the vertical distance between floors that the stairs will span. In the majority of instances, the complete rise is already determined, therefore it is sufficient to merely measure the height.
This space should be maintained between the top of the finished floor below and the top floor. When determining your stringers, you must consider whether or not the floor is unfinished.
Determine the desired height of each step. The height of each step can vary slightly, but there are broad guidelines to follow. Standard riser height is around 7 inches (18 cm), so utilize this measurement unless you have unique constraints, such as low headroom.
This dimension is also known as the individual climb of the steps.
Divide the overall rise by the individual rise to get the number of stairs.
For this calculation, you just determine the number of stairs required to reach the desired height. Use a calculator or perform the calculations by hand, as they are typically straightforward.
For example, if you desire 7-inch-tall (18-cm-tall) steps with a total climb of 56-inch-tall (140-cm-tall), then 56/7 = 8. You will need eight steps.
Automatically, the number of treads (individual runs) will be one less than the number of risers.
Determine the required run for each stair. The horizontal distance between the top and bottom of the stairs constitutes your total distance run. Depending on your needs, the protrusion of the stairs might vary, but stairs should generally be at an angle of roughly 40 degrees.
Determine how long the stringer should be. Once the overall rise and run of the stairs have been determined, the stringer length can be calculated. You have the option of using an online stair calculator, a hypotenuse calculator, or performing the calculations manually.
Check your measurements twice before beginning to mark your cuts. Check your arithmetic and calculations to avoid wasting time and materials by cutting risers that do not fit. It is preferable to take a few minutes to double-check your work than to squander a great deal of time redoing it.
Preparing the Cuts
Commence construction on the first stair. Place a framing square close to the end of a 2 x 12 (38 x 286 mm) board, leaving a few inches before the square's end. Use the rise and run figures marked on the outer scales of the square that correspond to the specified dimensions. These figures should extend to the board's upper edge.
The short end (tongue) of the square should fall on the rising measurement. The square's (body's) long side (run) should be measured.
To give yourself some wiggle room, the board should be at least 12 inches (30.48cm) longer than the desired length of the stringer.
Outline the perimeter of the square along its outer edges. If necessary, move the square down to extend the run line to the lower board edge. This is the diagram of your uppermost stair.
Lay out the rest of the stairs. Move the framing square along the board until the scale run figure reaches the end of the first marked run line. Mark your second stair after ensuring that your rise and run figures are aligned with the top edge of the board.
Continue along the board while aligning the scale's rise and run figure with the upper edge. Mark the new outline and repeat until one further set of runs and rises is marked.
Mark the base of the stringer. To make the first step the same height as the others, subtract the depth of the thread from the rise, leaving the finished stair at 7 inches (18 cm). Simply draw another parallel mark to the right of the run line that is equal to the thread's thickness. This indicates the stringer's base.
Making Your Cuts
Prepare for the safe usage of a circular saw. Include safety glasses among your personal protective equipment. When operating a circular saw, it is also vital to observe general safety measures. These include keeping your body parts away from the blade while the tool is in use and keeping the cord out of the tool's path while it is in operation.
Additionally, you should clamp down your stringer board to prevent it from moving when you cut it.
Utilize a circular saw to cut along the designated lines on the stringer. Start the saw before making contact with the wood. Then, steadily work the saw from the outer border of the mark toward its end, where the rise and run intersect.
Complete your cuts using a handsaw. Cutting beyond the intersection of the rise and run lines can significantly weaken a building. Choose to finish your cuts using a handsaw so that you can be precise instead of accidently going too far with the circular saw.
Trim the stringer's bottom and top ends. Cut the stringer's top at the first rise line. Then, clip the marked bottom run line so that it is equal to the thread thickness of your stairs shorter than the others.
Use the first completed stringer as a model. Use this stringer as a template for your other stringers so that they all match precisely. In most circumstances, you will only need one or two additional stringers, but a really wide staircase may require more.