Although stairs are among the more challenging home projects, building stairs with landings are not a great deal more challenging than a regular staircase. If you think of them as two (or more) separate stairways, the process is simpler. Just follow these seven steps.
Step 1 – Measure Rise of Stairs
Measure the entire height of the completed staircase. Put a board out from the edge of the floor that is at the top of the staircase and measure from the end of the board to the floor or ground where the staircase will land.
As an example, say the height between one floor and the next or one level of a deck and the next is 85 inches.
Step 2 – Calculate the Number of Steps and the Tread
Next you will decide how many standard steps will be needed to cover that distance. The standard rise on steps is seven inches, so normally the total rise is divided by seven (12.1), so you know that the steps will require 12 risers. Since the number was rounded slightly, you will need to divide 85 by 12 to get the exact height of each riser, which is 7.08 inches.
A standard tread size is 10 inches. This fits two 2 x 6 pieces if you are using decking boards. They can be larger, but should not be smaller under any condition. Check building code in your area, since stairs are highly regulated.
Step 3 – Determine Height of the Landing
Now that you know exactly how much rise each step will have, you can calculate the height of the landing. It will need to be at exactly the height of one of the stairs. Since we have 12 stairs on this sample staircase, we will divide them in half and have six before the landing and six after.
This means my landing needs to have a height of six risers, or (6 x 7.08), which equals 42.48 inches.
Step 4 – Build the Landing
Create a square or rectangular box that is 42.48 inches off of the floor, including the subfloor or decking surface. Place the landing in the proper place.
Step 5 – Cut the Stringers
Since you know the rise and the tread size, you are ready to cut the stringers that hold up the stairs. Use 2 x 12 boards for this purpose. You need at least two stringers for each section of staircase, but using more is perfectly acceptable, especially for wide steps.
Use a carpenter’s square with a carpenter’s square that has a stair gauge attached. Mark the rise on one side of the square, the tread width on the other. With the stair gauge, you are able to mark the first notch, then move the square so that the gauge aligns with the edge of the first notch and that puts the square exactly into place for the next notch. Mark six notches in this way.
Use a circular saw to cut the notches, being careful not to over cut. Use a handsaw to finish cuts, if necessary. Once the first is cut, use it to mark the rest of the stringers. Trim the stringers the height of a tread so that the steps meet the top floor evenly.
Don't forget to wear the proper safety gear (i.e.: gloves and goggles) and to take precautions when working!
Step 6 – Complete Bottom Stairway
Attach the stringers to the landing. Add the boards for the risers and the tread boards with wood screws. Be sure to secure them firmly.
Step 7 - Attach the Top Stairway
One the bottom stairs are aligned, attach the stringers to the top stairway.
You can either go straight or have an L shaped staircase. Fasten the risers and treads, and enjoy your stairs with a landing!