Building stairs in your home is a job that can be satisfying and helpful. Although the actual work involved in cutting the pieces and assembling them into stairs is fairly basic, the skill needed for building stairs is great. Stairs must meet code, be perfectly uniform to prevent tripping and hazards, and be well constructed to avoid accidents.
While a sense for geometry and angles is certainly useful for this construction, if you measure carefully, plan well, and take advantage of pre-constructed pieces, you can easily install stairs in your home.
Step 1 - Calculate Rise
The first thing to do is calculate and write down the overall height or vertical rise the stairs will cover.
Assuming a staircase built onto a deck or porch, put a board straight out from the top of the deck. Measure from the end of the board down to the place where the staircase will land.
For the sake of example, say the height is 49. Then calculate the rise of each step, which is accomplished by figuring out how many standard steps go into that amount. Steps generally have a 7-inch rise, so dividing the total of 49 by 7 gives you the number of steps you will need – 7.
Step 2 - Calculate Run
To find the run, or the distance horizontally that the steps with cover, you use the number of steps you calculated you will need to bridge the necessary height, then calculate the planned width of each step.
Ideally, each step will be at least 10 inches deep, room enough for two 2 x 6s. Using this example, the staircase has seven steps at 10 inches each, so the total run is 70 inches.
Step 3 - Mark the Stringers
The stringers are the support beams under the steps. Cutting the stringers is certainly the most challenging step of the process of building stairs. Use 2 x 12s for stringers. You need at least two stringers, but you can use more for stability.
First, determine if the stringers will attach to the top joist so the stairs are even with the top surface, or if they will mount under a deck or landing and the stringers will be attached to the joists underneath or to the blocking pieces that are found between joists. If they attach under, you need to cut the ends longer.
Mark the notches for the treads by using a framing square. If you add a stair gauge to your square, you are able to mark a number of notches in an identical way. These brass fixtures are clamped onto the square at exactly the rise measurement. The other is attached at the run measurement. You can use this tool as a template, sliding it down so it is in line with the previous notch and mark the next notch.
Step 4 - Cut the Stringers
After the notches are completely marked, use a circular saw to cut the notches out. Do not extend the cuts past any of the marks.
If necessary, finish the cuts by hand with a jigsaw or handsaw.
Step 5 - Trim Bottom of Stringer
From the bottom of each stringer, trim a piece equal to the thickness of a tread – for a 2 x 6 tread (nominal size) trim 1 ½ inches from the bottom of the stringers.
Step 6 - Attach the Stringers
Firmly attach stringers with wood screws. Use brackets if you wish. Use an electric drill with a screwdriver bit. Stringers are commonly 16 inches apart but can be a lesser or greater distance
Step 7 - Attach the Risers
Use wooden risers between steps for a more finished look. Casual staircases can skip this step, although it does increase safety for homes where there are small children.
Step 8 - Install the Treads
Use the screwdriver and screws to install 2x6 boards on the treads of the staircase. Leave a 1/8 to ¼ inch gap between the two treads.