Things You'll Need
Building a widened staircase can significantly spruce up your home's interior or exterior. Walking up and down narrow and steep staircases is a daunting and challenging task for many people, whereas a widened, gently rising staircase is inviting and is not imposing to traverse. Building widened stairs is generally easier for new construction because it doesn't require the tear-out of an old staircase or a widening of the space in which the stairs are already located.
Consult local building codes to determine what the minimum specifications for a staircase are in your community.
Calculate the rise and the run for your staircase according to local building codes. These codes usually require a maximum rise and run. If you're going to build a wider than normal staircase, then your rise and run should be more gradual. Use the Rule of 25 to determine how wide each stair tread should be. In the Rule of 25, subtract the number of inches you want your treads to be from 25. Then divide this number by 2 to get the rise of your staircase. For example, if you want the steps to be 14 inches wide, subtract this number from 25 to get 11. Divide 11 by 2 to get 5.5 inches for the rise of your stairs.
Mark the stringers for the stairs by using three 2-by-12 boards using a framing square. The rise and run of your stairs should determine the length and the height of each step.
Cut out the stairs that you've marked using a jigsaw.
Measure and cut the treads for your stairs using 2-by-6 or 2-by-12-inch boards. Using a 2-by-6 will allow you to create a seam or small gap between the two boards that make up your treads.
Attach the back of the top riser to a 2-by-8-inch joist. Drive wood screws through the back side of the joist into the stair risers. Two screws into each riser should suffice.
Screw the 2-by-8-inch joist into the wall or deck where your stairs are intended to go. Use several wood screws on either side of the stairs to ensure that the stairs will be secure.
Cut and attach the treads and risers for each step according to the rise and run you determined at the beginning of the project. Drive wood screws through these into the edge of the stringers to secure them in place.