Article: Before you begin purchasing materials and building your deck stairs, you need to go online, call your local government, or contact a building inspector to make sure you’re following your local building codes. Building codes can vary, so you need to be sure you’re following your local codes or you could face a fine and be forced to remove your deck stairs. Many local governments list their building codes online. The first thing you need to do is find where your stairs will end, or where the landing spot will be. Picture a line running from the edge of your deck down to the ground at a 40-degree angle. Place a tape measure on the ground where you think the stairs will end. It does not have to be measured precisely. The 40-degree slope should start the bottom of the support beam of the deck because this is where the stringers will be attached. Take a 2 in (5.1 cm) by 4 in (10 cm) board and lay it on the top of the deck so it stretches over the landing spot that you estimated. Use a 4 ft (1.2 m) level to make sure the board is level above the landing spot. Use a tape measure to measure from the landing spot on the ground to the bottom of the straight board to find the approximate height, or total rise, of your stairs. Write down the measurements so you can calculate the materials later. Take the measurement you made of the total rise, divide it by 7, and round the number to find the total number of stairs you’ll need for your deck. If you have a number with a decimal that is 0.5 or more, then round the number up. If your number is less than 0.5, then round the number down.  For example, if your total rise was 60 inches (150 cm), then divide that number by 7 to get 8.57. Round that number up to get 9 stairs. Write down this number to use in your calculations. The actual rise, or height, of each step can be calculated by dividing the total rise by the approximate number of stairs. This will tell you how tall each step will be.  For example, if your total rise is 60 inches (150 cm) and your approximate number of steps is 9, divide 60 inches (150 cm) by 9 to get 6.67 inches (16.9 cm) per step. Most building codes say stair risers should not be taller than 7.75 inches (19.7 cm). The treads boards create the part of the stair that you step on. According to many building codes, the stair treads should be at least 36 inches (91 cm) long  10 inches (25 cm) wide. The number of steps you calculated is the number of treads that you’ll need. Stringers are boards that have sawtoothed or stair-shaped notches cut into them and run diagonally along the length of the stairs to support them. To find their length, add together the square of the run, or tread, and the square of the rise. Then take that number, find the square root, and multiply it by the number of steps to find the actual length of the stringers you’ll need. For example, if your tread is 10 inches (25 cm), square 10 by multiplying the number by itself, which gives you 100. If your rise is 7 inches (18 cm), square that number by multiplying it by itself to get 49. Add 100 to 49 to get 149, then find the square root of 149, which is 12.206. Multiply that by the number of steps that you have to find the total length of your stringers.
What is a summary of what this article is about?
Check your local building codes regarding deck stairs. Imagine a 40-degree slope to find the landing zone of your stairs. Rest a straight board on the deck and make it level over the landing spot. Measure the total rise from the landing spot to the straight board. Divide the total rise by 7 to find the approximate amount of steps. Find the rise of each step by dividing the total rise by the number of steps. Use tread boards that are at least 10 inches (25 cm) wide. Find the length of the staircase by calculating the length of the stringers.