Building a set of wood stairs is not nearly as hard as you may think. With some basic wood tools and a bit of algebra you can easily build your own. Of course this can get a bit tricky for stairs with several landings but method is still same.
This article will cover steps for building a straight set of stairs. Chances are if you are reading this then you are still learning and won't be taking on a complex stair anyway.
Now, we will assume that it is from a deck to a concrete pad. The deck is going to be 48" wide and at eye level from ground.
Tools you will need: 1. Circular saw 2. Framing square 3. Hand saw 4. Carpenters pencil 5. Measuring tape 6. 4' Level 7. Masking tape
You will also need: 1. 3 @ 10' / 2" x 12" boards - Choose best only, make sure they are straight with no check (cracks). Very Important! 2. 2 @ 8' / 2" x 4" boards 3. 8 @ 8' / 2" x 6" boards - Once again choose good ones. These are going to be steps so... 4. 1 @ 45" / 2" x 6" boards 5. 1 sheet of plywood @ 1/2" / 8" x 48" 6. Of course, 3-1/2" framing nails and deck screws or nails for steps.
Find overall rise We want to know exact vertical distance from top of concrete pad to top of deck. Take one of 8' 2x4's and rest one end on deck and hold other over pad, Place level on 2x4 and level board. Then simply measure from bottom of 2x4 to pad. Lets say it is 64". This is overall rise.
Now determine overall run Before we can do this we have to determine how many steps we need. So first..
Take overall rise, 64", and divide it by 7.25", which is typical height of 1 riser (step). This gives us 8.83, which rounds up to 9, So we will go with 9 risers.
Important: There is always 1 less tread then risers. Whether you go up or down last step is onto deck or pad. So 1 less tread.
Now we take 10.5", width of a typical step, and multiply it by 8. This gives us 84". This is overall run.
While we are doing math we need to figure out exact rise of each step. We simply take overall rise of 64" and divide it by 9 and we get 7.111" or 7-1/8", or close enough to it. So each riser will be 7-1/8".
Time for some layout First thing. Grab your framing square. The long leg is tread (step) leg and short leg is riser leg. Also, use numbers on outside of square only.
Take some masking tape and wrap a piece around framing square to establish you rise and run. Mark 10.5" on outside of long leg and 7-1/8" on outside of short leg.
Layout one of 2x12's on your saw horses or work bench. WIth long leg of your framing square towards end of board start to line up tape marks to edge of board facing you. Once you have square in position mark outside edge of it with your pencil.