This project will take the mystery out of designing stairs for your deck and have you quickly marking the stringers.
The ascent should be gradual for outdoor stairs -- short risers and deep treads are the rule.
At first glance, designing stairs for your deck may seem mysterious, but a simple rule makes it easy twice the riser height (the height of each step to the top of the tread) plus its run (the front-to-back depth of the tread) should equal between 24 and 27 inches.
Start by measuring the total rise and run for your stairs. You can plan a specific location for the stairway landing pad and cut stringers (the diagonal supports) to meet it. Or you can decide how many steps and what rise and run you want and position the pad according to the stair calculations. Even better is to start with a prospective pad location and estimate whether the resulting rise and run will be comfortable and aesthetically pleasing.
Stringers are the key stair components. Choose straight, clear 2x12s, preferably boards with vertical grain. Don't settle for second-best boards for stringers; buy the best lumber you can find.
About seven hours to measure and cut the stringers and install the treads, not including installation of concrete pad
Tape measure, framing square, stair gauges, circular saw, jigsaw or handsaw, cordless drill, socket wrench
Using simple mathematical formulas, measuring, cutting, fastening
Install decking and landing pad
Calculate the rise and run for each step and place stair gauges at these measurements on your framing square. Set the gauge for the rise on the tongue of the square and for the run on the blade. Starting at what will be the top of the stringer, set the framing square on the stringer so the tongue (the short side) intersects the corner. Mark the rise and run lines. Extend the line for the rise to the opposite edge of the stringer (you will cut at this line later).
Move the framing square up the board by the thickness of the tread, and mark a line parallel to the bottom run line. You will actually cut on this second line because the stringer needs to be shortened by the thickness of the tread. Otherwise the bottom step will be too high.
If your design requires only two closed stringers, mark them as you would an open stringer but cut only the top extended rise and the bottom edge and rise. If your design calls for more than two stringers, those in the middle will be open stringers. Mark and cut one stringer and use it as a template to mark the others. Do not cut the outside stringers.