Building Deck Stairs:
Here are the basics on how to build deck stairs:
Step 1: Choose Material
Deck stairs can be manufactured using wood, composite or a combination of both. A common setup is to use wood for the frame and composite for the stair tread. Two beams are needed for the top of each stair (called the tread).
Step 2: Measure
Place a long level on the surface of the deck, hanging off the edge. Use a tape measure to determine the exact rise from the ground to the deck. Divide the number of desired steps into the total rise to find out the height of each riser. Mark the height of an individual riser and the width of the tread (minus 1/2 inch for overhang) onto a rigid square. Now place the square onto a piece of 2×12 pressure treated wood and mark a toothed pattern along the edge. You are creating a piece known as the stringer.
Step 3: Make the Stringers
Use a jigsaw to cut out each triangle, taking care to not cut past the marked lines. Use this stringer to trace out additional stringers. Now the stringers must be adjusted. The back edge of the stringer must be cut to the thickness of a single riser. The bottom ends must be cut to the thickness of a single tread.
Step 4: Fasten the Stringers
The left and rightmost stringers can now be fastened to the deck using brackets. The middle stringers can be attached with 3 inch screws. (Drive the screw through the deck first and then into the backside of each stringer).
Step 5: Install Riser, Treads and Rail Posts:
Start by installing the risers with 3 inch screws. Four-inch posts to support the railing may be installed with the same screws. Holes must be cut in some of the treads so they can fit over the deck stair railing posts. Finally, install the remaining treads using screws.