More in Outdoors
Saw the first stringer along the lines made for the rise and run of the stairs. (Image 1). Use a reciprocating saw to make the large cuts and then come back with a jigsaw to cut perfect 90-degree angles. Use the first cut stringer as a template for the other two and a great tip is to position the template so as to saw off any imperfections in the board. Note: A circular saw will not be able to make a perfect angular cut for the stringer, so you'll need to use a jigsaw to get the intricate 90-degree angled corners cut perfectly (Image 2).
Install a 2x8 base board onto the top of the staircase landing. Attach the outer stringers to the support posts and the inner stringer to the middle of the plate board. Start with an outside stringer and line it up so it is flush with the top of the support board and is lined up in the middle of the support post. Nail into place. Repeat process with outer stringer. The bottom of the outside stringers will eventually be bolted to handrail posts. Place a level or straight board along the top of the first two stingers and position the last stringer so it just touches the bottom. Nail the last stringer through the back of the support board.
Install the stair treads using 2x6 boards cut to length. Place the good boards in front of the step and boards with imperfections toware the back of the step. Place two screws through each tread and into the corresponding stringer.