If you're planning on building a stand alone staircase, there are a few things you'll need to take into consideration before getting started. First, you'll need to decide on the overall height and width of the staircase. The next thing to consider is the rise and run of each step. Once you have those measurements, you can begin cutting the stringers—the pieces of lumber that support the steps—to size. Notch out the stringers so they fit snugly around the treads and risers, then attach them to the treads and risers with screws or nails.
After the stringers are in place, it's time to install the handrail. Cut your handrail material to length, then use brackets or newel posts to attach it securely to the stairs. With everything in place, give your staircase a good once-over to make sure all screw heads are flush with surrounding wood and that there are no protruding nails. Once everything looks good, your stand alone staircase is complete!