We recently received a question from one of our newsletter readers, Mike H., about deck stairs. Here’s his question and our reply.
“The middle stringer of stairs going from the ground to my deck, which is 10 feet above the ground, is made out of 2 parts that are scabbed together with a couple of 2x6s. It is my understanding that they should be one solid piece. What would be the proper way to improve this?”
I’ve been preaching for nearly 20 years that you can tell how well built a house (or, in this case, a deck) is by how the stairs are built. In most homes, the stairs are the most challenging piece of framing (and trim!), so they are a great test of a carpenter’s skill. To the specific question, in most residential applications, a single 2×12 stringer with appropriate (i.e., minimal) saw-tooth shape cuts to mount the stair tread and riser is common practice. What remains to provide the strength to support stair traffic could be described (and is sometimes constructed) as a 2×6 with small triangle shaped blocks to support the treat and riser. If it is completed with care and the right connections, it probably could be just as strong as the cut 2×12 method. In general, however, I’d recommend replacement of the center stringer you described with a more traditional single piece. Proper cuts and end connections are crucial to help keep the stair assembly from collapse. All of this assumes that the stringer span is adequate. Thanks for the question – hope this reply has been helpful!