I didn't follow code or conventional design for the stairs in my barn. The rise is 13', so it's a long staircase. I didn't notch the side stringers, gluing and screwing 2X blocks instead. The stringers are fully supported by walls, creating a storage closet underneath. Here's the different part: I have no middle stringers on 42" wide stairs! I made the risers part of the structure, using 3/4" plywood, and gluing and nailing them to the back of each 2X12 tread. They are also glued and fastened to the same blocks that support the treads. The tread rests on the top of the riser below it, and since the riser is strongly attached, it results in a rigid box beam. They are the strongest set of stairs I've ever built. I'm not sure what a building inspector would make of them, but I don't care. I stole the idea from a company that used a similar system, but with metal supports on each end. They seem to have gone out of business, though.