Thanks for reaching us here at Spyglass. Glad you like our work. This stair is custom made with steel, iron, and reclaimed barn beams. It has support spine of a single steel I-beam with bracketing for the steps----bolted to 2nd floor beams at top, and floor at bottom. Totally free-standing. Stair treads are formed of oak beam material. Railing of iron rods and tube, fastened to treads. Railing cap is wood, stained. All designed to meet railing and open tread codes. All metal has a special finish, acid etched and waxed, by our fantastic local fabrication shop. Follow Spyglass for more cool stuff like this!