Available in standard diameters from 3 1/2 feet to 6 feet in hot-dipped galvanized steel or powder-coated aluminum, stairs from SalterSpiralStair can be manufactured to any height at the company’s Collegeville, Pa., plant.

Galvanized stairs—fabricated from 12-gauge steel—are shipped with the material’s characteristic gray color but can be painted on site. Powder-coated-aluminum stairs are available in hundreds of stock colors as well as in standard white and black. In either material, treads come grated for drainage or diamond-plated for slip-resistance. The stairs have a lifetime warranty on the fabrication and a 5-year warranty on the finishes.

Lead time runs from about 5 weeks in slower seasons to 8 weeks during peak spring and summer construction seasons. An 8-foot galvanized stair with a 3 1/2-foot diameter costs $1,400; in powder-coated aluminum, it would cost about $4,000.

SalterSpiralStair, 866.368.8280, salterspiralstair.com