Building a Steel Stair

Basics

• The building of custom steel stairs requires precise calculations to ensure that their geometry is structurally sound, and joins floors safely and decoratively. The specialized tools for cutting, shaping and joining metal parts are usually not found in the average homeowner’s toolbox. Only professionals should attempt construction. They are three types of professionals suited for this type of project. The most expensive are custom metalworkers who create unique constructions. Fabricated-steel manufacturers can produce standard designs quickly. And, finally, component manufacturers of railings and balusters can supply parts that installers can assemble into semi-custom designs.

Spirals

• One type of steel staircase that is within the capabilities of handy homeowners, and is also relatively inexpensive, is the prefabricated spiral. Because parts come in kit form and require only screws, bolts and fasteners for assembly, no special tools or calculations are needed. Buyers must supply the exact space measurements to their suppliers; these calculations usually only requires basic math and geometry. Those who are uncertain about their measurement skills can hire contractors to do the preliminary calculations, make the initial floor cuts and place the kit order. The homeowner can then take over.

Standard Stair Codes

• Whether steel stairs are custom-built or pre-assembled, they must follow local and state building regulations to be approved for occupant use. These codes are all based on the International Residential Code maintained by the International Code Council. Standard incline steel stairs must be at least 36 inches wide. If they have more than three risers, they need a handrail on at least one side. The handrail must not project more than 4.5 inches into either side of the stairway. Stair steps must be at least 10 inches deep, and the risers, or vertical surfaces between steps, must be no more than 7.75 inches high. All measurements must be uniform across the entire flight of steps, with a variance of under 0.375 inches.

Spiral Stair Codes

• The clear width for spiral steel stairs above and below the handrail must be at least 26 inches. The minimum headroom is 78 inches. The minimum tread depth is 7.5 inches, as measured 1 foot from the narrowest edge. Risers must be under 9.5 inches high. Unless otherwise specified, spiral stairs must follow all the codes for standard incline stairs.