|Julie Harris peers over the edge of an extremely cool|
spiral staircase in the Robert Wise-directed film
The Haunting (1963)
First, a few definitions for terms that are easily confused: A true spiral stair has treads radiating from a center post. A circular stair, on the other hand, has an opening in the middle: it’s basically just a regular stair that curves. A winding stair is a conventional stairway with angled treads where the corner landings would normally be. The last two are not spiral stairs.
|Metal spiral stair available in kit form. Treads can typically|
be ordered in wood or plain or nonskid (checkerplate) steel.
Generally, the minimum nominal diameter allowed by building codes is 5’. The maximum riser height on a spiral stair can be 9 1/2”—considerably steeper than the 8-inch rise allowed for conventional stairs. However, because spiral stairs are steeper and more dangerous than conventional stairs, buildings codes restrict their use in certain situations—check with your local building department for specifics. The distance between balusters—the vertical pieces in the railing—can be no more than 4”. Floor openings can be either round or square, or the staircase can be entirely freestanding adjacent to an upper floor gallery.
|Wood spiral stairs are generally better suited|
to traditional home styles. The wood species
and finish can be matched to existing trim.
Wood spiral stairs have an even wider range of designs, making them appropriate for both traditional and contemporary home styles. They’re available with ornamental turned balusters or simple dowel-like ones, and a large range of finishes are possible.
Although top-of-the-line spiral stairs are usually custom-fabricated, many manufacturers offer more economical spiral stair kits in both metal and wood, some starting at less than $1000. These kits are assembled on site. Some of them require the total rise to be specified before ordering; others can be adjusted to suit varying field conditions.