Published kit examples

Prefabricated spiral stair kit

Approximately $1,000–$10,000+

per stair, product package

Published manufacturer guidance spans basic adjustable steel kits (one listed 3 ft 6 in steel kit is about $1,190) through larger, exterior, premium, or highly customized spiral systems. Freight, installation, opening modifications, landings, permits, and local work may be additional.

Sources: Salter Spiral Stair, Paragon Stairs

The Salter Spiral Stair FAQ states that spiral stairs range from about $1,000 to $10,000 — roughly $1,000 for a 3 ft 6 in nine-tread kit up to about $10,000 for a 6 ft diameter, three-story aluminum stair. Paragon Stairs lists specific configurations rather than “starting at” prices: for example, a 3 ft 6 in steel kit for 7 ft 1 in–7 ft 11 in floor-to-floor at about $1,190, and a 3 ft 6 in kit for 11 ft 4 in–12 ft 8 in at about $2,209, both product only.

Basic steel, premium steel, galvanized, aluminum, and wood

Kit familyPlanning range (product)Basis
Basic adjustable steel spiral kit$1,000–$2,800Published kit examples
Premium or custom steel spiral$3,500–$9,500Planning model within the published overall range
Galvanized exterior steel spiral$2,500–$6,500Planning model within the published overall range
Aluminum exterior spiral$3,000–$8,000Planning model within the published overall range
Wood or wood-and-metal spiral$5,500–$15,000Planning model within the published overall range

Ranges are for about a 5 ft diameter up to roughly 10 ft 6 in floor-to-floor. The basic steel range is anchored to the published kit examples above; the other families are planning-model tiers placed within the published overall range. Galvanized steel and aluminum are the usual exterior choices; wood and premium steel are interior features. Wood tread inserts add about $40–$110 per tread and solid wood treads $90–$220 in the planning model.

Diameter, floor-to-floor height, and opening size

Spiral stair plan showing diameter and floor openingA circular stair with treads radiating from a center column sits inside a square floor opening slightly larger than the stair diameter. A platform guard runs along the open edges of the opening.DiameterPlatform guardat the openingOpening (product-specific)

Larger diameters walk more comfortably and carry more, at more cost — the planner adds $150–$500 per 6 in above 60 in. Taller floor-to-floor heights add treads ($80–$240 per extra riser). Paragon’s diameter guidance sizes the floor opening at the stair diameter plus 2 in, and notes that a 26 in clear walking path needs about a 5 ft diameter. That is one manufacturer’s product rule, not a market-wide standard.

Platform rails and finish

The guard around the floor opening is often a separate line on the order, priced at about $80–$210 per foot in the planning model. Powder coat, galvanizing, and custom colors change both price and lead time.

Freight, assembly, opening and framing work, and permits

A kit may be sold as a configurable product while the surrounding building work remains project-specific. Plan for freight ($250–$1,300), assembly or installation ($1,000–$4,200 if you hire it out), creating or reframing the floor opening, and permits ($150–$1,200). Many kits are designed for owner assembly; the opening and structural attachment are usually best left to a builder.

Primary versus secondary stair, headroom, and code verification

Whether a spiral stair may serve as the required or primary stair depends on the code path, the product, and the authority having jurisdiction. Code-version spiral kits are sized and detailed differently and cost more. For context, the 2021 IRC model provisions for spiral stairways include 26 in minimum clear width; 6¾ in minimum tread depth at the walkline (walkline radius not more than 24½ in); 9½ in maximum riser; 6 ft 6 in minimum headroom (2021 IRC R311.7.10.1; 2024 IRC R318.7.11.1 — model code; verify locally). Confirm headroom along the full spiral path with the manufacturer’s drawings. This site does not certify spiral stairs for any use.

Sources

  1. Salter Spiral Stair frequently asked questionsManufacturer · Published overall spiral stair price range ($1,000–$10,000) and opening-size guidance. Accessed October 14, 2026.What the page showed: States spiral stairs range from about $1,000 to $10,000: roughly $1,000 for a 3 ft 6 in nine-tread kit up to about $10,000 for a 6 ft three-story aluminum stair. Opening = diameter + 2 in.
  2. Salter Spiral Stair guide to spiral stair costManufacturer · Spiral stair cost drivers (diameter, material, height, finish). Dollar figures are cited from the Salter FAQ instead. Accessed October 14, 2026.
  3. Paragon Stairs spiral stair kitsManufacturer · Range of steel, aluminum, and wood spiral stair kit families. Accessed October 14, 2026.
  4. Paragon prefabricated metal spiral stair kitManufacturer · Published starting configurations for basic adjustable steel spiral kits. Accessed October 14, 2026.What the page showed: A 3 ft 6 in diameter steel kit for 7 ft 1 in–7 ft 11 in floor-to-floor listed at $1,190; DIY kit; freight not included.
  5. Paragon 12-foot spiral stair exampleManufacturer · How taller floor-to-floor heights change a spiral kit configuration. Accessed October 14, 2026.What the page showed: A 3 ft 6 in diameter kit for 11 ft 4 in–12 ft 8 in floor-to-floor listed at $2,209.
  6. Paragon spiral stair diameter and opening guidanceManufacturer · One manufacturer’s relationship between stair diameter and floor-opening size (product-specific, not a market rule). Accessed October 14, 2026.What the page showed: Opening = stair diameter + 2 in (e.g. 44 × 44 in up to 74 × 74 in); a 26 in clear walking path needs about a 5 ft diameter.
  7. Paragon spiral stair quick pricingManufacturer · Published kit pricing by diameter and height. Accessed October 14, 2026.
  8. 2021 International Residential Code, Chapter 3 (Building Planning)Model code (official) · Full 2021 IRC stair (R311.7), guard (R312), and spiral-stair model provisions quoted in the code guide. Accessed October 14, 2026.What the page showed: Readable in a browser. Stair width 36 in; headroom 6 ft 8 in; riser 7¾ in max; tread 10 in min; handrail 34–38 in; guards 36 in (34 in on stair sides) where more than 30 in above the floor below; spiral 26 in width, 6¾ in tread at walkline, 9½ in riser, 6 ft 6 in headroom.

See all sources