---
kind: "section"
citation: "29 C.F.R. § 1917.121"
title: "29"
number: "1917.121"
heading: "Spiral stairways."
url: "https://uscodex.org/cfr/29/1917.121"
---

# §1917.121. Spiral stairways.

- (a) **Definition.** “Spiral stairway” means one with closed circular form, uniform sector-shaped treads and a supporting column.
- (b) **Requirements.** Spiral stairways shall meet the following requirements:
  - (1) Stairways shall conform to the minimum dimensions of Figure F-1;
  - (2) Stairway risers shall be uniform and shall range from 6 1/2 to 10 1/2 inches (16.5 to 26.67 cm) in height;
  - (3) Minimum loading capability shall be 100 pounds per square foot (4.79kN), and minimum tread center concentrated loading shall be 300 pounds (1334 N);
  - (4) Railings shall conform to the requirements of [§ 1917.112(c)(1)](/cfr/29/1917.112.md?p=c-1). If balusters are used, there shall be a minimum of one per tread. Handrails shall be a minimum of 1 1/4 inches (3.18 cm) in outside diameter; and
  - (5) Vertical clearance shall be at least 6 feet, 6 inches (1.98 m) above the top step.
- (c) **Maintenance.** Spiral stairways shall be maintained in safe condition.

## Notes

### Amendments

[48 FR 30909, July 5, 1983, as amended at 62 FR 40201, July 25, 1997; 65 FR 40942, June 30, 2000]

### Authority

Authority: 33 U.S.C. 941; 29 U.S.C. 653, 655, 657; Secretary of Labor's Order No. 12-71 (36 FR 8754), 8-76 (41 FR 25059), 9-83 (48 FR 35736), 1-90 (55 FR 9033), 6-96 (62 FR 111), 3-2000 (65 FR 50017), 5-2002 (67 FR 65008), 5-2007 (72 FR 31160), 4-2010 (75 FR 55355), 1-2012 (77 FR 3912), 8-2020 (85 FR 58393), or 7-2025 (90 FR 27878), as applicable; and 29 CFR part 1911. Sections 1917.28 and 1917.31 also issued under 5 U.S.C. 553. Section 1917.29 also issued under 49 U.S.C. 1801-1819 and 5 U.S.C. 553.

### Source

Source: 48 FR 30909, July 5, 1983, unless otherwise noted.

### Amendments

[48 FR 30909, July 5, 1983, as amended at 62 FR 40201, July 25, 1997; 65 FR 40942, June 30, 2000]