Federal regulations · Through 2026-08-25 · Newer source version available

29 CFR 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;
Spiral Stairway—Minimum Dimensions
A (half-tread width) B
Normal use by employees 11 inches (27.94 cm) 6 inches (15.24 cm).
Limited access 9 inches (22.86 cm) 5 inches (12.7 cm).
(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). 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.

Where this section sits in the code

Title 29—Labor
Subtitle B—Regulations Relating to Labor
CHAPTER XVII—OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR
PART 1917—MARINE TERMINALS
Subpart F—Terminal Facilities

(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;

Spiral Stairway—Minimum Dimensions

A (half-tread width) B

Normal use by employees 11 inches (27.94 cm) 6 inches (15.24 cm).

Limited access 9 inches (22.86 cm) 5 inches (12.7 cm).

(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). 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.

Collected 2026-08-27T02:25:20Z. Source file · JSON

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