The required minimum width for industrial fixed stairs is 22 inches (56 cm), measured between vertical barriers such as handrails or walls. This standard comes from OSHA regulation 1910.25, which governs stairways in general industry workplaces. Different stair types have different minimums, so the exact number depends on what you’re building or inspecting.
Standard Fixed Stairs: 22 Inches
Under OSHA 1910.25(c)(4), standard industrial stairs must have a minimum width of 22 inches between vertical barriers. “Vertical barriers” means the handrails, stair rail systems, or walls on either side of the stairway. This is the clear, usable walking space, not the total width of the stair structure itself.
That 22-inch figure is notably narrower than what most building codes require for commercial or residential stairs (which typically call for 36 inches or more). Industrial stairs have a tighter minimum because they often serve as access to equipment platforms, mezzanines, or elevated work areas where space is limited and foot traffic is lower. If your stairs serve as a primary means of egress or see heavy two-way traffic, you’ll likely need something wider than the bare minimum to meet fire code and practical safety needs.
Width Requirements by Stair Type
OSHA defines several categories of industrial stairs, each with its own minimum width:
- Standard stairs: 22 inches (56 cm) minimum clear width between vertical barriers.
- Spiral stairs: 26 inches (66 cm) minimum clear width. The wider requirement accounts for the curved treads, which are harder to navigate.
- Ship stairs (ship ladders): 18 inches (46 cm) minimum tread width. These are steep, compact stairs typically used where space is extremely tight and access is infrequent.
- Alternating tread stairs: 7 inches (18 cm) minimum tread width, measured at the leading edge (nosing) of each tread. These are the narrowest option OSHA permits and are only appropriate for limited-access situations.
These stair types aren’t interchangeable. OSHA restricts when you can use the more compact designs. Ship stairs and alternating tread stairs are generally allowed only where standard stairs aren’t feasible due to space constraints and where foot traffic is low enough to justify the trade-off in usability.
How Width Is Measured
The 22-inch measurement is taken between vertical barriers, not from the outside edges of the stair stringers or the outer surfaces of handrails. This distinction matters because handrails project inward from the stair’s structural frame. If your stair structure is 28 inches wide but the handrails reduce the clear walking space to less than 22 inches, you’re out of compliance.
Handrails must also maintain a minimum clearance of 3 inches between the rail and any wall, stair rail system, or adjacent object. This keeps enough room for a worker to get a full grip on the rail, which is especially important in an emergency or when carrying tools.
Landing Dimensions
Landings are part of the stair system, and they have their own size requirements. For general industry, stair landings must be at least 20 inches deep. Where a door or gate opens onto a stairway, a landing platform is required, and the door swing cannot reduce the standing area on that landing to less than 18 inches in depth.
For construction stairways (covered under a separate OSHA standard, 1926.1052), landings must be at least 30 inches deep in the direction of travel and at least 22 inches wide, with a landing required at every 12 feet of vertical rise. These construction-specific numbers are useful to know if you’re installing temporary stairs during a build-out.
When 22 Inches Isn’t Enough
Meeting the OSHA minimum doesn’t always mean you’ve met every applicable requirement. State and local building codes, fire codes, and the International Building Code (IBC) may impose wider minimums depending on the occupancy type, the number of people the stair serves, and whether the stairway is part of a required means of egress. Many jurisdictions require 36 or 44 inches for egress stairs in commercial and industrial buildings.
The ANSI A1264.1 standard, which OSHA references as a consensus standard for workplace walking surfaces, also recommends avoiding long, uninterrupted flights of stairs without landings or intermediate platforms. Even if your stair width meets the letter of the regulation, breaking up long vertical runs with landings reduces fall risk significantly.
If two workers need to pass each other on the stairs, or if anyone will be carrying materials up and down regularly, 22 inches will feel extremely tight. Practical stair design for most industrial settings lands in the 30 to 36-inch range, with the 22-inch minimum reserved for access stairs in space-constrained areas with light, one-directional traffic.