Mezzanine Stairs: A Guide to OSHA and IBC Requirements

In warehouses and factories, mezzanines are widely adopted as a means to effectively utilize limited floor space. While they allow for increased storage and workspace by taking advantage of ceiling height, multiple standards apply to mezzanine access stairs, making it an area prone to oversights during the design phase.

This article explains the OSHA and IBC requirements applicable to mezzanine stairs.

Which Standards Apply to Mezzanines?

The standards applicable to mezzanines vary depending on the building's use, intended purpose, and users. While OSHA's occupational safety and health standards apply to employee work and storage spaces, the building design and egress routes must comply with the building codes of the governing state or municipality (such as IBC requirements in areas where it is adopted).

Even for the same type of mezzanine, the design standards to be met change depending on the application and jurisdiction. Therefore, it is a fundamental prerequisite to carefully examine the applicable regulations for each project.

Mezzanine Access Stair Requirements Under OSHA Standards

For mezzanine access stairs used by workers, the stair requirements of OSHA 1910.25 may apply. Under this standard for "Standard stairs," the stair angle must be between 30 and 50 degrees, the minimum tread depth is 9.5 inches, and the maximum riser height is 9.5 inches. Note that these figures apply to standard fixed stairs. Since separate dimensional standards exist for ship stairs and spiral stairs, it is necessary to check the applicable regulations based on the type of stair.

Furthermore, OSHA 1910.28 requires the installation of stair rail systems and handrails on stairs with at least three treads and four risers. Separately, fall protection measures such as guardrails are required under 1910.28 for unprotected sides and edges of walking-working surfaces, including floors and landings, that are 4 feet or more above a lower level. Since the triggering conditions for both are different, be sure to individually check the applicable requirements for the number of stair treads and the height of the platforms and landings. Specific specifications for handrail and guardrail systems are defined in 1910.29.

Mezzanine Egress Requirements Under the IBC

The applicable requirements for stairs and egress routes installed on mezzanines vary depending on the IBC edition, building occupancy, occupant load, and floor level. While the IBC specifies general dimensional requirements for stair risers and treads, the number of egress routes is not determined uniformly by occupant load alone.

It is assessed by combining multiple factors, including occupancy classification, floor level, travel distance, and exit configuration. Therefore, simple assumptions like "Only 1 route is needed / 2 routes are required because the occupant load is X" cannot be made. It is a prerequisite to individually verify compliance against the applicable IBC edition and local jurisdiction codes.

Considerations for Mezzanine Width and Load Capacity

The stair width and load capacity of a mezzanine are items that must be individually designed and verified according to the application and installation environment. OSHA 1910.25 sets the minimum width for fixed stairs at 22 inches, but wider dimensions may be required for routes intended for material transport or simultaneous use by multiple people.

Regarding the structural strength of stairs, OSHA requires designs capable of supporting at least five times the normal anticipated live load, or a concentrated load of at least 1,000 pounds, whichever is greater. These items need to be verified separately from the floor load requirements of the mezzanine itself (based on the IBC and applicable building codes). It is important to perform structural calculations for both the stairs and platforms based on the intended use (storage, work, transit) and the weight of the loads.

Key Points for Guardrail Installation

For elevated mezzanines, installing compliant guardrails at openings and platform edges is essential to protect workers and visitors from accidents.

As a specific dimension, in facilities subject to OSHA standards, the top rail of a guardrail must be set at a height of "42 inches (approx. 107 cm) ± 3 inches above the walking-working surface."

Cases Where Multiple Egress Routes Are Required for Mezzanines

The number of egress routes from a mezzanine is not determined solely by the occupant load. It fluctuates based on a combination of multiple factors, such as building occupancy, floor level, travel distance, spatial configuration, and exit configuration.

Therefore, in facilities where the IBC applies, it is a prerequisite to individually identify the specific number of routes in accordance with the relevant edition and the building codes of the local jurisdiction.

If You Are Considering OSHA- and IBC-Compliant Mezzanine Stairs

When installing stairs on a mezzanine, safety requirements such as dimensions and guardrails are strictly regulated by OSHA and the IBC. Since the standards to be met change depending on conditions like building occupancy, users, and location, it is necessary to grasp these accurately.

Whether for new construction or renovation, the quickest way to ensure a smooth project is to consult with an experienced specialized manufacturer from the initial design stage. By organizing your facility's installation environment and receiving support, you can plan the optimal access equipment that strictly meets all requirements.