Stair Tread Depth vs. Stair Riser Height illustration

Safety with Every Step: Stair Tread Depth vs. Stair Riser Height

Rise and Run for Stairs

Following building codes specific to stairs is essential in any new construction or remodeling project to ensure safety for everyone. This article outlines stair code requirements to make it easy for builders to meet relevant regulations and safety standards.

Building Codes for Stair Tread Depth

The depth of a stair tread is the horizontal distance from the vertical planes of the foremost projection to adjacent stair treads, as seen from a 90-degree angle to the leading edge of a tread. It measures the available surface area for a person’s foot to rest when ascending or descending the stairway.

Stair Tread Depth vs. Stair Riser Height illustration
ComplianceStair DepthRiser Height
OSHA9.5″ (240 mm)
Minimum
9.5″ (240 mm)
Minimum
IBC11″ (279 mm)
Minimum
4″ (102 mm) – 7″ (178 mm)
Minimum – Maximum
IBC Occupancy Exceptions
Group R-2, R-3, and U
(see chart below)
10″ (254 mm)
Minimum
7-3/4″ (197 mm)
Maximum
Occupancy ClassificationGroup
Residential transient – occupancies containing sleeping units where the occupants are primarily transient. Structures like hotels, motels, and boarding housesR-1
Residential permanent – occupancies containing sleeping units or more than two dwelling units where the occupants are primarily permanentR-2
Residential group – occupancies where the occupants are primarily permanent and not classified as Group R-1, R-2R-3
Utility and Miscellaneous – General Buildings and structures of an accessory character and miscellaneous structures not classified in any specific occupancy shall be constructed, equipped, and maintained to conform to the requirements of this code commensurate with the fire and life hazard incidental to their occupancy.U

Standard Stair Tread Depth

The Industrial Building Code (IBC) and the Occupational Safety and Health Administration (OSHA) have varying tread depth specifications for various stair types. In its 2017 revision to the required walking-working surfaces, OSHA added minimum tread depths. On the other hand, IBC has long mandated a minimum tread depth.

OSHA and IBC use research on stairways with varying tread and riser dimensions to determine the minimum tread depths and maximum riser heights.

According to OSHA, a standard stair refers to any fixed or permanent stairway aside from alternating tread stairs, ship stairs, or spiral stairs. Standard stairs must, at minimum, maintain a tread depth of 9.5 inches, or 24 cm, under OSHA 1910.25(c)(3).

IBC 1011.5.2, on the other hand, stipulates that stair treads must be at least 11 inches (27.94 cm) deep, measured horizontally between the vertical planes of the foremost projection of consecutive treads and perpendicular to the leading edge of the treads.

The minimum tread depth must be 10 inches in all group R-3 occupancies, all dwelling units in R-2 occupancies, and all group U occupancies supplementary to either group R-3 occupancies or individual dwelling units in R-2 occupancies. Most multi-family dwellings intended to get occupied permanently must adhere to the standard of a minimum tread depth of 10 inches (25.4 cm).


Building Codes for Stair Riser Height

The upright (vertical) or inclined element of a stair that gets positioned at the rear of a stair tread or platform and links near the front edge of the next higher tread, platform, or landing is referred to as the stair riser height.

Standard Stair Riser Height

Depending on the type of stairway, OSHA and IBC also have varying maximum stair riser height regulations.

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Standard stairs must have a maximum riser height of 9.5 inches (24 cm) following OSHA 1910.25(c)(2). IBC 1011.5.2 stipulates that the minimum and maximum stair riser heights must be 4 inches (10.16 cm) and 7 inches (17.78 cm), respectively.

In groups R-3, R-2, and U auxiliary occupancies, the maximum riser height is 7-3/4 inches.

Conclusion

The purpose of building codes for metal stairs is to ensure the safety of everyone who uses them. Any safety risk will significantly decrease if all steps and stairs have the same tread depth and riser height parameters.

For more than 13 years, Upside Innovations has been creating modular metal stairs and platforms. When it comes to design and innovation for a variety of prefabricated metal stair kits as well as custom solutions, Upside Innovations is unmatched in the industry.

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Continuing Education – Efficiencies with Prefabricated Stairs, Access Platforms & Ramps

UPSIDE’S Continuing Education

Step It Up: Increased Efficiency with Prefabricated Modular Stairs, Access Systems, & Ramps

Does your project need to step it up when it comes to stairs and safety? Our CE course discusses prefabricated modular metal stairs, access platforms, and ramps that are as easy to reconfigure as they are to assemble. Participants will not only learn about relevant codes from OSHA, IBC, and ADA regarding stairs, ladders, and handrails, but they will also learn how to specify modular stair components and configurations to best facilitate code compliance and increase site productivity.

Learning Objectives: 

  1. Compare and contrast conventional stairs versus modular stairs and access systems as they relate to efficiency, sustainability, and productivity.
  2. Determine which modular stair components and configurations will best suit your application for improved flexibility now and in the future.
  3. Identify relevant and updated codes from OSHA, IBC, and ADA regarding stairs, ladders, handrails, and ramps and discuss how modular stair and access systems can help facilitate code compliance.
  4. Illustrate the cost- and time-efficiency possible through the utilization of modular stairs and access systems by analyzing case studies.

Design Category (CSI Division): (05) Metals

means of egress parts

Means of Egress

Estimated reading time: 3 minutes

The means of egress requirements are part of the International Building Code (IBC) which refer to the ability to exit the building and the path to get outside. Every new building must have means of egress, but the number of means of egress paths and sizes differ from building to building.


What is means of egress?

A means of egress is a continuous, clear path from any occupied portion of a building, structure or space to a public way, such as an outdoor sidewalk. A means of egress consists of three parts: exit access, exit, and exit discharge.


Means of egress

A means of egress consists of three parts:

  1. The exit access – path within the building that leads to an exit
  2. The exit – doors to the outside, enclosed exit stairways, and horizontal exits
  3. The exit discharge – the route from the exit to the public way

Are you looking for an IBC-compliant stairway?

Part 1: Exit Access

Exit access is defined as a corridor, hallway, or path in a room to an exit. When the IBC talks about “accessible,” it means that somebody in a wheelchair can use whatever thing they are referring to. Therefore, an “accessible space” means that a person in a wheelchair can enter and exit that space via an “accessible means of egress” (i.e. walkway, ramp, or elevator).

Accessible spaces must have two accessible means of egress, and they are typically required to be no less than 36″ wide.

For Non-accessible spaces, which are floors above or below the ground floor, the accessible pathway must lead to an exit stairway, elevator, or horizontal exit. These areas serve as an Area of Refuge where emergency responders will come to help people in wheelchairs.

The required number of means of egress is determined by occupant load:

Occupant LoadRequired Means of Egress
<5002
500-9993
>1,0004
*Exception: Buildings that have a low occupant load, such as mercantile spaces, only require one exit.

Part 2: Exit

The exit consists of an exit stairway or elevator with standby power. The exit is separated from other interior spaces by fire-resistant construction. Refer to the IBC stair and handrail specifications sheet and the refuge areas to ensure your means of egress are compliant.

Part 3: Exit Discharge

The exit discharge consists of either an accessible route, such as an ADA ramp or walkway, or a stair and platform with a refuge area. Can be inside the building such as the main lobby or outside to an egress court, courtyard, alley, or public way. A public way is defined as an area outside the building between the exit discharge and a public street with a minimum clearance height and width of at least 10 feet.


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