Building owners and facility managers frequently ask questions when adding or replacing stairs in their facilities about compliance to code. Before you decide on which code to comply with, it’s important to understand their differences.
The IBC (International Building Code) and OSHA (Occupational Safety and Health Administration) regulate stair safety requirements (depending on usage) in the United States. Typically, IBC sets the standard for stairs used by the public, including stairways that connect a building to a public space. OSHA, on the other hand, regulates stairways found in working environments or areas inaccessible to the public, such as those found in factories and warehouses. OSHA also shapes some of their regulations to the type of person you would expect to find on a set of stairs. For example, a mechanic carrying heavy hand or power tools is more likely found in an OSHA-regulated facility. Both codes set the minimum standards for sizes, shapes and features for stairs to ensure that they are appropriate and safe for their functional use.
While significant differences exist between the two standards, broadly speaking, the two do share some similarities:
- Uniformity: The riser and tread depths should be of uniform shape and size according to both IBC and OSHA
- Slope of stairs: Stair measurements take place at the horizontal angle and vary from 50 to 70 degrees
- Watch your head: Headroom on any stair should be 80 inches according to both codes
Can you imagine trying to walk up or down steps that are shaped differently with each step? What if you had to worry about hitting your head with each step? Both organizations tame that problem.
So, what’s different? Let’s look at a contrast below:
Let’s first make sure everyone understands the terms used in stair codes. Balusters are the vertical bars that attach to a handrail on a staircase. They work a bit like a fence to prevent people or objects from falling off the staircase. They ensure the safety of the person walking on the stairs and the person who might be walking beneath (or adjacent to) the stairs. That said, let’s go over some of the similarities and differences between OSHA and IBC when it comes to balusters.
- OSHA requires balusters to be no more than 19 inches apart [1910.29 (b)(2)(iv)]
- IBC requires balusters to be no more than 4 inches apart [IBC 1011.13]
- OSHA also requires that all mid-rails, balusters or any intermediate vertical can withstand a total force of 150 pounds coming from any downward or outward direction. [OSHA 1910.29 (b)(5)] The IBC remains silent on this issue
Comparison of OSHA and IBC baluster requirements.
Since OSHA stairs support factory and construction worksites, the stairs must be built stronger. This allows them to protect against the weight of the person on the stairs, plus the weight of tools, materials or equipment being carried on them.
The IBC’s focus on the public sphere drives the large differences between the OSHA and IBC baluster spacing (4" vs 19"), meaning that these codes apply to stairs that everyday people use, including children. Can you imagine how easy it would be for a child to slip through the balusters on a staircase built by OSHA codes?
Riser Heights and Tread Depths
First, let’s define what we mean by riser heights and tread depths. The riser height is essentially the height of the stair. It’s the vertical distance between the tread, or walking surface, of one stair to another. The riser itself is the vertical kickplate connecting each tread. The tread depth, on the other hand, is the horizontal walking surface of each stair. Tread depth is also known as the stair run.
Illustration showing riser height and tread depth areas of measurement.
So what do the requirements look like?
- OSHA makes provision for a maximum riser height of 9.5 inches with no minimum requirement [OSHA 1910.25 (c)(2)]
- IBC allows for a maximum riser height of 7 and ¾ inches with a 4-inch minimum requirement [IBC 1011.5.2]
- OSHA requires a minimum tread depth of 9.5 inches [OSHA 1910.25 (c)(3)]
- IBC requires a minimum tread depth of 11 inches [IBC 1011.5.2]
- IBC also requires that risers are solid, whereas OSHA is silent on this provision [IBC 1011.5.5]
Comparison of OSHA and IBC riser height and tread depth requirements.
The difference in riser height (9.5" vs 7") makes OSHA stairs to be a little harder to climb when compared to IBC stairs. A person climbing must lift their weight up by an additional 2.5” for each step. While this makes an OSHA stair steeper, they end up taking up less floor space in a facility because they achieve the needed climb with fewer steps and thus, less horizontal run.
OSHA compliant stairs are steeper to climb, but take up less floor space.
The extra 1.5 inches in tread depth on an IBC stair provides more room for error when stepping down. This IBC provision is important for staircases used by the everyday population. The extra spacing also makes the slope significantly gentler, making staircases safer for everyone.
The IBC requirement that a riser be “solid” (not required by OSHA) means that each stair tread be connected by a riser that essentially won’t allow someone’s foot to “kick” under the next vertical tread. This might prevent a person from catching their foot underneath a stair tread as they ascend a stair. IBC provides a few exceptions to this rule, notably if stairs aren’t considered an “accessible means of egress.”
Stair Width and Ramp Clearance Differences
Again, let’s review what we mean by stair width and ramp clearances. The stair width is simply the width of the stair or walking space of the stair. IBC dictates different stair widths depending on “means of egress” calculations using occupancy, but they do specify certain minimums. Ramp clearance, on the other hand, is the excess spacing at the top of a staircase where a door opens out onto a landing. Ramp clearance requirements let the builder know how far out a door can swing before the landing area would become unsafe.
Comparison of OSHA and IBC ramp clearance requirements.
Now let’s look at the requirements.
- IBC stairways “between stories” of the building require a clear width of 48 inches between handrails [IBC 1011.2]. However, IBC stairways accommodating fewer than 50 people must measure at least 36 inches wide [IBC 1011.2.1]
- OSHA requires stair landings to be at least the width of the stair and at least 30 inches in depth, measured in the direction of travel [OSHA 1910.25 (b)(4)]
- IBC requires the same width as OSHA. However, it requires that the stair landings be at least the width of the stair or 48 inches, whichever is less. [IBC 1011.6]
- According to OSHA, when a door or gate opens onto a landing it cannot reduce the usable depth of the landing to less than 20 inches for platforms installed before 1/17/2017 and 22 inches for platforms installed on or after 1/17/2017 [OSHA 1910.25 (b)(5)]
- IBC requires that doors or gates do not project more than 7 inches onto the platform, and cannot reduce the landing to less than half its width [IBC 1011.6]
- IBC requires a stair landing for every 12 feet of rise [IBC 1011.8]
IBC requires a stair landing for every 12 feet of rise.
Stair landings tend to be ignored or forgotten when installing stairs. These definitions prevent doors (as they open) from pushing people or objects off a landing. They also provide safety on the “last step” as people exit to the walking surface below. A common mistake is to ignore the rise of the last step to the walking surface, especially when mounting a stair outdoors to uneven ground or perhaps ground covered in shale or rocks. That creates a scenario where the last step “is a doozy.” There are many great reasons why both OSHA and IBC set standards for the area to be stepped to and the “uniformity” requirements in rise and run.
IBC tends to have more requirements as well as exceptions that OSHA does not make provision for, such as exceptions for “Group R-3” stairways (Group R-3 refers to stairways located in single-family homes and duplexes). Some examples of extra requirements for stairways built according to IBC include the stairway not rising vertically more than 12 feet without a landing in between or walking surfaces not sloping more than 2%.
OSHA, because it governs private spaces, lists fewer requirements overall, as well as fewer exceptions to those requirements.
One implied takeaway: greater regulation leads to greater cost. Compliance with IBC codes will cost more than compliance with OSHA codes, simply due to added material costs. Here are a few examples:
- IBC requires more stairway landings, and larger ones, than OSHA codes
- IBC baluster spacing requirements will drive the need for more balusters
- The rise and run in IBC stairs will utilize more space and use more material than OSHA stairs and consume more floor space in a facility
That said, cost considerations should not be the primary driver when safety is involved, but everyone has a budget and a responsibility to the people in their facility at the same time.
In the end, the difference between building a staircase according to OSHA requirements versus IBC requirements is the difference between an unsafe or safe stairway for the public. It’s important that each staircase is built according to the correct standards for the environment, be it in a house, a factory, or an outdoor public space.
This summarizes the similarities and differences of stair requirements. Both IBC and OSHA put these requirements in place to maintain safety standards in the workplace and in public spaces. For more information regarding stair requirements please reach out to Banks Industrial at 856.687.2227.