In the A/E design community, the term "open stair" is frequently used to describe a stair that is not enclosed with walls, partitions or barriers. While "open stair" is not a term used in the International Building Code, it generally aligns with a stairway (which is a defined term in the IBC) not used for egress purposes or an exit access stairway (also a defined term). The terms "communicating stair" and "convenience stair" are also used in the same line of discussion, though depending on the situation, these could be referring to communicating spaces or convenience openings, both types of vertical openings defined in NFPA 101.

In this post, we'll review the IBC requirements for open stairs and describe several code paths that can be used to provide open stairs in your design. I will use the term "open stair" throughout the post, but remember, since this is not a defined term, any formal documentation on drawings, plans etc. should use the proper nomenclature identified in this overview. This post will be limited to stairs within a building and will not address exterior stairways.

Stairway Connecting Levels within a Story
The first and most simple type of open stair connects one or more levels within a single story. This stair could be provided to access a raised floor area or a mezzanine, or to access areas on a story that are at different elevations due to a sloping site.

​If the open stair is not used as part of the means of egress, the IBC would view it as simply a "stairway." If it is on the path of egress, it then becomes an exit access stairway. In either case, since this type of stair does not connect multiple stories, there is no code requirement to enclose the stairway or provide a rated separation (IBC 1019.2).

One other important point for this type of open stair is the requirement for accessible means of egress (IBC 1009). An exit access stair connecting levels on the same story is not permitted to be part of an accessible means of egress, unless the stair is providing the means of egress from a mezzanine (IBC 1009.3.1). If you are not sure how to address required vs. accessible means of egress requirements, check out this post for more details.

Stairway Connecting Two Stories
If your open stair does connect two stories, a few additional requirements are triggered. First, IBC 712.1.9 gives a number of requirements for vertical two-story openings. These include:

• Does not penetrate a horizontal assembly separating a fire area or smoke compartment
• Is not concealed within a wall, floor or ceiling assembly
• Is not open to a Group I or R corridor
• Is not open to any corridor on a nonsprinklered floor
• Is separated from openings serving other floors by construction conforming to required shafts

​If your open stair is part of the means of egress (exit access stairway), IBC 1019.3 gives similar requirements. Note that open stairs connecting two stories are not permitted in Group I-2 and I-3 occupancies.

Stairway Connecting Three or More Stories
If your open stair connects three or more stories, the most common approach is to use a draft curtain and closely spaced sprinklers per IBC 1019.3.4. Use of this provision requires the following:

• The building must be fully sprinkler-protected in accordance with NFPA 13
• The area of the vertical opening must not exceed twice the horizontal projected area of the stairway
• The opening must be protected with a draft curtain and sprinklers per NFPA 13

​In Group B and M occupancies, there is no limit to the number of stories that can be connected with this approach. In all other occupancies, this is limited to four connected stories, except Groups I-2 and I-3, where it is not permitted at all.

Open Stairs in Group R Occupancies
In Group R-1, R-2 and R-3 occupancies, open stairs up to four stories are permitted if they are contained within a single dwelling unit, sleeping unit or live/work unit.

Open stairs are also permitted in Group R-3 congregate living facilities and Group R-4 occupancies.

​Open Stairs within an Atrium
If located within an atrium, open stairs are permitted with no limit to the number of stories connected. Keep in mind that atriums have a host of additional requirements in the code, such as smoke control and rated separation from other building spaces.  Open stairs in an atrium are permitted to serve as exit access stairways, though the travel distance when using such stairs is limited to 200 feet (IBC 404.9.3).

​Other Situations
There are a few other situations where the code allows open stairs without any rated enclosure or separation:

• In open parking garages where the stair serves only the parking garage
• In smoke-protected or open-air assembly seating areas complying with IBC 1029.7
• In theaters, auditoriums and sports facilities, open stairs connecting balconies, galleries or press boxes to the main assembly floor
• Stairs within mall buildings complying with IBC 402

There are many cases where the IBC allows open stairs. When open stairs are used as part of the means of egress for a building, they are considered "exit access stairways." Otherwise, they would fall under the "stairway" definition in the code. If your project is required to comply with NFPA 101, be sure to check out Chapter 8, which has more stringent requirements for vertical openings than the IBC.

It's been a full summer here on my end, at least in one sense. While the pandemic has forced vacation cancellations and generally fewer social gatherings, work has been full steam ahead for the past few months. I've also been working on a weekly basis to help PE Roadmap clients as they study for the Fire Protection PE exam this fall. As we get towards the last remaining months before the October exam, I am looking forward to some more regular posts on the blog, which I anticipate to be a mixture of life safety tools, cheat sheets and code questions.

On another front, I've also had some recent conversations with Joe Meyer over at MeyerFire regarding our Code Calls initiative. While we are still soliciting feedback from Indiana AHJs regarding their local requirements, we are also looking for some ways to further jump start our progress. One of these is putting together a database that provides a link to State/City/County/Municipality local amendments, as well as the link to that jurisdiction's website where you can find contact information. Similar to the main Code Calls database, we are starting in Indiana and hoping to branch out from there. More on that in the coming months.

On a recent project, an architect I am working with received a comment stating that openings in stairways are only permitted from normally occupied spaces. I have come across this requirement before, which originates from IBC 1023.4.

While I am quite familiar with this requirement, the fact that it was brought up in this particular situation was shocking. That's because the floor in question, a basement, was designed with two exit stairs and an enclosed corridor running the length of the building and connecting the stairs. I've sketched up a simplified version of the layout below. The plan review comments indicated that the openings into the stairs were from not-normally occupied spaces and did not comply with IBC 1023.4.

If either of the stairs opened up directly into the mechanical, electrical or storage rooms, this comment would make sense to me. However, the openings into both stairs are from the corridor, which I have always considered normally occupied space. In fact, the IBC actually requires rated corridors to continue to an exit (IBC 1020.6). While the corridors in this design are not currently rated, if the code requires corridors continuity to an exit in certain situations, how could a corridor be considered not-normally occupied here?

Upon a followup conversation with the plan reviewer, the local jurisdiction has taken the position that because all of the rooms (mechanical, electrical and storage) on the floor are considered not-normally occupied, the corridor serving those rooms should be treated the same. The reviewer also cited concern that corridor could be used for storage and result in potential fire spread into the stair.

When I brought up potential solutions, it seems that rating the corridor (or providing a rated stair vestibule) would satisfy the jurisdictions concerns.

I would love to hear your thoughts on this situation. Should this corridor be considered not normally occupied? Does this design meet the intent of IBC 1023.4? Let me know in the comments section!

I'm currently working on a large, multi-family apartment building that includes several-hundred dwelling units. The building is four stories tall and each story has multiple exits. The building is divided up by several fire walls for allowable area purposes, so the exits are a combination of exit stairs and horizontal exits.

​In a recent discussion, the AHJ indicated that he thought Emergency Escape and Rescue Openings complying with IBC 1030 were required for each bedroom in the building. On past projects, I have not seen this required in buildings where each story has two or more exits, so I decided to do a deep dive into the code requirements.

This project is under the 2015 IBC, but I have also included the 2018 language below, as this seems to further clarify the requirements.

In the 2015 language, the first sentence seems to indicate that for a Group R-2 occupancies, the emergency escape requirements apply when triggered by Table 1006.3.2(1) or 1006.3.2(2). As I described in a recent cheat sheet for single exits, these tables are allowances for having a single exit or access to a single exit from a story. In this case, every story has multiple exits, so the provisions of these tables do not apply. The 2018 IBC makes this even clearer.

The AHJ on this project is pointing to the second sentence from the 2015 IBC 1030.1, stating that all sleeping rooms below the fourth story require the openings. The second paragraph from the 2018 IBC has similar language.

In my opinion, the first sentence of IBC 1030.1 essentially functions as scoping language for the rest of the requirements. Since this project does not meet the conditions described in this scoping sentence, the rest of the requirements do not apply and the openings are not required.

In a Group R-2 building where each story has multiple exits, are emergency escape and rescue openings required?

Let me know your thoughts in the comment box!

​For years, architect clients have asked me for solutions to mitigate a dead end corridor condition. As a quick reference, dead ends are limited to 20 feet, except in Groups B, E, F, I-1, M, R-1, R-2, R-4, S and U with a full NFPA 13 sprinkler system, where the limit is increased to 50 feet (2015 IBC 1020.4).

But on a recent project, a local AHJ has taken the stance that a cross corridor door does not mitigate a dead end condition. I scheduled a meeting with the AHJ to explain how this has been done on other projects and to share the ICC interpretation, but they were reluctant to budge. After some negotiations, the AHJ allowed the door, but insisted that it not be held open and also required a large "Not an Exit" sign on the door itself.

I have drawn up a similar situation in the image below. The corridor is serving a Group A occupancy, so the dead end limit is 20 feet. The added door is shown in red.

Do cross-corridor doors mitigate the 20 foot dead end limit? Do you think they should be permitted to be held open?
Let me know your thoughts in the comment box!

Yet in certain locations, the crowds of people are growing.

For example, cities across the US are seeing a rise in temporary emergency shelters. Many hospitals are expanding with new temporary patient sleeping areas, and homeless shelters are expanding to arenas, convention centers and other large facilities to accommodate a drastic increase in occupants. In Alaska, one homeless shelter has taken over a sports arena and is housing double the number of people originally expected. In Arizona, one homeless shelter has moved to a head-to-toe sleeping mat arrangement to allow for some level of social distancing while still accommodating as many people as possible. You can find similar stories across the country. 

So what does this mean for calculating occupant loads? 

In the long term, it's impossible to say for sure. Things could very well go back to normal once the pandemic ends, leaving the nature of occupant loading strategies unaffected. But on the other hand, does COVID-19 change how we work and gather as a society? Will there be a sharp increase in the number of employees working from home when this is all over? Or separately, does the pandemic go on for quite some time such that we have to asses things differently as new buildings are designed in the coming months or years?

With the current CDC guidelines, the recommendation for social distancing involves maintaining 6 feet of separation from other individuals. Six feet of separation in both direction results in each occupant of a building taking up 36 square feet of space. 

So how might this impact an occupant load calculation?

Here's one example: a 750 square foot conference room with tables and chairs would normally be assigned an occupant load of 50 (using a factor of 15 square feet per occupant), but following the CDC guidelines, no more than 20 occupants should be in the room.

Another example is a 500 square foot classroom, which would normally be assigned an occupant load of 25 (using a factor of 20 square feet per occupant). But following the CDC guidelines, no more than 13 occupants should be in the room.

As long as the CDC guidance and government direction is in place, any gatherings or meetings that are still occurring will likely be smaller and less dense than normal. And with most schools around the US canceled and many meetings moving to a virtual format, there's a good change that many conference rooms and classrooms are vacated completely.

But what about locations where the crowds are increasing?

Let's take the temporary emergency shelter as an example.

As more and more people are impacted by COVID-19 and the demand for emergency shelters increases, staff members of these locations are already facing the growing tension of trying to accommodate more people while still maintaining some level of social distancing.

During Hurricane Katrina in 2005, the field of the Superdome in New Orleans was converted to an emergency shelter for displaced local residents. As you can see from the image below, the field was densely packed with sleeping cots. For families, cots were pushed together with no space in between and each group of cots was only 1-2 feet away from the next group.

​Now compare this to a recent photo from a temporary emergency shelter in Alaska, where there is at least 6 feet of space between each sleeping cot.

Assuming the pandemic continues and the number of people forced into shelters grows, the challenge of this tension will also grow. With a limited amount of space and resources, is it better to limit the occupant load in order to maintain social distancing? Or should shelters attempt to help more people at the expense of housing people closer together?

The world is facing an unprecedented situation in the current COVID-19 pandemic. In the short term, major cities are seeing a complete desertion of many offices, public spaces and streets. Yet emergency facilities such as hospitals and shelters are seeing a sharp increase in occupants.

For life safety consultants like me, this raises the question: how does this impact occupant load strategies?

While I'm hopeful that the pandemic ends soon and life returns to normal, I also have a small inkling that COVID-19 will have some change on how we work and gather as a society in the future. Maybe it will be an increase in the number of people working from home. Perhaps large public gatherings look different in the future. At this point, it's impossible to say for sure.

What are your thoughts? Have you seen occupant loads change drastically in your community? Do you expect the pandemic to change how we gather together in the future? Please share your thoughts in the comments section!

​

All definitions and requirements are from the 2015 International Building Code (IBC). Note that the IBC does not always include the word “required” when referring to a means of egress. Generally, when the code references either “required means of egress” or “means of egress,” it’s referring to the first definition below. The IBC always uses the full term “accessible means of egress” when referring to the second definition.

Definitions (IBC 202):
Means of Egress: “A continuous and unobstructed path of vertical and horizontal egress travel from any occupied portion of a building or structure to a public way. A means of egress consists of three separate and distinct parts: the exit access, the exit and the exit discharge.”

Accessible Means of Egress: “A continuous and unobstructed way of egress travel from any accessible point in a building or facility to a public way.”

From these definitions, notice that both involve “a continuous and unobstructed…” path or way of egress, and that both will lead you “…to a public way.” But the definitions differ in starting point. For a means of egress, the starting point is “from any occupied portion of a building or structure,” whereas for an accessible means of egress, the starting point is “an accessible point in a building or facility.”

So simply from these definitions, we can gather an important distinction: an accessible means of egress only originates from an accessible point in a building or facility. If a building or portion of a building is not required to be accessible, it is not required to have an accessible means of egress (IBC 1009.1).

Means of Egress Components
A required means of egress consists of 3 distinct components: the exit access, the exit and the exit discharge.

*serving levels other than the level of exit discharge
**serving exits at the level of exit discharge

You’ll notice that some of these components can also be part of a required means of egress – interior and exterior exit stairways, exit access stairways and ramps. But an accessible means of egress can include specific components for occupants who need accessible accommodations, such as elevators, lifts and exterior areas for rescue assistance, that are not part of the required means of egress.

Another important component is the accessible route, which is always required as part of an accessible means of egress. Since all portions of a building that are accessible require both an accessible route an accessible means of egress, you can’t provide one without the other. An accessible route could also be part of the required means of egress, but it’s not necessarily required.

Key Differences
Unlike the required means of egress, elevators can be used as a part of an accessible means of egress. And for buildings with an accessible floor located four or more stories above the level of exit discharge, at least one elevator is required as part of the accessible means of egress (IBC 1009.2.1).

Another important distinction exists for exit access stairs, which are permitted as part of the required means of egress and in certain cases as part of an accessible means of egress. However, exit access stairs that connect levels in the same story are not permitted as part of an accessible means of egress (IBC 1009.3). This means that stairs connecting levels within a single story, even if a just single step, are not considered part of an accessible means of egress.

Accessible Means of Egress: Where Required
The criteria for where an accessible means of egress is required are simple. Any accessible space within a building requires at least one accessible means of egress. Where two or more means of egress are required for any space, at least two accessible means of egress are required for that space (IBC 1009.1). There are several exceptions for existing buildings, mezzanines and assembly areas with seating areas served by aisles.
​
There is no code requirement for more than two accessible means of egress to serve any space.

Required Means of Egress: Where Required
The number of means of egress required from any space is governed by one of the following sections:

1006.2. If the number of occupants in a room or space or the common path of egress travel exceeds the value listed in Table 1006.2.1, two means of egress are required.

1006.3. Generally, all stories require at least two means of egress. If the story contains more than 500 occupants, the requirements increases to 3 means of egress, and increases again to a minimum of 4 when the story has an occupant load of more than 1,000.

The above code sections contain numerous exceptions, so be sure to review for your specific situation.