Key Takeaway: Winder stairs are generally limited to dwelling units or very small spaces, unless the stair can meet the more restrictive requirements for curved stairways.
Winder stairs, or specifically, winder treads, are a unique architectural feature that an architect or engineer can use when designing a stairway. The International Building Code (IBC) has several limitations on the use of winder treads through, restricting the situations where they can be used. In this post, we are going to explore the code requirements for winder treads to determine how they need to be designed and where they can be used. All references are to the 2021 IBC. If you are working on a one or two family dwelling, a separate set of requirements from the International Residential Code (IRC) likely applies.
What is a Winder Stair?
A winder stair is a stair consisting of winder treads. A winder tread is defined in the IBC as “a tread with nonparallel edges.”
In a traditional stair, the opposite edges of each tread are parallel, meaning the tread is rectangular in shape. In a winder stair, the opposite edges are not not parallel, so the tread forms a trapezoidal shape.
Winder Tread Requirements (IBC 1011.5.2)
Winder treads are required to have a minimum depth of 11 inches, measured at the walkline. IBC 1011.4 defines the walkline as the line located 12 inches from the side of the tread where the winders are narrower. Additionally, the winder tread is required to have a minimum depth of 10 inches anywhere within the clear width of the stair, including inside of the walkine.
Similar to regular stairs, the maximum riser height for a winder stair is 7 inches.
There are several exceptions to the above requirements:
In Group R-2 dwelling units and Group R-2 occupancies, the minimum winder tread depth at the walkline is reduced to 10 inches and minimum winder tread depth anywhere in the clear width is reduced to 6 inches. Riser heights in this situation are permitted to be a maximum of 7.75 inches.
In spiral stairways, the minimum winder tread depth at the walking is reduced to 6.75 inches at the walkline. The maximum riser height is 9.5 inches and the minimum clear width is 26 inches for spiral stairs.
And finally, curved stairways must comply with the IBC 1011.5.2 requirements, plus the inner radius of the stair must be at least twice the required width of the stair itself.
Where are Winder Treads Permitted (IBC 1011.5.3)?
For projects under the IBC, there are limited situations where winder treads can be provided. Generally, winder treads cannot be used as part of a required egress stairway, except when located within a dwelling unit.
There are two exceptions: curved stairways and spiral stairways.
Curved stairways can be used anywhere in a building, but many designers will not choose this option due to the large required radius of the stair.
Spiral stairways can only be used in the following situations:
Winder stairs are generally limited to dwelling units or very small spaces, unless the stair can meet the more restrictive requirements for curved stairways.
When provided, winder treads must be a minimum of 11 inches in depth at the walkline and 10 inches in depth inside the walkline, with some reductions in depth for dwelling units and spiral stairs.
Key Takeaway: The IRC and IBC both provide a variety of requirements for stairways and staircases, including minimum width, minimum and maximum riser/tread dimensions, minimum headroom height and maximum total rise.
A stairway is a key part of the means of egress for any multi-story building or structure. Also known as a stair or staircase, stairways provide a path for occupants to traverse from one level to another within a building or space. In this post, we’ll review some of the key requirements for stairways from both the International Residential Code (IRC) and the The International Building Code (IBC). All references are to the 2021 editions of these codes.
What is a Stairway?
There are two key definitions here that are important to understand: Stair and Stairway. Both the IRC and IBC defines these terms as follows:
Stair: “A change in elevation, consisting of one or more risers.”
Stairway: “One or more flights of stairs, either exterior or interior, with the necessary landings and platforms connecting them, to form a continuous and uninterrupted passage from one level to another.”
So a stair is simply the change in elevation that is created by one or more risers, while a stairway includes both the stairs and the required landing and platforms. Note that the term “staircase” is frequently used when referring to a stairway, but neither code actually uses this term. If you are working on a project that contains an unenclosed stairway (also known as an open stairway), be sure to check out this post on additional requirements.
Minimum Width for IRC Stairways (R311.7)
For projects falling under the IRC, the minimum stair width is 36 inches. The minimum width must be provided at all points above the permitted handrail height and below the required headroom height (meaning walls or other protruding objects cannot decrease this minimum width).
Any provided handrails cannot protrude more than 4.5 inches into the minimum width. So if a handrail is provided on one side, the minimum clear width is 31.5 inches and if a handrail is provided on both sides, the minimum clear width is 27 inches.
Note that the following stairways are not required to meet the minimum width requirements:
Minimum Width for IBC Stairways (1011.2)
For projects falling under the IBC, there are two width requirements that apply: minimum width and required capacity.
Generally, the minimum stair width is 44 inches, unless the stairway serves an occupant load of less than 50, in which case the minimum width is 36 inches. Note that if the stairway is serving as an accessible means of egress, the minimum width between handrails is 48 inches, unless the building is fully sprinkler-protected or the stairway is provided with an area of refuge. Check out this article for more information on the required means of egress vs. accessible means of egress.
Note that the following stairways are not required to meet the minimum width requirements:
The second width requirement is the required egress capacity of the stairway (IBC 1005.3.1). The required capacity is determined by multiplying the occupant load using the stairway by a capacity factor of 0.3 inches per occupant. In other than Group H and Group I-2 occupancies, this factor is reduced to 0.2 inches per occupant when the building is fully sprinkler-protected and equipped with a voice fire alarm system. There are also reductions available for open-air or smoke-protected assembly seating spaces.
Note that for multi-story buildings, only the occupant load of each individual story is considered when calculating the required capacity for each stair, not the cumulative occupant load using the stair.
Similar to the IRC, the IBC allows handrails to project a maximum of 4.5 inches into the required width. So for a stair with handrails on each side that has a minimum required width of 44 inches, the minimum width between handrails would be 35 inches.
In both the IRC and IBC, handrails are required to be located a minimum of 34 inches and a maximum of 38 inches above the stair. Specifically, this dimension is measured vertically from the stair tread nosing.
Note that when handrails are transitioning between flights or at the start of a stairway, the fitting and bendings are permitted to exceed the maximum height.
Stair Treads and Risers (R311.7.5)
For projects falling under the IRC, the minimum tread depth is 10 inches, plus a required nosing of at least ¾ inch. If a tread of at least 11 inches is provided, there is no required nosing. The maximum permitted nosing is 1.25 inches. In any stairway, the tread depth and nosing depth have a maximum permitted variation of ⅜ inch. Note that under the IRC, the tread depth is measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's leading edge.
The maximum riser height is 7.75 inches, with a similar maximum permitted variation of ⅜ inch in any single stairway. Risers must be vertical or have a maximum slope of 30 degrees from vertical.
Stair Treads and Risers (1011.5.2)
For projects falling under the IBC, the minimum tread depth is 11 inches. There is no requirement to provide a nosing, but the maximum nosing projection is 1.25 inches. Note that under the IBC, the tread depth is measured horizontally between the vertical planes of the foremost projection of adjacent treads and at a right angle to the tread's nosing.
The IBC requires stairs to have a minimum riser height of 4 inches and a maximum height of 7 inches.
Note that the following stairways are not required to meet the minimum riser/tread requirements:
Both the IRC and IBC have similar requirements for headroom clearance. In both codes, the minimum headroom clearance is 80 inches, measured vertically from a line connected to the edge of each nosing.
Both codes have exceptions for spiral stairways and where the nosings of treads at the side of a flight extend under the edge of a floor opening through which the stair passes (limited to Group R-2 dwelling units and Group R-3 in the IBC).
Vertical Stairway Rise
Under the IRC, a single flight of stairs can have a maximum vertical rise of 12 feet 7 inches between floor levels or landings (R311.7.3). Under the IBC,the maximum rise is 12 feet (1011.8).
The requirements for stairways depend on whether your project falls under the IRC or IBC.
For IRC Stairways:
Minimum Width = 36”
Maximum Handrail Projection = 4.5” each side
Minimum Tread Depth = 10”
Minimum Nosing = ¾” or provide 11” tread
Maximum Nosing = 1.25”
Maximum Riser Height = 7.75”
Minimum Headroom = 6’-8”
Maximum Stairway Rise = 12’-7”
For IBC Stairways:
Minimum Width = 44” or 36” for smaller occupant loads. See also required capacity requirements.
Maximum Handrail Projection = 4.5” each side
Minimum Tread Depth = 11”
Minimum Nosing = Not Required
Maximum Nosing = 1.25”
Minimum Riser Height = 4”
Maximum Riser Height = 7”
Minimum Headroom = 6’-8”
Maximum Stairway Rise = 12’
Key Takeaway: Egress windows are required in all sleeping rooms for projects falling under the IRC and in many sleeping rooms for projects falling under the IBC. When required, the openings must meet specific egress window sizing requirements, and when provided below grade, must open into an area well.
If you are working on a residential design or construction project, an important design consideration is the requirement for egress windows. While most people in the design community understand what you are referring to with this term, “egress windows” is not actually defined in the code. The International Building Code (IBC) and International Residential Code (IRC) both refer instead to Emergency Escape and Rescue Openings (EEROs).
In this article, we’ll refer to egress windows and EEROs interchangeably, but remember that the code only defines EEROs. A window can be used to meet the EERO requirements, but doors and other openings are also an option. All references are to the 2021 IBC and IRC.
What is an Egress Window?
Egress Windows, or as the code calls them, EEROs, are defined in the IBC as “an operable exterior window, door or other similar device that provides for a means of escape and access for rescue in the event of an emergency.
Essentially, an egress window or EERO is a way for a building occupant to escape in the event of an emergency or for a first responder or other personnel to access a building for the purposes of rescue. A fire is the obvious emergency that comes to mind, but the openings could be used for any emergency situation.
When are Egress Windows Required?
If you are working on a residential project in the United States, your building likely falls under one of two codes: the International Building Code or the International Residential Code. While the adoption of these codes varies by State and local jurisdiction, generally the IBC applies to apartments and larger residential facilities while the IRC applies to one and two family dwellings and townhouses. Many jurisdictions amend these codes, so be sure to check the applicable code enforced by your local authority having jurisdiction.
If your project falls under the IBC, emergency escape and rescue openings are required in the following occupancies (IBC 1031.2):
If you meet either of these conditions, then the IBC requires you to provide emergency escape and rescue openings in any basement or sleeping room below the fourth story above grade plane. There are numerous exceptions where EEROs would not be required:
If your project falls under the IRC, Emergency Escape and Rescue Openings are required in basements, habitable attics and every sleeping room. If the basement contains more than one sleeping room, an EERO is required in each sleeping room (IRC 310.1).
There are numerous exceptions where EEROs would not be required:
Egress Window Sizing Requirements
Both the IBC and IRC have the same dimensional sizing requirements for EEROs:
These dimensions are required to be a result of the normal operation of the window or door - you cannot break or alter the window/door in order to achieve the required dimensions.
Basement Egress Windows
Area wells are required to be a minimum of 9 square feet in area with a minimum dimension of 36 inches in both length and width. The area well must also be of sufficient size to allow the EERO to fully open.
If the area well has a depth of more than 44”, a ladder or steps are required. The egress window or door opening into the area well cannot obstruct the ladder or steps when fully open.
If you choose to provide a ladder for the area well, the ladder must have an inside width of at least 12 inches, must project at least 3 inches from the area well wall and the ladder rungs must be spaced no more than 18 inches apart for the entire height of the area well.
If you choose to prove steps for the area well, the steps must have a minimum width of 12 inches, a minimum tread depth of 5 inches and a maximum riser height of 18 inches for the entire height of the area well.
Finally, area wells are required to be connected to the buildings foundation drainage system unless the building is located on well-drained soil or sand-gravel mixture soils as defined by IBC 1803.5.1 and IRC 405.1
Bars, Grilles, Covers and Screens over Egress Windows
When bars, grilles, covers, screens or other similar devices are placed over EEROs or area wells, these devices cannot reduce the minimum required dimensions described above. Additionally, the bar, grilles, cover or screen must be releasable or removable from the inside without a key or tool and cannot require a greater force than what is required to open the EERO itself.
Egress windows, which the code refers to as “Emergency Escape and Rescue Openings” (EEROs) are required in all sleeping rooms for projects falling under the IRC and in many sleeping rooms for projects falling under the IBC.
When required, EEROs must meet the following size requirements:
If the EERO is below grade level, a minimum 36” x 36” area well is required. If the area well is more than 44” deep, a ladder or steps are required.
In projects of Type II, III, IV or V construction, architects are often forced to balance the allowable area limits of lesser construction types and the added cost of higher construction types. A fire wall is an ideal solution, as it allows for the cost savings of a lower construction type while allowing the structure on either side of the fire wall to be considered independently from an allowable area standpoint.
On several recent projects, I have seen plan reviewers treat any door opening in the fire wall as a horizontal exit, even if that was not the design team’s intention. The reviewers then issued review comments regarding compliance with the horizontal exit code requirements. This has led me to the question: is an opening in a fire wall automatically a horizontal exit?
Before I get to my answer, you might be asking: why does this matter?
Horizontal exits come with several code requirements, but in the recent projects I mentioned, the plan reviewers were citing the following:
Per IBC 1026.1, a horizontal exit can provide up to one half of the total number of exits, total exit width and total egress capacity. So if the door in the fire wall is a horizontal exit, then it can not be providing more than half of the required number of exits or required exit width.If you have a single door in the fire wall and then an exit stair on either side, this is no problem. But once you have multiple doors in the fire wall, the horizontal exit can easily exceed one half of the total required exits/width.
Per IBC 1026.4, when a horizontal exit approach is used, a refuge area is required in the space on the other side of the horizontal exit. This refuge area must be large enough to accommodate the original occupant load of the space plus 3 square feet for each occupant entering into the refuge area from the horizontal exit.
Depending on the building arrangement and capacity, providing this refuge area may be a design challenge.
Standpipe Hose Connections
Per IBC 905.4.2, a standpipe hose connection is required on each side of a horizontal exit. An exception does exist if the floor areas adjacent to the horizontal exit are within 130’ of standpipe hose connection with an exit stair.
So if any door in a fire wall is a horizontal exit, each of these code requirements must be met, adding additional cost and design coordination.
Coming back to the original question:
Is an opening in a fire wall automatically a horizontal exit?
I believe the answer is no. A door opening in a fire wall can be a horizontal exit, but it is not required to be a horizonal exit.
My opinion is based on a few factors.
First, let’s look at the definition of fire wall (IBC Chapter 2):
A fire-resistance-rated wall having protected openings, which restricts the spread of fire and extends continuously from the foundation to or through the roof, with sufficient structural stability under fire conditions to allow collapse of construction on either side without collapse of the wall.”
This definition does not mention or describe a horizontal exit at all.
Similarly, we can go to IBC Chapter 5, where the general requirements for building height and area are given. Per IBC 503.1:
For the purposes of determining area limitations, height limitations and type of construction, each portion of a building separated by one or more fire walls complying with Section 706 shall be considered to be a separate building.”
This statement indicates that a fire wall creates separate buildings for the purposes of allowable height/area and construction type, but again, it does not mention or describe a horizontal exit.
Finally, if we return to the horizontal exit section of IBC Chapter 10, we see in Section 1026.2 that a horizontal exit is permitted to be provided as either a fire wall or a fire barrier. No where in this section is a fire wall required; it is just given as one of two options. I have never heard of any AHJ requiring all fire barriers to be a horizontal exit, so why would we apply that logic to fire walls?
Icing on the Cake: An ICC Committee Interpretation
I am not the first person to ask this question, and fortunately, the ICC released a committee interpretation on this same issue a few years ago.
To summarize the committee’s interpretation, fire door openings in a fire wall are not required to be considered as a horizontal exit unless the design of the egress system intends to utilize the provisions of a horizontal exit.
While you would think that the code support described above, plus an ICC committee interpretation would be sufficient to persuade any AHJ, I have still experience pushback on this issue from plan reviewers.
Despite this, I believe the intent of the code is to allow a door in a fire wall to be used as a horizontal exit, but not require it. And if the design intention is not to utilize the horizontal exit provisions, then you do not need to be concerned about the exit capacity restrictions, refuge area requirements and additional standpipe hose connections that I described previously.
Have you encountered a similar issue before? If so, please comment below and let me know.
Guide to Locking Egress Doors
In almost every building, owners or tenants have a need for some level of security or access control. The IBC covers a wide range of door locking and control techniques, but the shear number of sections and underlying requirements can be tough to digest. Many folks have trouble knowing which code sections apply, and even if the correct section is identified, it can be a challenge to understand the requirements.
In this post, I take a number of these door locking requirements and translate them into (hopefully) more clear and concise language. I also provide some general commentary on my experience in using each type of door/locking arrangement. References are provided to the last 3 editions of the IBC.
Click one of the door/lock types in table below to jump to that section.
Many designers don't realize that a revolving door can be used in an egress path, as long as certain requirements are met.
All revolving doors must meet the following requirements, but be sure to check out the paragraph below this one for additional requirements for egress/non-egress doors.
Auto/Power Revolving Doors
Door Diameter (Feet)
Max Speed (RPM)
- Count towards no more than 50% or required egress width or capacity.
- Each door counts towards a maximum of 50 occupants when performing egress calculations.
- Maximum breakout force of 130 pounds.
Revolving doors that are not egress components must have a breakout force of 180 pounds or less. A breakout force of more than 180 pounds is permitted if the breakout force reduces to 130 pounds or less under one of the following conditions:
- Door power failure
- Sprinkler system activation
- Smoke detector activation with 75 feet of the revolving doors
- Activation of a manual control switch in a clearly identified location
Power-operated swinging doors, power-operated sliding doors and power-operated folding doors must comply with BHMA A156.10. Power-assisted swinging doors and low-energy power-operated swinging doors must comply with BHMA A156.19. (2018 and Beyond): Low-energy power-operated sliding doors and low-energy power-operated folding doors must comply with BHMA A156.38.
Exceptions to the above requirements:
- Group I-2 occupancies
- Special purpose horizontal sliding, accordion or folding doors (see related section in this article)
- For a biparting door in the emergency breakout mode, a door leaf located within a multiple-leaf opening is exempt from the minimum 32-inch single-leaf requirement, provided that a minimum 32-inch clear opening is provided when the two biparting leaves meeting in the center are broken out.
Special Purpose Horizontal Sliding, Accordion or Folding Doors
- The doors are power operated and are capable of being operated manually in the event of power failure.
- The doors are openable by a simple method from both sides without special knowledge or effort.
- The force required to operate the door cannot exceed 30 pounds to set the door in motion and 15 pounds to close the door or open it to the minimum required width.
- The door must be openable with a maximum force of 15 pounds when a force of 250 pounds is applied perpendicular to the door adjacent to the operating device.
- The door assembly must comply with the applicable fire protection rating and, where rated, must be:
- Self-closing or automatic closing by smoke detection in accordance with IBC 7126.96.36.199.
- Installed in accordance with NFPA 80.
- Comply with IBC 716.
- The door assembly must have an integrated standby power supply.
- The door assembly power supply must be electrically supervised.
- The door must open to the minimum required width within 10 seconds of the operating device.
Locking Arrangements in Educational Occupancies
- The door is capable of being unlocked from outside the room with a key or other approved method. Remote door unlocking is permitted in addition to the key.
- The door is openable from within the room per IBC 1010.2
- Modification are not permitted to listed panic hardware, fire door hardware or closers.
- (2021 only) Modifications to fire doors assemblies must be in accordance with NFPA 80.
Group I-1 and I-2 Controlled Egress Doors
- The door must unlock upon actuation of the sprinkler or smoke detection system.
- The door must unlock upon power loss.
- The door must have an unlocking switch, located at the fire command center, nursing station or other approved location, that directly breaks power to the lock.
- No more than one controlled egress door before reaching an exit
- Door unlocking procures must be included and approved in the required Fire Code emergency planning (see IFC Chapter 4).
- All clinical staff must have a key or other means to operate the locked door
- Emergency lighting is required at the door.
- The door locking system must be UL 294 listed.
- Areas where persons require restraint or containment as part of the function of a psychiatric treatment area or (2021 only) cognitive treatment area.
- Where a listed egress control system is used to reduce child abduction risk from nursery and obstetric area of a Group I-2 hospital.
Delayed egress locking systems are permitted in any occupancy except Groups A, E or H when the building is fully sprinkler protected per NFPA 13 or provided with smoke/heat detection throughout.
2018 and Beyond:
Delayed egress locking systems are permitted in the following situations when the building is fully sprinkler protected per NFPA 13 or provided with smoke/heat detection throughout.
- Group B, F, I, M, R, S and U
- Group E classrooms with an occupant load less than 50
- In courtrooms, on other than the main exit doors, when the building is fully sprinkler protected per NFPA 13.
The delayed egress locking system must meet all of the following requirements:
- The delay electronics must allow immediate and free egress upon actuation of the sprinkler system or fire detection system.
- The delay electronics must allow immediate and free egress upon power loss.
- The delay electronics must have the capability to be deactivated from the fire command center or other approved location.
- When an effort is applied to the egress door hardware for not more than 3 seconds, an irreversible process must star that allows for the egress door to open in 15 seconds or less. The irreversible process must activate an audible signal near the door. Once the delayed egress door has been deactivated, the door can only be rearmed by manual means.
- Exception: Where approved by the AHJ, a delay of not more than 30 seconds is permitted.
- The egress path cannot pass through more than one delayed egress locking system.
- 2015 Exception: In Groups I-2 or I-3, the egress path can pass through up to two delayed egress locking systems if the combined delay is 30 seconds or less.
- 2018 Exception: In Groups I-2 or I-3, the egress path can pass through up to two delayed egress locking systems if the combined delay is 30 seconds or less. In Groups I-1 or I-4, the egress path can pass through up to two delayed egress locking systems if the combined delay is 30 seconds or less and the building is fully sprinkler protected per NFPA 13.
- 2021 Exception: In Groups I-1 Condition 2, I-2 or I-3, the egress path can pass through up to two delayed egress locking systems if the combined delay is 30 seconds or less. In Groups I-1 Condition 1 or I-4, the egress path can pass through up to two delayed egress locking systems if the combined delay is 30 seconds or less and the building is fully sprinkler protected per NFPA 13.
- A sign must be provided on the door and located above and within 12 inches of the door exit hardware:
- For doors swinging in direction of egress, the sign must read “PUSH UNTIL ALARM SOUNDS. DOOR CAN BE OPENED IN 15  SECONDS.”
- For doors swinging in against the direction of egress, the sign must read “PULL UNTIL ALARM SOUNDS. DOOR CAN BE OPENED IN 15  SECONDS.”
- The sign must comply with the visual character requirements in ICC A117.1.
- Exception: Where approved in Group I occupancies, the sign is not required where care recipients have a clinical needs requiring restraint or containment as part of the function of the treatment area.
- Emergency lighting must be provided on the egress side of the door.
- The delayed egress systems must be UL 294 listed.
Sensor Release of Electrically Locked Doors
Sensor release locks are permitted on any egress door in Groups A, B, E, I-1, I-2, I-4, M, R-1 or R-2 occupancy.
2018 and Beyond:
Sensor release locks are permitted on any egress door except in Group H occupancies.
Sensor release locks must be installed and operated per the following requirements:
- Sensor installed on egress side of door to detect an occupant approaching the door and cause the electric lock system to unlock.
- Door unlocks upon loss of power or signal to the sensor.
- Door unlocks upon loss of power to the lock or locking system.
- Doors can be unlocked from a manual device located 40” to 48” above the floor and with 5 feet of the doors. The unlocking device must be readily accessible and be clearly identified with a “PUSH TO EXIT” sign. The unlocking device must directly interrupt power to the lock independent of other electronics and keep the door unlocked for at least 30 seconds.
- Door unlocks upon activation of the building fire alarm system and remain unlocked until fire alarm system is reset.
- Door unlocks upon activation of the sprinkler system or fire detection system and remain unlocked until the fire alarm is reset.
- Door lock system must be UL 294 listed.
- (2021 Only) Emergency lighting must be provided on the egress side of the door.
Electromagnetically Locked Doors
- Hardware is affixed directly to the door leaf and has an obvious method of operation under all lighting conditions.
- Hardware can be operated with one hand.
- Operating the door hardware immediately interrupts power to the Mag Lock and unlocks the door immediately.
- Door unlocks upon lows of power to the locking system.
- Where panic or fire exit hardware is required, operation of that hardware also releases the Mag Lock.
- Lock system must be UL 294 listed.
Door Hardware Release of Electrically Locked Doors
- Hardware is affixed directly to the door leaf and has an obvious method of operation under all lighting conditions.
- Hardware can be operated with one hand and meets IBC unlatching requirements.
- Operating the door hardware immediately interrupts power to the lock and unlocks the door immediately.
- Door unlocks upon lows of power to the locking system.
- Where panic or fire exit hardware is required, operation of that hardware also releases the lock.
- Lock system must be UL 294 listed.
- Activation of the building sprinkler system
- Actvaition of a manual fire alarm pull station
- A signal from a constantly attended location.
In the 2015 IBC, use of this provision is limited to Groups A-2, A-3, A-4, B, E, F, I-2, I-3, M and S occupancies within correctional and detention facilities. In 2018 and beyond, use of this section is permitted in any building within a correctional and detention facility.
- Stair discharge doors can be locked from the outside (must be unlocked in direction leaving the stair).
- Stair doors in high rise buildings complying with IBC 403.5.3 (see section below).
- (2015 Only): In stairs serving 4 stories or fewer, stair doors can be locked from the inside provide they have the capability of being simultaneously unlocked (without unlatching) by a signal from the fire command center or location inside the main entrance of the building.
- (2018 and Beyond): Stair doors can be locked from the inside provide they have the capability of being simultaneously unlocked (without unlatching) by a signal from the fire command center or location inside the main entrance of the building.
- Stair doors in Group B, F, M and S occupancies where the only interior access to a tenant space is from the exit stair can be locked from the inside of the stair (must be unlocked in direction of egress).
- Stair doors in Group R-2 dwelling units where the only interior access to the unit is from the exit stair can be locked from the inside of the stair (must be unlocked in direction of egress).
In high rise buildings, stairway doors can be unlocked from the stairway side provided they have the capability of being unlocked (without unlatching) by a signal from the fire command center. when this provision is used, a telephone or other two-way communication system connected to a constantly attended location is required on every fifth floor in every stairway with locked doors.
Panic and Fire Exit Hardware
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.
Open Stairs - 2018 IBC Code Paths
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).
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
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.
Code Question - Openings in Stairs From Normally Occupied Spaces
Openings in interior exit stairways and ramps other than unprotected exterior openings shall be limited to those necessary for exit access to the enclosure from normally occupied spaces and for egress from the enclosure. (2015 IBC 1023.4)
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.
What Do You Think?
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.
2015 IBC 1030.1
In addition to the means of egress required by this chapter, provisions shall be made for emergency escape and rescue openings in Group R-2 occupancies in accordance with Tables 1006.3.2(1) and 1006.3.2(2) and Group R-3 occupancies. Basements and sleeping rooms below the fourth story above grade plane shall have at least one exterior emergency escape and rescue opening in accordance with this section. Where basements contain one or more sleeping rooms, emergency escape and rescue openings shall be required in each sleeping room, but shall not be required in adjoining areas of the basement. Such openings shall open directly into a public way or to a yard or court that opens to a public way.
2018 IBC 1030.1
In addition to the means of egress required by this chapter, emergency escape and rescue openings shall be provided in the following occupancies:
Basements and sleeping rooms below the fourth story above grade plane shall have not fewer than one exterior emergency escape and rescue opening in accordance with this section. Where basements contain one or more sleeping rooms, emergency escape and rescue openings shall be required in each sleeping room, but shall not be required in adjoining areas of the basement. Such openings shall open directly into a public way or to a yard or court that opens to a public way.
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.
Emergency Escape and Rescue Openings: What Do You Think?
Let me know your thoughts in the comment box!
One other item to keep in mind - if your project is a single-family home, you may actually be permitted under the International Residential Code (IRC), not the IBC. The IRC also has requirements for emergency escape and resuce openings, so be sure to check those out if applicable to your project.
On a related note, I was recently asked to provide input for an article on Redfin for basement remodelling projects (likely permitted under the IRC). Check out the link to the article here!
Mitigating Dead End Corridors
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.
Dead End Corridors: What Do You Think?
Let me know your thoughts in the comment box!
In many urban areas, once crowded streets and public gathering spaces are now deserted. Major cities around the US have closed non-essential businesses, rendering office and conferences rooms vacant for the time being. Congested highways where cars formerly crawled along during rush hour are now empty.
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?
Occupant Load Factors Meet Social Distancing
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.
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!
Chapter 10 - Means Of Egress
Chapter 11 - Accessibility
Chapter 14 - Exterior Walls
Chapter 1 - Scope And Administration
Chapter 24 - Glass And Glazing
Chapter 2 - Definitions
Chapter 33 - Safeguards During Construction
Chapter 4 - Special Detailed Requirements
Chapter 5 - General Building Heights And Areas
Chapter 6 - Types Of Construction
Chapter 7 - Fire And Smoke Protection Features
Chapter 9 - Fire Protection Systems