This week, the ICC Committee Action Hearings (CAH) kicked off, where proposed code changes for the 2024 ICC Codes are heard by the various ICC committees. In yestereday's session, the IBC General committee heard several proposed changes related to occupied roofs and the classification of high-rise buildings. In recent code cycles, there have been several key changes to occupied roof requirements, but none of these have addressed whether an occupied roof over 75' would trigger classification of a high-rise building.
As a quick reminder, the 2021 IBC currently defines a high-rise building as "A building with an occupied floor located more than 75 feet above the lowest level of fire department vehicle access."
While previous code editions have remained silent on the issue, the ICC website does have two articles addressing high rise classification due to an occupied roof.
This article, authored by ICC staff member Chris Reeves, clearly states that an occupied roof is not intended to count as a floor for the purposes of evaluating the high-rise building definition. Another article, authored by ICC staff member Kimberly Paarlberg, states "What has not yet been clarified is if an occupied roof is considered an occupied floor when determining if the building does or does not have to meet the high-rise provisions in the code..."
While the two articles above are both informal opinions from ICC staff, it appears the 2024 IBC will now address this issue directly. During today's hearing, the IBC General Committee voted in favor of proposal G15-21, which is copied below:
Revise as follows:
[BG] HIGH-RISE BUILDING. A building with an occupied floor or occupied roof located more than 75 feet (22 860 mm) above the lowest level of fire department vehicle access.
This proposed change to the definition of a high-rise building would require any building with an occupied roof above 75' to meet all of the high-rise building requirements. Several proposals, including G12-21 and G14-21, were aimed the other way, attempting to clarify that an occupied roof would not trigger a high-rise classification. Both of these were disapproved by the committee.
When a building is classified as a high-rise, there are numerous additional requirements, including:
What Do You Think?
Do you agree with the General Committee on this issue? Should an occupied roof above 75' trigger the classification as a high rise building? Please share your thoughts in the comments section!
If you disagree with this viewpoint, there is still time to have your opinion heard before the change is codified. The ICC code development process includes a public comment period, which will be open between May 24 and July 2. Any one is free to submit a comment on this issue or any other proposed changes moved forward by ICC committees. The ICC Public Comment Hearings (PCH) will take place between September 22-29 in Pittsburgh (also open to the public).
After a really nice response on the fire and smoke damper cheatsheet I have created a questionnaire tool that makes the process way easier. You answer a series of yes/no questions and the tool kicks out the damper requirement and code reference! Enter your info below to checkout the tool...
The 2021 IBC includes several changes that impact Group I-2 occupancies. These changes build upon updates from 2018 edition and continue with the sub-grouping of occupancies into either Condition 1 or 2 that started in the 2015 edition. As a quick reminder, IBC 308.3 defines these as:
Group I-2, Condition 1: "facilities that provide nursing and medical care but do not provide emergency care, surgery, obstetrics or in-patient stabilization units for psychiatric or detoxification, including but not limited to nursing homes and foster care facilities."
Group I-2, Condition 2: "facilities that provide nursing and medical care and could provide emergency care, surgery, obstetrics or in-patient stabilization units for psychiatric or detoxification, including but not limited to hospitals."
The 2021 IBC provides two changes related to corridors doors in Group I-2 occupancies.
First, Section 407.3.1.1 has been added for corridor doors that are not required to have a fire protection rating. Generally, Group I-2 corridor walls are not required to have a fire-resistance rating unless they are part of an enclosure for an exit or vertical opening, or if they are separating an incidental use room that requires a rating per IBC 509.4.
This new section now addresses the following:
Second, Section 407.6.1 has been added for automatic-closing doors on hold-opens. Previously, these doors were only required to close upon actuation of a smoke detector or loss of power to the hold-open or smoke detector. Now, these doors must also close upon activation of the fire alarm system or sprinkler system.
Exit Access Through Care Suites
Section 407.4.4.3 has been revised and no longer considers the number of doors or care suites in the path of exit access. Previously, this code section limited exit access to not require passage through more than three doors before reaching the corridor. Now, the code does not provide a maximum number of doors and simply limits care suites to no more than 100' of travel to reach a corridor. When a care suite requires two exit access doors, the second exit access door must lead directly to a corridor, exit or adjacent care suite.
Nursing Home Cooking Facilities
The 2021 IBC makes an organizational change to requirements for nursing home cooking facilities, moving the requirements for the cooking appliances into a separate section. This builds upon a change in the 2018 edition, which provided specific provisions to allow cooking facilities to be open to the corridor in Group I-2, Condition 1 occupancies.
Under the 2021 IBC, these requirements are now organized as follows:
Nursing Home Cooking Facilities (407.2.6): In Group I-2, Condition 1 occupancies, spaces containing a cooking facility with a domestic cooking appliance are permitted to be open to the corridor when all of the following criteria are met:
Domestic Cooking Appliances (407.2.7): In Group I-2 occupancies, cooking appliances in domestic cooking facilities must comply with the following:
The 2021 IBC includes several changes related to Group I-2 occupancies. These changes build upon provisions enacted during past cycles and include changes to corridor doors, care suite arrangement and nursing home cooking facility requirements.
As more and more states move to adopt the 2018 IBC, it's important to know about a few code updates that impact the design of occupied roof spaces. And if you're jurisdiction is on the ball and already adopted the 2021 IBC, there are a few additional items that apply to you.
Occupied Roofs Under the 2018 IBC
In the 2015 IBC and prior editions, the code remained silent in regards to occupied roof decks and requirements for allowable height and area. Under the 2018 IBC, there are now specific provisions addressing this issue.
First, IBC 302.1 has been updated with specific requirements for classifying an occupied roof space:
This added language forces designers to classify an occupied roof with an occupancy, whereas some jurisdictions has not previously required it.
Next, IBC 503.1.4 brings in a major new requirement:
This section limits the occupancy on an occupied roof to those allowed on the story immediately below the roof. So if your building construction type allows an assembly occupancy on the top story, you are also permitted an assembly occupancy on the roof. The code does offer two major exceptions:
Take the image below for an example, a 4 story building consisting of Type IIIA construction. If the building is fully sprinkler protected in accordance with NFPA 13, a Group A-3 occupancy would per permitted on Level 4. As long as occupant notification is provided on the roof, the 2018 IBC now explicitly allows a Group A-3 occupancy on the roof.
The provision of Section 503.1.4.1 do limit elements on the roof to no more than 48" above the roof surface, with exceptions for penthouses, tower, domes, spires and cupolas. If you have elements above this height, the roof would have to be classified as a story. As an example, the overhang in the image above of the Facebook building would likely trigger the roof being classified as a story.
Another common question is whether an occupied roof can trigger classification as a high-rise building. The IBC itself does not address this issue, but this staff opinion from the ICC is very helpful in clarifying the intent. The opinion clearly states, "Just because a roof is an occupied roof does not make it a floor with respect to the definition of a high-rise building. "
Occupied Roofs Under the 2021 IBC
The 2021 IBC updates Section 503.1.4 to explicitly clarify that an occupied roof should not be included when determining building height or number of stories per IBC 504. Language was also added to clarify that this only applies when penthouse and other rooftop structures, when present, comply with IBC 1511. This further supports the notion described above that an occupied roof should not by itself trigger a classification as a high-rise building.
Additionally, the 2021 IBC clarifies that the Exception 1 to 503.1.4 for occupant notification would only require a voice fire alarm system on the roof if the system is required elsewhere in the building. In other words, if you aren't required to have a voice fire alarm in the building, you don't have to provide it on the roof in order to use Exception 1.
Finally, the 2021 IBC updates Section 1511.2.2, Use Limitations for Penthouses, to specifically allow "ancillary spaces used to access elevators and stairways" to be considered part of a penthouse. This means that a stair or elevator tower to the roof will not force an occupied roof to be classified as a story, even though those elements are taller than 48" from the roof surface.
In the last year or so, there have been several fire incidents during the construction of wood-framed residential buildings. Recently, in January 2021, a fire at the Ely at Fort Apache apartment complex in Las Vegas completely destroyed the building, racking up an estimated $25-30 million in damages. Or last year, a Jacksonville, Florida grew so large that it shut down a portion of nearby Interstate 295 and forced the local fire department to deploy 45 apparatus, including 14 engines and seven ladder trucks. In both of these cases, as well as other similar fires, there were two clear similarities:
According to a recent NFPA report, between 2013 and 2017, "fires in structures under construction caused an average of four civilian deaths, 49 civilian injuries, and $304 million in direct property damage annually." In the same report, it is noted that three out of every four construction fires occur in residential buildings. During the 5 year timeframe in the report, 42% of the direct property damage was caused by fires starting from electrical distribution and lighting equipment.
Fires in wood buildings are certainly not a new development, but over the last several building code cycles, various code changes have been enacted that allow for larger and more complex wood buildings. For example, in the 2015 IBC, the "podium" concept, where a wood-framed buildings can be constructed on top of a Type IA podium, allowing for an overall larger building, was expanded to allow multiple levels of Type IA construction beneath the podium. More recently, in the 2021 IBC, Type IV construction has been significantly expanded to now include three different sub-categories (Types IV-A, IV-B and IV-C), allowing for substantially taller and larger heavy timber buildings.
Without a doubt, there are numerous benefits to wood-framed construction. Reduced carbon emissions, faster construction and reduced building costs - all are positive reasons for designers to choose wood buildings. But the very nature of wood being a combustible material brings inherent risks, particularly during construction where fire protection systems are not yet in place.
How to Respond?
While recent code changes have allowed for larger and more complex wood buildings, requirements for safeguards during construction have evolved as well. For example, in the 2021 IBC, Chapter 33 has been updated with a few notable changes:
NFPA 241, Standard for Safeguarding Construction, Alteration, and Demolition Operations, does provide requirements that are often more stringent than IBC Chapter 33. But many jurisdictions do not adopt or enforce compliance with this standard.
Apart from the model codes, many local jurisdictions have enacted their own requirements. In addition to requirements for protection during construction, I am also seeing local requirements for pursuing phased occupancy, where building owners want to occupy a portion of a building while other areas are still under construction. For example, Fairfax County, VA publishes a standard operating procedure document for phased occupancy that institutes a variety of building and site requirements that have to be met before phased occupancy can be considered.
But even with national and local codes addressing the issue, the magnitude of these fire losses does force you to ask: Is enough being done?
What are you Seeing?
What trends are you seeing in your area? Does your local building or fire department have any specific requirements for fire protection during construction or phased occupancy, particularly for wood buildings? While I don't think there is a one size fits all solution to such a problem, I'm very interested in hearing a variety of perspectives from across the country. Please share in the comment section below!
While working in the early phases of a project, a mechanical engineer recently asked for an estimate of the required stair pressurization system fan capacity. On this particular project, I am planning to do a CONTAM analysis, but won't start that portion until later in the Design Development phase.
Since I wanted to give the mechanical engineer an estimate for sizing purposes, I put together a quick calculator to estimate the fan size. Check it out at the link below!
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.
Open Stairs - 2018 IBC Code Paths
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:
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:
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:
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.
UPDATE: See new average grade plane calculator, linked below.
In the past few months, I've had several clients ask me questions regarding grade plane calculations - most often related to determining whether a particular story counts as a story above grade plane or as a basement. Here is quick rundown of how to do the calculation and the implications.
Average Grade Plane
Chapter 2 of the IBC defines Grade Plane (often referred to synonymously as Average Grade Plane) as:
A reference plane representing the average of finished ground level adjoining the building at exterior walls.
So if you have a completely flat site, the elevation where the finished ground level adjoins the building exterior walls is your grade plane. If your site is sloped, you need to take several elevations where the finished ground level adjoins the building and average them to determine the grade plane.
The most common question I receive on this: how many elevation points do you need to account for this in average?
First, the IBC does not give any specific requirements or instructions to answer this question. Your local jurisdiction could potentially have some guidance on how they want to see the calculation performed, but in my experience, most do not.
Typically, I advise clients to base the number of elevation points on the slope of the site. If you have a relatively flat site, a small number of elevation points will give you an accurate grade plane elevation. You may only need one elevation point per face of the building. On the other hand, if you have an irregular, highly-sloped site, you will need many elevation points. I once worked on a building that was built into the side of a steep hill - there we measured the elevation every 10 feet in some areas. If in doubt, the greater number of elevation points in your calculation will result in a more accurate measurement.
In the simple example above, the grade plane measurement is just the average of the elevations at the end of each wall segment (e.g. for the east wall, (280+270)/2 = 275'). However, with a more severe grade, particularly where the slope is irregular, you will need to take additional measurements, as shown in the example below.
Another common question: What if my site slopes perpendicular to the exterior walls?
The Implication - Determining a Story Above Grade Plane
Why does the grade plane calculation matter? On my projects, this always comes up when a client is trying to determine whether a particular story is actually a story above grade plane or a basement.
Chapter 2 of the IBC defines "Story Above Grade Plane" as:
Any story having its finished floor surface entirely above grade plane, or in which the finished surface of the floor next above is:
This definition has caused some confusion in the past, so here is a step by step breakdown:
There are numerous code requirements that differ between a story and a basement, but the most common one is complying with the allowable number of stories based on occupancy and construction type. I had a project this year where the floor surface of the level above was 5 feet, 10 inches above the grade plane elevation, just barely passing as a basement. 2+ inches more and the building would haven been one story taller, resulting in requirements for a more robust construction type, higher shaft ratings and substantial additional cost.
If your situation is that close, I suggest including a plan in the permit package that clearly shows the grade elevations around the building and shows your grade plane calculation. This makes it easy for plan reviewers to follow your logic and hopefully agree with your approach (remember, there are no specific IBC instructions or requirements for how to do the calculation).
What do you Think?
Have you had a project that required a detailed grade plane calculation? Have you every had a plan reviewer or code official disagree with your calculation? Let me know in the comment box!
Delayed egress doors are one of the most commonly-used features in design situations where some level of access control is needed on the path of egress. Under normal conditions, delayed-egress doors are a deterrent to building occupants, limiting access through the door unless necessary for an emergency. During an emergency, the delay function will deactivate (whether upon loss of power, or sprinkler/fire alarm activation), effectively making the door a normal egress door.
Similar to the other cheatsheets I have put together, this one is motivated by numerous architect requests for clarification as to when a delayed egress door can be provided.