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Anyone who has spent time navigating a building or fire code will quickly come to realize that there are many design alternatives, exceptions, and sometimes different interpretations of the “rules” of the code, and that is ever clear when posing this question – when is elevator pressurization required?
Something about the codes that we may lose sight of is that only a little is absolute. In fact, elevator pressurization is one of a few methods to provide hoistway opening protection for elevator shafts. Some additional methods observed by the International Building Code (IBC) include elevator lobbies or UL-listed smoke-rated doors. Certain jurisdictions may also observe the ICC Evaluation Report for the use of smoke-rated curtains.
Each method of compliance has its place in buildings depending on budget and other design objectives. Elevator pressurization tends to be the most popular option for providing hoistway opening protection since it is a cost-effective approach that also provides architectural design flexibility.
Most commonly, you will see elevator pressurization systems utilized in high-rise buildings. Remember that the definition of a “high-rise building” can vary from jurisdiction to jurisdiction.
For example, the International Building Code (IBC) defines a highrise building as “a building with an occupied floor located more than 75 feet above the lowest level of fire department vehicle access.” However, the state of Nevada has amended the base IBC to “55 feet above the lowest level of fire department access.” It is important to understand how local amendments can impact the design of elevator pressurization systems.
Just because the building meets the definition of a high-rise does not necessarily imply that every elevator shaft, or any elevator shaft for that matter, must be provided with elevator pressurization. The IBC requires hoistway opening protection where all the following conditions apply:
For example, an elevator serving only a couple of stories within a high-rise building would not be required to be provided with hoistway opening protection, i.e., elevator pressurization. Or an elevator hoistway that is located within an atrium or serving an open parking garage would not need to be provided with elevator pressurization.
In buildings where corridors are required to be fire-resistance rated, elevator hoistway openings must be protected, and elevator pressurization can be utilized. In a rated corridor, the opening protectives for fire partitions must have a fire-resistance rating of 20 minutes and smoke/draft control. Most elevator doors satisfy the fire-resistance rating requirement but fall short of the smoke-rating requirements for a fire partition.
The IBC requires rated corridors for any building meeting all the following conditions:
Corridors provide fire protection to occupants as they travel along a confined path. In the event of a fire, it is critical that the path remains free of smoke. Providing elevator pressurization is one of the accepted methods to protect corridors.
No*, fire service access elevators are required to be provided with lobbies that meet a very specific set of requirements designed for fire department use during a fire emergency. In summary, fire service access elevator lobbies must meet the following requirements:
These elevators are a special safety feature provided only for very tall buildings. The requirements for fire service access elevators were developed based on research by the U.S. General Services Administration (GSA) and the National Institute of Standards and Technology (NIST), which focused on features necessary for the safe operation of elevators by firefighters during a fire emergency.
*You may be wondering about the initial asterisk on the No: the state of Florida, for example, has adopted an exception to fire service access elevator lobbies. This exception within the Florida Building Code (FBC) allows for a comprehensive alternative approach to providing fire service access elevator lobbies:
“Where a fire service access elevator is required, a 1-hour fire-rated fire service access elevator lobby with direct access from the fire service access elevator is not required if the fire service access elevator opens into an exit access corridor that is no less than 6 feet wide for its entire length and is at least 150 square feet with the exception of door openings, and has a minimum 1-hour fire rating with three-quarter hour fire- and smoke-rated openings; and during a fire event the fire service access elevator is pressurized and floor-to-floor smoke control is provided.”
So, in certain cases, yes, a fire service access elevator hoistway must be pressurized.
The objective of an elevator pressurization system is to prevent the migration of smoke from the area surrounding the elevator into the elevator shaft and onto other floors. Elevator shafts are among the largest vertical shafts in multistory buildings and therefore present the most potential for smoke spread. In the 1980 fire at the MGM Grand Hotel in Las Vegas, 70 of the 84 deaths occurred on the 14th to 24th floors, although the fire was on the first level. This was largely due to unprotected vertical openings, such as elevator hoistways.
An elevator pressurization system is considered a smoke control system and is subject to the many requirements of Chapter 909 in the building code. Providing elevator pressurization will require that a rational analysis be prepared by a qualified design professional. You can read more about smoke control rational analysis in our blog.
Understanding when hoistway protection is required and options for how it can be implemented is important for building code compliance and designing useful, beautiful buildings. If you aren’t sure about your options, work with a fire protection engineer. They understand the intricacies of the code and can help you make decisions that align with the objectives of your project.
If you want to learn more about elevator pressurization systems and smoke control design, please feel free to reach out to Performance Based Fire at email@example.com or check out our past work.