High-Rise Building Requirements: An Overview for Architects and Engineers

​The design and construction of high-rise buildings come with unique challenges, particularly when it comes to fire and life safety. The 2021 International Building Code (IBC) outlines specific requirements for high-rise buildings that affect construction type, fire protection, egress, and emergency systems. These requirements play a major role in the design of a high-rise building, so it’s important for architects and engineers to know and understand the requirements from the beginning of the design process.
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In this article, we’ll provide an overview of the key requirements from the 2021 IBC that apply to high-rise buildings.

If you're interested in a cheat sheet that summarizes these requirements, scroll down to the bottom of the article to download your free one-page cheat sheet.

What is a High-Rise Building?

Per the 2021 IBC, a high-rise building is defined as:

 A building with an occupied floor located more than 75 feet above the lowest level of fire department vehicle access."

Any building with an occupied floor higher than this 75 foot threshold is considered a high-rise building and must comply with all of the requirements listed in this article.

Starting in the 2024 IBC, the definition of high-rise building has been changed to be:

A building with an occupied floor or occupied roof located more than 75 feet above the lowest level of fire department vehicle access."

This new definition means that an occupied roof above the 75 foot threshold now also will trigger designation as a high-rise building.

Construction Type and Fire Resistance Ratings

The IBC establishes fire resistance rating requirements based on building height and occupancy type. High-rise buildings generally fall under Type I construction, which mandates noncombustible materials with high fire resistance ratings. However, some reductions are permitted (IBC 403.2.1):

• For buildings ≤ 420 feet, fire resistance ratings can be reduced to Type IB, except for columns supporting floors.
• For most occupancies, the ratings for Type IB can be further reduced to Type IIA, except for Groups F-1, H, M, and S-1.
• Despite reductions, height and area limitations remain based on the original construction type before reductions.
• In buildings ≤ 420 feet, shaft fire barriers (except for interior exit stairs and elevators) may be reduced to 1-hour rated if sprinklers are installed at the top and at alternate floors.

​Structural Integrity

Shaft enclosures play an important role in maintaining fire and smoke compartmentation. Key requirements include (IBC 403.2.2):

• For buildings > 420 feet or those classified as Risk Category III or IV, interior exit stair and elevator hoistway enclosures must meet one of the following impact resistance requirements:
  • Two layers of Hard Body Impact Level 2 panels
  • One layer of Hard Body Impact Level 3 panels
  • Multiple layers of any material meeting Hard Body Impact Level 3
• Concrete or masonry walls automatically meet these requirements.
• Sprayed Fire-Resistant Materials (SFRM) must meet specific bond strength requirements:
  • ≥ 430 psf for buildings ≤ 420 feet
  • ≥ 1,000 psf for buildings > 420 feet

​Fire Sprinkler Systems

High-rise buildings must be fully sprinkler-protected per NFPA 13. Additional fire suppression measures include (IBC 403.3):

• For buildings > 420 feet:
  • A minimum of two sprinkler risers, supplying alternate floors, located in separate exit stairs.
  • Fire pumps must be supplied by at least two water mains from different streets (or two connections to one main with isolation valves).
• Seismic Design Categories C, D, E, or F: A secondary on-site water supply is required.

​Fire Alarm and Smoke Detection Systems

Fire detection and alarm systems play a big role in the safety of high-rise buildings. Key requirements include (IBC 403.4):

• Smoke detection in mechanical, electrical, and transformer rooms not protected by sprinklers.
• Smoke detection in elevator machine/control rooms and lobbies.
• Duct smoke detection required in:
  • Return/exhaust plenums of HVAC systems > 2,000 CFM.
  • Each return connection to duct risers serving two or more stories.
• Emergency voice/alarm communication system required.

Fire Department Response

High rise buildings pose a unique challenge to responding fire departments. To assist local fire departments, the following features a required:

• A Fire Command Center (FCC) is required to centralize emergency response operations.
• Post-fire smoke removal must be provided through either operable windows/panels or a mechanical system.
• Fire department communication system required (emergency responder radio enhancement or wired system where approved).
• A standpipe system is required

Egress and Stairway Design

Ensuring proper means of egress is critical in high-rise buildings. The IBC includes the following key stairway requirements:

• At least two interior exit stairs must be 30 feet apart or ¼ of the diagonal distance of the area served.
• For buildings > 420 feet (except Group R-2): An additional exit stair is required beyond the base requirements of IBC Chapter 10. An occupant evacuation elevator can be provided instead of this extra stair.
• Stairway doors may be locked from the stair side if they can be unlocked simultaneously from the Fire Command Center. Two-way communication devices required at every fifth floor if stairway doors are locked.
• Smokeproof enclosures required for interior exit stairs serving floors > 75 feet above fire department access. This is most commonly achieved by stairway pressurization, but can also be done using other methods.
• Luminous egress path markings required in Group A, B, E, I-1, M, and R occupancies.

Elevator Requirements

Elevators play a key role in both evacuation and firefighter access in high-rise buildings. The 2021 IBC requires:

• For buildings > 120 feet: At least two fire service access elevators (or all elevators must meet fire service access requirements).
  • Each elevator must have a minimum capacity of 3,500 pounds.
  • Elevators must have lobby and direct stair access per IBC 3002.4.
• Occupant evacuation elevators are permitted as an alternative to an additional exit stair in buildings > 420 feet.

Emergency Power and Fire Command Center

To support critical life safety systems, high-rise buildings must have emergency power systems:

• Generators must be housed in a 2-hour rated room, with fuel lines protected in 2-hour enclosures or by other approved methods.
• Emergency power must be provided for additional required systems, including fire alarms, elevators, and life safety systems.

Conclusion

High-rise buildings are among the most complex structures from a code compliance perspective. The 2021 IBC outlines extensive requirements covering construction type, fire protection, egress, elevators, and emergency systems. While some provisions allow for flexibility, such as fire resistance reductions and alternative egress solutions, most of these requirements are above and beyond what is required in smaller building. Understanding and integrating these high-rise requirements early in the design process helps streamline approvals and avoid costly redesigns.

Free High Rise Code Requirements Cheat Sheet