Is My Building a High-Rise?

Is my building a high-rise?

By Steven Dannaway, PE, DBIA | Managing Principal, Fire Protection Engineering, Los Angeles

A high-rise building classification triggers several different fire protection and life safety requirements for a building per the 2024 International Building Code (IBC) Section 403. It is important that design teams properly determine the low-rise or high-rise classification when considering the cost impact and design complexity introduced by a high-rise building classification.

Is My Building a High-Rise?

Chapter 2 of the 2024 IBC defines a high-rise building as:

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

Two pieces of information are necessary to determine a high-rise classification. These two elevations are described in this article.

1. Elevation of the highest occupied floor level or the highest occupied roof level of the building.
2. Elevation of the lowest level of fire department vehicle access.

2024 IBC Code Change: A code change was approved for the 2024 IBC that will include “occupied roofs” in the definition of high-rise buildings. This change will remove the ambiguity surrounding occupied roofs and whether they contribute to the high-rise building height measurement.

Upper Measurement

The upper elevation of the measurement is taken to the floor elevation of the highest occupied floor or occupied roof. The key distinction is that the level must be “occupied.” Mechanical equipment floors, mechanical equipment penthouses, and unoccupied roofs are examples of “unoccupied” areas of the building. The high-rise measurement would not consider floors or roofs with these types of unoccupied uses.

In past code cycles, it was open to debate whether an occupied roof contributed to the high-rise building measurement. This ambiguity was removed in the 2024 IBC with the modification to the definition of “high-rise buildings.” New projects under the 2024 IBC need to factor this code change into their project planning. For projects under earlier code editions, it would not be surprising to encounter a project that designed the highest occupied floor level to be at 74 ft to maintain a low-rise classification. For example, a seven-floor elevation in a multi-family apartment building may have a roof deck with a pool on top of Level 7 with a roof elevation of 85 ft. Under prior code cycles, this approach would qualify as a low-rise building classification in many jurisdictions. Projects that fall under the 2024 IBC would need to classify this same building as a high-rise building.

Lower Measurement

The lower elevation of the measurement is taken from the lowest level of fire department vehicle access. When the building site is flat, this measurement is straightforward. On sloped sites with varying grade elevations around the perimeter of a building, it may not be clear which elevation qualifies as the lowest level of fire department vehicle access. One example is where a basement level daylights at a loading dock, which is accessed by a service road/fire access road that slopes down from the site fire access road at Level 1. The primary fire department access roads are at the street level; however, the lowest level of fire department access could be argued to be the basement level elevation.

Project teams should consult the local fire code official to determine from which elevation the high-rise measurement should be taken. Considerations may include the location of aerial apparatus roads, the primary staging locations of the fire apparatus, enforcement by the local fire code official, hose pull coverage, and general fire access coverage around the building’s exterior perimeter.

What Does This Mean for My Building?

High-rise buildings potentially require added fire/life safety features, which may include but are not limited to a fire command center, pressurized stairways, a fire pump, a secondary water storage tank, fire service access elevators, or luminous egress path markings, among other code requirements. It is important that design professionals understand how to determine if a high-rise classification is triggered so that the appropriate fire/life safety features can be incorporated into the building design. Projects subject to the 2024 IBC must consider the new code change and the impact of occupied roofs on a potential high-rise building classification.

For more information, contact Steven Dannaway, PE, DBIA.