Fire Wall Use for “MAQ Control Areas” has been greatly expanded!

The 2021 International Building Code (IBC) has revised how firewalls can be used to establish “control areas” within a structure. 

Section 414.2.3 Number states:

Occupancy classifications of buildings containing HAZARDOUS MATERIALS are based on the maximum allowable quantities (MAQs) concept. The maximum amounts are identified for the various hazardous materials based on various conditions. Where the MAQ is exceeded, the uses are to be classified as Group H occupancies.

In those cases where the amounts do not exceed the MAQs, a classification other than Group H that best represents the building’s use is assigned. It is often quite desirable to the designer that an occupancy classification of other than Group H be assigned due to the restrictive nature of the code when it regulates high-hazard uses. A fundamental method of maintaining a non-Group H condition is the creation of control areas. CONTROL AREAS are portions of a building that contain hazardous materials that do NOT exceed the MAQs and are separated from other areas containing hazardous materials by fire-resistant construction.

Any combination of hazardous materials, up to the MAQs, is permitted in a control area. The intent is that each control area is regulated for MAQs rather than the building as a whole, thereby increasing the amounts of hazardous materials that can be present without triggering a Group H classification. However, there is a limit to the number of control areas that can be created in a building, as set forth in Table 414.2.2.

For example, NO MORE THAN four control areas can be provided in a single-story building. Therefore, a Group H classification will be mandated where the quantities of hazardous materials require creating MORE THAN four (4) control areas.

Using one or more firewalls to create separate buildings is NOW APPLICABLE TO THE CONTROL AREA CONCEPT, allowing the permissible number of control areas to be increased. Where a structure is divided into separate buildings through the use of complying firewalls, each such separate building may now contain the maximum number of control areas permitted by Table 414.2.2.

This application of the separate building concept is VERY LIMITED. Section 503.1 mandates that a firewall only creates separate buildings for the purposes of determining area limitations, height limitations, and type of construction. This very short list, which reflects the scoping limitations of a fire wall’s use to create separate buildings, has been expanded
through a new allowance applicable to the limitation on the number of control areas permitted. As a result, an increased amount of hazardous materials may now be present without classification as a Group H occupancy, where firewalls divide a structure into separate buildings.

Source: https://www.iccsafe.org/ (may require membership in ICC)