NFPA and IBC Occupancy Classifications when Hazardous Materials are Present
Hazardous materials are those chemicals or substances that are classified as a physical hazard material or a health hazard material (see this blog for more information). There's often some confusion around what the appropriate occupancy classification is when hazardous materials are present. Unfortunately, there isn't a straight answer. It is going to depend on what code is applicable in your particular situation. This blog is going to take a closer look at the differences in occupancy classification when using NFPA Codes and the International Building Code (IBC). For some basic information regarding the differences in occupancy classification check out this blog. Before digging into the actual differences between the codes it's helpful to understand the concepts of maximum allowable quantity (MAQ) and control areas. Although NFPA Codes and the IBC both address these concepts in their own documents, the overall approach is similar. For a closer look at how to determine a MAQ using NFPA 1, Fire Code, be sure to look at this blog.
One of the major differences between the way the IBC and NFPA codes address occupancy classification for spaces using hazardous materials, is the actual creation of a unique occupancy classification within the IBC. NFPA codes do not create a separate occupancy classification specific to hazardous materials. Instead, regardless of whether they contain hazardous materials or not, all buildings are given an occupancy classification(s) based on how the space is being used and the expected characteristics of the occupants. Then, if the building contains hazardous materials additional provisions must be met. If the hazardous materials in a given control area exceed the MAQ, additional protections are required. These are called Protection Levels and they range from Protection Level 1 to Protection Level 5. It is important to note that although a building must comply with the additional protection levels, the occupancy classification itself does not change. This means when the MAQ is exceeded and NFPA documents apply, you are required to comply with both the requirements specific to that occupancy as well as the appropriate protection level requirements for that hazardous material.
NFPA Approach- Protection Levels
Features for Protection Level 1 through Protection Level 3 are intended primarily to provide protection from physical hazards.
Protection Level 1 is the highest level of protection. This protection level is required when high hazard Level 1 contents exceed the MAQ. These materials are unstable and can pose a detonation hazard. Examples of high hazard level 1 contents include Class 4 oxidizers; detonable pyrophoric solids or liquids; Class 3 detonable and Class 4 unstable (reactive) solids, liquids, or gases; and detonable organic peroxides. This protection level requires that the materials be stored in a one story in height, detached building that is used for no other purpose.
Protection Level 2 is designed to limit the spread of fire from materials that deflagrate or accelerate burning. Additionally, the protection features are designed to limit the potential for fire to spread from an outside source and affect the hazardous materials in the building. This protection level is required when high hazard Level 2 contents exceed the MAQ. These materials present a deflagration hazard or a hazard from accelerated burning. Examples of high hazard Level 2 contents include Combustible dusts that are stored, used, or generated in a manner that creates a severe fire or explosion hazard; Class I organic peroxides; flammable gases; nondetonable pyrophoric solids, liquids, or gases; and Class 3 water-reactive solids and liquids.
Protection Level 3 is one of the most common protection levels encountered in the general inspection of storage and industrial operations that use hazardous materials. These types of operations and storage facilities normally operate with amounts of hazardous materials greater than the MAQ while conducting business. This protection level is required when high hazard Level 3 contents exceed the MAQ. These materials readily support combustion or present a physical hazard. Examples of high hazard level 3 contents include Class IIA, Class IIB, and Class III organic peroxides; Class 2 solid or liquid oxidizers; Class 2 unstable (reactive) materials; and oxidizing gases.
Protection Level 4 is intended to mitigate the acute health hazards resulting from the storage, use, or handling of high hazard Level 4 materials. These contents include corrosives, highly toxic materials, and toxic materials. The objective is to protect evacuating occupants and arriving first responders from being injured by these hazardous materials.
Protection Level 5 applies to semiconductor fabrication facilities. Buildings that require Protection Level 5 must comply with NFPA 318, Standard for the Protection of Semiconductor Fabrication Facilities.
The IBC uses a High-Hazard Group H, occupancy classification for buildings that, among others, manufacture, process, generate, or store hazardous materials in excess of the MAQ in a control area. There are 5 sub-categories within the High Hazard Group H occupancy, H-1 through H-5 which closely resemble the protection levels in NFPA documents.
IBC Approach- Occupancy Subclassifications
- H-1 is the subclassification for buildings that contain hazardous materials that pose a detonation hazard.
- H-2 is the subclassification for buildings that contain hazardous materials that pose a deflagration hazard or a hazard from accelerated burning.
- H-3 is the subclassification for buildings that contain hazardous materials that readily support combustion or that pose a physical hazard.
- H-4 is the subclassification for buildings that contain hazardous materials that are health hazards.
- H-5 is the subclassification for semiconductor fabrication facilities and comparable research and development areas.
Although at first glance it seems like NFPA and the IBC handle things extremely different, the overall concepts are actually not all that different. The IBC creates an entirely separate occupancy classification while NFPA uses protection levels. In both cases, compliance with additional provisions is going to be required to minimize the risk associated with the presence of hazardous materials in those quantities.