A Comprehensive Guide to Building Occupancy Classifications

Posted on August 19, 2024August 19, 2024 by Jason Somers

The International Building Code (IBC) has created occupancy classifications that must be followed by builders, fire safety professionals, and architects. These classifications have been put in place to make sure the right safety measures are integrated into each building’s design. For example, the occupancy classification for your building might task you with installing an enhanced fire sprinkler system.

Occupancy classifications effectively separate structures into different types of buildings. Each type of building comes with different safety codes that developers and owners must meet. Before you construct a building, you’ll need to work with local authorities to set the right occupancy classification to ensure the well-being of occupants. This guide provides a detailed understanding of the many different occupancy classifications.

The Role of Building Codes in Occupancy Classifications

Building codes are comprehensive laws that set the minimum requirements for how natural gas units, structural components, and HVAC systems are designed and built in residential and commercial buildings. By following these codes, you can be confident that your building is safe to enter. It’s also important to meet local building codes to avoid the penalties and fines that occur if you don’t.

Each occupancy classification is paired with different building codes. For example, Group H buildings that store or use hazardous materials need to be equipped with advanced fire safety equipment. The organizations and standards that govern occupancy classifications include the International Building Code (IBC) and the National Fire Protection Association (NFPA).

Types of Building Occupancy Classifications

Below is a comprehensive overview of the different types of building occupancy classifications. Keep in mind that buildings can have multiple classifications.

Assembly (Group A)

There are five assembly occupancy subgroups, which include A-1 to A-5. They are classified by how the structure is used. These occupancy classifications include all buildings that are used for meetings and gatherings of people who are taking part in drink consumption, religious functions, or social events. Some examples of assembly buildings include auditoriums, stadiums, arenas, dance halls, theaters, and banquet halls.

The type of activity that occurs in the building determines which subgroup it’s part of. Small conference rooms or coffee shops that maintain an occupant load of 50 people or less don’t need to follow the strictest Group A requirements.

Business (Group B)

Group B is a business occupancy classification that applies to offices or professional settings. These buildings can have spaces for records and accounts storage. Buildings within this category can also be used for academic areas like colleges and universities.

Educational (Group E)

Group E applies to all educational purposes until the 12th grade. As long as classes consist of six or more people who meet for at least four hours a day or 12 hours per week, the building will have a Group E classification. This occupancy type includes daycare facilities, schools, and preschools.

Fire protection is highly regulated to make sure staff members and children are kept safe. Some daycare facilities can be part of Group I-4. However, there’s a substantial difference in fire safety requirements between these occupancy types, which is why it’s important to obtain the right classification.

Factory and Industrial (Group F)

The F-1 and F-2 subgroups involve factory and industrial buildings where items are processed or manufactured. Group F-1 applies to factories with moderate hazards, which means that materials aren’t highly combustible or flammable. Group F-2 involves low-hazard buildings with non-combustible environments. However, safety measures are crucial in both subgroups.

High Hazard (Group H)

Group H consists of five subcategories, which extend from H-1 to H-5. These buildings involve the production, manufacturing, or storage of any materials that have a high potential to cause health issues, fires, or explosions. H-1 is the most hazardous subgroup. All buildings in this group must comply with sprinkler system and fire safety regulations.

Institutional (Group I)

The industrial group includes subgroups I-1 to I-4. The types of buildings that fall under this classification include daycare facilities with over five children, some assisted living centers, prisons, nursing homes, and hospitals. Fire safety planning is a critical component of this classification.

Mercantile (Group M)

Group M applies to all mercantile buildings that sell or display merchandise, such as markets and department stores. Since these settings often consist of numerous combustibles and have high occupancy requirements, the building owners must comply with various life safety and fire requirements.

Residential (Group R)

The residential occupancy type involves subgroups R-1 to R-4. For example, the R-1 subgroup covers all hotels. Single-family homes are part of the R-3 subgroup. The fire safety and design requirements differ based on the classification. Regardless of the subgroup that your building is part of, the fire protection requirements for this group are highly restrictive.

Storage (Group S)

The S-1 and S-2 subgroups include buildings for all types of storage that aren’t considered high-hazard. An S-1 building can be used to house combustible materials, while an S-2 building is meant to be paired with non-combustible items. Your building’s fire protection needs depend on the number of stored items as well as the combustibility of them.

Utility and Miscellaneous (Group U)

Group U covers all utility and miscellaneous buildings. For example, buildings that don’t meet any of the other occupancy classifications will be part of this category. The types of structures that apply include carports, fences that are taller than six feet, and agricultural buildings. Fire protection requirements are typically minimal.

Factors Determining Building Occupancy Classification

Many factors influence the classification of a building, which include the following:

• Building usage and purpose
• Number of occupants
• Hazardous materials storage or use
• Fire safety and egress requirements
• How mixed-use buildings are classified

For example, buildings that store or use hazardous materials will be tasked with following more stringent fire safety guidelines. In mixed-use buildings that have multiple occupancy classifications, the stricter code is often enforced.

Keep in mind that classification is usually determined by the building’s owner as well as the designer and local authorities. Before your building is finalized, the local authorities will perform an inspection to ensure it meets all of the requirements.

Impact of Occupancy Classification on Building Design

Occupancy classification plays a major role in the architectural design of a building. For example, it’s an important part of NFPA 101, which is the Life Safety Code. This code provides a framework that ensures homes and other buildings are constructed with a focus on the safety of occupants.

Each occupancy classification has different requirements for the types of safety measures and fire protection systems that need to be implemented. High-hazard buildings are required to comply with strict fire safety guidelines. Depending on the type of building you’re constructing and the occupancy classification it has, you’ll need to follow specific structural requirements.

For example, each classification can have different load-bearing capacities based on the number of occupants that will be allowed within the building. The occupancy classification of your building can also impact your implementation of accessibility and emergency exits. While many buildings require two emergency exits, high-hazard ones might need more.

Changing or Reclassifying Building Occupancy

There are a couple of scenarios where reclassification might be necessary for building occupancy. For example, if the occupancy use is changing, you’ll likely need to seek reclassification. The same is true if the occupancy group designation has changed. The process for updating a building’s occupancy classification varies based on where it’s located.

Los Angeles only allows a building to be changed from one rating classification to another if the structure is altered to adhere to the requirements of the higher-risk classification by upgrading life safety features. This may not be needed if your building is being reclassified into a lower-risk rating.

If you don’t comply with the new requirements, the city may not accept the reclassification. They’ll perform an inspection after you submit a reclassification application. You’ll receive an inspection report that informs you of any additional corrections that need to be made. Once you comply with all regulations, you should receive a Certificate of Building Compliance. Depending on the scope of the improvements or renovations, you might be tasked with obtaining a building permit during this process.

Common Mistakes and Misconceptions in Occupancy Classification

When you’re designing or planning a building, determining the correct occupancy classification is crucial. One of the most common mistakes involves incorrectly applying a subgroup of a specific classification. As mentioned previously, there are five assembly occupancy subgroups for Group A. Each subgroup can have different requirements for life and fire safety features. A single mistake when determining occupancy classification can create wide-ranging problems with the design of your building and the entire development process.

These misconceptions can lead to non-compliance. If the city discovers the issue, you could be fined thousands of dollars. Accurate classification is necessary to avoid legal and safety problems. For example, let’s say that your building is incorrectly classified, and you end up installing the wrong fire sprinkler system. If a fire occurs, your sprinkler system might not be sufficient to douse the flames. You could then be held liable for any damage and injuries that take place.

Conclusion

Understanding occupancy classifications is crucial when you’re designing and constructing a new building. These classifications are defined by building regulations and are necessary for fire and building code enforcement. The accurate classification of your structure contributes to building safety and compliance. For proper occupancy classification, consult with experienced professionals who can help you achieve and maintain compliance.