Gregory Harrington

#101Wednesdays - Life Safety Basics in Assembly Occupancies

Blog Post created by Gregory Harrington Employee on Dec 7, 2016

Welcome to premier edition of #101Wednesdays (with apologies and all credit to my colleague, Kristin Bigda, who inspired me with her weekly posts on NFPA 1 in #FireCodeFridays (be sure to follow her @KristinB_NFPA). Each week I’ll explore an issue related to NFPA 101, Life Safety Code, and hopefully generate some discussion. My goals are to share some of what I’ve learned working with the Code over the last 20 years, and also to learn from you, the usersin the real world. This is a two-way street. I’m looking forward to getting the conversation started.


In this edition, in the wake of last week’s tragic Oakland warehouse dance party fire that claimed 36 lives, I’ll review some of the basic NFPA 101 requirements for assembly occupancies. The first thing that is important to understand is, “What exactly is an assembly occupancy?” The Code defines an assembly occupancy as an occupancy (1) used for a gathering of 50 or more persons for deliberation, worship, entertainment, eating, drinking, amusement, awaiting transportation, or similar uses; or (2) used as a special amusement building, regardless of occupant load ( – references are to the 2015 edition of NFPA 101). For this discussion, I’ll focus on Item (1) in the definition, which is a “typical” assembly occupancy. Item (2) refers to things like haunted house attractions, and the like. Based on the definition, two criteria must be met for an occupancy to be classified as assembly: there must be 50 or more people, AND they must be collocated in the occupancy for one of the specified purposes (deliberation, worship, entertainment, eating, drinking, amusement, awaiting transportation, or similar uses). If 50 or more people are working in a densely occupied call center, it’s most likely a business occupancy based on its use. If there are 50 or more people in a large conference room, that is an assembly occupancy. The 50-person threshold is determined based on the calculated occupant or the actual expected number of occupants, whichever is GREATER ( With the occupancy classification established, let’s look at some of the basic life safety requirements.




The importance of providing adequate means of egress from assembly occupancies can’t be overstated. For new assembly occupancies, the general rule is at least two means of egress are needed for not more than 500 occupants; three are needed for 501 to 1,000 occupants; and four are needed for more than 1,000 (7.4 and For existing assembly occupancies, two means of egress are good for up to 600 occupants; the other thresholds are the same as for new assembly occupancies (13.2.4). Early reports indicate the second floor performance space in the Oakland warehouse was accessed by a single, makeshift stair. NFPA 101 would have required, in all likelihood, at least two stairs because of the strict 20 ft common path of travel limit for egress paths in assembly occupancies serving more than 50 people ( and


In addition to adequate numbers of means of egress, sufficient egress capacity (width) is needed. As a Boston area native, I make an analogy to the old Central Artery, which was an elevated highway that snaked its way through Downtown Boston. Before the infamous “Big Dig,” I-93 was a relatively wide, three- and four-lane highway north and south of Boston. Where the highway hit the city, however, it narrowed down to two lanes in each direction. This narrowing resulted in traffic jams, day in and day out. The same phenomenon exists where occupants attempt to egress through a relatively narrow doorway or via a stair. The reduction in egress width results in queuing; the wider the opening, the shorter the wait time to move through the opening. Section 7.3, 12.2.3, and 13.2.3 provide all the details on means of egress capacity. If insufficient capacity is provided, the occupant load must be carefully controlled to prevent overcrowding and exceeding the available egress capacity, or additional egress capacity must be provided.


An additional egress consideration is the main entrance/exit. People will have a natural tendency to try to go out the way they came in. In an emergency, if everyone makes their way to the main entrance/exit, the evacuation can be significantly delayed. For this reason, the Code requires the main entrance/exit to be sized to accommodate at least half of the occupant load. For certain new assembly occupancies, such as nightclubs, the main entrance/exit needs to accommodate at least two-thirds of the occupant load ( & (The two-thirds criterion was added to the Code following the 2003 fire that killed 100 concertgoers at The Station nightclub in Rhode Island.)




New assembly occupancies are required to be protected by automatic sprinklers where the occupant load exceeds 300. In addition, any new nightclub-like assembly occupancy must be provided with sprinklers if the occupant load is 50 or greater. For existing nightclub-like assembly occupancies, sprinklers are required if the occupant load is greater than 100. Otherwise, sprinklers are required for existing exhibition facilities that are more than 15,000 ft2 in area. Fire alarm systems are required in both new and existing assembly occupancies with an occupant load exceeding 300, and in theaters with more than one audience-viewing room. The alarm system is required to alert personnel at a constantly attended receiving station for the purpose of initiating an emergency response. Alternatively, the system is permitted to automatically provide voice notification to the occupants. There are some exceptions to and variations of the sprinkler and fire alarm requirements for assembly occupancies; see 12.3.4, 12.3.5, 13.3.4, and 13.3.5 for all the details.




ALL assembly occupancies must be provided with at least one trained crowd manager to facilitate an orderly response to an emergency (12.7.6 & 13.7.6). (There is an exception for assembly occupancies used for religious worship with an occupant load of not more than 500.) Additional crowd managers must be provided where the occupant load exceeds 250 at a ratio of one crowd manager for every 250 occupants. Guidance on the required crowd manager training is provided in Annex A of the Code (A. and A. Crowd managers are an integral component of the life safety package prescribed by the Code for an assembly occupancy and should not be overlooked. Organizations such as the International Association of Venue Managers offer online training for trained crowd managers and crowd manager supervisors; go to for details.




The life safety criteria for assembly occupancies prescribed by NFPA 101 that I’ve described here is only the tip of the iceberg. The Code has much more: interior finish regulations; vertical opening protection; emergency lighting; construction limits; seating arrangements; I could go on for days! (In fact, I frequently do when I instruct NFPA’s three-day Life Safety Code Essentials seminar.) But hopefully this brief review helps you gain an understanding of some of the basics. It’s still early in the Oakland fire investigation, but I won’t be surprised if some, if not all of the items described here were missing.


Let me know what challenges you encounter related to assembly occupancies. If we can keep the discussions going, and continue to raise awareness, maybe we can help to prevent future tragedies like the one we witnessed in Oakland last week. Check out my earlier blog post about the unsettling 13-year trend of large loss-of-life assembly occupancy fires. I hope you’ll return next week for another edition of #101Wednesdays. Until then, stay safe.


Did you know NFPA 101 is available to review online for free? Head over to and click on “Free access to the 2015 edition of NFPA 101.”