#101Wednesdays: Since multiple-occupancy buildings lead to multiple questions and interpretations, who’s right?

Blog Post created by gharrington Employee on Nov 8, 2017

Image: Wikimedia Commons

Over the 20+ years I’ve been working with  NFPA 101, Life Safety Code, the concept of multiple-occupancy buildings hasn’t been all that controversial. In fact, I’d go so far as to say it’s been relatively straightforward—until recently.

Over the past couple weeks, I’ve seen a spate of questions relating to buildings with multiple tenants having the potential for different occupancy classifications. I’ve also seen some interpretations from authorities having jurisdiction (AHJs) that don’t align with the code’s intent. While I recognize that the AHJ has the final say with regard to code interpretation, it doesn’t make an incorrect interpretation right. I don’t like disagreeing with the AHJ; I was one for several years, and I know how difficult the job is given the volume of work and limited resources. AHJs take their responsibilities very seriously; after all, the safety of the public and emergency responders is in their hands. But my job is to educate and inform about the intent of the Life Safety Code, and when I know it is being misapplied, I have a duty to share that information.

NFPA is transforming from a codes-and-standards organization into a knowledge-and-information organization. Here is some knowledge and information to help everyone get on the same page with regard to multiple-occupancy buildings.

Occupancy classification is addressed in Section 6.1 (all references are to the current 2018 edition). The term “multiple occupancy” has the following definition: Multiple Occupancy. A building or structure in which two or more classes of occupancy exist.

NFPA’s headquarters in Quincy, Massachusetts is an example of a multiple-occupancy building. Our building contains offices (business occupancy) and a cafeteria with an occupancy load of more than 49 persons (assembly occupancy).

Where a building contains multiple occupancies, it must comply with the requirements for mixed occupancies in or the requirements for separated occupancies in, as prescribed by Here is the key takeaway: use of the separated-occupancy criteria is not mandatory unless specified by another section of the code. This occurs only in a few instances. For example, a health care occupancy (e.g., a hospital or nursing home) is permitted to be in a building containing other occupancies only when it is separated from the other occupancies by a two-hour fire barrier (see Chapters 18 and 19 for details). Even if a building looks like it contains multiple-separated occupancies, nothing prohibits it from being classified as a multiple-mixed occupancy as long as all of the occupancies comply with the most restrictive requirements of the occupancies involved, unless separate safeguards are approved, as stated in

Conversely, situations exist where the code mandates the use of the multiple-mixed occupancy provisions. Where multiple occupancies lack separation by fire barriers (occupancy separations) as required by, the occupancies are mixed by default. Also, where multiple occupancies share common exit access travel paths (e.g., corridors) as described in, the occupancies are mixed. Note that multiple-separated occupancies are permitted to share common exits (e.g., stair enclosures). Let’s take a closer look at Where exit access from an occupancy traverses another occupancy, the multiple occupancy shall be treated as a mixed occupancy.

I’m aware of a jurisdiction extrapolating this to mean where exit access from an occupancy does not traverse another occupancy, the multiple occupancy must be treated as a separated occupancy. This is not the case; the code doesn’t work like that. If that was the code’s intent, it would specifically say so, and it does not. Part of the confusion arises from the definition of “mixed occupancy” and the use of the undefined term “intermingled”: Mixed Occupancy. A multiple occupancy where the occupancies are intermingled.

What constitutes intermingling of occupancies? Based on the mandatory requirements in the code, intermingling occurs where multiple occupancies share exit access paths or lack occupancy separation fire barriers, or both. The definition describes a condition resulting from the mandatory code provisions.

As an example, consider the generic “strip mall” depicted in the accompanying figure. This is a classic example of a multiple-separated occupancy building provided that the partitions separating the different tenants are fire barriers meeting the requirements of

Also, each tenant space is provided with independent exit access. As a result, the code’s requirements for each occupancy are applied independently. If the space identified as an assembly occupancy is a new nightclub, it requires automatic sprinkler protection ( If the occupancies are separated, the code requires the installation of an automatic sprinkler system only in the assembly occupancy; the other occupancies would be permitted to remain nonsprinklered.

But does anything require these occupancies to be separated by fire barriers? The answer is no as long as each occupancy meets the more restrictive requirements of the occupancies involved. It’s less expensive to build non-rated partitions to separate the tenant spaces. If the owner can show that the entire building meets the most restrictive requirements, they have the right to use the mixed occupancy provisions even though the occupancies are separated by non-rated tenant separations and have independent exit access.

I suspect this is really an enforcement issue. Once the building is constructed with non-rated tenant separations, it might be challenging for the AHJ to enforce the separation requirements when a tenant comes along that impacts the other tenants or needs to be separated so as to not adversely impact the other tenants (e.g., the previously described nightclub). In my experience, this needs to be addressed at the permitting stage. Building permits for “speculative-use” buildings (i.e., the occupancy classification is unknown) should be for the “shell building” only. Certificates of occupancy should only be issued once the occupancy classification is known and inspected. Subsequent certificates of occupancy should be issued only after being reviewed by the AHJ whenever a change of occupancy classification occurs as required by NFPA 1, Fire Code. If the shell building tenant separations are to be non-rated, make it clear in the permit process that additional protection in the form of occupancy separation fire barriers might be required depending on the occupancies ultimately present.

If the building owner chooses to go this route, it’s their problem down the road if upgrades are needed. An example: I once had the pleasure of telling a tire storage facility that their occupancy wasn’t permitted in a spec-use warehouse protected by an ESFR sprinkler system that wasn’t designed to protect the hazard – after they had moved in. Good times. The job of the AHJ isn’t always sunshine and lollipops. I’m sure there were some animated meetings between the owner and the tenant after I broke the bad news. Buyer beware.

It’s important for developers and AHJs to work together to achieve a safe building design. The mixed- and separated-occupancy protection strategies are both safe, and the owner has the right to choose which one works best for their building unless the code explicitly mandates the use of one or the other based on the arrangement or occupancies involved. I know this will put me in the doghouse with at least some jurisdictions, but I didn’t take this job to be popular. You can relate to that, right AHJs? Hopefully we’re all on the same page now. #InfoKnowledge

Thanks for reading, and as always, stay safe.

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