Occupant Load and Means of Egress

[Michael.L]

I'm trying to determine the minimum width of a service corridor serving the "back of house" for two restaurants. This property is in a city that is currently operating under the 2015 International Building Code, although the building was constructed back in the 1980's.

The two restaurants are located in a ground-level indoor mall that has both retail and office spaces. The service corridor extends from the mall's ground-level loading/service dock to the central public space in the mall's interior. However, there is no public access to the service corridor (there is a combination lock on the door that connects the corridor to the public space) and it is not marked as an emergency exit. So the only persons with normal access to this service corridor are the staff of the two restaurants via the back doors from the restaurant's respective kitchen areas.

Restaurant #1 is large: it used to be two restaurant spaces that were combined into one. The total occupancy rating is 273. This restaurant shares an exterior wall of the building and the public has access to the restaurant via doors that open out to the exterior (private parking lot) and via doors that open into the mall's interior public space. This restaurant is counter service only with some outside seating; the majority of its space is occupied by kitchen, counter display, and storage. There are two back doors for staff into the service corridor.

Restaurant #2 is small. The total occupancy is 13. It is located entirely within the interior of the mall. This restaurant is also counter service only. Customers enter from the mall's interior public space via a pair of double doors. There is a single back door for staff into the service corridor.

For sizing the minimum corridor width and capacity, I believe I refer to 2015 IBC Section 1020.2. Table 1020.2 specifies a minimum width of 44 inches for "facilities not listed below" (none of which apply). However, Section 1020.2 also stipulates that the required capacity of corridors shall be determined as specified in Section 1005.1. There, we find that Section 1005.2.3 specifies that the capacity, in inches, shall be calculated by multiplying the occupant load served by a "means of egress capacity factor" of 0.2 inch per occupant. An exception is made that allows the use of an egress capacity factor of 0.15 inch per occupant in buildings equipped with automatic sprinkler systems and "an emergency voice/alarm communication system in accordance with Section 907.5.2.2." This building does have an automatic sprinkler system, but the fire alarm system is siren/horn only; no voice announcement system (I believe the building is grandfathered under a an older building code). In any case, I suspect the 0.15 inch per occupant capacity factor cannot be used.

My first question is, what number must I use for the "occupant load served by the means of egress." Do I use the total combined occupant loads of the two spaces (273 + 13) even though restaurant customers cannot normally get to this service corridor? If I were to use the total combined occupant loads, then 286 occupants multiplied by 0.2 inch per occupant would mean the minimum corridor width requirement would be 57.2 inches. Is this correct?

At this point, you're probably wondering why I want to calculate the minimum corridor width and capacity since the building (and corridor) is already built and both restaurants were approved by the city's Building Department and have been built-out and operating for well over a year. The reason is, when the owners of these two restaurants signed their leases (at about the same time), they were both told by the previous property owner that they could set up storage shelving in the service corridor along one wall. However, the new property owner recently sent an email to all the tenants instructing them to remove everything from the service corridor to allow emergency egress. Part of the problem is that employees of restaurant #1 were piling bags of trash in the clear area of the service corridor throughout the day. Also, some of their kitchen staff would eat meals in the corridor and leave chairs and junk in the service corridor's clear area. Because of their messiness, the new owners told everyone to clean out and remove everything, which was an overreaction IMO.

The service corridor width is 95 inches, but with the shelving in place, the available clear width without obstruction is 58.5 inches. So I believe that, even when using the total combined occupant loads, this clear width is acceptable and meets code requirements (assuming the employees of restaurant #1 are made to clean up their act).

To back up my assessment, I found a PDF document listed as "IBC Interpretation 06-11" (based on the 2009 IBC) that had the following Q & A:

Q: Are combustible, nonhazardous items such as tables, chairs, vending machines, furnishings, fixtures, displays,
etc. permitted to be located within an exit access corridor provided the minimum width of the exit access corridor is
maintained?

A: Yes. Sections 1005.1 and 1018.2 specify the required minimum width for corridors. If this clear width is available
without obstruction, design is acceptable in accordance with Section 1018.3. An obstruction to egress travel is not
created unless an object is placed or located within the required egress width.

My second question is, am I correct in determining that 58.5 inches of clear width meet the code requirements for means of egress?

 

[TheCommish]

A drawing would be helpful

 

[Jay Smith]

I suggest checking the section on covered malls in 2015 IBC Chapter 4. The UBC in the 1980s also had a section on malls. The occupant load in a mall is based on GLA and goes to the malls exits and exit passageways, which are required to be at least 66 inches in width. It sounds like at your property maybe they’ve locked an exit passageway.

 

[Michael.L]

A drawing would be helpful

I'm not exactly sure how a drawing would be helpful; perhaps I've made this too complicated by providing too much information. Basically, we're dealing with a straight corridor, running east/west that is 95 inches wide. Along the south lengthwise wall, are free-standing storage shelves that reduce the clear area width of the corridor to 58.5 inches.

My questions are:

1. Do I use the total rated occupancy load of the two restaurants to calculate the required clear width of this corridor? It seems counterintuitive to do so since only the back-of-house staff of the two restaurants have free access to the back doors that exit into this corridor. (And that's ignoring the fact that there's no way that restaurant #1 will ever contain more than a small fraction of its rated capacity of 273 occupants.) On the other hand, how do we determine a lesser number to use? I don't think there's anything in the code for splitting the total occupancy based on the distribution of persons throughout a facility.

2. Am I interpreting the relevant sections of the code in coming up with a calculated clear width of 57.2 inches for this corridor?

 

[Michael.L]

I suggest checking the section on covered malls in 2015 IBC Chapter 4. The UBC in the 1980s also had a section on malls. The occupant load in a mall is based on GLA and goes to the malls exits and exit passageways, which are required to be at least 66 inches in width. It sounds like at your property maybe they’ve locked an exit passageway.

This corridor is not, nor has it ever been, an emergency exit passageway for the general public area of the mall. It is simply a service corridor for maintenance personnel and for commercial tenants to access the loading dock area of the building (e.g., for receiving deliveries, taking out garbage, etc.).

My question is simply about the required clear width of the corridor for occupants of the two restaurants to use in the event of an emergency evacuation.

 

[steveray]

The 13 OL space should not need it as a second MOE; and it sounds like the larger one has an exit to the exterior and one to the interior of the mall, which should be all it needs....Are there exit signs directing people into the "service corridor"?

 

[Paul Sweet]

If the service corridor is only used by back-of-house staff, then the occupant load would be the anticipated number of cooks, waiters, etc., and not the number of customers in the dining area.

I don't think that the Owner's order for everyone to clean out and remove everything was an overreaction, since the tenants were creating unsafe conditions and he couldn't police them.

 

[Michael.L]

The 13 OL space should not need it as a second MOE; and it sounds like the larger one has an exit to the exterior and one to the interior of the mall, which should be all it needs....Are there exit signs directing people into the "service corridor"?

I'm not sure about restaurant #1, but I don't believe so. I know that restaurant # 2 does not have such signage; there is only an exit sign over the main entrance door that leads to the mall's interior public space.

The 13 OL space should not need it as a second MOE; and it sounds like the larger one has an exit to the exterior and one to the interior of the mall, which should be all it needs.

And the smaller one that only has an exit to the interior of the mall?

 

[Michael.L]

If the service corridor is only used by back-of-house staff, then the occupant load would be the anticipated number of cooks, waiters, etc., and not the number of customers in the dining area.

That seems reasonable. But how does one determine that load? Is there a code reference to back this up?

I don't think that the Owner's order for everyone to clean out and remove everything was an overreaction, since the tenants were creating unsafe conditions and he couldn't police them.

While I agree that the staff of restaurant #1 were creating an unsafe condition by leaving obstacles in the clear area (including bags of trash, which is also a health code violation), the appropriate response would be for the owner to demand they remove such obstacles and maintain the required clear width within the corridor. Demanding that the storage shelves also be removed is clearly an overreaction and is probably due to a lack of understanding of the code requirements. Hence the reason for this post.

 

[Jay Smith]

Here’s my take on it. If I’m wrong, someone please correct me.

2015 IBC 1005.5 requires that the loss of one exit must not reduce the exit capacity to less than 50 percent of the required capacity. That tells me one exit from the restaurant is not responsible for the entire restaurant occupant load.

Assuming at least 32 inches clear at each door, there is capacity of at least 160 occupants at the exterior door and at least 160 at the door into the mall. There would be no need for a width calculation at the corridor, although it does have a minimum width in 1020.2.

The occupant loads that exit into the mall are like those of the other stores. They go to the mall exits that should be sized based on an occupant load for the mall.