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Dead End Corridor in a Mixed Occupancy Building

M

MKALLAY

Registered User
Joined
Oct 4, 2022
Messages
27
Location
New York NY
I have a question regarding allowable dead end corridor length in a mixed occupancy building. Here is the scenario:

  • The project is located in Tennessee, and falls under the Tennessee State Building Code (IBC 2012)
  • The project is higher education, so generally classified as B occupancy, but also contains lecture rooms over 50 occupants - A occupancy. The building is mixed use, unseparated.
  • There are corridors and circulation spaces that serve both occupancies. There are also some corridors that are contained within segregated suites (e.g., faculty offices) that do not serve assembly occupancies.
  • The building is fully sprinklered.

My understanding of the Code is that the corridors must conform to the requirements per the occupancies served. Section 1018.4 generally requires that dead end corridors shall not exceed 20', but allows the 50' exception for B occupancies in a sprinklered building. I am therefore reading that all corridors which serve the assembly occupancies should confirm to the 20' maximum. Corridors within suites limited to business occupancies may be 50'.

On the other hand, I have a designer who is making the case that in a mixed occupancy building, corridors are included in the gross area of the business occupancy, and therefore all corridors are classified as B occupancy and subjected only to the 50' restriction.

Which interpretation is correct here? And, if the requirement applies on the basis of the spaces served - where do I find the reference in the Code that will confirm this? (I am looking at the top of the chapter, Section 1001.1, which generally states that "Buildings or portions thereof shall be provided with a means of egress system as required by this chapter", but this seems a little vague).
 
I have done a lot of higher education work, and here is how I typically address this type of situation.

If the floor is predominately of Group B occupancies with a few Group A occupancies, I typically include the corridors within the Group B occupancy, but the corridors must still conform to the more restrictive requirements for Group A occupancies because they serve the Group A occupancies.

If the floor is predominately of Group A occupancies, I would include the corridors within the Group A occupancy, which makes it easy in determining which requirements apply to the corridors.
 
OK, I think I've found the Code passage I'm looking for - This is found in kind of an obscure location (it is in Section 1004, pertaining to Occupant Load), but I think the meaning is quite clear:

1004.6 Multiple Occupancies

Where a building contains two or more occupancies, the means of egress requirements shall apply to each portion of the building based on the occupancy of that space. Where two or more occupancies utilize portions of the same means of egress system, those egress components shall meet the more stringent requirements of all occupancies that are served.

I think it is clear, this passage refers to the entire means of egress system, which would include the exit access components (i.e., corridors) that provide a means of egress from a space.
 
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