Occupancy calc of a university classroom?

[Arch_teach]

Hypothetical question for an academic project, seems to be a gray zone to clarify.

I instruct an integrated design studio for professional architecture degree. Normally I'm clear on the code, but a question has come up I'm unclear on. Project is a classroom building on a college campus.

The IBC classifies adult education facilities such as colleges and universities as B occupancies. In adult education facilities, however, the IBC changes the occupancy classification from B (classroom) to A-3 (lecture hall) if the occupant load of the classroom exceeds 49.

For classrooms, IBC Table 1004.1.2 provides an occupant load factor of 20 square feet per person for exiting purposes. The Table does not list a category for large classrooms, but using the Assembly category, without fixed seats, unconcentrated (tables and chairs), one could determine the occupant load for such a lecture hall at 15 square feet per person.

So the question is >What is the transition border? Using 20per, a classroom would hit 50 occupancy at 1000sf; but 15per would mean hitting 50 occupancy at 750sf. Which is the better number to use? This has a big potential impact on student projects, both in terms of occupancy and in number of room exits. I wasoriginally going by the 20per, but then had doubts.

Any advice would be appreciated.

 

[RLGA]

Occupancy classification per Chapter 3 and function of space per Table 1004.1.2 are different things. Use Table 1004.1.2 to identify how the space is used and not how it is classified per Chapter 3.

A classroom in a college still uses 20 sq. ft. per occupant for "Classroom area" per Table 1004.1.2, but could be classified as a Group B if the occupant load does not exceed 49.

 

[ChrisCampbell]

Agree with RLGA!

 

[Arch_teach]

Occupancy classification per Chapter 3 and function of space per Table 1004.1.2 are different things. Use Table 1004.1.2 to identify how the space is used and not how it is classified per Chapter 3.

A classroom in a college still uses 20 sq. ft. per occupant for "Classroom area" per Table 1004.1.2, but could be classified as a Group B if the occupant load does not exceed 49.

Yes, I agree they are different things. But the change in occupancy TYPE is based on hitting a certain occupancy LOAD. Your last sentence implies you rthink it is the 20per to use up to 1000, I think.

 

[ChrisCampbell]

Yes, I agree they are different things. But the change in occupancy TYPE is based on hitting a certain occupancy LOAD. Your last sentence implies you rthink it is the 20per to use up to 1000, I think.

In my opinion, you would apply 1:20 to the room. If the resulting occupant load is 49 or less, it would be Group B. If 50 or more, it would be Group A-3. The 1:20 would apply regardless of being above or below 1,000 SF in area.

 

[RLGA]

Yes, I agree they are different things. But the change in occupancy TYPE is based on hitting a certain occupancy LOAD. Your last sentence implies you rthink it is the 20per to use up to 1000, I think.

Not quite. You use 20 sq. ft. per occupant up to 49 occupants, or up to 999 sq. ft. I know, there's a debate as to whether you round up or round down--the IBC does not stipulate, but your plans examiner may have an opinion/interpretation. My opinion is there is no such thing as a fractional person, so I always round down.

Regardless, at 1000 sq. ft., the occupant load is 50 and then the space must be classified as a Group A-3.

 

[Arch_teach]

Not quite. You use 20 sq. ft. per occupant up to 49 occupants, or up to 999 sq. ft. I know, there's a debate as to whether you round up or round down--the IBC does not stipulate, but your plans examiner may have an opinion/interpretation. My opinion is there is no such thing as a fractional person, so I always round down.

Regardless, at 1000 sq. ft., the occupant load is 50 and then the space must be classified as a Group A-3.

thank you

 

[Arch_teach]

In my opinion, you would apply 1:20 to the room. If the resulting occupant load is 49 or less, it would be Group B. If 50 or more, it would be Group A-3. The 1:20 would apply regardless of being above or below 1,000 SF in area.

Interesting. The bit I quoted in my original post, about switching to 15per as an assembly / lecture hall, came from City of Phoenix Planning Department guidance. It does lead to a weird transition, where at 999 sf you are under 50 (or at 979 sf if you round occupancy number up). But at 1000 sf the occupancy jumps to 66/67 people due to the 15per taking over.

 

[RLGA]

Interesting. The bit I quoted in my original post, about switching to 15per as an assembly / lecture hall, came from City of Phoenix Planning Department guidance. It does lead to a weird transition, where at 999 sf you are under 50 (or at 979 sf if you round occupancy number up). But at 1000 sf the occupancy jumps to 66/67 people due to the 15per taking over.

Well, I live in Phoenix and they have never enforced that on me and I have done several higher education buildings for the ASU downtown campus and Maricopa County Community College District.

Just because it is a Group A occupancy does not mean you use the assembly occupant load factors--the room is still a classroom. However, if the room is used for any other assembly purpose other than a classroom, then I would agree that one of the assembly occupant load factors would apply.

To paraphrase Shakespeare's Romeo and Juliet, "A classroom by any other name would still be determined at 20 sq. ft. per occupant."

 

[Arch_teach]

Well, I live in Phoenix and they have never enforced that on me and I have done several higher education buildings for the ASU downtown campus and Maricopa County Community College District.

Just because it is a Group A occupancy does not mean you use the assembly occupant load factors--the room is still a classroom. However, if the room is used for any other assembly purpose other than a classroom, then I would agree that one of the assembly occupant load factors would apply.

To paraphrase Shakespeare's Romeo and Juliet, "A classroom by any other name would still be determined at 20 sq. ft. per occupant."

OK. thanks