Yesterday, I posted a partial floor plan, and I asked some questions to help you put some of what you have learned about codes to use.  I think we could all benefit from the practice.

Spoiler Alert: If you want to look at the original post rather than skipping right to the answers (below), it is here.

Here’s the floor plan for a music classroom in a high school, and the assignment was to answer the questions below using any edition of the International Building Code.

Here are the questions, along with the answers (click the links for more info and code references):

A) What is the calculated occupant load of this classroom?

To calculate the occupant load of a room or space, you take the area and divide by an occupant load factor.  The IBC lists these factors in a table, and the factor for educational classrooms is 20 square feet per person.  The area of this room is 1,120 square feet (40′ x 28′), and the occupant load is 56 people (1,120 square feet / 20 square feet per person).  Finding the occupant load is the first step to answering the other questions.

There were some questions about whether maybe an occupant load factor for assembly occupancies should be used, or whether the chairs should be counted as fixed seats.  This building has separate rooms for the band and chorus, so I think this room is intended to be a classroom and would not be considered assembly.  For a lecture hall or bleacher seating, the occupant load is calculated based on fixed seats, but I’m guessing the desks and chairs shown here are not actually fixed seats.

B) Are all 3 doors (2 singles and 1 pair) required for egress?

When the occupant load of a room is over 49 people, the room typically requires at least 2 egress doors.  Very large occupant loads (500+) would require 3 egress doors or more, but with a load of 56 occupants, 2 exits would be sufficient (1 exit would not be sufficient for this occupant load).

There are 3 doors here and only 2 are required for egress.  If more doors are provided for egress purposes, even if they are not required, then they have to comply with the IBC requirements (more on that here).  I would not consider the doors to the OT/PT room to be provided for egress purposes from the music classroom, so the other two doors are sufficient for egress doors.  One reader commented on the required distance between the two egress doors (1/2 the diagonal dimension of the room), and I will write a separate post about that.

C) Are the doors serving this room required to be outswinging?

The IBC requires doors that are serving an occupant load of more than 49 people to swing in the direction of egress (doors serving high hazard occupancies with any occupant load must also be outswinging).

D) Do the doors require panic hardware?

This school is an educational occupancy, and the IBC requires educational and assembly occupancies with an occupant load of 50 people or more to have panic hardware – IF the door is equipped with a lock or latch.  I would assume that this music classroom would have locking hardware to prevent access, so the doors would require panic hardware, or fire exit hardware for doors that are fire rated.  If the doors were not required to lock or latch, and if they were not fire doors, they could have push plates/bars and pulls, instead of panic hardware.

One reader asked about omitting the panic hardware on the inactive leaf of the pair, and only installing it on the active leaf.  While the IBC does not specifically state whether one or both leaves would require panic hardware, the common interpretation is that both leaves should have panics.  NFPA 101 is a little different, and could be interpreted to mean that only the required/active leaf would need panic hardware.  To avoid problems in the field, I would specify panic hardware for both leaves.

Any questions?  Thanks to everyone who participated!

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