Occupant Load

[ihavefaith]

I had a question about occupant load calculations.

If an office building has 20 rooms, bathroom, hall etc. Do you just lump them all together and divide by the load factor if using gross given no net areas exist? Not room by room. Reason I ask is because I am seeing multiple ways of doing this. Some do a room by room, some do a whole area or building. Reading the code I would assume it to be room by room, but would like some clarification. Thank you

 

[mtlogcabin]

You design according to
1004.1 Design occupant load.
In determining means of egress requirements, the number of occupants for whom means of egress facilities are provided shall be determined in accordance with this section.

You provide a means of egress plan based on the number of occupants in each room
A] 107.2.3 Means of egress.
The construction documents shall show in sufficient detail the location, construction, size and character of all portions of the means of egress including the path of the exit discharge to the public way in compliance with the provisions of this code. In other than occupancies in Groups R-2, R-3, and I-1, the construction documents shall designate the number of occupants to be accommodated on every floor, and in all rooms and spaces.

Room by room is the best way to do it for egress purposes.
The means of egress plan will be used to determine the minimum width of egress components within the building or on a floor. This can be confusing when you have multiple means of egress paths.
I had a school with three 48" wide stairs serving the second floor. The DP just divided the occupant load by 3 and attributed an equal amount to each stairway However when following the egress plan submitted and adding up occupants and sending 1/2 of each room in each direction one stairway needed to be 5 inches wider to accommodate the extra 15 people using that plan.

 

[ihavefaith]

You design according to
1004.1 Design occupant load.
In determining means of egress requirements, the number of occupants for whom means of egress facilities are provided shall be determined in accordance with this section.

You provide a means of egress plan based on the number of occupants in each room
A] 107.2.3 Means of egress.
The construction documents shall show in sufficient detail the location, construction, size and character of all portions of the means of egress including the path of the exit discharge to the public way in compliance with the provisions of this code. In other than occupancies in Groups R-2, R-3, and I-1, the construction documents shall designate the number of occupants to be accommodated on every floor, and in all rooms and spaces.

Room by room is the best way to do it for egress purposes.
The means of egress plan will be used to determine the minimum width of egress components within the building or on a floor. This can be confusing when you have multiple means of egress paths.
I had a school with three 48" wide stairs serving the second floor. The DP just divided the occupant load by 3 and attributed an equal amount to each stairway However when following the egress plan submitted and adding up occupants and sending 1/2 of each room in each direction one stairway needed to be 5 inches wider to accommodate the extra 15 people using that plan.

Thanks a lot. The confusion comes with hallways and bathrooms, lobbies etc for me.

If you have say 8 rooms, all offices, a bathroom, a hallway, and lobby in one building, which area does the hallway go to? The bathroom? Do I calculate the hallway by itself? Or lump it with one of the 8 rooms? The bathroom?

I just haven't seen to many examples of someone doing a occupant load calc on a hallway or bathroom alone.

 

[Jay Smith]

Given that there is no code requirement to send occupants of any particular room to any particular exit, and all occupants are provided access to all the required exits, I follow the definition of Floor Area, Gross in Chapter 2. After all, the occupant load factor for business areas is called gross in 2018 IBC Table 1104.5. I’ve submitted it this way many times with no objection yet.

 

[Jay Smith]

Given that there is no code requirement to send occupants of any particular room to any particular exit, and all occupants are provided access to all the required exits, I follow the definition of Floor Area, Gross in Chapter 2. After all, the occupant load factor for business areas is called gross in 2018 IBC Table 1104.5. I’ve submitted it this way many times with no objection yet.

Typo in reference to Table 1004.5. I tried proofreading that reply three times.

 

[ihavefaith]

Typo in reference to Table 1004.5. I tried proofreading that reply three times.

So everything together. Yes, that is definitely easier. Which I prefer. However, I would see a difference in the rounding using individual spaces vs a whole area.

8 rooms combined vs each one separated would give a different number. Although probably not big, I would assume it could make a difference in some situations.

 

[ihavefaith]

So if everyone is doing it differently, doesn't this create issues?

 

[steveray]

So if everyone is doing it differently, doesn't this create issues?

It gets "complicated" but as long as the BO and designer can have an intelligent conversation, no issues...THAT is the tricky part...

 

[Phil B]

How about support rooms. i.e. Mechanical, Electrical, Storage in a Business occupancy? The Official says they are accessory to the Business Occupancy. Should they be calculated at 1 person per 150 sf, or 1 per 300 sf?