Domain 4: Means of Egress Evaluation
Egress questions dominate Fire Inspector II because egress failures produce the largest life loss. This domain tests computing occupant load, sizing and counting exits, checking travel and common-path distances, and verifying doors, illumination, and marking in the field.
Occupant load
Use the factors in the code's occupant load table: assembly with tables and chairs 15 net; concentrated assembly 7 net; standing space 5 net; business 100 gross; mercantile 60 gross; classrooms 20 net; residential 200 gross; storage 300 gross. Applying gross where net is required inflates or deflates the load and cascades into every downstream calculation.
Capacity and number of exits
- Stairways are sized at 0.2 inch per occupant; other egress components at 0.15 inch per occupant, with the higher value where sprinkler protection and an approved voice alarm system are provided.
- Two exits are generally required once the occupant load reaches 50; where two are required, each must handle at least half the total capacity, but minimum clear widths still govern.
- Doors must provide the required clear width with the door open; corridors serving 50 or more occupants are wider than those serving fewer.
Travel
For common occupancies such as business and mercantile, maximum travel distance is 200 feet unsprinklered and 250 feet sprinklered; common path of travel is 100 feet unsprinklered and 75 feet sprinklered; dead-end corridors are limited to 20 feet, or 50 feet where sprinklered. Exits must also be remotely located from one another.
Worked example
A 2,400-square-foot dining room with tables and chairs: 2,400 ÷ 15 = 160 occupants. Required egress width for other components: 160 × 0.15 = 24 inches, so each of two exits must provide at least 12 inches of capacity - but the minimum door clear width governs and each exit must be far larger than 12 inches. If the path includes stairs, 160 × 0.2 = 32 inches of stair width is required.
Traps that cost marks
Using the wrong gross/net factor; forgetting the half-capacity rule; measuring door clear width with the door partly closed; accepting a path that runs through a stockroom or under a roll-down gate; ignoring added occupant load from new seating.