Life Safety, Egress, and Occupancy Protection
Life Safety, Egress, and Occupancy Protection
This domain tests means-of-egress design and occupancy protection under NFPA 101 concepts. Questions commonly require calculating occupant load, egress width, exit count, travel distance, and the protection features required by occupancy classification.
Core rules
- Occupant load is calculated from use and floor area using Table 7.3.1.2 factors. Common gross factors include 100 ft² per person for business, 30 ft² for mercantile, 200 ft² for industrial, and 300 ft² for storage. Assembly uses net factors such as 15 ft² unconcentrated, 7 ft² concentrated, and 5 ft² standing space.
- Egress capacity is width-based: commonly 0.2 in (5 mm) per person for level components, 0.15 in (3.8 mm) for stairs, and 0.3 in (7.6 mm) for ramps. Door clear width is typically 32 in (813 mm) minimum.
- Two means of egress are generally required when occupant load reaches 50 or more, and exit remoteness rules apply. Dead-end corridors are commonly limited to 20 ft; common-path travel is limited by occupancy, often 75 ft.
- Travel distance limits vary by occupancy and sprinkler protection, commonly 200–250 ft and longer when sprinklered. Exit access must be continuous and unobstructed.
- Exit signs must be visible, illuminated, and marked with directional indicators where the path is not obvious. Emergency lighting commonly provides 90 minutes of illumination.
- Doors serving assembly or high-occupant spaces need panic hardware. Doors must swing in the direction of travel where serving 50 or more, and cannot be locked against egress.
- Occupancy classification drives construction type, sprinkler requirements, detection, and separation. Mixed occupancies require analysis of each area and its separations.
Worked example
A 20,000 ft² mercantile occupancy uses the 30 ft² gross factor: 20,000 ÷ 30 = 667 occupants. Required level egress width is 667 × 0.2 in = 133.4 in. Four 36 in doors with 32 in clear width provide 128 in, which is insufficient. Five doors provide 160 in and satisfy width, and the layout must still meet remoteness and exit-access rules. The calculation must use clear width, not nominal door size.
Traps
- Using net factors for gross-area occupancies, or the reverse.
- Checking total width but ignoring the minimum number of exits and their remoteness.
- Measuring travel distance around furniture or through a locked room as if it were a valid path.
- Forgetting that doors must swing in the direction of egress for high-occupant spaces.
- Assuming a sprinklered building removes all egress requirements.