Life Safety, Egress, and Passive/Smoke Control Systems
The egress system, in order
NFPA 101 divides egress into exit access (travel within the room or floor), exit (the protected way out - enclosed stair, exit passageway, exterior door at grade), and exit discharge. Questions usually ask you to classify a feature, so name the component before applying a number.
Capacity and geometry: occupant load factors give the population, and width is sized in inches per occupant (about 0.2 in for level components and 0.3 in for stairs and ramps, reducible in fully sprinklered buildings with voice evacuation). Minimum clear widths and door clear widths generally govern over the arithmetic. Two exits are required once the occupant load passes the occupancy threshold (commonly 50), and they must be remote from each other - at least half the diagonal of the floor, reducible to one-third where the building is fully sprinklered. Travel distance, common path, and dead-end limits come from the occupancy chapter.
Doors: swing in the direction of egress when serving 50 or more occupants, provide panic hardware where required, keep opening force at or below 30 lbf, and never permit locking that prevents egress. Illumination is about 1 fc along the path, with 90-minute emergency lighting and exit signs with 6 in letters.
Passive protection and smoke control
Fire walls, fire barriers, fire partitions, and smoke barriers differ in purpose and rating. Openings need listed protectives (NFPA 80 fire doors, NFPA 105 smoke door assemblies, NFPA 90A dampers) and firestopped penetrations. NFPA 92 covers pressurization and exhaust: stairwell pressurization holds a positive differential while keeping door opening force at or below 30 lbf; atria use exhaust sized to a design fire.
Worked example
A 200 ft × 100 ft floor has a diagonal of about 224 ft. Unsprinklered, the two exits must be at least 112 ft apart; fully sprinklered, at least about 75 ft.
Traps
Using the one-third remoteness credit in an unsprinklered building; forgetting 90-minute emergency lighting; treating a smoke barrier as a fire barrier with the same rating logic.