What this module covers
Means of Egress alone is 10% of B2, the heaviest single sub-area, and opening protectives add 2%. Expect about 10 of the 80 questions, and more arithmetic here than anywhere else in the exam. Every calculation follows the same chain: occupant load, then the number of exits and egress width, then the travel limits.
Occupant load and egress capacity
What to know
- Occupant load for a space is its floor area divided by the occupant load factor for its use. Some uses take gross area and some net area, and fixed seating is counted by seats.
- Number of exits grows with occupant load and depends on occupancy and sprinkler status. A space with a small load and short travel may have one exit; larger loads need two or more.
- Egress width is the occupant load times a width factor per occupant, one for stairs and one for other components, often smaller in sprinklered buildings. The result is compared with the minimum widths the code also sets.
- Balance. Where more than one exit is required, losing one cannot remove more than a set share of capacity.
How to apply it
Invented example. A training room of 2,400 sq ft net. Assume a load factor of 18 sq ft net per occupant and a width factor of 0.25 in. per occupant for doors.
- Occupant load: 2,400 ÷ 18 = 133.3, rounded up to 134 occupants.
- Door width: 134 × 0.25 = 33.5 in. of total clear width.
- Then compare with the number of exits the code requires for 134 occupants in that occupancy, and the minimum clear width per door.
Common traps
- Using gross area where the use takes net, or the reverse.
- Dividing width among doors before checking how many doors are required.
- Forgetting that a calculated width below the code minimum still has to meet the minimum.
Exit access, exits and exit discharge
What to know
A means of egress has three parts: exit access (the path from any point to an exit), the exit itself (an exterior door, a rated stair enclosure, an exit passageway, a horizontal exit), and exit discharge (from the exit to a public way). The inspector checks:
- Travel distance and common path of egress travel, both limited by occupancy and sprinklers.
- Dead-end corridors, limited in length.
- Exit separation. Where two exits are required, they must be far enough apart relative to the space's diagonal.
- Doors. Swing in the direction of egress above a set occupant load or in high-hazard areas, hardware operable without special knowledge, panic hardware where required, and clear width.
- Exit enclosures rated and kept free of uses other than egress.
- Exit signs and illumination, and emergency power for them.
- Special occupancies and emergency escape and rescue openings where the code requires them.
Common traps
- Measuring travel distance in a straight line through walls instead of along the natural path.
- Letting storage rooms open into a rated exit stair.
Stairs, ramps, guards and handrails
What to know
- Stairs. Riser height and tread depth within limits and uniform within a small tolerance along a flight, headroom, landings, and width.
- Ramps. Slope (rise over run) and cross slope within limits, landings at top, bottom and changes in direction, and edge protection.
- Guards where a walking surface drops more than the code allows, with height and opening limits.
- Handrails on both sides of most stairs and ramps, at the required height, graspable, continuous and extended at the ends.
How to apply it
Invented example. Field measurements of risers on one flight: 6.75, 6.75, 7.00, 6.50 and 6.75 in. The largest minus the smallest is 7.00 − 6.50 = 0.50 in. Compare that difference with the uniformity tolerance in your book. A ramp rising 24 in. over 22 ft (264 in.) has a slope of 24 ÷ 264 = 0.091, or about 1 in 11.
Common traps
- Checking each riser against the maximum but never comparing risers with each other.
- Writing a slope as run over rise.
Opening protectives, penetrations and joint systems
What to know
- Opening protectives. Fire doors and fire windows carry labels for their rating, match the rating the wall needs, and are self-closing or automatic-closing and latching. Frames and hardware are labeled too.
- Ducts passing through rated assemblies get fire dampers or smoke dampers where the code requires, with access for inspection.
- Penetrations by pipes, cables and conduits are sealed with a tested firestop system matched to the penetrant, the assembly and the annular space.
- Joint systems between rated assemblies, and at the edge of floors at curtain walls, use tested systems for the movement they allow.
- Fireblocking and draftstopping close concealed spaces where the code requires them.
Common traps
- Accepting generic sealant in place of the listed firestop system.
- Allowing a fire door to be propped open or fitted with a hold-open device that is not tied to fire detection.
Check yourself
Try the three questions at the end of this module before moving on.
Where to look in your own books
- IBC: the means of egress chapter (occupant load, egress width, number of exits, travel distance, doors, stairs, ramps, guards, handrails, exit discharge, emergency escape and rescue openings)
- IBC: the fire-resistance-rated construction chapter (opening protectives, ducts and air transfer openings, penetrations, joint systems, fireblocking and draftstopping)
- Listings for each fire door, damper, firestop and joint system named on the plans
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