6.5 Emergency Escape & Rescue Openings and Assembly Seating Egress

1. Where Emergency Escape and Rescue Openings Are Required (IBC 1031.2)

Emergency escape and rescue openings (EEROs) are a life-safety backstop that exists in addition to the required means of egress. Under IBC Section 1031.2 they are required in:

1. Group R-2 occupancies located in stories with only one exit or access to only one exit, as permitted by Tables 1006.3.4(1) and 1006.3.4(2).
2. Group R-3 and R-4 occupancies.

Within those occupancies, basements and sleeping rooms below the fourth story above grade plane must have not fewer than one EERO. Where a basement contains one or more sleeping rooms, each sleeping room needs an opening, but adjoining basement areas do not. Openings must discharge directly to a public way, or to a yard, court or egress balcony that leads to a public way.

Five exceptions are heavily tested:

1. Basements with a ceiling height of less than 80 inches.
2. Basements or sleeping rooms with an exit door or exit access door opening directly to a public way, yard, court or exterior egress balcony leading to a public way.
3. Basements without habitable space and not more than 200 square feet in floor area.
4. Storm shelters constructed in accordance with ICC 500.
5. Within individual dwelling and sleeping units in Groups R-2 and R-3 in a building sprinklered throughout under 903.3.1.1, 903.3.1.2 or 903.3.1.3, basement sleeping rooms are exempt where the basement has either one means of egress plus one EERO, or two means of egress.

Openings must be operable from the inside without keys, tools or special knowledge, and ASTM F2090 window opening control devices are permitted on EERO windows (1031.2.1).

2. EERO Geometry: The Four Numbers (IBC 1031.3)

The net clear dimensions must result from normal operation of the opening — you cannot count the frame opening or a sash that must be removed. Note the arithmetic trap: an opening at exactly the 24-inch minimum height needs a width of 34.2 inches to reach 5.7 square feet, and one at exactly the 20-inch minimum width needs a height of 41 inches. Meeting the two minimum dimensions alone does not satisfy the area requirement.

Where a door serves as the EERO, it must be a swinging or sliding door (1031.4).

3. Area Wells and Bars, Grilles and Covers (IBC 1031.5, 1031.6)

Where the bottom of the clear opening is below adjacent grade, an area well is required:

• Minimum horizontal area: 9 square feet, with a horizontal projection and width of not less than 36 inches (1031.5.1). The well must allow the EERO to be fully opened; a required ladder or steps may encroach not more than 6 inches.
• Wells deeper than 44 inches require a permanently affixed ladder or steps (1031.5.2), not obstructed by the opening when it is open. Ladders need 12-inch minimum inside width, 3-inch minimum projection from the wall, and rungs spaced not more than 18 inches on center; steps need 12-inch minimum width, treads greater than 5 inches deep, and risers not greater than 18 inches (1031.5.2.1, 1031.5.2.2).
• Drainage must connect to the foundation drainage system required by Section 1805, unless the foundation sits on well-drained Group I soils per Section 1803.5.1 (1031.5.3).

Bars, grilles, covers and screens (1031.6) are permitted only if the required net clear opening is maintained and the device is releasable or removable from the inside without a key, tool or force greater than normal operation.

4. Assembly Aisles and Aisle Accessways (IBC 1030)

The B3 blueprint's "special exiting" content is largely IBC Section 1030, Assembly. Start with the two capacity rules that override Chapter 10 defaults:

• Main exit (1030.2): where an assembly space with an occupant load greater than 300 has a well-defined main exit, that exit must serve not less than one-half of the occupant load, and in Group A it must front on a street or a 10-foot minimum unoccupied space adjoining a street or public way.
• Other exits (1030.3): each level must also have additional egress serving not less than one-half of the occupant load of that level.

Minimum aisle widths (1030.9.1):

Dead-end aisles (1030.9.5) are limited to 20 feet, with an exception permitting longer dead ends where seats beyond the 20-foot point are not more than 24 seats from another aisle measured along a row having 12 inches clear width plus 0.6 inch per seat above seven.

Aisle accessways between rows (1030.13.2): the clear width between the back of one row and the nearest projection of the row behind is 12 inches minimum for rows of 14 or fewer seats. For rows served by aisles at both ends, the maximum is 100 seats per row, and the 12-inch clear width increases 0.3 inch for each seat beyond 14 (beyond 21 for seats without backrests), never required to exceed 22 inches (1030.13.2.1). For rows served at one end only, the increase is 0.6 inch for each seat beyond seven (beyond 10 without backrests) (1030.13.2.2).

Common path of egress travel (1030.8) in fixed-seating assembly spaces is limited to 30 feet, extended to 75 feet for areas serving fewer than 50 occupants and 50 feet for smoke-protected or open-air assembly seating.

Stepped aisle geometry (1030.14.2): treads not less than 11 inches with 3/16-inch uniformity tolerance, and risers not less than 4 inches and not more than 8 inches — deliberately different from the 7-inch/11-inch stairway rule in Section 1011, because aisle steps follow the seating gradient. Nonuniform risers must be marked with a 1-inch to 2-inch contrasting stripe at the nosing.

Guards at the end of aisles (1030.17.4) require a fascia or railing not less than 36 inches high where the foot of the aisle is more than 30 inches above the floor below, providing not less than 42 inches measured diagonally between the top of the rail and the nosing of the nearest tread.

Bleachers, grandstands and folding and telescopic seating that are not building elements are regulated by ICC 300 (1030.1.1), and spaces under grandstands or bleachers must be separated with 1-hour fire barriers and horizontal assemblies unless they are ticket booths under 100 square feet, toilet rooms, or sprinklered accessory areas of 1,000 square feet or less (1030.1.1.1).

5. Plan Review Scenario: Mixed R-2 and Assembly Project

Submittal: a four-story Group R-2 apartment building over a 340-seat Group A-3 community room. The R-2 building is sprinklered throughout under NFPA 13. Basement sleeping rooms are shown with 30-inch-wide by 22-inch-high casement windows at a 46-inch sill, in a 30-inch-deep window well. The community room shows 20-inch clear aisle accessways, a 36-inch level aisle with seating on both sides, and a 26-foot dead-end aisle.

Findings:

1. EERO height fails. The 22-inch clear height is below the 24-inch minimum (1031.3.2); net area of 30 x 22 inches is 4.58 square feet, also below 5.7 square feet.
2. Sill height fails. A 46-inch sill exceeds the 44-inch maximum (1031.3.3).
3. Window well fails. The well must be 9 square feet minimum with 36-inch projection and width (1031.5.1).
4. Aisle width fails. A level aisle with seating on both sides requires 42 inches, not 36 inches, because the room exceeds 50 seats (1030.9.1).
5. Dead-end aisle fails. The 26-foot dead end exceeds the 20-foot limit unless the 24-seat measurement exception can be documented (1030.9.5).
6. Main exit capacity. With 340 occupants — greater than 300 — the main exit must carry not less than one-half of the occupant load (1030.2).

6. Common Plan Review and Exam Traps

• Trap 1: Using 5.0 square feet everywhere. The 5.0-square-foot value applies only to grade-floor openings; all others are 5.7 square feet.
• Trap 2: Treating the minimum dimensions as sufficient. A 20-inch by 24-inch opening is only 3.33 square feet.
• Trap 3: Applying stairway riser rules to stepped aisles. Aisle risers are 4 inches to 8 inches (1030.14.2.2), not 4 inches to 7 inches.
• Trap 4: Forgetting the sprinklered R-2 basement exception. Exception 5 of 1031.2 needs one means of egress plus one EERO, or two means of egress.
• Trap 5: Sizing assembly rows without the per-seat increase. Twelve inches is the base; add 0.3 inch or 0.6 inch per seat depending on whether the row is served at both ends or one end.