Egress and Exit Standards
egress-and-exit-standards define the requirements for safe evacuation from buildings, varying significantly by occupancy group in the 1935-miami-dade-building-code. The 1935-Miami-Dade-Building-Code_p45_64 details specific mandates for Groups A through E, while later sections of the code provide detailed construction requirements for stairways, ramps, and smokeproof towers 1935-Miami-Dade-Building-Code_p245_264.
Stairway and Exit Construction Requirements
Stairways must lead directly to the street or via fire-resistive passageways, with widths equal to the aggregate width of exits discharging into them (p. 245). For buildings with sleeping rooms, schools, or detention facilities, exits must allow travel in either direction from any point in a corridor (p. 245).
Dimensions and Features
- Width: Minimum clear width of 44 inches for most uses, reducible to 3 feet for certain dwellings and mezzanines (p. 246).
- Rise and Tread: Maximum rise of 7.5 inches and minimum tread of 10 inches for general use; dwellings and mezzanines may have an 8-inch rise and 9-inch tread (p. 246).
- Landings: Must be at least 44 inches in length and width, level, and aligned with the floor they serve (p. 247).
- Railings: Handrails are required on at least one side, with intermediate rails for stairways over 7 feet wide (p. 246).
Enclosures and Smokeproof Towers
Interior stairways in buildings three stories or more must be enclosed with two-hour fire-resistive construction fire-resistive-construction-requirements (p. 247). Group D, E, F, G, and H occupancies in buildings three stories or more are required to have smokeproof-towers constructed of incombustible materials with four-hour fire-resistive walls (p. 250). These towers must provide continuous egress to street grade and include vestibules or balconies open to the exterior to prevent smoke infiltration (p. 250-251). Horizontal exits may be used if protected by one-hour fire-resistive doors (p. 249).
Group-Specific Egress Requirements
Group A: Large Assembly Occupancies
Group A buildings (seating capacity ≥1,000 or ≥3,500) have the strictest egress requirements (p. 45):
- Number of Exits: At least three exits on different sides of the auditorium are required (p. 46).
- Width Calculations: Main entrance width is calculated based on seating capacity (e.g., 2 feet per 100 persons up to 1,000 persons) (p. 46). Side exits require 22 inches of width per 150 seats on the main floor (p. 47).
- Foyers: A foyer is required at the main entrance with an area of 1 square foot per seat (p. 46).
- Aisles: Aisles must be at least 3 feet wide (one side) or 3.5 feet wide (both sides), increasing in width toward the foyer (p. 48).
- Balconies: Balconies with >50 seats require exits from both sides, with widths calculated at 22 inches per 75 seats (p. 47).
Group B: Medium Assembly Occupancies
Group B buildings (seating capacity 300–999 or 750–3,499) follow Group A exit requirements with exceptions (p. 52):
- No Foyer: A foyer is not required (p. 52).
- Balconies: Balconies are only permitted in Type I construction buildings (p. 52).
Group C: Small Assembly and Schools
Group C buildings (seating capacity <300 or <750) have modified egress standards (p. 54):
- Schools: Exit stair widths are calculated in 22-inch units based on 100 occupants per unit (p. 57). Hallways must have a minimum clear width of 4.5 feet (p. 57).
- Exceptions: Foyers are not required, and seats need not be fixed (p. 57). In Division 3 (small rooms), all exits may be on one side if no point is more than 35 feet from an exit (p. 57).
Group D: Detention and Hospitals
Group D buildings have specialized egress needs (p. 60):
- Hospitals: Ramps with a slope of no more than 1:6 are required instead of or in addition to stairs for areas with bed-ridden patients (p. 61).
- Detention: Exit doors must use self-releasing latches or panic bolts, except in places of detention where security devices are permitted (p. 61).
- Minimum Exits: At least two exits are required from each floor regardless of building height or area (p. 61).
- Smokeproof Towers: Group D buildings exceeding two stories in height must be provided with at least one smokeproof tower smokeproof-tower (p. 249).
General Requirements
- Door Hardware: Exit doors must swing in the direction of travel and use self-releasing latches like panic bolts (p. 48). Doors in exit enclosures must be self-closing and of one-hour fire-resistive construction fire-resistive-construction-requirements (p. 245).
- Exit Lighting: Illuminated “EXIT” signs with dual circuits are required in Group A buildings (p. 49). Lights in exit signs must be kept burning at all times the building is occupied (p. 246).
- Obstructions: No obstructions are allowed in aisles, exits, or foyers (p. 49). No mirrors may be placed in stairways (p. 247).
- Travel Distance: No portion of any building shall be more than 150 feet from the nearest exit, and no corridor exit door shall be more than 100 feet from the nearest exit (p. 245).
These standards complement fire-separation-standards and occupancy-classification to ensure life safety.