Dade County Building Code (1935)

fire-resistive-construction-requirements

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descriptionMinimum standards for fire-resistive materials, structural protection, and assemblies in the 1935 Miami-Dade Building Code.

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Fire-Resistive Construction Requirements define the minimum standards for materials and assemblies designed to resist fire spread and structural collapse for a specified duration. These requirements are central to the construction-type-classifications in the 1935-miami-dade-building-code, particularly for building-inspection-protocol compliance in fire-zones. The code establishes specific definitions, material lists, and application standards for structural protection, heating systems, stages, and motion picture booths.

Key Standards and Definitions

The code specifies fire-resistive ratings based on building height, occupancy, and specific functional requirements:

  • Structural Members: In Type I buildings, structural steel or iron columns, beams, and girders require four-hour protection for buildings over eight stories (85 feet) and three-hour protection for those eight stories or less (p. 110). Floors require three-hour or two-hour protection respectively (p. 111).
  • Walls and Partitions: Exterior walls in Type I buildings must have not less than four-hour fire-resistive construction (p. 109). Interior partitions in Type I buildings must be at least one-hour fire-resistive (p. 109). In Type II buildings, exterior walls must also have four-hour protection, while interior partitions require one-hour protection (p. 114, 115).
  • Vertical Openings: Enclosures for elevator shafts, stairwells, and vent shafts must be of two-hour fire-resistive construction in Type I and II buildings (p. 110, 115). In Type III buildings, these enclosures require one-hour protection (p. 123). In Type V buildings, vertical openings (except in Group I dwellings) require one-hour fire-resistive enclosure walls, with chute and dumb-waiter shafts allowed to be lined with asbestos and sheet metal (p. 139).
  • Doors and Windows: Openings in exterior walls of Type I and II buildings must be protected by one-hour fire-resistive construction, with exceptions for openings facing wide public streets (p. 112, 117). Type III buildings may use wood or plain glass unless specified otherwise by occupancy or location (p. 124). In Type IV buildings, openings must be protected by metal doors/windows unless set back 16 feet from property lines (p. 127). Type V buildings require gravity self-closing doors for vertical openings (p. 139).

Application by Construction Type

  • Type I (Fire-Resistive): Requires comprehensive fireproofing of the structural frame, floors, and roofs. Combustible materials are heavily restricted, with specific allowances for decorative wood and mezzanine floors (p. 113).
  • Type II (Heavy Timber): Allows heavy timber structural members without fireproofing, provided they meet minimum dimension requirements (e.g., 8-inch columns, 6-inch beams) (p. 116). Steel members require fireproofing unless the building is single-story or under 65 feet (p. 116).
  • Type III (Ordinary Masonry): Exterior walls must be masonry or reinforced concrete. Interior partitions and floors may be wood, but in buildings over two stories, bearing partitions must be one-hour fire-resistive (p. 123). The underside of combustible floor construction in Group C and D occupancies must be protected with one-hour fire-resistive construction (p. 124). Penthouses and skylights must be one-hour fire-resistive (p. 125).
  • Type IV (Metal Frame): Structural members (steel, iron, masonry, concrete) do not require fireproofing (p. 126). Exterior walls and roofs must be metal or incombustible (p. 125-126). Skylights must be one-hour fire-resistive (p. 127).
  • Type V (Wood Frame): Combustible materials are permitted throughout. Attached garages must have one-hour fire-resistive ceilings and walls (p. 139). Vertical openings require one-hour fire-resistive enclosure (p. 139).

Specific Assembly Requirements

Beyond general construction types, the code mandates specific fire-resistive constructions for hazardous equipment and assemblies:

  • Heating Systems: Furnaces in enclosed rooms require one-hour fire-resistive ceiling protection (p. 265). Stoves must have partitions behind them protected by one-hour fire-resistive construction (p. 265). Combustible partitions near gas ranges must be protected with asbestos or one-hour fire-resistive construction (p. 266).
  • Stages: In Group A and B occupancies, the proscenium wall separating the stage from the auditorium must be solid masonry of not less than four-hour fire-resistive construction (p. 273). Space under raised platforms in assembly rooms must be one-hour fire-resistive throughout (p. 274).
  • Motion Picture Booths: Machine booths using inflammable films must have walls and ceilings of not less than one-hour fire-resistive construction (p. 275). Ventilation flues passing through occupied rooms must be encased in four inches of solid masonry (p. 276).
  • Incinerators: Combustion chambers in integral building incinerators must have walls of solid masonry or reinforced concrete, with inner linings of fire brick (p. 268).

Structural Protection Details

Section 4301 provides detailed tables for the minimum protection of structural parts based on time periods (1, 2, 3, and 4 hours) and various incombustible insulating materials structural-fire-protection-tables (p. 285).

  • Steel and Cast Iron: Columns, beams, and trusses require specific thicknesses of Grade A or B concrete, gunite, brick, or gypsum blocks. Grade A concrete contains aggregates with less than 65% siliceous material, while Grade B contains others; unknown aggregates default to Grade B (p. 286).
  • Reinforcement: Specific cover depths are mandated for reinforcing steel in columns, beams, joists, and slabs to ensure fire resistance (p. 285).
  • Installation: Plaster protections over one inch thick require additional galvanized metal lath or mesh embedded securely (p. 286). Soffit tiles protecting beam flanges must be tied to the flange with steel or iron ties (p. 286).

Fire-Resistive Walls and Partitions

Section 4302 details requirements for bearing and non-bearing walls fire-separation-standards (p. 287). Minimum thicknesses are provided for various constructions, including solid or hollow brick, concrete, clay tile, and gypsum blocks (p. 288–289). Plastering contributes to fire resistance only if it is gypsum or Portland cement plaster applied to an average thickness of not less than one-half inch on each side (p. 287). Gypsum plaster board may substitute for galvanized metal lath for resistance periods of not more than two hours, provided specific reinforcement and testing conditions are met (p. 287–288).

Floor and Ceiling Protection

Fire-resistive floor construction is categorized by rating floor-construction-standards (p. 291):

  • Three-hour: Requires reinforced concrete, gypsum, or solid masonry slabs not less than 4 inches thick, or hollow masonry with a 2-inch solid top covering.
  • Two-hour: Requires slabs not less than 2½ inches thick or hollow masonry not less than 3 inches thick with a 1-inch solid top covering.
  • One-hour: Allows for wood joisted construction with a double wood floor and fire-resistive ceiling, provided specific thicknesses are met. Ceiling protection thicknesses may be reduced by ½ inch if a free air space of at least 1 inch exists between the member and protection (p. 291).

Fire Doors, Shutters, and Windows

Section 4304 outlines specifications for one-hour fire-resistive doors fire-resistive-door-specifications (p. 292). Acceptable types include tin-clad wood-core doors, sheet metal doors with asbestos insulation, and metal-clad wood panel doors. Hardware must be of heavy-duty malleable iron or steel, and sliding tracks must be securely supported (p. 293). Fire-resistive windows must use wire glass at least ¼ inch thick, with maximum light areas of 720 square inches (p. 294–295).

Roof Coverings

Section 4305 classifies roofs as “Fire Retardant” or “Ordinary” roof-construction-standards (p. 295).

  • Fire Retardant Roofs: Must meet underwriters-laboratories Class A or B specifications or specific layer requirements for roll roofing, felt, shingles, or tile (p. 295–297). Concrete slab roofs need no additional covering (p. 297).
  • Ordinary Roofs: Meet Class C specifications or specific lighter layer requirements (p. 298).
  • Wood Shingles: Must be heartwood (e.g., red cedar) and meet specific thickness and exposure standards based on roof pitch (p. 298–299).

Construction and Public Property

Chapter 44 regulates temporary street use during construction code-enforcement-mechanisms (p. 301). In Fire Zone No. 1 or for buildings over two stories, a temporary covered walkway at least 5 feet wide and 8 feet high must be constructed to protect pedestrians (p. 302). Chapter 45 restricts permanent projections over public property, allowing limited extensions for cornices, marquees, and balconies under strict conditions (p. 303–304).

These requirements work in conjunction with fire-separation-standards to ensure overall building safety and limit fire damage within occupancy-classification categories. Specific applications for stage-fire-safety-construction, motion-picture-booth-safety, and proscenium-curtain-specifications rely heavily on these fire-resistive standards.

See also: 1935-Miami-Dade-Building-Code_p225_244

See also: 1935-Miami-Dade-Building-Code_p245_264

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