Dade County Building Code (1935)

building-material-specifications

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descriptionMaterial specs for structural, fire-resistive, and roofing components in the 1935 code.

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Building Material Specifications define the required materials, dimensions, testing standards, and assembly methods for various construction types to ensure structural integrity and fire safety. The 1935-miami-dade-building-code outlines specific requirements for Type III, IV, and V buildings, emphasizing the use of incombustible materials for structural frameworks and exterior walls in certain classifications. Detailed specifications for masonry and wood materials are provided in Chapters 24 and 25, while reinforced-concrete-design is governed by Chapter 26. Chapter 27 establishes rigorous standards for structural-steel-design, including quality, allowable stresses, and connection details. Additionally, Chapters 38–43 specify materials for fire protection systems, stages, and heating appliances, requiring the use of asbestos, galvanized iron, and specific fire-resistive assemblies 1935-Miami-Dade-Building-Code_p265_284. Chapter 43 further details minimum protection thicknesses for structural parts using concrete, gunite, brick, and gypsum 1935-Miami-Dade-Building-Code_p285_304.

Type III and IV Requirements

For construction-type-classifications, specifically Type III buildings, wood construction is permitted but restricted from passing through exterior walls (p. 125). Cornices and marquees must be constructed of substantial incombustible materials (p. 125). fire-resistive-construction-requirements mandate that penthouses and skylights in Type III buildings have at least one-hour fire-resistive construction (p. 125).

Type IV buildings, defined as metal frame structures, require structural frameworks of steel, iron, masonry, or reinforced concrete (p. 125). Exterior walls must be of galvanized iron (not less than 22 gauge) or other approved non-corrosive metal, attached to horizontal incombustible supports spaced no more than three feet apart (p. 126). Interior partitions must also be of metal or other incombustible materials (p. 126). Unlike other types, fireproofing of structural members is not required for Type IV buildings (p. 126).

Type V (Wood Frame) Specifications

Type V buildings are primarily wood-frame structures. Foundations must be continuous masonry or reinforced concrete walls, or reinforced piers (p. 128). Exterior walls require studding of at least 2”x4” spaced no more than 16 inches on centers (p. 130).

Wall Coverings

Exterior wall coverings must meet specific thickness and application standards:

  • Weatherboarding: Average thickness of not less than 5/8 inch (p. 132).
  • Shingles/Shakes: Applied over sheathing not less than 25/32 inch thick (p. 133).
  • Stucco: Requires two coats totaling at least 7/8 inch thickness, applied over metal lath reinforcement (p. 133-134).
  • Masonry Veneer: Not less than 3 3/4 inches thick, bonded to diagonal sheathing (p. 134-135).

Structural Wood

Floor and roof joists must adhere to maximum allowable spans based on size, spacing, and species (e.g., Southern Yellow Pine or Douglas Fir) (p. 136, p. 137). Joists must have an 18-inch clearance from the ground (p. 136, p. 165). fire-separation-standards require fire stops in wood framing to limit concealed air spaces to seven feet (p. 125, p. 131, p. 164).

Wood sills and plates in contact with masonry or concrete must be isolated using approved materials like slate-covered roofing or galvanized iron (p. 165). Permitted lumber for these locations must meet high durability standards, such as Heart Long Leaf Southern Yellow Pine or treated Cypress, with brush treatment prohibited except for end cuts (p. 165). Wood posts cannot rest directly on concrete floors; they require concrete floatings or metal plates (p. 165). Foundation walls under Type II buildings must have ventilated openings covered with non-corrosive wire mesh, proportioned at 2 square feet per 15 lineal feet of wall to ensure cross-ventilation (p. 165-166), aligning with foundation-ventilation-requirements. Loose wood storage under buildings is prohibited (p. 166).

Masonry Material Specifications

Chapter 24 of the code establishes strict quality standards for masonry materials, including brick, concrete, gypsum, and stone. The building-inspector may require tests to determine material quality, with costs borne by the owner or contractor (p. 145). All tests must adhere to american-society-for-testing-materials (ASTM) standards (p. 145).

  • Brick: Burned clay/shale, sand-lime, and concrete bricks must have an average absorption of not more than 12% and an average modulus of rupture of at least 450 psi (p. 146–147).
  • Concrete Block: Hollow concrete blocks for exterior walls must meet specific compressive strength requirements based on face shell thickness (e.g., 700 psi average for 1¼”+ thickness) and absorb no more than 10% water (p. 147). “Special” units must comply with underwriters-laboratories standards (p. 148).
  • Gypsum: Used for floors, roofs, and partitions, gypsum products must meet specific compressive strength criteria (e.g., 1800 psi for neat gypsum) and conform to ASTM specifications (p. 148–149).
  • Hollow Clay Tile: Load-bearing tile must be Grade A or B, with specific limits on absorption and compressive strength (e.g., Grade A requires 1400 psi minimum end construction strength) (p. 149).
  • Cast Stone: Must have an average compressive strength of 5,000 psi and absorption not exceeding 7% (p. 149).

Mortars must be lime-cement or cement mortar, with cement mortar required for wet conditions or below-grade masonry (p. 150). Allowable working stresses vary by material and mortar type. For example, brick masonry with 4500 psi unit strength allows 400 psi stress with cement mortar (p. 151). Plain concrete allowable stress is 0.20 (p. 151).

Wood Material Specifications and Grading

Chapter 25 mandates that all wood construction conform to American Lumber Standards as set forth by the united-states-department-of-commerce (p. 153). Lumber is classified into three categories: Structural Lumber, Yard Lumber, and Other Lumber (p. 154). Structural Lumber must be grade-marked, while Yard and Other Lumber require inspection and stress assignment by the building-inspector (p. 154–155).

Allowable stresses are determined by grade, species, and location (dry/wet).

  • Structural Lumber: Table I provides stresses, such as 1800 psi extreme fiber bending for Dense Douglas Fir (Coast Region) (p. 156).
  • Yard/Other Lumber: Table II provides basis stresses, such as 1200 psi bending for Douglas Fir (Coast Region) (p. 157), based on recommendations from the united-states-forest-products-laboratory.
  • Columns: Table III details allowable stresses for timber columns based on length-to-dimension ratios (p. 158). For intermediate columns, the Forest Products Laboratory formula is used; for long columns, the Euler formula applies (p. 159). Columns are limited to a slenderness ratio of 50 (p. 159).

Reinforced Concrete Specifications

Chapter 26 covers the quality and design of reinforced-concrete-design. These regulations supplement the general code and govern in cases of conflict (p. 166). Special concrete systems not covered by standard provisions may be reviewed by a “Board of Examiners for Special Construction” (p. 166).

Materials and Testing

Materials must conform to ASTM standards. Portland cement must meet Specification C9-30 (p. 171). Aggregates must be clean, durable, and free from excessive deleterious materials like shale or silt (p. 171). Metal reinforcement must conform to Specifications A 15-35 (billet-steel) or A 16-35 (rail-steel) (p. 171-172). The building-inspector has the right to order tests for materials and completed structures, with load tests requiring a superimposed load of 1.5 times the live load plus 0.5 times the dead load for 24 hours (p. 170).

Concrete Quality and Stresses

Concrete quality is determined by the water-cement ratio. For average materials, specific ratios correspond to assumed 28-day compressive strengths, ranging from 1,500 to 3,000 psi (p. 172-173). When established by test, the water-cement ratio must yield a strength 15% higher than the minimum required (p. 173). Allowable unit stresses in concrete depend on the 28-day strength (). For example, extreme fiber stress in compression () is limited to (p. 176). Allowable stresses in reinforcement include 20,000 psi for tension in intermediate grade billet steel (p. 177).

Construction Practices

Concrete mixing must ensure uniform distribution and color, with mixing continuing for at least one minute after all ingredients are added (p. 178). Concrete must be placed continuously and thoroughly compacted (p. 179). Curing requires keeping exposed surfaces moist for at least 7 days (p. 179). In cold weather, concrete must be maintained at at least 50°F for 72 hours (p. 179). Forms must be substantial and tight, and reinforcement must be free from rust and scale before placement (p. 180-181). Protective concrete cover for reinforcement ranges from 1 inch in slabs to 3 inches in footings (p. 181). Construction joints must be located to minimize strength impairment, with horizontal joints requiring cleaning and roughening of the hardened surface (p. 181).

Design Assumptions

Design is based on working stresses and safe loads, assuming steel takes all tensile stress (p. 181). The ratio of modulus of elasticity of steel to concrete () is defined as (p. 182). Design loads must account for all dead and live loads, with wind loads allowing a 50% increase in allowable unit stresses (p. 184).

Structural Steel and Iron Specifications

Chapter 27 mandates that structural steel, cast steel, and cast iron conform to specific ASTM standards: A9-33 for structural steel, A27-24 for cast steel, and A48-32T for gray iron castings (p. 206). The building-inspector may require testing, with results filed at the owner’s expense (p. 207).

Allowable Unit Stresses

The code defines maximum static stresses for various conditions (p. 207-208):

  • Tension: 18,000 psi for rolled steel, 16,000 psi for cast steel.
  • Compression: 18,000 psi for short lengths of rolled steel. Column formulas are provided for structural steel, steel pipe, and cast iron columns, incorporating slenderness ratios ().
  • Bending: 18,000 psi for extreme fibers of rolled shapes if laterally supported. Unsupported lengths are limited to 40 times the width of the compression flange.
  • Shear: 13,500 psi for power-driven rivets and turned bolts; 10,000 psi for hand-driven rivets and unfinished bolts. Web shear is limited to 12,000 psi if .

Connections and Workmanship

Rivets are preferred for main members carrying live loads or subject to stress reversal (p. 213). Unfinished bolts are permitted for secondary members. welding (fusion welding) is allowed with allowable stresses of 13,000 psi for tension in butt welds and 11,300 psi for shear in fillet welds (p. 213). Welders must demonstrate competence, with sample butt welds showing an average tensile strength of 45,000 psi (p. 214).

Workmanship standards require hot-driven rivets heated to a light yellow color (1950°F) and driven before cooling to blood red (1000°F) (p. 217). Gas cutting is permitted for preparation but not for replacing milling on bearing surfaces (p. 217-218). All structural steel must be painted with a chemically inert shop coat and a field coat that does not saponify under cement mortar (p. 218).

Foundations and Piles

Chapter 28 regulates excavations and foundations. Footings must be of masonry, reinforced concrete, or steel encased in concrete (p. 219). Allowable soil bearing capacities include 5 tons/sq. ft. for solid rock and 2.5 tons/sq. ft. for natural sand bed (p. 219-220).

Pile Foundations

pile-foundation-engineering requirements specify that wood piles be Dade County pine or approved creosoted wood (p. 221). Allowable loads are determined by hammer formulas, capped at 20 tons for untreated and 15 tons for creosoted piles (p. 221). Concrete piles must meet Chapter 26 standards, with allowable working stress at 12% of ultimate compressive strength (p. 221). Load tests are required when deemed necessary, sustaining twice the design load for 48 hours (p. 222).

Fire-Resistive and Specialized Materials

Beyond structural components, the code specifies materials for fire protection and specialized systems. fire-resistive-construction-requirements define materials such as brick, concrete, gypsum, metal, and metal-and-asbestos assemblies as fire-resistive (p. 281). Plaster fire protection must use gypsum or Portland cement mortar, reinforced with galvanized metal mesh or lath when applied to steel or iron members (p. 282).

Fire-Resistive Structural Protection

Section 4301 provides tables for minimum protection of structural parts based on time periods (1 to 4 hours) using various incombustible insulating materials 1935-Miami-Dade-Building-Code_p285_304.

  • Concrete Grades: Grade A concrete uses aggregates with less than 65% siliceous material (e.g., limestone, trap rock), while Grade B uses others; unknown aggregates default to Grade B (p. 286).
  • Steel and Iron: Columns, beams, and trusses require specific thicknesses of Grade A/B concrete, gunite, brick, or gypsum blocks. For example, steel columns require 2 inches of Grade A concrete for 4-hour protection (p. 285).
  • Reinforcement: Reinforcing steel in concrete columns and beams requires 1.5 inches of Grade A concrete for 4-hour protection (p. 285).
  • Ties and Mesh: Galvanized wire mesh or ties must be embedded in concrete, gypsum, and gunite protections. Mesh for plaster bases must weigh at least 2.2 lbs per square yard (p. 286-287).

Fire-Resistive Walls and Partitions

Section 4302 specifies minimum thicknesses for fire-resistive walls fire resistive walls (p. 287).

  • Masonry: Solid unplastered brick requires 8 inches for 4-hour protection; hollow rowlock brick requires 12 inches (p. 288).
  • Concrete: Solid concrete with 0.2% reinforcement requires 6 inches for 4-hour protection (p. 289).
  • Plaster: Gypsum or Portland cement plaster must be at least ½ inch thick on each side to contribute to fire resistance (p. 287). Gypsum plaster board (3/8 inch) may substitute for metal lath in 2-hour constructions if reinforced (p. 287-288).

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 (p. 292, 293).
  • Sheet metal doors with asbestos insulation (p. 292, 293).
  • Metal-clad wood panel doors (p. 293). 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).

Heating and Solar Systems

Heating appliances require specific protective materials. Low-pressure steam heating plants must rest on masonry or reinforced concrete and be protected by asbestos (p. 265). Stoves must have metal and asbestos pads at least 3/8 inch thick (p. 265). Gas ranges and water heaters require double metal shields with air spaces or metal-and-asbestos pads for combustible protection (p. 265-266). solar-heater-construction-standards mandate that coil boxes be made of 24-gauge galvanized iron and tanks be galvanized or rust-resisting, tested to 150 psi hydrostatic pressure (p. 268). Insulation for solar tanks must be at least 5 inches of ground regranulated cork (p. 269).

Stage and Booth Materials

stage-fire-safety-construction requires that gridirons and fly galleries be constructed of incombustible materials (p. 273). Proscenium walls in Group A and B buildings must be solid masonry with four-hour fire resistance (p. 273). motion-picture-booth-safety mandates that booths be enclosed with one-hour fire-resistive construction, with floors of masonry or reinforced concrete (p. 275). Ports must be covered with plate glass and protected by shutters of No. 10 gauge sheet metal, operated by fusible links (p. 275-276). Film storage cabinets must be made of galvanized iron or steel with metal partitions (p. 276).

proscenium-curtain-specifications require curtains to be made of asbestos cloth reinforced with monel metal, nickel, brass, or similar alloys, weighing at least 3¼ pounds per square yard (p. 278). The cloth must be painted with mineral paint to prevent smoke passage (p. 278). Operating equipment includes steel guides, counter-weights, and safety chains (p. 279-280).

Fire Extinguishing Apparatus

automatic-sprinkler-installation-requirements and standpipe-system-regulations specify materials for fire suppression. Standpipes must be wrought iron or galvanized steel (p. 271). Basement pipe inlets must be cast iron, steel, brass, or bronze with cast brass or bronze lids (p. 273). Tanks for standpipe systems must have incombustible supports (p. 273).

Material Quality and Treatment

Wood sills resting on masonry must be of high-quality lumber, such as heart Long Leaf Southern Yellow Pine or treated redwood, and isolated from the masonry with slate or galvanized iron to prevent moisture absorption (p. 132, p. 165). structural-load-calculations dictate that the carrying capacity of all members be calculated using accepted principles of mechanics, with actual timber dimensions used for stress determinations (p. 139).

Termite provisions mandate preventive measures, such as removing stumps, using concrete foundations, and keeping wood 6 inches above grade (p. 164).

See 1935-Miami-Dade-Building-Code_p125_144, 1935-Miami-Dade-Building-Code_p145_164, 1935-Miami-Dade-Building-Code_p165_184, and 1935-Miami-Dade-Building-Code_p205_224 for detailed code sections.

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

See also: 1935-Miami-Dade-Building-Code_p305_324

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