This document outlines Chapter 24 (Masonry) and Chapter 25 (Wood) of the 1935 Miami-Dade Building Code, establishing quality standards, allowable working stresses, and framing details for construction materials.
Chapter 24: Masonry
Material Quality and Testing The code defines masonry materials including brick (clay, sand-lime, concrete), plain concrete, hollow concrete block, gypsum, hollow clay tile, and stone (p. 145). The building-inspector has the authority to require tests for 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 and Stresses 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). Gypsum suspension systems require a factor of safety of at least 4 (p. 151).
Chapter 25: Wood
General Requirements and Grading All wood construction must conform to American Lumber Standards (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 Unit Stresses Allowable stresses are determined by grade, species, and location (dry/wet).
- Table I provides stresses for Structural Lumber, such as 1800 psi extreme fiber bending for Dense Douglas Fir (Coast Region) (p. 156).
- Table II provides basis stresses for Yard/Other Lumber, such as 1200 psi bending for Douglas Fir (Coast Region) (p. 157).
- Table III details allowable stresses for timber columns based on length-to-dimension ratios (p. 158).
For intermediate columns, the united-states-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).
Framing Details
- Vertical Members: Wood columns must have metal base plates and anchors, and be protected from dampness (p. 160).
- Horizontal Members: Beams entering masonry must have a 4-inch bearing with fire protection (e.g., asphalt felt) and preservative treatment (p. 160). Joists and rafters must have minimum 4-inch bearings and be anchored where entering masonry (p. 160–161).
- Stud Walls: Bearing partition studs must be at least 2”x4”, increasing to 2”x6” or 3”x4” if supporting more than one floor and the roof (p. 162).
- Roof Framing: Valley rafters must be at least 1⅝”x5½”, and flat-deck roofs require parapets and ventilation spaces (p. 163).
- Fire Stops: Required at all intersections of walls and floors, and in stud walls to prevent concealed air spaces greater than 7 feet (p. 163–164).
Termite Provisions The code mandates termite extermination notices and preventive measures, such as removing stumps, using concrete foundations, and keeping wood 6 inches above grade (p. 164).