Metal Roofing and Siding Specifications
metal-roofing-and-siding-specifications outlines the requirements for the installation of steel and aluminum roofing and siding materials in buildings. These specifications were introduced via amendments to the 1935-miami-dade-building-code to ensure durability, weather resistance, and structural integrity.
Steel Roofing and Siding
Steel roofing and siding may be corrugated, deck, standing seam, V Crimp, or flat type. All materials must have a protective coating, such as paint (if not exposed to weather), zinc, or other non-corrosive metals. Stainless steel without a protective coating is also approved (p. 339).
- Gauge and Sheathing: The minimum gauge for steel sheets is No. 26 when used on solid wood sheathing. If wood sheathing is eliminated and sheets span between supports (e.g., purlins, rafters, or girts), the minimum gauge increases to No. 24 (p. 339).
- Corrugations: For unsupported spans, corrugations must be at least 1/2” high. Load-carrying capacity must be established by manufacturer’s load tables or mathematical computations using a fiber stress of 18,000 lbs per square inch (p. 339).
- Fastening: Sheets must be fastened to sheathing with approved galvanized roofing nails and minimum 3/8” diameter lead or neoprene washers. Nailing should occur through high corrugations, standing seams, or V crimps. Side laps must be bolted or riveted at 12” centers. Mastic cement is required at side and end laps (p. 339).
- Eaves: Eaves must be sheathed solid, and steel sheets at this location must be nailed at each corrugation (p. 339).
Aluminum Roofing and Siding
Aluminum roofing and siding can be of the same types as steel but have specific gauge and fastening requirements (p. 339-340).
- Gauge: The minimum gauge is .024 (24 gauge) when used on solid wood sheathing. If wood decking is eliminated, the minimum gauge is .027, with corrugations at least 1/2” high. Exception: 2 1/2”x1/2”x.027 corrugated sheets are not permitted for spans greater than 30” (p. 340).
- Load Capacity: For unsupported spans, load-carrying capacity must be established by manufacturer’s load tables or mathematical computations using a factor of safety of 2 and a fiber stress not exceeding 12,000 lbs per square inch (p. 340).
- Fastening: Aluminum hot-dipped galvanized or cadmium-plated nails, bolts, screws, or rivets must be used. Heavy (18 ga.) aluminum or asphalt-coated 20-gauge steel straps are required where supports are steel and widely spaced. Washers may be of aluminum, lead, or neoprene (p. 340).
- Corrosion Protection: Aluminum sheets must not be in direct contact with steel members. A barrier such as bitumastic paint, aluminum asphalt asbestos combination paint, or equal must be provided (p. 340).
Approval of Special Types
Special types of steel or aluminum sheets or fastenings not covered by these codes may be approved by the building-inspector upon submission of adequate proof of their required strength and durability (p. 340).