Standing seam: 24 gauge Galvalume (55% Al-Zn) steel, painted with Kynar 500/Hylar 5000 (PVDF) fluoropolymer coating. Panel width: 12-18 in. Seam height: 1-1/2 to 2 in. Types: snap-lock (residential, slope ≥3:12), mechanical seam (commercial, low slope to 1/4:12). Clip attachment allows thermal expansion. Panels: shop-fabricated or field-formed by portable roll former. ASTM A792 steel, ASTM A653 galvanized. Wind uplift: UL 580 Class 90, FM 4471. Fire: Class A. Cost: $300-$700/square installed. Lifespan: 40-70 years. Advantages: longevity, low maintenance, snow shedding, cool roof (Energy Star reflective colors), fully recyclable. Disadvantages: cost, oil canning (cosmetic waviness), hail denting, dissimilar metal corrosion. CSI 07 41 13.