Metal Panel Roofing Fundamentals, Materials, and Panel Profiles
This domain tests whether you can name the panel families, match a metal and coating to a service environment, and apply the slope and movement limits each profile carries. Expect questions that pair a building description with a request for the correct panel type or minimum slope.
Panel families
- Structural standing seam panels span between clips or purlins; seams are 1½–3 in. tall and may be hydrostatic (factory sealant) or lap-seamed.
- Architectural standing seam panels sit on solid decking; seams are 1–1½ in., and snap-lock versions need more slope than mechanically seamed versions.
- Through-fastened (exposed fastener) panels depend on washer screws and side laps; treat 3:12 as the practical minimum.
- Batten and decorative shake/tile profiles carry their own clip and slope rules.
Materials
Base metals include G90 galvanized steel, Galvalume (AZ50), 0.032–0.040 in. aluminum, 16–20 oz copper, 0.8 mm zinc, and stainless. Standard steel thickness is 24 ga; 22 ga is used for long spans and severe wind. Coatings: 70% PVDF for color retention, SMP and acrylic for economy.
Movement
Thermal coefficients (in./in./°F): steel 6.5×10⁻⁶, aluminum 13×10⁻⁶, copper 9.8×10⁻⁶. Panels must float on clips; never fix both ends of a run.
Worked example
A 40 ft aluminum panel with a 100°F swing moves 40 × 12 × 13×10⁻⁶ × 100 ≈ 0.62 in. The same run in steel moves ≈ 0.31 in. This is why clips and endlaps are slotted and why aluminum runs are kept shorter.
Traps
Assuming sealant replaces slope; pairing galvanized fasteners with copper; using a snap-lock architectural panel at 2:12; and quoting panel length without allowing for shipping limits.