Metal roofing types — standing seam vs exposed-fastener (R-panel) vs stone-coated steel

Three common formats of residential metal roofing differ enough that "metal roof" without specifying which one obscures meaningful tradeoffs. Standing seam metal panels are formed from coil stock — galvalume-coated steel, aluminum, copper, or zinc — into long vertical panels with raised seams along each edge. Adjacent panels lock together at the seam, and the fasteners that hold the panels to the deck are concealed beneath the seam, never exposed to weather. The concealed-fastener design produces the metal roof's longest realistic lifespan (commonly 40-70 years on quality galvalume installations, longer on copper or zinc), the strongest weathertightness, and the cleanest visual line. Standing seam is the most expensive metal format — panels are roll-formed on-site or specially fabricated, and installation is more labor-intensive. Wind ratings are high (commonly 120-180 mph rated). Exposed-fastener panels (variously called R-panel, screw-down panel, or 5V crimp depending on the profile) use through-panel screws with rubber or EPDM gaskets to fasten the panels directly to the deck or purlins. Installation is faster and material cost is lower than standing seam, which makes exposed-fastener the entry-tier metal option. Rubber and EPDM gaskets degrade under sustained UV and Texas heat, and gasket failure at any of the hundreds of screw penetrations becomes a leak path. Realistic lifespan in Texas conditions runs shorter than standing seam (commonly 20-40 years depending on gasket quality and maintenance), and gasket replacement maintenance becomes a cyclic cost roughly every 10-15 years. Exposed-fastener metal is widely used on agricultural and outbuilding roofs, less commonly chosen for primary residences in Houston. Stone-coated steel is a hybrid format: a steel substrate is stamped into shingle, shake, or tile profiles and then finished with a stone-granule coating that mimics the aesthetic of asphalt or tile. Stone-coated steel typically carries 30-50 year warranties, performs well in hail and wind, and is meaningfully lighter than concrete or clay tile (often a structural advantage on existing homes that cannot support tile load). Cost typically sits between exposed-fastener and standing seam. Metal installation is more specialized than asphalt; the contractor's metal-specific experience matters. Cross-reference D1-006 for the cross-material Texas lifespan table. What to ask a metal contractor: which panel type and why for this roof (standing seam vs exposed-fastener vs stone-coated); whether fastening is concealed (standing-seam clips) or exposed (screws driven through the panel face); the steel gauge and metallic coating (e.g. Galvalume) and the paint/finish warranty (a PVDF/Kynar finish resists fade far longer than SMP); for standing seam, whether floating clips are sized for thermal movement so panels can expand in Houston heat; for exposed-fastener, the gasket-washer material and the re-torque/replacement schedule (the gaskets at each screw are the known failure point); and how many metal roofs like this one the contractor has installed locally, since metal is a distinct trade from shingles. [Source: NRCA Roofing Manual metal panel and metal shingle chapters; Metal Construction Association residential metal roofing guidance; Galvalume Sheet Producers Council literature; manufacturer install specifications — McElroy Metal, Decra Stone-Coated Steel; ASTM A792 standard for steel sheet aluminum-zinc alloy coated]