Valley detailing on exposed fastener metal roofs involves carefully managing how two roof planes meet to prevent leaks and ensure durability. In woven valleys, strips of metal are alternately overlapped from each roof slope, creating a visually appealing weave pattern while directing water efficiently. Closed-cut valleys involve a metal piece laid under one slope and over the other, with a seam that is often sealed with a compatible, flexible sealant. Open metal valleys feature a separate metal channel installed in the valley, with roofing panels butted up tight on each side. These methods help control water flow, but due to the nature of exposed fasteners, valleys require precise installation to avoid water infiltration, fastener backout, or panel misalignment over time.
To check valley integrity safely yourself, start by inspecting from a ladder if comfortable—look for any loose or missing fasteners, warped panels, or signs of rust around the valley metal or fasteners. Run your hand gently along seams and overlaps for gaps or deteriorated sealant. Avoid walking directly on the valley to prevent damage. If you notice any cracking, lifting, or persistent moisture stains inside your attic during or after rain, it’s time to call a professional roofer. When consulting a contractor, ask how they ensure fastener integrity around valleys and what sealants or underlayment products they use to maintain long-term water tightness. Also, clarify their approach to metal compatibility to prevent corrosion between dissimilar metals, which can void warranties if not handled properly.