Which option best describes the edge-related failure patterns in roofing systems?

• A. Flow concentration at corners.
• B. Puncture resistance only.
• C. Edge maintenance reduces failures.
• D. Flow separation, turbulence, and pressure amplification.

Answer: (D)

Edge-related failures come from how wind-driven air behaves at roof boundaries. When air flows around edges like parapets, eaves, and flashing, the boundary layer can detach at sharp edges or discontinuities. This flow separation creates swirling eddies and turbulence, which disrupts the normal pressure pattern and can produce local suction that magnifies uplift forces on the edge and along flashings. Those intensified pressures concentrate on the edge details, driving failures such as flashing peeling away, seams opening, or membranes tearing at fasteners. The combination of flow separation, turbulence, and pressure amplification best explains why edges fail, as opposed to focusing only on puncture resistance or a simple concentration of flow at corners. Regular maintenance helps, but it doesn’t describe the underlying failure mechanism.