What may happen if the nails used in bottom cap flashing rust?

When nails used in bottom cap flashing rust, it can lead to significant issues, primarily because rusting compromises the integrity of the flashing system. As the nails corrode, their structural strength diminishes, which can compromise their ability to hold the flashing securely in place. This insecure fastening can result in gaps or breaks in the flashing, allowing water to seep behind the flashing. Once water infiltrates these gaps, it can penetrate through to the framing of the structure, potentially causing water damage, mold growth, and deterioration of the building materials over time. This scenario emphasizes the importance of using corrosion-resistant materials for flashing components and fasteners to ensure a long-lasting and effective roofing system.