What is a function of flashing in roofing systems?

Flashing serves a crucial role in roofing systems by preventing water intrusion at intersections and penetrations in the roof, such as chimneys, vents, and skylights. One of its important functions is to isolate dissimilar metals. When different metals come into contact, there can be a galvanic reaction that may lead to corrosion. Flashing materials are typically chosen to prevent this reaction, thus extending the lifespan of both the roofing materials and any metal components.

While enhancing water drainage is a significant aspect of flashing, it primarily functions to direct water away from critical areas, rather than acting solely as a drainage enhancement. Additionally, it does not contribute to insulation efficiency or provide structural support. The main purpose lies in keeping moisture out and protecting against potential corrosion threats from the interaction of varied metals.