What is the function of counter flashing in roofing?

Counter flashing serves a crucial role in roofing systems by covering and protecting the underlying flashing installed at intersections of walls and roofs, particularly at chimneys and other vertical elements. This additional layer of protection is essential for directing water away from these vulnerable areas, thus preventing leakage that could lead to significant damage over time.

By integrating counter flashing with the primary flashing, it creates a more robust barrier against water infiltration. This layering helps to ensure that any water which might run down the wall does not seep behind the primary flashing, as it is effectively channeled away from the structure.

In contrast to its purpose, sealing edges, providing support, or simply enhancing aesthetics are not primary functions of counter flashing. While those aspects have their importance in roofing, the main intent of counter flashing is clearly to safeguard the underlying components, thereby enhancing the roof's overall durability and longevity.