Which of the following is NOT typically considered a roof accessory?

Vents, drains, and flashing are all essential components typically classified as roof accessories. Vents facilitate ventilation, allowing moisture and heat to escape from the roofing system, which helps to maintain its longevity and performance. Drains are crucial for managing water runoff, ensuring that water does not accumulate on the roof surface and lead to water damage. Flashing acts as a protective element that directs water away from vulnerable areas, such as joints and intersections, preventing leaks.

Insulation, while important for the overall energy efficiency and thermal performance of a building, is primarily considered part of the roofing assembly rather than an accessory. It is integrated into the system to enhance energy conservation and comfort within the building rather than functioning as a surface accessory that manages water or air flow. Therefore, insulation does not fall into the same category as the other elements listed, which serve specific, functionally distinct roles on the roof.