That portion of the flashing built into a vertical surface to prevent the flow of water behind the base flashing. The cap flashing overlaps and caps off the top of the base flashing. French (Chapeau solin)

(1) Connecting devices that seal membrane joints at walls, expansion joints, drains, gravel stops, and other places where the membrane is interrupted. Cap Flashing shields the exposed edges and joints of the base flashing; (2) Usually composed of metal, used to cover or shield the upper edges of the membrane base flashing, wall flashing or primary flashing. See FLASHING and COPING.

Flashing on a vertical surface to prevent the flow of water from getting behind the base flashing. The cap flashing overlaps the base flashing. This flashing (AKA counter flashing) is generally not changed in a reroofing job.