Which term describes the portion of flashing attached to a vertical surface to prevent water from migrating behind the base flashing?

• A. Base flashing
• B. Blow-off
• C. Cap flashing
• D. Certificate of Compliance

Answer: (C)

Cap flashing is the part that is fastened to the vertical surface and overlaps the base flashing to stop water from migrating behind it. By securing to the wall, cap flashing creates a barrier that directs water away from the joint where the roof meets the wall, preventing infiltration behind the base flashing. The base flashing is the lower piece at the joint, while the other terms don’t describe this vertical-covering component.