The key to good flashing? Tiny end curbs.
To make sure the flashing works, the ends of the flashing at each far end of the fascia board should be turned up, making a tiny curb. This forces the water to flow off the front of the flashing across the face of the fascia.
Without these tiny curbs, the water can roll under the end of the flashing, especially in a fierce wind-driven rainstorm. This expert detailing is often not done by rookies or by people who haven’t got a grasp of what’s going on.
Furthermore, because of capillary attraction, the end of the flashing that folds down over the front of the fascia board should have a space between the flashing and the fascia board. The downturned edge of the flashing actually should kick out away from the fascia board so the water forms into droplets that fall to the ground.
If the flashing is tight against the face of the fascia board, the capillary attraction of the water can actually pull the water uphill under the flashing and into the back of the fascia board. Never underestimate the power of capillary attraction: It has rotted out many a home.