How Important is Wall Flashing?
Take a look for yourself.
I spotted these water and dirt stains on the face of a brick wall. The water and dirt stains are directly under the joint of the metal wall cap.
The lap on the metal cap is too short to prevent surface runoff from rainfall on top of the wall from draining under the cap and onto the top of the brick and into the wall where it emerges from a mortar joint.
If a flexible flashing had been placed under the metal cap, surface runoff would not have infiltrated the wall, causing the staining we see.
A longer lap would also have helped to keep surface runoff from getting under the cap and into the wall.