Windows and doors interrupt a wall’s water protection layer creating vulnerable spots for leakage. Properly installed flashing is critical and often required by code to stop water intrusion around doors and windows. Pan flashing is an element installed at the sills of windows and doors, the location most vulnerable to water intrusion. It has to integrate with jamb flashing and overlap the wall water barrier below to collect and direct any water that may leak through or around the opening back out to the exterior.