Roof flashing is a critical weatherproofing component installed at transitions, penetrations, and intersections on a roof to direct water away from vulnerable areas. When flashing is missing, improperly installed, or deteriorated, water can penetrate the roof system and cause damage to sheathing, framing, insulation, and interior finishes. Missing roof flashing is one of the most common defects identified during home inspections, and it is a leading cause of roof leaks that may go undetected for months or years before visible damage appears inside the home. Flashing is typically made from galvanized steel, aluminum, copper, or lead and is installed at roof-to-wall junctions, valleys, chimneys, plumbing vents, skylights, and dormer walls. Each of these locations requires specific flashing techniques and materials to prevent water intrusion. When flashing is absent, water follows gravity and capillary action to find the path of least resistance into the building envelope. Understanding where flashing is needed and recognizing when it is missing empowers homeowners, buyers, and inspectors to identify and address this common but preventable source of water damage.