Flashing

Flashing is a thin, formed metal profile (typically galvanized steel, aluminum, or copper) that directs water away from vulnerable joints and transitions in the building envelope. Flashings are installed below windows, at the top of the foundation wall, at wall-to-roof junctions, around chimneys, at eaves, and at any other point where different building surfaces meet and water could penetrate.

Properly designed and installed flashing is one of the most critical elements of a building's weather protection system. The flashing creates a physical barrier that catches water and directs it outward before it can enter the structure. Without flashing — or with improperly installed flashing — water penetrates through joints and transitions, causing hidden moisture damage that can go undetected for years.

Common flashing problems include improper slope (flashing should always direct water away from the structure), inadequate overlap at joints, incompatible metals causing galvanic corrosion, and sealant failure. Flashing that has been painted over, caulked over, or modified by subsequent work may no longer function as intended. Wind-driven rain can also penetrate poorly detailed flashing during storms.

Flashing condition should be verified during annual exterior inspections. Look for rust, gaps, lifted edges, and any signs of water staining on the wall surface below a flashing location. If flashing is damaged or missing, repair should be prioritized, as the resulting moisture damage can quickly escalate. Flashing repair and replacement is typically performed by a roofer or sheet metal specialist.