Definition - What does Metal Flashing mean?
Metal flashing refers to the protection of a metal surface against corrosion by inhibiting its contact with water by the use of impervious materials.
Corrosionpedia explains Metal Flashing
Metal flashing is performed by layering a sacrificial anode based thin sheet on the metal to be protected. Common flashing materials are zinc, aluminum and stainless steel. The sheet is adhered to the base metal to prevent the passage of water (such as rain) to the metal. Metal flashing is often used in construction of roofs, vent pipes and other outdoor surfaces.