Flashing in the context of construction refers to thin pieces of impervious material installed to prevent the passage of water into a structure from a joint or as part of a weather resistant barrier system. Typically, flashing materials may include metals such as aluminum or galvanized steel, but can also be made from plastic, rubber or other materials. The primary purpose of flashing is to direct water away from critical areas of the building envelope, such as windows, doors, and roof joints, where water penetration could potentially occur. Proper installation of flashing is critical in maintaining the integrity of a building’s moisture barrier, and ensuring that water is effectively channeled away from vulnerable areas to prevent damage such as rot, mold growth, and structural deterioration. Flashing is an essential component in roofing systems, around chimneys, at deck connections, and in many other exterior locations where material transitions occur or where water runoff needs to be managed.