What principle does flashing operate on to prevent water penetration?

Flashing operates primarily on the principle of utilizing gravity to direct water away from vulnerable areas of a building, such as joints, seams, and penetrations in the roof or wall. By positioning flashing in a way that encourages water to flow away from these critical areas, it effectively prevents water penetration and potential damage.

This strategy recognizes the natural movement of water and employs materials shaped and installed to divert any rain or moisture runoff away from walls, windows, and doors, thereby reducing the risk of leaks and water intrusion. Effective design and correct installation of flashing are crucial in managing water flow, ensuring that it always moves to a designated drainage route, rather than accumulating where it could lead to structural issues or damage.