The answer to 'best flashing' is that the best flashing for a roof is typically metal flashing. Metal flashing, such as aluminum or galvanized steel, is durable, weather-resistant, and can effectively seal the joints and edges of a roof to prevent leaks. It is a crucial component of a well-designed and long-lasting roof system.
Metal flashing is often used around chimneys, skylights, dormers, and other roof penetrations to create a watertight seal. It can also be used to protect the edges of the roof, such as at the eaves and rakes, to prevent water intrusion. Properly installed metal flashing can significantly extend the lifespan of a roof and prevent costly water damage to the home.