What does the crimped section in valley metal help to control?

The crimped section in valley metal is specifically designed to control crosswash. Crosswash occurs when water runs off the roof surface and can flow into areas where it may not be desired, potentially leading to issues like water pooling or erosion in valleys. By incorporating crimping into the valley metal, it enhances the ability of the metal to channel water efficiently, thus directing it away from critical areas and reducing the risk of water intrusion.

This addition also helps to prevent debris accumulation and assists in guiding water down the valley in a controlled manner. Properly managing crosswash is essential for maintaining the integrity of the roof and preventing water damage, particularly in valleys where water naturally collects.