When preparing to install the main roof, what should be used to flash valleys?

When installing the main roof, flashing valleys with a 36" wide strip is considered optimal due to its ability to effectively manage water runoff and direct it away from the vulnerable areas where two roof planes meet. Valley flashing is crucial because it protects these intersections from water intrusion, which could lead to leaks and subsequent damage to the roofing structure and interior spaces.

A 36" strip provides enough coverage to extend adequately across the valley and overlap with adjacent roofing materials for a secure fit, reducing the likelihood of water pooling or seeping beneath the roofing layers. This width strikes a balance between being wide enough to protect the valley and manageable enough to install without excessive weight or complications.

Using wider or narrower strips may impact the effectiveness of the flashing. A wider strip could add unnecessary weight and complexity, while a narrower option might not cover the valley adequately, posing a risk for water penetration. Therefore, the selection of a 36" wide strip is based on practical application, ensuring that the roof is protected while maintaining structural and aesthetic integrity.